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Full text of "2009 Edition Log Interpretation Charts"

Schlumberger 







Log 

Interpretation 

Charts 







2009 Edition 











Intro < ► Contents 



Schlumberger 

225 Schlumberger Drive 

Sugar Land, Texas 77478 

www.slb.com 

© 2009 Schlumberger. All rights reserved. 

No part of this book may be reproduced, stored 
in a retrieval system, or transcribed in any 
form or by any means, electronic or mechanical, 
including photocopying and recording, without 
the prior written permission of the publisher. 
While the information presented herein is 
believed to be accurate, it is provided "as is" 
without express or implied warranty. 

Specifications are current at the time of printing. 

09-FE-0058 



An asterisk (*) is used throughout this document to 
denote a mark of Schlumberger. 



Intro < ► Contents 



Intro < ► Contents 



Contents 



Schlumberger 

Contents 



Foreword xi 

General 

Symbols Used in Log Interpretation Gen-1 1 

Estimation of Formation Temperature with Depth Gen-2 3 

Estimation of R in f and R mc Gen-3 4 

Equivalent NaCl Salinity of Salts Gen-4 5 

Concentration of NaCl Solutions Gen-5 6 

Resistivity of NaCl Water Solutions Gen-6 8 

Density of Water and Hydrogen Index of Water and Hydrocarbons Gen-7 9 

Density and Hydrogen Index of Natural Gas Gen-8 10 

Sound Velocity of Hydrocarbons Gen-9 11 

Gas Effect on Compressional Slowness Gen-9a 12 

Gas Effect on Acoustic Velocity Gen-9b 13 

Nuclear Magnetic Resonance Relaxation Times of Water Gen- 10 14 

Nuclear Magnetic Resonance Relaxation Times of Hydrocarbons Gen-lla 15 

Nuclear Magnetic Resonance Relaxation Times of Hydrocarbons Gen-llb 16 

Capture Cross Section of NaCl Water Solutions Gen-12 18 

Capture Cross Section of NaCl Water Solutions Gen-13 19 

Capture Cross Section of Hydrocarbons Gen- 14 21 

EPT* Propagation Time of NaCl Water Solutions Gen-15 22 

EPT Attenuation of NaCl Water Solutions Gen-16 23 

EPT Propagation Time -Attenuation Crossplot Gen-16a 24 

Gamma Ray 

Scintillation Gamma Ray — 3%- and 1%-in. Tools GR-1 25 

Scintillation Gamma Ray — 3%- and 1%-in. Tools GR-2 26 

Scintillation Gamma Ray— 3%- and 1%-in. Tools GR-3 27 

StimPulse* and E-Pulse* Gamma Ray Tools GR-6 28 

ImPulse* Gamma Ray— 4.75-in. Tool GR-7 29 

PowerPulse* and TeleScope* Gamma Ray— 6.75-in. Tools GR-9 30 

PowerPulse Gamma Ray— 8.25-in. Normal-Flow Tool GR-10 31 

PowerPulse Gamma Ray— 8.25-in. High-Flow Tool GR-11 32 

PowerPulse Gamma Ray— 9-in. Tool GR-12 33 

PowerPulse Gamma Ray — 9.5-in. Normal-Flow Tool GR-13 34 

PowerPulse Gamma Ray — 9.5-in. High-Flow Tool GR-14 35 

geoVISION675* GVR* Gamma Ray— 6.75-in. Tool GR-15 36 

RAB* Gamma Ray— 8.25-in. Tool GR-16 37 

arcVISION475* Gamma Ray— 4.75-in. Tool GR-19 38 



Intro 



Contents 



Schlumberger 



arcVISION675* Gamma Ray— 6.75-in. Tool GR-20 39 

arcVISION825* Gamma Ray— 8.25-in. Tool GR-21 40 

arcVISION900* Gamma Ray— 9-in. Tool GR-22 41 

arcVISION475 Gamma Ray— 4.75-in. Tool GR-23 42 

arcVISION675 Gamma Ray— 6.75-in. Tool GR-24 43 

arcVISION825 Gamma Ray— 8.25-in. Tool GR-25 44 

arcVISION900 Gamma Ray— 9-in. Tool GR-26 45 

EcoScope* Integrated LWD Gamma Ray— 6.75-in. Tool GR-27 46 

EcoScope Integrated LWD Gamma Ray— 6.75-in. Tool GR-28 47 

Spontaneous Potential 

Rweq Determination from Essp SP-1 49 

Rweq versus R w and Formation Temperature SP-2 50 

Rweq versus R w and Formation Temperature SP-3 51 

Bed Thickness Correction — Open Hole SP-4 53 

Bed Thickness Correction — Open Hole (Empirical) SP-5 54 

Bed Thickness Correction — Open Hole (Empirical) SP-6 55 

Density 

Porosity Effect on Photoelectric Cross Section Dens-1 56 

Apparent Log Density to True Bulk Density Dens-2 57 

Neutron 

Dual-Spacing Compensated Neutron Tool Charts 58 

Compensated Neutron Tool Neu-1 60 

Compensated Neutron Tool Neu-2 61 

Compensated Neutron Tool Neu-3 63 

Compensated Neutron Tool Neu-4 64 

Compensated Neutron Tool Neu-5 65 

Compensated Neutron Tool Neu-6 67 

Compensated Neutron Tool Neu-7 69 

Compensated Neutron Tool Neu-8 71 

Compensated Neutron Tool Neu-9 73 

APS* Accelerator Porosity Sonde Neu-10 75 

APS Accelerator Porosity Sonde Without Environmental Corrections Neu-11 76 

CDN* Compensated Density Neutron, adnVISION* Azimuthal Density 

Neutron, and EcoScope* Integrated LWD Tools Neu-30 78 

adnVISION475* Azimuthal Density Neutron— 4.75-in. Tool and 6-in. Borehole Neu-31 80 

adnVISION475 BIP Neutron— 4.75-in. Tool and 6-in. Borehole Neu-32 81 

adnVISION475 Azimuthal Density Neutron— 4.75-in. Tool and 8-in. Borehole Neu-33 82 

adnVISION475 BIP Neutron— 4.75-in. Tool and 8-in. Borehole Neu-34 83 



Intro 



Contents 



Schlumberger 



adnVISION675* Azimuthal Density Neutron— 6. 75-in. Tool and 8-in. Borehole Neu-35 . 

adnVISION675 BIP Neutron— 6. 75-in. Tool and 8-in. Borehole Neu-36 . 

adnVISION675 Azimuthal Density Neutron— 6. 75-in. Tool and 10-in. Borehole Neu-37 . 

adnVISION675 BIP Neutron— 6. 75-in. Tool and 10-in. Borehole Neu-38 . 

adnVISION825* Azimuthal Density Neutron— 8.25-in. Tool and 12.25-in. Borehole Neu-39 . 

CDN Compensated Density Neutron and adnVISION825s* Azimuthal Density Neutron — 

8-in. Tool and 12-in. Borehole Neu-40 . 

CDN Compensated Density Neutron and adnVISION825s Azimuthal Density Neutron — 

8-in. Tool and 14-in. Borehole Neu-41 . 

CDN Compensated Density Neutron and adnVISION825s Azimuthal Density Neutron — 

8-in. Tool and 16-in. Borehole Neu-42 . 

EcoScope* Integrated LWD BPHI Porosity— 6. 75-in. Tool and 8.5-in. Borehole Neu-43 . 

EcoScope Integrated LWD BPHI Porosity— 6. 75-in. Tool and 9.5-in. Borehole Neu-44 . 

EcoScope Integrated LWD TNPH Porosity— 6. 75-in. Tool and 8.5-in. Borehole Neu-45 . 

EcoScope Integrated LWD TNPH Porosity— 6. 75-in. Tool and 9.5-in. Borehole Neu-46 . 

EcoScope Integrated LWD— 6. 75-in. Tool Neu-47 . 

Nuclear Magnetic Resonance 

CMR* Tool CMR-1. . 



.84 
.85 
.86 
.87 



.91 



.94 



Resistivity Laterolog 

ARI* Azimuthal Resistivity Imager RL1-1 . . 

High-Resolution Azimuthal Laterolog Sonde (HALS) RL1-2 . . 

High-Resolution Azimuthal Laterolog Sonde (HALS) RL1-3 . . 

High-Resolution Azimuthal Laterolog Sonde (HALS) RL1-4 . . 

High-Resolution Azimuthal Laterolog Sonde (HALS) RL1-5 . . 

High-Resolution Azimuthal Laterolog Sonde (HALS) RL1-6 . . 

High-Resolution Azimuthal Laterolog Sonde (HALS) RL1-7 . . 

High-Resolution Azimuthal Laterolog Sonde (HALS) RL1-8 . . 

High-Resolution Azimuthal Laterolog Sonde (HALS) RL1-9 . . 

HRLA* High-Resolution Laterolog Array RL1-10. 



.101 
.102 
.103 
.104 
.105 
.106 
.107 
.108 
.109 
.110 



HRLA High-Resolution Laterolog Array RL1-11 Ill 

HRLA High-Resolution Laterolog Array RL1-12 112 

HRLA High-Resolution Laterolog Array RL1-13 113 

HRLA High-Resolution Laterolog Array RL1-14 114 

GeoSteering* Bit Resistivity— 6. 75-in. Tool RL1-20 115 

GeoSteeringarcVISION675 Resistivity— 6. 75-in. Tool RL1-21 116 

GeoSteering Bit Resistivity in Reaming Mode— 6. 75-in. Tool RL1-22 117 

geoVISION* Resistivity Sub— 6. 75-in. Tool RL1-23 118 

geoVISION Resistivity Sub— 8.25-in. Tool RL1-24 119 

GeoSteering Bit Resistivity— 6. 75-in. Tool RL1-25 120 



Intro 



Contents 



Schlumberger 



CHFR* Cased Hole Formation Resistivity Tool RL1-50 121 

CHFR Cased Hole Formation Resistivity Tool RL1-51 122 

CHFR Cased Hole Formation Resistivity Tool RL1-52 123 

Resistivity Induction 

AIT* Array Induction Imager Tool RInd-1 125 

AIT Array Induction Imager Tool 126 

Resistivity Electromagnetic 

arcVISION475 and ImPulse 4 3 /4-in. Array Resistivity Compensated Tools— 2 MHz REm-11 131 

arcVISION475 and ImPulse 4 3 /4-in. Array Resistivity Compensated Tools— 2 MHz REm-12 132 

arcVISION475 and ImPulse 4 3 /4-in. Array Resistivity Compensated Tools— 2 MHz REm-13 133 

arcVISION475 and ImPulse 4 3 /4-in. Array Resistivity Compensated Tools — 2 MHz REm-14 134 

arcVISION675 6 3 /4-in. Array Resistivity Compensated Tool— 400 kHz REm-15 135 

arcVISION675 6 3 /4-in. Array Resistivity Compensated Tool— 400 kHz REm-16 136 

arcVISION675 6 3 /4-in. Array Resistivity Compensated Tool— 400 kHz REm-17 137 

arcVISION675 6 3 /4-in. Array Resistivity Compensated Tool— 400 kHz REm-18 138 

arcVISION675 6 3 /4-in. Array Resistivity Compensated Tool— 2 MHz REm-19 139 

arcVISION675 6^-in. Array Resistivity Compensated Tool— 2 MHz REm-20 140 

arcVISION675 6%-in. Array Resistivity Compensated Tool— 2 MHz REm-21 141 

arcVISION675 6M-in. Array Resistivity Compensated Tool— 2 MHz REm-22 142 

arcVISION825 8K-in. Array Resistivity Compensated Tool— 400 kHz REm-23 143 

arcVISION825 8K-in. Array Resistivity Compensated Tool— 400 kHz REm-24 144 

arcVISION825 8%-in. Array Resistivity Compensated Tool— 400 kHz REm-25 145 

arcVISION825 8K-in. Array Resistivity Compensated Tool— 400 kHz REm-26 146 

arcVISION825 8K-in. Array Resistivity Compensated Tool— 2 MHz REm-27 147 

arcVISION825 8%-in. Array Resistivity Compensated Tool— 2 MHz REm-28 148 

arcVISION825 M-in. Array Resistivity Compensated Tool— 2 MHz REm-29 149 

arcVISION825 8K-in. Array Resistivity Compensated Tool— 2 MHz REm-30 150 

arcVISION900 9-in. Array Resistivity Compensated Tool— 400 kHz REm-31 151 

arcVISION900 9-in. Array Resistivity Compensated Tool— 400 kHz REm-32 152 

arcVISION900 9-in. Array Resistivity Compensated Tool— 400 kHz REm-33 153 

arcVISION900 9-in. Array Resistivity Compensated Tool— 400 kHz REm-34 154 

arcVISION900 9-in. Array Resistivity Compensated Tool— 2 MHz REm-35 155 

arcVISION900 9-in. Array Resistivity Compensated Tool— 2 MHz REm-36 156 

arcVISION900 9-in. Array Resistivity Compensated Tool— 2 MHz REm-37 157 



Intro 



Contents 



Schlumberger 



arcVISION900 9-in. Array Resistivity Compensated Tool— 2 MHz REm-38 158 

arcVISION675, arcVISION825, and arcVISION900 Array Resistivity Compensated Tools— 400 kHz REm-55 160 

arcVISION and ImPulse Array Resistivity Compensated Tools — 2 MHz REm-56 161 

arcVISION675 and ImPulse Array Resistivity Compensated Tools — 2 MHz and 16-in. Spacing REm-58 162 

arcVISION675 and ImPulse Array Resistivity Compensated Tools — 2 MHz and 22-in. Spacing REm-59 163 

arcVISION675 and ImPulse Array Resistivity Compensated Tools — 2 MHz and 28-in. Spacing REm-60 164 

arcVISION675 and ImPulse Array Resistivity Compensated Tools — 2 MHz and 34-in. Spacing REm-61 165 

arcVISION675 and ImPulse Array Resistivity Compensated Tools — 2 MHz and 40-in. Spacing REm-62 166 

arcVISION675 and ImPulse Array Resistivity Compensated Tools — 2 MHz with Dielectric Assumption REm-63 167 

Formation Resistivity 

Resistivity Galvanic Rt-1 168 

High-Resolution Azimuthal Laterlog Sonde (HALS) Rt-2 169 

High-Resolution Azimuthal Laterlog Sonde (HALS) Rt-3 170 

geoVISION675* Resistivity Rt-10 171 

geoVISION675 Resistivity Rt-11 172 

geoVISION675 Resistivity Rt-12 173 

geoVISION675 Resistivity Rt-13 174 

geoVISION825* 8^-in. Resistivity-at-the-Bit Tool Rt-14 175 

geoVISION825 8X-in. Resistivity-at-the-Bit Tool Rt-15 176 

geoVISION825 8X-in. Resistivity-at-the-Bit Tool Rt-16 177 

geoVISION825 8 l A-m. Resistivity-at-the-Bit Tool Rt-17 178 

arcVISION Array Resistivity Compensated Tool— 400 kHz Rt-31 179 

arcVISION and ImPulse Array Resistivity Compensated Tools— 2 MHz Rt-32 180 

arcVISION Array Resistivity Compensated Tool— 400 kHz Rt-33 181 

arcVISION and ImPulse Array Resistivity Compensated Tools— 2 MHz Rt-34 182 

arcVISION Array Resistivity Compensated Tool— 400 kHz Rt-35 183 

arcVISION and ImPulse Array Resistivity Compensated Tools— 2 MHz Rt-36 184 

arcVISION675 Array Resistivity Compensated Tool— 400 kHz Rt-37 185 

arcVISION675 and ImPulse Array Resistivity Compensated Tools— 2 MHz Rt-38 186 

arcVISION Array Resistivity Compensated Tool— 400 kHz Rt-39 187 

arcVISION and ImPulse Array Resistivity Compensated Tools— 2 MHz Rt-40 188 

arcVISION Array Resistivity Compensated Tool— 400 kHz in Horizontal Well Rt-41 190 

arcVISION and ImPulse Array Resistivity Compensated Tools — 2 MHz in Horizontal Well Rt-42 191 



Intro 



Contents 



Schlumberger 



Lithology 

Density and NGS* Natural Gamma Ray Spectrometry Tool Lith-1 193 

NGS Natural Gamma Ray Spectrometry Tool Lith-2 194 

Platform Express* Three-Detector Lithology Density Tool Lith-3 196 

Platform Express Three-Detector Lithology Density Tool Lith-4 197 

Density Tool Lith-5 198 

Density Tool Lith-6 200 

Environmentally Corrected Neutron Curves Lith-7 202 

Environmentally Corrected APS Curves Lith-8 204 

Bulk Density or Interval Transit Time and Apparent Total Porosity Lith-9 206 

Bulk Density or Interval Transit Time and Apparent Total Porosity Lith-10 207 

Density Tool Lith-11 209 

Density Tool Lith-12 210 

Porosity 

Sonic Tool Por-1 212 

Sonic Tool Por-2 213 

Density Tool Por-3 214 

APS Near-to-Array (APLC) and Near-to-Far (FPLC) Logs Por-4 216 

Thermal Neutron Tool Por-5 217 

Thermal Neutron Tool— CNT-D and CNT-S 2^-in. Tools Por-6 218 

adnVISION475 4.75-in. Azimuthal Density Neutron Tool Por-7 219 

adnVISION675 6.75-in. Azimuthal Density Neutron Tool Por-8 220 

adnVISION825 8.25-in. Azimuthal Density Neutron Tool Por-9 221 

EcoScope* 6.75-in. Integrated LWD Tool, BPHI Porosity Por-10 222 

EcoScope 6.75-in. Integrated LWD Tool, TNPH Porosity Por-lOa 223 

CNL* Compensated Neutron Log and Litho-Density* Tool (fresh water in invaded zone) Por-11 225 

CNL Compensated Neutron Log and Litho-Density Tool (salt water in invaded zone) Por-12 226 

APS and Litho-Density Tools Por-13 227 

APS and Litho-Density Tools (saltwater formation) Por-14 228 

adnVISION475 4.75-in. Azimuthal Density Neutron Tool Por-15 229 

adnVISION675 6.75-in. Azimuthal Density Neutron Tool Por-16 230 

adnVISION825 8.25-in. Azimuthal Density Neutron Tool Por-17 231 

EcoScope 6.75-in. Integrated LWD Tool Por-18 232 

EcoScope 6.75-in. Integrated LWD Tool Por-19 233 

Sonic and Thermal Neutron Crossplot Por-20 235 

Sonic and Thermal Neutron Crossplot Por-21 236 

Density and Sonic Crossplot Por-22 238 

Density and Sonic Crossplot Por-23 239 

Density and Neutron Tool Por-24 241 



Intro 



Contents 



Schlumberger 



Density and APS Epithermal Neutron Tool Por-25. 

Density, Neutron, and R xo Logs Por-26. 

Hydrocarbon Density Estimation Por-27. 



Saturation 

Porosity Versus Formation Resistivity Factor SatOH-1. 

Spherical and Fracture Porosity SatOH-2. 

Saturation Determination SatOH-3. 

Saturation Determination SatOH-4. 

Graphical Determination of Sw from Swt and Swb SatOH-5. 

Porosity and Gas Saturation in Empty Hole SatOH-6. 

EPT Propagation Time SatOH-7. 

EPT Attenuation SatOH-8. 

Capture Cross Section Tool SatCH-1. 

Capture Cross Section Tool SatCH-2. 



.243 
.245 
.246 

.247 
.248 
.250 
.252 
.253 
.254 
.255 
.256 
.258 
.260 



RST* Reservoir Saturation Tool— 1.6875 in. and 2.5 in 261 

RST Reservoir Saturation Tool— 1.6875 in. and 2.5 in. in 6.125-in. Borehole SatCH-3 262 

RST Reservoir Saturation Tool— 1.6875 in. and 2.5 in. in 9.875-in. Borehole SatCH-4 263 

RST Reservoir Saturation Tool— 1.6875 in. and 2.5 in. in 8.125-in. Borehole with 4.5-in. Casing at 11.6 lbm/ft .... SatCH-5 264 

RST Reservoir Saturation Tool— 1.6875 in. and 2.5 in. in 7.875-in. Borehole with 5.5-in. Casing at 17 lbm/ft SatCH-6 265 

RST Reservoir Saturation Tool— 1.6875 in. and 2.5 in. in 8.5-in. Borehole with 7-in. Casing at 29 lbm/ft SatCH-7 266 

RST Reservoir Saturation Tool— 1.6875 in. and 2.5 in. in 9.875-in. Borehole with 7-in. Casing at 29 lbm/ft SatCH-8 267 

Permeability 

Permeability from Porosity and Water Saturation Perm-1 269 

Permeability from Porosity and Water Saturation Perm-2 270 

Fluid Mobility Effect on Stoneley Slowness Perm-3 271 



Cement Evaluation 

Cement Bond Log — Casing Strength. 



.Cem-1 274 



Appendixes 

Appendix A 



Appendix B 
Appendix C 
Appendix D 
Appendix E 
Appendix F 
Appendix G 
Appendix H 



Linear Grid 275 

Log-Linear Grid 276 

Water Saturation Grid for Resistivity Versus Porosity 277 

Logging Tool Response in Sedimentary Minerals 279 

Acoustic Characteristics of Common Formations and Fluids 281 

Conversions 282 

Symbols 285 

Subscripts 287 

Unit Abbreviations 290 

References 292 



Intro 



Intro < ► Contents 



Foreword 



Foreword 



Schlumberger 



This edition of the Schlumberger "chartbook" presents several 
innovations. 

First, the charts were developed to achieve two purposes: 

■ Correct raw measurements to account for environmental effects 

Early downhole measurements were performed in rather uniform 
conditions (vertical wells drilled through quasi-horizontal thick 
beds, muds made of water with a narrow selection of additives, 
and limited range of hole sizes), but today wells can be highly 
deviated or horizontal, mud contents are diverse, and hole sizes 
range from 2 to 40 in. Environmental effects may be large. In 
addition, they compound. It is essential to correct for these effects 
before the measurements are used. 

■ Use environmentally corrected measurements for interpretation 



Charts related to measurements that are no longer performed 
are not included in this chartbook. However, because many oil and 
gas companies use logs acquired years or even decades ago, the 
second chartbook, Historical Log Interpretation, Charts, contains 
these old charts. 

Why publish charts on paper in our electronic age? It is true that 
software may be more effective than pencil to derive results. Even 
more so, this chartbook cannot cope with the complex well situations 
that are encountered. Using software is the only way to proceed. 

Thus, the chartbook has two primary functions: 

■ Training 

The chartbook is essential for educating junior petrophysicists 
about the different effects on the measurements. In the interpre- 
tation process, the chartbook unveils the relationships between 
the different parameters. 

■ Sensitivity analysis 

A chart gives the user a graphical idea of the sensitivity of an out- 
put to the various inputs (see Chart Gen-1). The visual presenta- 
tion is helpful for determining if an input parameter is critical. 
The user can then focus on the most sensitive inputs. 



Back to Contents 



-4 ► 



Back to Contents 



General 



Symbols Used in Log Interpretation 



Schlumberger 



Gen-1 

(former Gen-3) 



] Resistivity of the zone 
O Resistivity of the water in the zone 
/\ Water saturation in the zone 




Mud 



Adjacent bed 



Adjacent bed 



Invasion diameters) 






© Schlumberger 



Purpose 

This diagram presents the symbols and their descriptions and rela- 
tions as used in the charts. See Appendixes D and E for identifica- 
tion of the symbols. 



Description 

The wellbore is shown traversing adjacent beds above and below the 
zone of interest. The symbols and descriptions provide a graphical 
representation of the location of the various symbols within the well- 
bore and formations. 



< ► 



Back to Contents 



General 



Schlumberger 



Estimation of Formation Temperature with Depth 




Purpose 

This chart has a twofold purpose. First, a geothermal gradient can 
be assumed by entering the depth and a recorded temperature at 
that depth. Second, for an assumed geothermal gradient, if the tem- 
perature is known at one depth in the well, the temperature at 
another depth in the well can be determined. 

Description 

Depth is on the y-axis and has the shallowest at the top and the 
deepest at the bottom. Both feet and meters are used, on the left 
and right axes, respectively. Temperature is plotted on the x-axis, 
with Fahrenheit on the bottom and Celsius on the top of the chart. 
The annual mean surface temperature is also presented in 
Fahrenheit and Celsius. 



Example 

Given: 

Find: 
Answer: 



Bottomhole depth = 11,000 ft and bottomhole tempera- 
ture = 200°F (annual mean surface temperature = 80°F). 

Temperature at 8,000 ft. 

The intersection of 11,000 ft on the y-axis and 200°F 
on the x-axis is a geothermal gradient of approximately 
1.1°F/100 ft (Point A on the chart). 

Move upward along an imaginary line parallel to the con- 
structed gradient lines until the depth line for 8,000 ft is 
intersected. This is Point B, for which the temperature 
on the x-axis is approximately 167°F. 



Back to Contents 



General 



Estimation of Formation Temperature with Depth 



Schlumberger 



Gen -2 

(former Gen-6) 



Temperature gradient conversions: 1°F/100ft= 1.823°C/100m 

rC/100m=0.5486°F/100ft 

Annual mean 

surface temperature x ,.„, 
I r Temperature (°C) 

27 50 75 100 125 150 175 


16 ^25 






50 








75 






100 








125 






150 








175 


: 1 

i 2 
L 3 

: 4 

Depth 
(thousands 
: p. of meters) 


5 

10 

Depth 
(thousands 15 
of feet) 

20 
25 






















































































































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s, 




B^ 


\ 




V 


v 
















































\ 






^S 


s 




*v 














































0.6 0.8 


1.0 s 


V 1.2 


1.4 1.6°F/100fl 










Geothermal aradient 






























\ 




\ 




\ 


\ 










\ 


N. 






































\ 


v 


\ 


\ 




\ 


A 


\ 


N 








\ 






































\ 






V 




^ 




< 


s 








\ 


Ss 


































1.09 




1.46 


1.82 


2.19 


2.55 


2.92°C/100m 


































\ 












N 










V 


s 






































\ 












\ 












V 


t 


































> 


\ 












> 


^ 










V 


V 


































\ 














s 


V 












V 


































\ 














s 


k. 














• 


i 6 
: 7 














































N 


N 














































\ 
















\ 












































\ 


\ 


















v 










































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s 
















> 


s 










































\ 


















N 


s 




i 8 








































\ 


















N 










































1 


\ 




























































\ 


k 




























































\ 


\ 




























































\ 

\ 
















8 


3 


100 








150 








200 








250 








300 








350 






6 

An 
su 

© Schlumberger 


3 100 150 200 250 300 350 

, Temperature (°F) 
nual mean 

rface temperature 






< ► 



Back to Contents 



General 



Estimation of R m f and R mc 

Fluid Properties 



Schlumberger 



Gen -3 

(former Gen-7) 




Purpose 

Direct measurements of nitrate and mudcake samples are preferred. 
When these are not available, the mud filtrate resistivity (Rmf) and 
mudcake resistivity (R m c) can be estimated with the following 
methods. 

Description 

Method 1: Lowe and Dunlap 

For freshwater muds with measured values of mud resistivity (R m ) 
between 0.1 and 2.0 ohm-m at 75°F [24°C] and measured values of 
mud density (p m ) (also called mud weight) in pounds per gallon: 



log 



R 



mf 



V R my 



: 0.396- (0.0475 xp m ). 



Method 2: Overton and Upson 

For drilling muds with measured values of R m between 0. 1 and 
10.0 ohm-m at 75°F [24°C] and the coefficient of mud (K m ) given 
as a function of mud weight from the table: 



Mud Weight 



Ibm/gal 


kg/m 3 


Km 


10 


1,200 


0.847 


11 


1,320 


0.708 


12 


1,440 


0.584 


13 


1,560 


0.488 


14 


1,680 


0.412 


16 


1,920 


0.380 


18 


2,160 


0.350 



Example 

Given: 

Find: 
Answer: 



R m = 3.5 ohm-m at 75°F and mud weight = 12 lbm/gal 
[1,440 kg/m 3 ]. 

Estimated values of R in f and R mc . 

From the table, K m = 0.584. 

Rmt = (0.584) (3.5) 107 = 2.23 ohm-m at 75°F. 

R mc = 0.69(2.23) (3.5/2.23) 2 65 = 5.07 ohm-m at 75°F. 



R mf = K m (R m ) 

R mc = 0.69(R mf ) 



1.07 



/ n2.65 



v R mfy 



Back to Contents 



General 



Equivalent NaCI Salinity of Salts 



Schlumberger 



Gen -4 

(former Gen-8) 



2.0 


A 

Li(2.5) f OH 5.5) f 


2.0 


1.5 

1.0 
Multiplier 

0.5 



-0.5 


I T-— 










































1.0 



NH 


,U- 


ir 








„Mq 






























































































































































































































A 








Ca 






























































































nn- 










































-Na; 


mrl 


m 


1 ( 


i) -- 


















































K 


















































































!^c Ca 














" so, 






















■-^co 3 














- NCMO^)' 








































- Br(0.44) f 






HC( 


v 




















Qfl 


























































i (n ">Qit 




















urn 


— 1 (U. 




































3 






































































































































































































































































































Mg\ 




















































1 

© Schlumberger 


20 50 100 200 500 1,000 2,000 5,000 10,000 20,000 50,000 100,000 300,000 

Total solids concentration (ppm or mg/kg) 

' Multipliers that do not vary appreciably for low concentrations 
(less than about 10,000 ppml are shown at the left margin of the chart 




Purpose Example 

This chart is used to approximate the parts-per-million (ppm) con- Given: 

centration of a sodium chloride (NaCI) solution for which the total 

solids concentration of the solution is known. Once the equivalent 

concentration of the solution is known, the resistivity of the solution 

for a given temperature can be estimated with Chart Gen-6. p m( j. 

Description Answer: 

The x-axis of the semilog chart is scaled in total solids concentration 
and the y-axis is the weighting multiplier. The curve set represents 
the various multipliers for the solids typically in formation water. 



Formation water sample with solids concentrations 
of calcium (Ca) = 460 ppm, sulfate (SO4) = 1,400 ppm, 
and Na plus CI = 19,000 ppm. Total solids concentration 
= 460 + 1,400 + 19,000 = 20,860 ppm. 

Equivalent NaCI solution in ppm. 

Enter the x-axis at 20,860 ppm and read the multiplier 
value for each of the solids curves from the y-axis: 
Ca = 0.81, S0 4 = 0.45, and NaCI = 1.0. Multiply each 
concentration by its multiplier: 

(460 x 0.81) + (1,400 x 0.45) + (19,000 x 1.0) = 20,000 ppm. 



Back to Contents 



General 



Concentration of NaCI Solutions 



Schlumberger 



Gen -5 






Concentrations of NaCI Solutions 




Temperature Gradient 


Oil Gravity 




Density of NaCI 


Conversion 






g/Lat ppm grains/gal solution at 




Specific 




77°F at77°F 77°F[25°C] 


°F/100ft °C/100ft 


°API gravity (sg) at 60°F 




0.15 150 _, 


1.00 


2.0 


0.60 




0.2 . 


200 . 


. 10 

. 12.5 
. 15 




1.9 : 


. 3.5 


100 : 


. 0.62 




0.3 . 


300 . 


. 20 








90 : 


. 0.64 




0.4 1 


. 400 i 


. 25 




1.8 : 






. 0.66 




0.5 i 


'. 500 : 


. 30 








so : 


. 0.68 




0.6 : 


i 600 : 






1.7 : 














. 40 








70 1 


. 0.70 




0.8 - 


. 800 ~ 


. 50 






. 3.0 




















. 0.72 




1.0 : 


: 1,000 : 


. 60 




1.6 : 














. 70 








60 : 


. 0.74 








. 80 














1.5 : 


'. 1,500 J 


-90 




1.5 : 






. 0.76 








- 100 








50 : 


. 0.78 




2 1 


L 2,000 1 


- 125 










. 0.80 




3 . 


. 3,000 . 


. 150 
. 200 




1.4 : 


. 2.5 


40 : 


. 0.82 
. 0.84 




4 i 


'. 4,000 1 


. 250 




1.3 : 


. 


30 : 


. 0.86 
. 0.88 




5 1 


'. 5,000 1 


.300 














6 . 


. 6,000 . 


. 400 


. 1.005 


1.2 : 




20 : 


. 0.90 
. 0.92 




8 i 


'. 8,000 I 


. 500 








. 0.94 
. 0.96 




10 1 


L 10,000 I 


.600 




1.1 : 


. 2.0 




- 0.98 








. 700 








10 : 


. 1.00 








800 




. 


■ 




. 1.02 




15 : 


1 15,000 : 


. 900 




1.0 1 






. 1.04 




20 j 


L 20,000 1 


- 1,000 
. 1,250 


. 1.01 






o : 


. 1.06 
C 1.08 








- 1,500 




0.9 : 








30 . 


. 30,000 . 










141 5 
°API - 131 5 








. 2,000 


. 1.02 




. 1.5 


r\i \ — 1 Jl ,J 

sgat60°F 




40 . 


1 40,000 J 


. 2,500 




o.8 : 








50 : 




. 3,000 


. 1.03 










60 . 


i 60,000 : 


. 4,000 


. 1.04 


0.7 : 








80 1 


- 80,000 '. 


. 5,000 


. 1.05 










100 : 


'- 100,000 " 


. 6,000 


. 1.06 
. 1.07 


o.6 : 








125 . 




. 7,000 


. 1.08 




. 1.0 

.822°C/100m 
.5488°F/100ft 






150 . 

200 . 
250 . 


: 150,000 : 

: 200,000 : 


. 8,000 

- 9,000 

- 10,000 
. 12,500 
. 15,000 


. 1.09 
. 1.10 

. 1.12 
. 1.14 
. 1.16 


1°F/100ft= 1 

1°C/100m = C 






300 . 


- 250,000 . 


. 17,500 


. 1.18 
. 1.20 






© Schlumberger 











Back to Contents 



General 



Schlumberger 



Resistivity of NaCI Water Solutions 



Purpose 

This chart has a twofold purpose. The first is to determine the resis- 
tivity of an equivalent NaCI concentration (from Chart Gen-4) at a 
specific temperature. The second is to provide a transition of resis- 
tivity at a specific temperature to another temperature. The solution 
resistivity value and temperature at which the value was determined 
are used to approximate the NaCI ppm concentration. 

Description 

The two-cycle log scale on the x-axis presents two temperature 
scales for Fahrenheit and Celsius. Resistivity values are on the left 
four-cycle log scale y-axis. The NaCI concentration in ppm and 
grains/gal at 75°F [24°C] is on the right y-axis. The conversion 
approximation equation for the temperature (T) effect on the 
resistivity (R) value at the top of the chart is valid only for the 
temperature range of 68° to 212°F [20° to 100°C]. 

Example One 

Given: NaCI equivalent concentration = 20,000 ppm. 
Temperature of concentration = 75°F 

Find: Resistivity of the solution. 

Answer: Enter the ppm concentration on the y-axis and the tem- 
perature on the x-axis to locate their point of intersec- 
tion on the chart. The value of this point on the left 
y-axis is 0.3 ohm-m at 75°F. 



Example Two 

Given: Solution resistivity = 0.3 ohm-m at 75°F. 

Find: Solution resistivity at 200°F [93°C]. 

Answer 1: Enter 0.3 ohm-m and 75°F and find their intersection 

on the 20,000-ppm concentration line. Follow the line to 
the right to intersect the 200°F vertical line (interpolate 
between existing lines if necessary). The resistivity value 
for this point on the left y-axis is 0.115 ohm-m. 

Answer 2: Resistivity at 200°F = resistivity at 75°F x [(75 + 6.77)/ 
(200 + 6.77)] = 0.3 x (81.77/206.77) = 0.1186 ohm-m. 




< ► 



Back to Contents 



continued on next page 

7 



General 



Resistivity of NaCI Water Solutions 



Schlumberger 



Gen -6 

(former Gen-9) 




Conversion approximated by R 2 = R, [(T, + 6.77)/(T 2 + 6.77)]°F or R 2 = R, [(T, + 21.5)/(T 2 + 21.5)]°C 

m 




8 

6 
5 
4 

3 
2 

1 
0.8 

0.6 
0.5 

0.4 

Resistivity 

of solution 

(ohm-m) 

0.2 

0.1 
0.08 

0.06 
0.05 

0.04 
0.03 





























































































































































































































































































































^■sJ 1 "^. 






















g 

^^r- PPm 


■ains/gal 
at75°F 
































?0D 


10 

115 

E. 20 

_25 
_30 

_40 
_50 

1100 

I NaCI 
1150 concentration 

- onn (ppm ° r 
-200 grains/gal) 

_ 250 

_300 

_400 
_500 

11,000 

1 1,500 

L 2,000 
_ 2,500 
_ 3,000 

_ 4,000 
_ 5,000 

110,000 

1 15,000 
L 20,000 






*s^ 


































^ 
















% 
































^^ % 




















































_^ s — J uo 


















































JX °0q ^^ 


















































. ^>Lj j 






















































^*> s % ^--^. 


















































iL " Sn n — 


















































v w ^^^ 


^^^ "0 — , 














































^^\ 












^r- 


















































































































^< v '<On ^ 






































































Vs., '% ^ 
<0 0o \ 








*^J 














^^ 


^ ^> 














"^ 




























v fU °o 

^tm 4 '°°° 












































^ * s " s -oo ^ 
^^" i "- e .o 0o '*s s 












































"^">^. s ' ^fl/i. ^^ 




















































:^->. ' u °o r^ 




















































*S^ "Of) >^» 




















































^ ^^ lOn ^^ 




















































^, ,'% 


















































'*« - ■ te„ "^. 


















r^ 


























s^. ^^ 


^-;- '°0o ^ 


















' N s s ' — ■"^^— - 






















^^ ^nn \ 








































^-» "°0 




































^W: "■ /> *" — . 




























- ^»» 'OOn 


























====^^ 


■ ° N 


































0.02 
0.01 








































IN 






















































































■^, *-• <°0n "V 






































-3<w. 








s§: $ ^ 








































r 


JCn 








































































































„^S». ?o6° n °o 






















































































































































I3S~ ■ ■?"0/)n V 




















































Tr; s - 3f)n "li 


°F 5 
°C 1 


75 1C 
D 20 30 
i i 


125 
40 50 E 
i i 


1 
150 200 250 300 
70 80 90 100 120 140 16 



I 1 %, V. 

350 400 <1 
D 180 200 
i I 


© Schlumberger 


Temperature 





< ► 



Back to Contents 



General 



Schlumberger 



Density of Water and Hydrogen Index of Water and Hydrocarbons 



Gen -7 



Water 
density 
(g/cm 3 ) 



Water 



Temperature (°C) 

25 50 100 150 200 

.20 II J J L 




Hydrogen 
index 



40 100 



400 440 



Temperature (°F) 

Pressure 7,000 psi NaCI 

1,000 psi 

14.7 psi 



1.05 




Hydrogen Index of Salt Water 



1 no 












95 












nqn 












85 













50 100 150 200 

Salinity (kppm or g/kg) 



250 



Hydrocarbons 

Hydrogen Index of Live Hydrocarbons and Gas 



1.2 
1.0 














0.8 














Hydrogen 06 














index 

0.4 














0.2 






























© Schlumberger 



0.2 0.4 0.6 0.8 1.0 
Hydrocarbon density (g/cm 3 ) 



1.2 



Purpose 

These charts are for determination of the density (g/cm 3 ) and hydro- 
gen index of water for known values of temperature, pressure, and 
salinity of the water. From a known hydrocarbon density of oil, a 
determination of the hydrogen index of the oil can be obtained. 

Description: Density of Water 

To obtain the density of the water, enter the desired temperature (°F 
at the bottom x-axis or °C at the top) and intersect the pressure and 
salinity in the chart. From that point read the density on the y-axis. 



Example: Density of Water 

Given: Temperature = 200°F [93°C], pressure = 7,000 psi, and 
salinity = 250,000 ppm. 

Answer: Density of water = 1.15 g/cm 3 . 

Example: Hydrogen Index of Salt Water 

Given: Salinity of saltwater = 125,000 ppm. 

Answer: Hydrogen index = 0.95. 

Example: Hydrogen Index of Hydrocarbons 

Given: Oil density = 0.60 g/cm 3 . 

Answer: Hydrocarbon index = approximately 0.91. 



Back to Contents 



General 



Density and Hydrogen Index of Natural Gas 



Schlumberger 



Gen -8 




Gas 
density 
(g/cm 3 ) 



03 


Gas gravity = 0.6 
(Air = 1.0) 
















100^ 










/^ \W ^^^ 










^ inn . " 


n? 








0^.250^-^ 

^VSsoo^^ 

/^.350 










' Gas 










temperature 










(°R 


0.1 












n 













u 

n gas 

0.7 

_: 0.6 

_: 0.5 

_: 0.4 

_: 0.3 

_: 0.2 

_: o.i 

3 o 



2 4 6 

Gas pressure x 1,000 (psia) 



10 



Gas 
density 
(g/cm 3 ) 




Pressure 

17,500 
15,000 
12,500 

10,000 
7,500 

5,000 



2,500 



14.7 




© Schlumberger 



100 200 300 400 

Temperature (°F) 



Purpose 

This chart can be used to determine more than one characteristic 
of natural gas under different conditions. The characteristics are 
gas density (p g ), gas pressure, and hydrogen index (H gas ). 

Description 

For known values of gas density, pressure, and temperature, the value 
of Hgas can be determined. If only the gas pressure and temperature 
are known, then the gas density and Hgas can be determined. If the 
gas density and temperature are known, then the gas pressure and 
Hgas can be determined. 
10 



Example 

Given: Gas density = 0.2 g/cm 3 and temperature = 200°F. 

Find: Gas pressure and hydrogen index. 

Answer: Gas pressure = approximately 5,200 psi and Hg as = 0.44. 



Back to Contents 



General 



Sound Velocity of Hydrocarbons 



Schlumberger 



Gen -9 



5,000 



4,000 



Sound 3 000 
velocity 
(ft/s) 



2,000 



1,000 



Natural Gas 

Temperature (°C) 
100 150 





Sound 

slowness 

(Us/ft) 



50 100 150 200 250 300 

Temperature (°F) 



350 



© Schlumberger 



Purpose 

This chart is used to determine the sound velocity (ft/s) and sound 
slowness (jas/ft) of gas in the formation. These values are helpful in 
sonic and seismic interpretations. 



Description 

Enter the chart with the temperature (Celsius along the top x-axis 
and Fahrenheit along the bottom) to intersect the formation 
pore pressure. 



Back to Contents 



General 



Gas Effect on Compressional Slowness 



Schlumberger 

Gen-9a 




200 


Sandstorm 




At c 

(US/ft) 

100 
50 












. 110|is/ft 
. 90u.s/ft 
i 70 us/ft 




""-"N 










\ 










xl 






























— -v^ 
































C 

© Schlumberger 


20 40 60 80 100 
Liquid saturation (%) 
Wnnri's law (h = 5) Pnwnr law (f> = 3) 



Purpose 

This chart illustrates the effect that gas in the formation has on the 
slowness time of sound from the sonic tool to anticipate the slowness 
of a formation that contains gas and liquid. 



Description 

Enter the chart with the compressional slowness time (At c ) from the 
sonic log on the y-axis and the liquid saturation of the formation on 
the x-axis. The curves are used to determine the gas effect on the 
basis of which correlation (Wood's law or Power law) is applied. The 
slowing effect begins sooner for the Power law correlation. The 
Wood's law correlation slightly increases At c values as the formation 
liquid saturation increases whereas the Power law correlation 
decreases At c values from about 20% liquid saturation. 



12 



Back to Contents 



General 



Gas Effect on Acoustic Velocity 



Sandstone and Limestone 



Schlumberger 



Gen-9b 



Sandstone 



25 



20 



Velocity '^ 
(1,000 xft/s) 

10 









No gas 

Gas bearing 








^*"* > »^^ 








^ 


\^ 








^*^^ 










^ 



10 20 30 

Porosity (p. u.) 



40 



Limestone 



© Schlumberger 



25 



Velocity 
(1,000 xft/s) 













Mo gas 




■0*v li ^ 









Gas bearing 


20 


















15 
















\A 




in 


**■**& 












V?* 






5 








""^fl^- 










^ 


n 











10 20 30 

Porosity (p. u.) 



40 



Purpose 

This chart is used to determine porosity from the compressional 
wave or shear wave velocity (V p and V s , respectively). 



Description 

Enter V p or V s on the y-axis to intersect the appropriate curve. Read 
the porosity for the sandstone or limestone formation on the x-axis. 



< ► 



Back to Contents 



13 



General 



Schlumberger 



Nuclear Magnetic Resonance Relaxation Times of Water 



Gen-10 




Longitudinal (Bulk) Relaxation 
Time of Water 



Relaxation 
time (s) 



100 



10 



1.0 



0.1 



0.01 



































ll- 

































































































































































































































































































20 60 100 140 

Temperature (°C) 



180 



Transverse (Bulk and Diffusion) 
Relaxation Time of Water 



100 



Relaxation 
time (s) 



















































































10 












T 2 (TE 


= 0.2ms) = 


















































































1.0 


-■-.. 










T 2 (TE = 


0.32 ms) 








•» -. w 
























































""* •■. 










" — — 












"— -» 


^ w 








~ 


- - - 


^ 


m 










--... 


T 2 (TE 


= 1 ms 


) 
















— ^~- 


■ ^ _ — 






















""* ■■ . 














■> \ 






















n.oi 





















20 60 100 140 180 

Temperature (°C) 



D Schlumberger 



Purpose 

Longitudinal (Bulk) Relaxation Time of Pure Water 

This chart provides an approximation of the bulk relaxation time 

(Ti) of pure water depending on the temperature of the water. 

Transverse (Bulk and Diffusion) Relaxation Time of Water 
in the Formation 

Determining the bulk and diffusion relaxation time (T2) from this 
chart requires knowledge of both the formation temperature and 
the echo spacing (TE) used to acquire the data. These data are pre- 
sented graphically on the log and are the basis of the water or 
hydrocarbon interpretation of the zone of interest. 



Description 

Longitudinal Relaxation Time 

The chart relation is for pure water — the additives in drilling fluids 
reduce the relaxation time (Ti) of water in the invaded zone. The 
two major contributors to the reduction are surfactants added to the 
drilling fluid and the molecular interactions of the mud filtrate con- 
tained in the pore spaces and matrix minerals of the formation. 

Transverse Relaxation Time 

The relaxation time (T2) determination is based on the formation 
temperature and echo spacing used to acquire the measurement. 
The TE value is listed in the parameter section of the log. Using 
the T2 measurement from a known water sand or based on local 
experience further aids in determining whether a zone of 
interest contains hydrocarbons, water, or both. 



14 



Back to Contents 



General 



Schlumberger 



Nuclear Magnetic Resonance Relaxation Times of Hydrocarbons 



Gen-11a 



T,(s) 



10 



0.1 



Longitudinal (Bulk) Relaxation 
Time of Crude Oil 

























Light oil: 45°-60° APIff 






















Rd D7i;n/rm 


3 








1 






























































































































M 


edium ni 




0.1 




















L|Q7R-nRRn/nm3-l 
















































-T, 
















































0.01 








































































































av 






















0.001 








He 


/oil: 10°-20° AP 

p0.85-0.95 a 


cm 
























ttttttl — 




ttttttl — 




































0.0001 



























10 100 1,000 10,000 100,000 

Viscosity (cp) 



T,(s) 



Transverse (Bulk and Diffusion) Relaxation 
Time of Crude Oil 



10 



0.1 



0.01 



0.001 



0.0001 



0.1 












































































TE - 2 ms 












































TE- 0.32 ms 






















TE - 1 ms 






















_ TE = 2 ms 











































































































































































































































































































































































































































































































































































10 100 1,000 10,000 100,000 

Viscosity (cp) 



Diffusion 
(cm 2 /s) 





Hyd 


ocarbon Diffusion Coefficient 


111- 3 




m- 4 
















3il(9°at20°C 


) 


10- 5 






— -""''--" 


^ 






' x 

— • 

/ C 


)il (40° at 20° 


:) 


10- 6 












/ 








IfF 











© Schlumberger 



50 100 150 

Temperature (°C) 



200 



Diffusion 
(10- 5 cm 2 /s) 



?n 


Water Diffusion Coefficient 


is 










in 










R 










n 











50 100 150 

Temperature (°C) 



200 



Purpose 

Longitudinal (Bulk) Relaxation Time of Crude Oil 
This chart is used to predict the Ti of crude oils with various viscosi- 
ties and densities or specific gravities to assist in interpretation of 
the fluid content of the formation of interest. 

Transverse (Bulk and Diffusion) Relaxation Time 

Known values of T2 and TE can be used to approximate the viscosity 

by using this chart. 

Diffusion Coefficients for Hydrocarbon and Water 
These charts are used to predict the diffusion coefficient of hydro- 
carbon as a function of formation temperature and viscosity and 
of water as a function of formation temperature. 



Description 

Longitudinal (Bulk) Relaxation Time 

This chart is divided into three distinct sections based on the compo- 
sition of the oil measured. The type of oil contained in the formation 
can be determined from the measured Ti and viscosity determined 
from the transverse relaxation time chart. 

Transverse (Bulk and Diffusion) Relaxation Time 
The viscosity can be determined with values of the measured T2 and 
TE for input to the longitudinal relaxation time chart to identify the 
type of oil in the formation. 



Back to Contents 



15 



General 



Schlumberger 



Nuclear Magnetic Resonance Relaxation Times of Hydrocarbons 



Gen-11b 






35 
30 
25 
20 
15 
10 
5 



Methane Diffusion Coefficient 


















^1,600 psi 










3,000^ 




Diffusion 
(1(Hcm 2 /s) 






^S 3^oo__ 








^ 


'***■ 




^-^>-" 


--"""'' 


0,JUU „ 

.-. — -'15,500 _ 




== = = = 


------- 


22,800 



T,(s) 



100 



10 



50 100 150 

Temperature (°C) 

Transverse (Bulk and Diffusion) 
Relaxation Time of Methane 



0.1 



0.01 



0.001 



200 































































































































































































































































































































TE = 0. 


2 ms 
























































































0.32 ms 
























lt = 














































^— 












































"^ j 


E - ' m 
















-^ 


































^ 


s 


■^ 
































-i — ^-** — 


























T- 


= 2 ms 


-^T 
































































^ 




































■"-« 



io-* 



10- 3 

Diffusion (cm 2 /s) 



10- 



T,(s) 



10 



Longitudinal (Bulk) Relaxation 
Time of Methane 





■> 


5 :: C 
5C 
>5°( 
75° 


























7 


























8 


1 

1 












































R 
























^ 


-"*' 


.,-•'" 






















s 

y 


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y 






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y 


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.... 


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* 














? 








.-** 


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n 

































3,000 6,000 9,000 12,000 

Pressure (psi) 



1.2 
1.0 
08 


Hydrogen Index of Live Hydroca 


rbons and Gas 


























Hydrogen 
index 0-6 

04 


























02 






























0.2 0.4 0.6 0.8 1.0 1.2 

Hydrocarbon density (g/cm 3 ) 



© Schlumberger 



Purpose 

Methane Diffusion Coefficient 

This chart is used to determine the diffusion coefficient of methane 

at a known formation temperature and pressure. 

Longitudinal and Transverse Relaxation Times of Methane 
These charts are used to determine the longitudinal relaxation time 
(Ti) of methane by using the formation temperature and pressure 
(see Reference 48) and the transverse relaxation time (T2) of 
methane by using the diffusion and echo spacing (TE), respectively. 



Hydrogen Index of Live Hydrocarbons and Gas 
This chart is used to determine the hydrogen index from the hydro- 
carbon density. 



16 



< ► 



Back to Contents 



General 



Capture Cross Section of NaCI Water Solutions 



Schlumberger 



Purpose 

The sigma value (E w ) of a saltwater solution can be determined from 
this chart. The sigma water value is used to calculate the water satu- 
ration of a formation. 

Description 

Charts Gen-12 and Gen-13 define sigma water for pressure condi- 
tions of ambient through 20,000 psi [138 MPa] and temperatures 
from 68° to 500°F [20° to 260°C]. Enter the appropriate chart for 
the pressure value with the known water salinity on the y-axis and 
move horizontally to intersect the formation temperature. The sigma 
of the formation water for the intersection point is on the x-axis. 



Example 

Given: Water salinity = 125,000 ppm, temperature = 68°F at 
ambient pressure, and formation temperature = 190°F 
at 5,000 psi. 

Find: E w at ambient conditions and E w of the formation. 

Answer: E w = 69 c.u. and E w of the formation = 67 c.u. 

If the sigma water apparent (£ W a) is known from a clean water 
sand, then the salinity of the formation can be determined by enter- 
ing the chart from the sigma water value on the x-axis to intersect 
the pressure and temperature values. 




< ► 



Back to Contents 



continued on next page 
17 



General 



Capture Cross Section of NaCI Water Solutions 



Schlumberger 



Gen-12 

(former Tcor-2a) 




© Schlumberger 


Equivalent water salinity 
(1,000 xppm NaCI) 


300 




300 


275 

250 

225 

200 

175 

150 

125 

100 

75 

50 

25 
































275 
250 
225 
200 


























/4 


<* 










































































*/. 
































^// 












300 
275 
250 
225 
200 


















































;/r 




















4l 


























§ 
„<?/ 
























<$? 




-175 j 








/ ZMZ, 


V 




















Aso 








150j 










300 

275 

250 

225 

200 

175 

150 

125 

100 

75 

50 

25 












^125 
































100 

75 

50 

25 






































n> 


























4 


§y 
























«# 


// 






























































































100 

75 

50 

25 






























































































































] 10 20 30 40 50 60 70 80 90 100 110 120 130 V 

S w (c.u.) 


10 



Back to Contents 



General 



Capture Cross Section of NaCI Water Solutions 



Schlumberger 



Gen-13 

(former Tcor-2b) 



© Schlumberger 


Equivalent water salinity 
(1,000 xppm NaCI) 


300 




300 


275 

250 

225 

200 

175 

150 

125 

100 

75 

50 

25 




























i 
Jh - 


275 
250 
225 
200 
























« 














































J>//, 
























J? /A 










































300 
275 
250 
225 
200 


























4% 












































.« 


&S 


















































v& 














<? 




































300 

275 

250 

225 

200 

175 

150 

125 

100 

75 

50 

25 












^125 


^150 








150 y 




















125/ 




<, 


100 

75 

50 

25 


















y "$£ 






















2* 






Vs 




















^ 


7/ 
























J 




























•v 




































































100 

75 

50 

25 






























































































































] 10 20 30 40 50 60 70 80 90 100 110 120 130 1 

EJc.u.) 


to 



Purpose 

Chart Gen-13 continues Chart Gen-12 at higher pressure values for 
the determination of E w of a saltwater solution. 



Back to Contents 



19 



General 



Capture Cross Section of Hydrocarbons 



Schlumberger 




Purpose 

Sigma hydrocarbon (Eh) for gas or oil can be determined by using 
this chart. Sigma hydrocarbon is used to calculate the water satura- 
tion of a formation. 

Description 

One set of charts is for measurement in metric units and the other 
is for measurements in "customary" oilfield units. 

For gas, enter the background chart of a chart set with the reser- 
voir pressure and temperature. At that intersection point move left 
to the y-axis and read the sigma of methane gas. 

For oil, use the foreground chart and enter the solution gas/oil 
ratio (GOR) of the oil on the x-axis. Move upward to intersect the 
appropriate API gravity curve for the oil. From this intersection 
point, move horizontally left and read the sigma of the oil on 
the y-axis. 



Example 

Given: 



Find: 
Answer: 



Reservoir pressure = 8,000 psi, reservoir temperature 
300°F, gravity of reservoir oil = 30°API, and solution 
GOR = 200. 

Sigma gas and sigma oil. 

Sigma gas = 10 c.u. and sigma oil = 21.6 c.u. 



20 



Back to Contents 



General 



Capture Cross Section of Hydrocarbons 



Schlumberger 



Gen-14 

(former Tcor-1) 



20.0' 

17.5 

15.0 

12.5 

10.0 

7.5 

5.0 

2.5 





4,000 



Reservoir pressure (psia) 
8,000 12,000 



16,000 20,000 



Me 


thane 
























































. 200 
300 






^ 


Customary 
















400 

'. 500 






















Temperati 
I 


ire(°F) 




































Liquid hydrocarbons 












:22 
































I ill 
,30°, 40°, and 50° API 






























;t^ 
























.20 

18 




(c.u 


) 














20° a 


nd 60° API 


























































/ 










































\ 


% 




% 




16 






































s 












































S, ( 



10 



100 1,000 

Solution G0R (ft 3 /bbl) 



10,000 



I h (c.u.] 



20.0 

17.5 

15.0 

12.5 

10.0 

7.5 

5.0 

2.5 





Reservoir pressure (mPa) 
14 28 41 55 69 83 97 110 124 138 



Me 


ithane 


































^52- 






















,aso- 






Metric 
















. 205- 
. 260' 




















Terr 


peratur 


e(°C) 


















. IT 






























Liquid hydrocarbons 
































0.78 to 0.88 mg/m 3 












.20 














































c.u 


) 












0J 


4c 


rO 


9' 


In 


ig/ 


Tl 3 / 


^ 


5s 
























.18 






























s 


* 


* 


.< 


\ 










































1° 






_16 










































. 

















































© Schlumberger 



10 100 

Solution G0R(m 3 /m 3 ) 



1,000 2,000 



< ► 



Back to Contents 



General 



EPT* Propagation Time of NaCI Water Solutions 



Schlumberger 



Gen-15 

(former EPTcor-1) 




qn 




























20° C 




< vr 




**? -250°F 


80 






'*' III 
















/ ,* ,.- 2UU h 




+ * <»' <• 




i ' * III 




S' ' -*'*~ ~ 80°C 






70 


/? , '*-* '* -175°F 




/ ' '* mi ii 


4* 




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f 


.y e*" _, 150°F 


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y •' .' .^ ' _ — o 


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J S ' 


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en £ /* 


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rf' X' »■ 


Jf /? 7 


' •' ' _ .»r< _ 


, . , i 7 ^ „^ ^ - 


t ns/m jf tl 7 + 






^ . "•_. -""" I UU r 




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xf 75°F 


Jttf/j ■' •* ^ 




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-- — 20°C 


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* *"* ..— •" 


II\f\ i ' ' j ' * *<£ 


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il\f\m ' i 4* ^ 


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ft 1 fft r f '' . " • *" 




40 'f/wW/ S ■' '" 




N i ff // / S ft"* '^ 




Ilta/jf/ J r* j*^ 




III ff/// J y 




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ffflMut/ / f.S S^ 




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mar^^y^^ 1 ^ 




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30 ~"9 




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n 




6- 




r 
















20 _ 




50 100 

Equivalent water salinity 

*Markof Schlumberger 
© Schlumberger 


150 200 250 
1,000 xppm or g/kg NaCI) 



Purpose 

This chart is designed to determine the propagation time (t pw ) of 
saltwater solutions. The value of t pw of a water zone is used to deter- 
mine the temperature variation of the salinity of the formation water. 



Description 

Enter the chart with the known salinity of the zone of interest and 
move upward to the formation temperature curve. From that inter- 
section point move horizontally left and read the propagation time 
of the water in the formation on the y-axis. Conversely, enter the 
chart with a known value of t pw from the EPT Electromagnetic 
Propagation Tool log to intersect the formation temperature curve 
and read the water salinity at the bottom of the chart. 



22 



Back to Contents 



General 



EPT* Attenuation of NaCI Water Solutions 



Schlumberger 



Gen-16 

(former EPTcor-2) 



5,000 



4,000 



Attenuation, 3 - 000 
A 
(dB/m) 

2,000 



1,000 













i9n°r 




,» '*"250°F 




" '** " 100°C 




+*."* ,* -^^.^ 200°F 






^*~* -.** .- '* - ( -* , "!l7R F- 




^ *'-' -**^ 150°F 




/' r * + w •'' ~~ 60°C 




^€ * * ^*' ^* *• '- ^^m25°F" 






_/ *t£^++* .^-^^-^ _; 4U u 


- *^ ■* •*"**' «-■* -■=• z-s:inn°F- 




y , , S -* ' -^ -t ■- i I I I I 


-X ZZ £ >^' ^£* ***" -*"" Tr-or 


^ *z? K ^ *"* —- 75°F 








2_j5 ' z z '2*~ *• "* -*** 


a' // / s/ ^ >£ J —** ■■"*" 


ZZZZ Z _j' j_.^ ** «•■*" 


frfr t> *■ $* - ''* 






/ ft A/ / j j, •/ **•**' 


i fix// J / ^ "^ ^ 


1 ffs\ff, / /f *'■*' 




ilfflAf * /' y? 1 


limfff/ J? / ^ 




IlKrW /^" 


1mm/ f /* 


Imi/fJp 


ml// aV 




Wm/m 




mm 


w\ 





50 100 150 200 

Equivalent water salinity (kppm or g/kg NaCI) 



250 




EPT-D Spreading Loss 




"N- 


s, 


*^ 


'v 


'. 


>. 


> 


\ 


^ 


"^k 


\ 


\ 


k 


> 


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3 


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3 


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t 


3 


L 


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^ 


r 


_l 



-40 
-60 
-80 

-100 

Correction 
" 12 ° toEATT 



(dB/m) 



-140 



-160 



-180 



-200 



*Markof Schlumberger 
© Schlumberger 



5 10 15 20 25 30 

Uncorrected t p i (ns/m) 



Purpose 

This chart is designed to estimate the attenuation of saltwater solu- 
tions. The attenuation (A w ) value of a water zone is used in conjunc 
tion with the spreading loss determined from the EPT propagation 
time measurement (t p i) to determine the saturation of the flushed 
zone by using Chart SatOH-8. 



Description 

Enter the chart with the known salinity of the zone of interest and 
move upward to the formation temperature curve. From that intersec- 
tion point move horizontally left and read the attenuation of the water 
in the formation on the y-axis. Conversely, enter the chart with a known 
EATT attenuation value of A w from the EPT Electromagnetic 
Propagation Tool log to intersect the formation temperature curve 
and read the water salinity at the bottom of the chart. 

23 

Back to Contents 



General 



EPT* Propagation Time-Attenuation Crossplot 

Sandstone Formation at 150°F [60°C] 



Schlumberger 



Gen-16a 




1,000 
900 
800 
700 

600 

Attenuation 
(dB/m) 500 

400 

300 

200 

100 



L 



Sandstor 




1 1 1 1 \/,'Y.s/s 



R mfa from EPT log 



ohm-m) 0.02 'V 0.05' , 



9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 

t p i (ns/m) 



*Markof Schlumberger 
© Schlumberger 



Purpose 

This chart is used to determine the apparent resistivity of the mud 
filtrate (Rmfa) from measurements from the EPT Electromagnetic 
Propagation Tool. The porosity of the formation (<|)ept) can also be 
estimated. Porosity and mud filtrate resistivity values are used in 
determining the water saturation. 

Description 

Enter the chart with the known attenuation and propagation time 
(t p i). The intersection of those values identifies Rmfa and (|)ept from 
the two sets of curves. This chart is characterized for a sandstone 
formation at a temperature of 150°F [60°C]. 



Example 

Given: Attenuation = 300 dB/m and t p i = 13 ns/m. 

Find: Apparent resistivity of the mud filtrate and EPT porosity. 

Answer: Rmf a = 0.1 ohm-m and (|>ept = 20 p.u. 



24 



< ► 



Back to Contents 



Gamma Ray — Wireline 



Scintillation Gamma Ray — 3%- and 1%-in. Tools 

Gamma Ray Correction for Hole Size and Barite Mud Weight 



Schlumberger 



GR-1 

(former GR-1) 



Scintillation Gamma Ray 



Correction 
factor 



10.0 



7.0 



5.0 



3.0 



2.0 



1.0 



0.7 



0.5 



0.3 

















































































• 














* 


*** 










3%- 


in. tool, centered ,.*" 












„-••' 




1 n /i6-in. tool. 


centered 












3 3 /8-in. tool. 


sccentered 








l 1 Vie-in. toe 


1, eccentered 




■*»2^ 


'€£Z- — """" 














-■-J^**^ 
















'■^ 


















































































10 



15 



20 
t(g/cm 2 ) 



25 



30 



35 



40 



© Schlumberger 



Purpose 

This chart provides a correction factor for measured values of forma- 
tion gamma ray (GR) in gAPI units. The corrected GR values can be 
used to determine shale volume corrections for calculating water 
saturation in shaly sands. 

Description 

The semilog chart has the t factor on the x-axis and the correction 
factor on the y-axis. 

The input parameter, t, in g/cm 2 , is calculated as follows: 



W, 



mud 



8.345 



2.54(d h ) 2.54( dsonde ) 



where 

W m ud = mud weight (lbm/gal) 

dj, = diameter of wellbore (in.) 

dsonde = outside diameter (OD) of tool (in.). 



Example 

Given: GR = 36 API units (gAPI), d h = 12 in, mud weight = 
12 lbm/gal, tool OD = 3% in., and the tool is centered. 

Find: Corrected GR value. 

Answer: 



12 



8.345 



2.54(12) 2.54(3.375) 



: 15.8 g/cm . 



Enter the chart at 15.8 on the x-axis and move upward to 
intersect the 3 3 /s-in. centered curve. The corresponding 
correction factor is 1.6. 

1.6 x 36 gAPI = 58 gAPI. 



< ► 



Back to Contents 



25 



Gamma Ray — Wireline 



Scintillation Gamma Ray — 3%- and 1%-in. Tools 

Gamma Ray Correction for Barite Mud in Various-Size Boreholes 



Schlumberger 



GR-2 

(former GR-2) 



1.2 






1.0 
0.8 
0.6 
0.4 
0.2 

















































1%-in. 


tool, conterod „ 


--'' 




















,.■*" 


"" 




















^ «*» 


.•,-*• ""' 


vv 


G-in. tool 


ecconterod 


»» — "** 












_ -* *"" 


-""" 


___-- 


-^s^z 


-~^J1_ 


3%7n. too 


, centored 






^, ■?_ 


^ ^ -* 


^i^ 


_ J 








3 3 /s-in. 


tool, eccentered 
1 







10 11 12 13 14 15 

Mud weight (Ibm/gal) 



16 



17 



19 



20 



1.2 
1.0 
0.8 
F bh 0.6 
0.4 
0.2 






























" "^ ^ 


„ - - 














3 /8-in. tool y 




m* 
















/ 4*- 


"'l"/i6-in.1 


ool 
















' S 
A 
S 


















/s 

























4 5 6 

dh-d sond0 (in.) 



10 



© Schlumberger 



Purpose 

These charts are used to further correct the GR reading for various 
borehole sizes. 

Description 

Two components needed to complete correction of the GR reading 
are determined with these charts: barite mud factor (B mu d) and 
borehole function factor (Fbh)- 

Example 

Given: Borehole diameter = 6.0 in., tool OD = 3% in., the tool 
is centered, mud weight = 12 lbm/gal, measured 
GR = 36 gAPI. 

Find: Corrected GR value. 



Answer: 



Enter the upper chart for B mu d versus mud weight at 
12 lbm/gal on the x-axis. The intersection point with the 
3 3 /8-in. centered curve is B muc i < 0.15 on the y-axis. 

Determine (dh - d son de) as 6 - 3.375 = 2.625 in. and enter 



26 



that value on the lower chart for Fbh versus 

(dh - dsonde) on the x-axis. Move upward to intersect 

the 3%-in. curve, at which Fbh = 0.81. 

Determine the new value of t using the equation from 
Chart GR-1: 



W, 



mud 



8.345 



12 



1.345 



2.54(d h ) 2.54( dsonde ) 

2 2 

2.54(6) 2.54(3.375) 



: 4.8 g/cm . 



The correction factor determined from Chart GR-1 is 0.9£ 
The complete correction factor is 

(Chart GR-1 correction factor) x [1 + (B mu d x Fbh)] 

= 1.12 x[l + (0.15x0.81)] =1.26. 
Corrected GR = 36 x 1.26 = 45.4 gAPI. 



Back to Contents 



Gamma Ray — Wireline 



Scintillation Gamma Ray — 3%- and 1%-in. Tools 

Borehole Correction for Cased Hole 



Schlumberger 



GR-3 

(former GR-3) 



10.0 


Scintillation Gamma Ray 




7.0 
5.0 

3.0 

2.0 
Correction 
factor 

1.0 

0.7 
0.5 

0.3 














































































































3%-in. tool 


















1 n /iG-in. tool 




































^, — '^>-"' 
































































































C 

© Schlumberger 


5 10 15 20 25 30 35 40 

t(g/cm 2 ) 




Purpose 

This chart is used to compensate for the effects of the casing, 
cement sheath, and borehole fluid on the GR count rate in cased 
holes for conditions of an eccentered 3 3 /s-in. tool in an 8-in. borehole 
with 10-lbm/gal mud. 

Description 

In small boreholes the count rate can be too large, and in larger 
boreholes the count rate can be too small. The chart is based on 
openhole Chart GR-1, modified by laboratory and Monte Carlo 
calculations to provide a correction factor for application to 
the measured GR count rate in cased hole environments: 



Example 

Given: 



2.54 
2 



W, 



8M5 ( d IDcsg- 



sonde 



'cs g (d 



ODcsg "iDcsg 



P cement \% d ODcsg 



Find: 
Answer: 



GR = 19 gAPI, hole diameter (dh) = 12 in., casing OD 
(doDcsg) = 9 5 /s in. and 43.5 lbm/ft, casing ID (dmcsg) = 
8.755 in., casing density (p cs g) = 7.96 g/cm 3 , tool OD 
(dsonde) = 3% in., cement density (pcement) = 2.0 g/cm 3 , 
and mud weight (W m ) = 8.345 lbm/gal. 

Corrected cased hole GR value. 

The chart input factor calculated with the equation is 
t = 21.7 g/cm 2 . Enter the chart at 21.7 on the x-axis. At 
the intersection point with the 3%-in. curve, the value of 
the correction factor on the y-axis is 2.0. The GR value is 
corrected by multiplying by the correction factor: 

19 gAPI x 2.0 = 38 gAPI. 



Back to Contents 



27 



Gamma Ray— LWD 



SlimPulse* and E-Pulse* Gamma Ray Tools 

Borehole Correction for Open Hole 



Schlumberger 



GR-6 




Correction 
factor 

*Markof Schlumberger 
© Schlumberger 


11 


















10 
9 
8 
7 
6 
5 
4 
3 
2 
1 







































































17.5- 


n. bit" 


















































































13.5- 


n. bit 






















































































12.25- 


in. bit 










































9.875 
8.5- 


-in. bi 
n. bit 


t 
















































































,7-in 












































. bit " 
































































i 


9 10 


11 12 13 14 

Mud weight (Ibm/gal) 


15 


16 


17 


18 


19 



Purpose 

This chart is used to provide a correction factor for gamma ray 
values measured with the SlimPulse third-generation slim measure- 
ments-while-drilling (MWD) tool or the E-Pulse electromagnetic 
telemetry tool. These environmental corrections for mud weight 
and bit size are already applied to the gamma ray presented on 
the logs. 



Description 

Enter the chart with the mud weight on the x-axis and move 
upward to intersect the appropriate openhole size. Interpolate 
between lines as necessary. At the intersection point, move 
horizontally left to the y-axis to read the correction factor that 
the SlimPulse or E-Pulse gamma ray value was multiplied by to 
obtain the corrected gamma ray value in gAPI units. 



28 



Back to Contents 



Gamma Ray— LWD 



ImPulse* Gamma Ray — 4.75-in. Tool 

Borehole Correction for Open Hole 



Schlumberger 



GR-7 



1.75 






1.50 

Correction , nc 
factor 

1.00 
0.75 






































































8.5-in. bit 










































__7-ir 
_ 6-ir 


. bit' 
. bit - 
































































*Markof Schlumberger 
© Schlumberger 


9 10 11 12 13 14 15 16 17 18 19 

Mud weight (Ibm/gal) 




Purpose 

This chart is used to provide a correction factor for gamma ray 
values measured with the ImPulse integrated MWD platform. These 
environmental corrections for mud weight and bit size are already 
applied to the gamma ray presented on the logs. 



Description 

Enter the chart with the mud weight on the x-axis and move 
upward to intersect the appropriate bit size. Interpolate between 
lines as necessary. At the intersection point, move horizontally left 
to the y-axis to read the correction factor that the ImPulse gamma 
ray value was multiplied by to obtain the corrected gamma ray 
value in gAPI units. 



Back to Contents 



29 



Gamma Ray— LWD 



PowerPulse* and TeleScope* Gamma Ray — 6.75-in. Tools 

Borehole Correction for Open Hole 



Schlumberger 



GR-9 








PowerPulse and TeleScope Gamma Ray 












ann 














2.75 


















































2.50 


















































2.25 






































































12.25 


in. bil 




















Correction 
factor 


2.00 




















































































































10.625-in. bit 

—--T 1 1 






















1.75 






















l___— 
9.875-in. bit 










































8.75-in. bit — 




m „ 


_ — 


--- 








- — """ 






1.50 
















- rr t 


. 


rtrr 





-8.5-in. bit" 






















r^= 


- = ^ : 


~^ r=z 


- — *" 








































1.25 


















































1.00 
















































E 


9 10 


11 12 13 14 15 


16 


17 


18 


19 






Mud weight (Ibm/gal) 










*Markof Schlumberger 
© Schlumberger 















Purpose 

This chart is used to provide a correction factor for gamma ray values 
measured with the PowerPulse 6.75-in. MWD telemetry system and 
TeleScope 6.75-in. high-speed telemetry-while-drilling service. 
These environmental corrections for mud weight and bit size are 
already applied to the gamma ray presented on the logs. 



Description 

Enter the chart with the mud weight on the x-axis and move upward 
to intersect the appropriate bit size. Interpolate between lines as 
necessary. At the intersection point, move horizontally left to the 
y-axis to read the correction factor that the PowerPulse or 
TeleScope gamma ray value was multiplied by to obtain the cor- 
rected gamma ray value in gAPI units. 



30 



Back to Contents 



Gamma Ray— LWD 



Schlumberger 



PowerPulse* Gamma Ray — 8.25-in. Normal-Flow Tool 

Borehole Correction for Open Hole 



GR-10 



5.00 








4.75 
4.50 
4.25 

4.00 

Correction qyc 
factor 

3.50 
3.25 
3.00 
2.75 
2.50 
























































17.5- 


n. bit 


























































































14.75- 


in. bi 
13.5- 










































n. bit 




















































































12.25- 


in. bit 














^ — 


-"-" 


--" 


.-'■ 
























0.625 


-in. b 


t" 


.-- 








m , — 


--- 


_-- 


--" 


--" 






_ 


_-- 


--" 


■ --' 


--" 


_ 


_ - - 


--" 


9.875 


in. bil 




"* 




















.-- 


-~~ 










































i 

*Markof Schlumberger 
© Schlumberger 


9 10 11 12 13 14 15 

Mud weight (Ibm/gal) 


16 17 18 19 




Purpose 

This chart is used to provide a correction factor for gamma ray values 
measured with the PowerPulse 8.25-in. normal-flow MWD telemetry 
system. These environmental corrections for mud weight and bit 
size are already applied to the gamma ray presented on the logs. 



Description 

Enter the chart with the mud weight on the x-axis and move upward 
to intersect the appropriate bit size. Interpolate between lines as 
necessaiy. At the intersection point, move horizontally left to the y-axis 
to read the appropriate correction factor that the PowerPulse gamma 
ray value was multiplied by to obtain the corrected GR value in gAPI 
units. 



Back to Contents 



Gamma Ray— LWD 



Schlumberger 



PowerPulse* Gamma Ray — 8.25-in. High-Flow Tool 

Borehole Correction for Open Hole 



GR-11 




4.25 












4.00 
3.75 
3.50 

3.25 

Correction 3 qq 
factor 

2.75 
2.50 
2.25 
2.00 
1.75 






































































































17.5- 


n. bit 
















































14.7 












































5-in. bit 
13.5-ii 


1. bit 

1 












































2.25-ir 


i. bit 














































10.6 


25-in. 


bit 
. 9.8 


_-- 


.-- 


- "* *" 






















_ ^ - 


--" 


--■ 


.-- 


— ■"* 


_ _ - 


--- 


75-in. 


bit 








.-- 


--" 


--* 


--■ 


- — "" 


_-- 


--- 


--- 


— ■* 








































































i 

*Markof Schlumberger 
© Schlumberger 


9 


10 


11 12 13 14 15 16 17 18 
Mud weight (Ibm/gal) 


19 



Purpose 

This chart is used to provide a correction factor for gamma ray values 
measured with the PowerPulse 8.25-in. high-flow MWD telemetry 
system. These environmental corrections for mud weight and bit 
size are already applied to the gamma ray presented on the logs. 



Description 

Enter the chart with the mud weight on the x-axis and move upward 
to intersect the appropriate bit size. Interpolate between lines as 
necessary. At the intersection point, move horizontally left to the 
y-axis to read the correction factor that the PowerPulse gamma ray 
value was multiplied by to obtain the corrected gamma ray value in 
gAPI units. 



32 



Back to Contents 



Gamma Ray— LWD 



Schlumberger 



PowerPulse* Gamma Ray — 9-in. Tool 

Borehole Correction for Open Hole 



GR-12 



7.50 












7.00 
6.50 
6.00 

5.50 

Correction gnn 
factor 

4.50 
4.00 
3.50 
3.00 
2.50 














































































































































22-in. 


bit 




























































































1 


7.5-in 


bit 














































14.75 


-in. b 


t 
: 13.5 


-in. bi 

_ J 


















--" 
























2.25- 


n. bit 


--" 


.--' 






















_-- 


--- 





— ""* 














.10 


625-i 


l. bit 











— 


— 














































*Markof Schlumberger 
© Schlumberger 




9 10 11 12 13 14 15 16 17 

Mud weight (Ibm/gal) 


18 


19 




Purpose 

This chart is used to provide a correction factor for gamma ray values 
measured with the PowerPulse 9-in. MWD telemetry system. These 
environmental corrections for mud weight and bit size are already 
applied to the gamma ray presented on the logs. 



Description 

Enter the chart with the mud weight on the x-axis and move upward 
to intersect the appropriate bit size. Interpolate between lines as 
necessary. At the intersection point, move horizontally left to the 
y-axis to read the correction factor that the PowerPulse gamma ray 
value was multiplied by to obtain the corrected gamma ray value in 
gAPI units. 



Back to Contents 



33 



Gamma Ray— LWD 



PowerPulse* Gamma Ray — 9.5-in. Normal-Flow Tool 

Borehole Correction for Open Hole 



Schlumberger 



GR-13 




8.00 






7.50 
7.00 
6.50 

6.00 

Correction gen 
factor 

5.00 
4.50 
4.00 

3.50 
3.00 
























































in. bi 










































LL 


t 


























































































1; 


.5-inT 


bit 














































147 


5-in. 


lit 










































3.5-i 


l. bit 












.-- 


--- 


--"" 


— """ 






















. - - • 


.-- 


--- 


.12.2 


5-in. t 


it 
























--- 


" ' 




















25-in. 


bit 










— 








" — "~ 






































*Markof Schlumberger 
© Schlumberger 


9 10 11 12 13 14 15 16 17 18 19 

Mud weight (Ibm/gal) 



Purpose 

This chart is used to provide a correction factor for gamma ray values 
measured with the PowerPulse 9.5-in. normal-flow MWD telemetry 
system. These environmental corrections for mud weight and bit 
size are already applied to the gamma ray presented on the logs. 



Description 

Enter the chart with the mud weight on the x-axis and move upward 
to intersect the appropriate bit size. Interpolate between lines as 
necessary. At the intersection point, move horizontally left to the 
y-axis to read the correction factor that the PowerPulse gammma ray 
value was multiplied by to obtain the corrected gamma ray value in 
gAPI units. 



34 



Back to Contents 



Gamma Ray— LWD 



Schlumberger 



PowerPulse* Gamma Ray — 9.5-in. High-Flow Tool 

Borehole Correction for Open Hole 



GR-14 



Correction 
factor 

*Markof Schlumberger 
© Schlumberger 


8 0(1 










7.50 
7.00 
6.50 
6.00 
5.50 
5.00 
4.50 
4.00 
3.50 
3.00 
2.50 

?no 






















2; 


!-in. bit 


















































































































































































17.5- 


n. bit 






























































































































14.75 


-in. bi 


t 






































.13.5 


-in. bi 


t 






_ 


_-- 


--" 


--" 


• --" 






















15 


.25-ir 


. bit" 


— " " 


















--- 


















--10.I 


525-in 


bit 




































































{ 


9 10 


11 12 13 14 15 
Mud weight (Ibm/gal) 


16 17 18 19 




Purpose 

This chart is used to provide a correction factor for gamma ray values 
measured by the PowerPulse 9.5-in. high-flow MWD telemetry sys- 
tem. These environmental corrections for mud weight and bit size 
are already applied to the gamma ray presented on the logs. 



Description 

Enter the chart with the mud weight on the x-axis and move upward 
to intersect the appropriate bit size. Interpolate between lines as 
necessary. At the intersection point, move horizontally left to the 
y-axis to read the correction factor that the PowerPulse gamma ray 
value was multiplied by to obtain the corrected gamma ray value in 
gAPI units. 



Back to Contents 



35 



Gamma Ray— LWD 



Schlumberger 



geoVISION675* GVR* Gamma Ray— 6.75-in. Tool 

Borehole Correction for Open Hole 



GR-15 




Correction 
factor 

*Markof Schlumberger 
© Schlumberger 


?75 
















2.50 
2.25 
2.00 
1.75 
1.50 
1.25 
1.00 
0.75 


































































































































































12.25- 


in. bil 




















































































.10.625-in. 


bit 






































9. 


375-in 


. bit" 
3 7R-i 


i hit 




































o.o-in 


. Dlt ~ 






















{ 


9 10 


11 12 13 14 15 
Mud weight (Ibm/gal) 


16 


17 


18 


19 



Purpose 

This chart is used to provide a correction factor for gamma ray 
values measured with the GVR resistivity sub of the geoVISION 6 3 /4-in. 
MWD/LWD imaging system. These environmental corrections for 
mud weight and bit size are already applied to the gamma ray 
presented on the logs. 



Description 

Enter the chart with the mud weight on the x-axis and move upward 
to intersect the appropriate bit size. Interpolate between lines as 
necessary. At the intersection point, move horizontally left to the 
y-axis to read the correction factor that the GVR gamma ray value was 
multiplied by to obtain the corrected gamma ray value in gAPI units. 



36 



Back to Contents 



Gamma Ray— LWD 



RAB* Gamma Ray — 8.25-in. Tool 

Borehole Correction for Open Hole 



Schlumberger 



GR-16 



Correction 
factor 

*Markof Schlumberger 
© Schlumberger 


3 no 


















2.75 
2.50 
2.25 
2.00 
1.75 
1.50 
1.25 
1.00 
0.75 
50 






















































































































17.5-in. 


bit ' 




























































































































,14.75-in. bit 






































— 13.5-in. bit 








































1 2.25 


-in. bi 


t 




625-i 


n. bit 





































■ -9.8" 


'5-in. 


bit- - 








- - 10 
































































f 


9 


10 


11 


12 13 14 15 16 
Mud weight (Ibm/gal) 


17 


18 


19 




Purpose 

This chart is used to provide a correction factor for gamma ray values 
measured with the RAB Resistivity-at-the-Bit 8.25-in. tool. These envi- 
ronmental corrections for mud weight and bit size are already 
applied to the gamma ray presented on the logs. 



Description 

Enter the chart with the mud weight on the x-axis and move upward 
to intersect the appropriate bit size. Interpolate between lines as 
necessary. At the intersection point, move horizontally left to the 
y-axis to read the correction factor that the RAB gamma ray value 
was multiplied by to obtain the corrected gamma ray value in gAPI 
units. 



Back to Contents 



37 



Gamma Ray— LWD 



Schlumberger 



arcVISI0N475* Gamma Ray — 4.75-in. Tool 

Borehole Correction for Open Hole 



GR-19 




1.75 






1.50 

Correction -i 25 
factor 

1.00 
0.75 


































































8.5-in. bit 










































_7-in 
_ 6-in 


. bit" 
. bit~ 


































































i 

*Markof Schlumberger 
© Schlumberger 


9 10 11 12 13 14 15 16 17 18 19 

Mud weight (Ibm/gal) 



Purpose 

This chart is used to provide a correction factor for gamma ray values 
measured with the arcVISION475 4 3 /4-in. drill collar resistivity tool. 
These environmental corrections for mud weight and bit size are 
already applied to the gamma ray presented on the logs. 



Description 

Enter the chart with the mud weight on the x-axis and move upward 
to intersect the appropriate bit size. Interpolate between lines as 
necessary. At the intersection point, move horizontally left to the 
y-axis to read the correction factor that the arcVISION475 gamma 
ray value was multiplied by to obtain the corrected gamma ray value 
in gAPI units. 



38 



Back to Contents 



Gamma Ray— LWD 



Schlumberger 



arcVISION675* Gamma Ray — 6.75-in. Tool 

Borehole Correction for Open Hole 



GR-20 



3.50 






3.25 
3.00 
2.75 
2.50 
2.25 

Correction 200 
factor 

1.75 
1.50 
1.25 
1.00 
0.75 
0.50 


































































































































































12.25- 


in. bil 




























































































































10.625- 


n hit 








































9 875-in bit" 








































































































































































































i 

*Markof Schlumberger 
© Schlumberger 


9 10 11 12 13 14 15 16 17 18 19 

Mud weight (Ibm/gal) 




Purpose 

This chart is used to provide a correction factor for gamma ray values 
measured with the arcVISION675 6 3 /4-in. drill collar resistivity tool. 
These environmental corrections for mud weight and bit size are 
already applied to the gamma ray presented on the logs. 



Description 

Enter the chart with the mud weight on the x-axis and move upward 
to intersect the appropriate bit size. Interpolate between lines 
as necessary. At the intersection point, move horizontally left to 
the y-axis to read the appropriate correction factor that the 
arcVISION675 gamma ray value was multiplied by to obtain 
the corrected gamma ray value in gAPI units. 



Back to Contents 



39 



Gamma Ray— LWD 



Schlumberger 



arcVISION825* Gamma Ray — 8.25-in. Tool 

Borehole Correction for Open Hole 



GR-21 




Correction 
factor 

*Markof Schlumberger 
© Schlumberger 


son 














2.75 
2.50 
2.25 
2.00 
1.75 
1.50 
1.25 
1.00 
0.75 
50 






















































































































17.5 


-in. bit 






























































































































14.7E 


-in. bit 






































1 

2.25- 


3.5-in 


bit 






































1 


n. bit 


































: -- 


--- 





- — 


::: 














_- 9 


875-i 


i. bit 


































































{ 


9 10 11 12 13 14 15 

Mud weight (Ibm/gal) 


16 


17 


18 


19 



Purpose 

This chart is used to provide a correction factor for gamma ray values 
measured with the arcVISION825 8!/4-in. drill collar resistivity tool. 
These environmental corrections for mud weight and bit size are 
already applied to the gamma ray presented on the logs. 



Description 

Enter the chart with the mud weight on the x-axis and move upward 
to intersect the appropriate bit size. Interpolate between lines as 
necessary. At the intersection point, move horizontally left to 
the y-axis and read the appropriate correction factor that the 
arcVISION825 gamma ray value was multiplied by to obtain 
the corrected gamma ray value in gAPI units. 



40 



Back to Contents 



Gamma Ray— LWD 



Schlumberger 



arcVISION900* Gamma Ray— 9-in. Tool 

Borehole Correction for Open Hole 



GR-22 



5.5 






5.0 
4.5 
4.0 

3.5 

Correction on 
factor 

2.5 
2.0 
1.5 
1.0 
0.5 
























































































































»2-in.' 


bit 












































































































































































7.5-i 


t. bit 






































1 


4.75-i 


n. bit 






































— 13 
























n. bit 
























"■ ■" 
















I0.625in. b 
















































i 

*Markof Schlumberger 
© Schlumberger 


9 10 11 12 13 14 15 16 17 18 19 

Mud weight (Ibm/gal) 




Purpose 

This chart is used to provide a correction factor for gamma ray values 
measured with the arcVISION900 9-in. drill collar resistivity tool. 
These environmental corrections for mud weight and bit size are 
already applied to the gamma ray presented on the logs. 



Description 

Enter the chart with the mud weight on the x-axis and move upward 
to intersect the appropriate bit size. Interpolate between lines as 
necessaiy. At the intersection point, move horizontally left to 
the y-axis and read the appropriate correction factor that the 
arcVISION900 gamma ray value was multiplied by to obtain the 
corrected gamma ray value in gAPI units. 



Back to Contents 



41 



Gamma Ray— LWD 



arcVISI0N475* Gamma Ray— 4.75-in. Tool 

Potassium Correction for Open Hole 



Schlumberger 



GR-23 




Correction 
subtracted 
for 5-wt% 
potassium 
(gAPI) 

*Markof Schlumberger 
© Schlumberger 


inn 




8 


9n 
8n 
7n 
6n 
sn 
4n 
3n 
2n 
in 
n 




































/" 










20 ppg ^ 


^ 










^^O^J6 ppg ^^ 










^- — "^14 ppg __ J2 ppg" 










-'' ^ JO ppg__'_ 
--"1.-^'£3ppc 


?ppg.1-' 






j«^]j«^\^^^''^ "* 


-c-'~~~ 


















<^' : '°- 












( 


i 8 10 12 14 16 1 

Hole size (in.) 



Purpose 

This chart is used to provide a correction that is subtracted from 
the borehole-corrected gamma ray from the arcVISION475 4 3 /4-in. 
tool. Environmental corrections for mud weight and bit size are 
already applied to the gamma ray presented on the logs. 



Description 

This chart is for illustrative purposes only. The indicated correction 
is already applied to the gamma ray log. 

To determine the correction that was applied to the log output, 
enter the chart with the borehole size on the x-axis and move upward 
to intersect the downhole mud weight. From the intersection point 
move horizontally left to read the correction in gAPI units that was 
subtracted from the borehole-corrected data. 

Charts GR-24 through GR-26 are similar to Chart GR-23 for 
different arcVISION tool sizes. 



42 



Back to Contents 



Gamma Ray— LWD 



arcVISION675* Gamma Ray— 6.75-in. Tool 

Potassium Correction for Open Hole 



Schlumberger 



GR-24 



50 



Correction 
subtracted 
for 5-wt% 
potassium 
(gAPI) 

















_ 20ppg - 






4F 




















-18ppg 






4n 


















. 16 ppg- 








35 


















. I4ppg 








30 


















I2ppg" 








?F 














„,. «- "" 


.,-'"' 


._- ioppg 










?n 












IF 


^- 


'""" 


.. — — **" 


"iTfbppg 


- 9 ppglll 





— — — — 






m 


■»■*"" _ - 


■*"* — — " ' "" 
















F 




















n 






















8.E 



9.0 



9.F 



10.0 



10.E 11.0 

Hole size (in.) 



11.5 



12.0 



12.5 



13.0 



*Markof Schlumberger 
© Schlumberger 



Purpose 

This chart is used to provide a correction that is subtracted from 
the borehole-corrected gamma ray from the arcVISION675 6 3 /4-in. 
tool. Environmental corrections for mud weight and bit size are 
already applied to the gamma ray presented on the logs. 



Description 

This chart is for illustrative purposes only. The indicated correction 
is already applied on the gamma ray log. 

To determine the correction that was applied to the log output, 
enter the chart with the borehole size on the x-axis and move 
upward to intersect the downhole mud weight. From the intersection 
point move horizontally left to read the correction in gAPI units that 
was subtracted from the borehole-corrected data. 



Back to Contents 



43 



Gamma Ray— LWD 



arcVISION825* Gamma Ray — 8.25-in. Tool 

Potassium Correction for Open Hole 



Schlumberger 



GR-25 




100 



90 



80 



70 



60 
Correction 
subtracted 
for5-wt% 50 
potassium 
(OAPI) 

40 



30 



20 



10 





































20 ppg 

1R nnn 










""^^ ___ 












16 ppg 




^ — ""* 


----"" 






/ ^^ J 4 ppg 


„ — *" 


*""" ---■""""' 


''''"'---" 






12 


ppg ,-' 


. - - ** V- - *■ *■ " 


"* 








,«•"* 'U PP9 

,'''9ppg,'- 














8.3 ppg 







































10 



12 



14 IE 

Hole size (in.) 



20 



22 



*Markof Schlumberger 
© Schlumberger 



Purpose 

This chart is used to provide a correction that is subtracted from 
the borehole-corrected gamma ray from the arcVISION825 8Vi-in, 
tool. Environmental corrections for mud weight and bit size are 
already applied to the gamma ray presented on the logs. 



Description 

This chart is for illustrative purposes only. The indicated correction 
is already applied on the gamma ray log. 

To determine the correction that was applied to the log output, 
enter the chart with the borehole size on the x-axis and move upward 
to intersect the downhole mud weight. From the intersection point 
move horizontally left to read the correction in gAPI units that was 
subtracted from the borehole-corrected data. 



44 



Back to Contents 



Gamma Ray— LWD 



arcVISION900* Gamma Ray— 9-in. tool 

Potassium Correction for Open Hole 



Schlumberger 



GR-26 



120 



Correction 
subtracted 
for 5-wt% 
potassium 
(gAPI) 



inn 
























an 










^^1 


20 ppg' 
8ppg^ 










„-•"'' 


fin 










^16 p| 

14ppg 


'9 


,-'''' 


-"'" 


,-''' 


_-.-- 


'-''' 


4n 






«• 
f 


JOppg 


)2ppg' 


„-''- 


,-.-'' 


~ ~~~' 








?n 






'8.3 ppg 


?ppg,- 
















n 


























10 



11 



12 



13 



14 15 

Hole size (in.) 



16 



17 



19 



20 



*Markof Schlumberger 
© Schlumberger 



Purpose 

This chart is used to provide a correction that is subtracted from 
the borehole-corrected gamma ray from the arcVISION900 9-in. tool. 
Environmental corrections for mud weight and bit size are already 
applied to the gamma ray presented on the logs. 



Description 

This chart is for illustrative purposes only. The indicated correction 
is already applied on the gamma ray log. 

To determine the correction that was applied to the log output, 
enter the chart with the borehole size on the x-axis and move upward 
to intersect the downhole mud weight. From the intersection point 
move horizontally left to read the correction curve in gAPI units that 
was subtracted from the borehole-corrected data. 



Back to Contents 



45 



Gamma Ray— LWD 



Schlumberger 



EcoScope* Integrated LWD Gamma Ray — 6.75-in. Tool 

Borehole Correction for Open Hole 



GR-27 




3.00 






2.75 
2.50 
2.25 

2.00 

Correction , jr 
factor 

1.50 
1.25 
1.00 
0.75 
0.50 
















































































































































































































25-in 




.,-- 


.--- 


.--- 


-"* 
























^ _ 


..-- 


---' 


,--- 


_12 


bit 
















_^_ 


---- 





.,— 



















10.625-in. bit 
— 1 1 
9.875-in. bit 

1 








































_J 


.75-in. bit— 
i.5-in. bit 


























! 


























































































*Markof Schlumberger 
© Schlumberger 


9 10 11 12 13 14 15 16 17 18 19 

Mud weight (Ibm/gal) 



Purpose 

This chart is used to provide a correction factor for gamma ray 
values measured with the EcoScope 6.75-in. Integrated LWD tool. 
These environmental corrections for mud weight and bit size are 
normally already applied to the gamma ray presented on the field 
logs. 



Description 

Enter the chart with the mud weight on the x-axis and move upward 
to intersect the appropriate bit size. Interpolate between lines as 
necessaiy. At the intersection point, move horizontally left to the 
y-axis to read the appropriate correction factor that the EcoScope 
6.75-in. gamma ray value was multiplied by to obtain the corrected 
gamma ray value in gAPI units. 



46 



Back to Contents 



Gamma Ray— LWD 



EcoScope* Integrated LWD Gamma Ray — 6.75-in. Tool 

Potassium Correction for Open Hole 



Schlumberger 



GR-28 



50 






45 
40 
35 

30 

Correction 
subtracted 
for5-wt% 25 
potassium 
(gAPI) 

20 

15 

10 

5 
























































,,--- 


.---''" 












M ppg" 


---"' ,,. 


_,,---' 


_---""" 








„. *•** 


16 


18 ppg'' 
D P g- 


__,-''" 


--'"'' 






,,'* 


- ,-.-*" ^*" 


^-*" 


-' 14pp 


g"" ^ 








+ '* ^. 


-''''.---' 


';;;::> 


10 


^I2ppg^ 
ppg" 










•'^--''', 


-**"*''" -~0~~~~' 




- 8.3 ppg 


^^~ — " 














































8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 13.0 

Hole size (in.) 

*Markof Schlumberger 
© Schlumberger 




Purpose 

This chart is used to illustrate the potassium correction that is sub- 
tracted from the borehole-corrected gamma ray from the EcoScope 
6.75-in. Integrated LWD tool. Environmental corrections for mud 
weight, bit size, and potassium are normally already applied to the 
gamma ray presented on the field logs. 



Description 

This chart is for illustrative purposes only. The indicated correction 
is already applied on the gamma ray log. The chart shows the correc- 
tion for a typical 5-wt% potassium concentration. 

To determine the correction that was applied to the log output, 
enter the chart with the borehole size on the x-axis and move upward 
to intersect the downhole mud weight. From the intersection point 
move horizontally left to read the correction curve in gAPI units that 
was subtracted from the borehole-corrected data. 



Back to Contents 



47 



Spontaneous Potential — Wireline 



Rweq Determination from Essp 



Schlumberger 




Purpose 

This chart and nomograph are used to calculate the equivalent for- 
mation water resistivity (R W eq) from the static spontaneous potential 
(Essp) measured in clean formations. The value of R weq is used in 
Chart SP-2 to determine the resistivity of the formation water (R w ). 
R w is used in Archie's water saturation equation. 

Description 

Enter the chart with Essp in millivolts on the x-axis and move 
upward to intersect the appropriate temperature line. From the 
intersection point move horizontally to intersect the right y-axis for 
Rmfeq/Rweq. From this point, draw a straight line through the equiva- 
lent mud filtrate resistivity (Rmfeq) point on the Rmf eq nomograph to 
intersect the value of R we q on the far-right nomograph. 

The spontaneous potential (SP) reading corrected for the effect 
of bed thickness (Espcoi) from Chart SP-4 can be substituted for Essp- 



Example 

First determine the value of Rmfe q : 

■ If Rmf at 75°F is greater than 0.1 ohm-m, correct Rmf 
to the formation temperature by using Chart Gen-6, 
and use Rmfeq = 0.85Rmf. 

■ If Rmf at 75°F is less than 0. 1 ohm-m, use Chart SP-2 
to derive a value of Rmfeq at formation temperature. 

Given: Essp = -100 mV at 250°F and resistivity of the mud 
filtrate (Rmf) = 0.7 ohm-m at 100°F, converted to 0.33 
at 250°F. 



Find: R weq at 250°F. 

Answer: Rmf eq = 0.85Rmf = 0.S 



xO.S 



: 0.28 ohm-m. 



Draw a straight line from the point on the Rmfeq/Rweq line 
that corresponds to the intersection of Essp = -100 mV 
and the interpolated 250°F temperature curve through 
the value of 0.28 ohm-m on the Rmfeq line to the R W eq line 
to determine that the value of R weq is 0.025 ohm-m. 

The value of Rmfeq/Rweq can also be determined from the 
equation 

ESSP = K c log (Rmfeq/Rweq), 

where K c is the electrochemical spontaneous potential 
coefficient: 

K c = 61 + (0.133 xTemp°F) 

K c = 65 + (0.24 x Temp°C). 



48 



Back to Contents 



Spontaneous Potential — Wireline 



Rweq Determination from Essp 



Schlumberger 



SP-1 

(former SP-1) 



0.3 

0.4 

0.5 
0.6 


















F 


mfe 


q/ n we q 

0.3 


R 
(oh 

feq 

n-m) 
01 


weq 

n-m) 
_ 0.001 

L 0.005 

1 0.01 
1 0.02 

1 0.05 

Z 0.1 
L 0.2 

L 0.5 

Z 1.0 

L 2.0 






















. 0.4 

R 


































-- 














0.6 (ohr 


0.8 
1 

2 














1111111111111111 












1 0.8 
11 1 


. 0.02 
I 0.04 

: o.o6 

L 0.1 

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. 20 

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I 100 










































































































































































































































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R mf /R w 4 
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© Schlumberger 


) -50 
Static spontaneous p 


1 X \ , 1 IV. I n I i« 

-100 -150 -200 : 
otential, E SSP (mV) - 



< ► 



Back to Contents 



49 



Spontaneous Potential — Wireline 



Rweq versus R w and Formation Temperature 



Schlumberger 



SP-2 

(customary, former SP-2) 




0.001 



0.002 



0.005 



0.01 



0.02 



''weq *■" ""mfeq 

(ohm-m) 0.05 1 



0.1 



0.2 L 



0.5 



1.0 



2.0 



|\ 500° F 
t\ 400° F 



300° F 







0.005 




J I i i i i 



0.02 0.03 



0.1 0.2 0.3 

R,„ or FL, (ohm-m) 



© Schlumberger 



Purpose 

This chart is used to convert equivalent water resistivity (R weq ) from 
Chart SP-1 to actual water resistivity (R w ). It can also be used to con- 
vert the mud nitrate resistivity (Rmf) to the equivalent mud filtrate 
resistivity (Rmf eq ) in saline mud. The metric version of this chart is 
Chart SP-3 on page 49. 



The dashed lines can also be used for gypsum-base mud nitrates. 



Example 

Given: 

Find: 
Answer: 



Description 

The solid lines are used for predominantly NaCl waters. The dashed 
lines are approximations for "average" fresh formation waters (for 
which the effects of salts other than NaCl become significant). 

50 

a ► Back to Contents 



From Chart SP-1, R weq = 0.025 ohm-m at 250°F in 
predominantly NaCl water. 

R w at250°F. 

Enter the chart at the R we q value on the y-axis and move 
horizontally right to intersect the solid 250°F line. From 
the intersection point, move down to find the R w value 
on the x-axis. R w = 0.03 ohm-m at 250°F. 



Spontaneous Potential — Wireline 



Rweq versus R w and Formation Temperature 



Schlumberger 



SP-3 

(metric, former SP-2m) 



0.001 






0.002 

0.005 
0.01 
0.02 

■■weq *-" ''mfeq 

(ohm-m) 0-05 
0.1 
0.2 

0.5 
1.0 
20 


r 


\ 


\ 


- 250°C 
_200°C 

\ 1 Rf 


)°C 

100°C 




\ 


\ 


I 


k 






\ 


] \ 






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\ V 




_75°C 






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^ 


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© Schlumberger 


5 0.01 0.02 0.03 0.05 0.1 0.2 0.3 0.5 1.0 2 3 4 

R w or R mf (ohm-m) 






Purpose 

This chart is the metric version of Chart SP-2 for converting equiva- 
lent water resistivity (R weq ) from Chart SP-1 to actual water resistiv- 
ity (Rw). It can also be used to convert the mud filtrate resistivity (Rmf) 
to the equivalent mud filtrate resistivity (Rmfeq) in saline mud. 

Description 

The solid lines are used for predominantly NaCl waters. The dashed 
lines are approximations for "average" fresh formation waters 



(for which the effects of salts other than NaCl become significant). 
The dashed lines can also be used for gypsum-base mud nitrates. 

Example 

Given: From Chart SP-1, R weq = 0.025 ohm-m at 121°C in 
predominantly NaCl water. 

Find: R w atl21°C. 

Answer: R w = 0.03 ohm-m at 12 FC. 



< ► 



Back to Contents 



Spontaneous Potential — Wireline 



Bed Thickness Correction — Open Hole 



Schlumberger 




Purpose 

Chart SP-4 is used to correct the SP reading from the well log for 
the effect of bed thickness. Generally, water sands greater than 
20 ft in thickness require no or only a small correction. 

Description 

Chart SP-4 incorporates correction factors for a number of condi- 
tions that can affect the value of the SP in water sands. 



The appropriate chart is selected on the basis of resistivity, inva- 
sion, hole diameter, and bed thickness. First, select the row of charts 
with the most appropriate value of the ratio of the resistivity of shale 
(R s ) to the resistivity of mud (R m ). On that row, select a chart for no 
invasion or for invasion for which the ratio of the diameter of invasion 
to the diameter of the wellbore (di/dh) is 5. Enter the x-axis with 
the value of the ratio of bed thickness to wellbore diameter (h/dh). 
Move upward to intersect the appropriate curve of the ratio of the 
true formation resistivity to the resistivity of the mud (Rt/R m ) for 
no invasion or the ratio of the resistivity of the flushed zone to the 
resistivity of the mud (R X o/Rm) for invaded zones, interpolating 
between the curves as necessaiy. Read the ratio of the SP read from 
the log to the corrected SP (Esp/Espcor) on the y-axis for the point of 
intersection. Calculate Espcor = Esp/(Esp/Esp C oi). The value of Egpcor 
can be used in Chart SP-1 for Essp. 



52 



Back to Contents 



Spontaneous Potential — Wireline 



Bed Thickness Correction — Open Hole 



Schlumberger 



SP-4 

(former SP-3) 



No Invasion 



Invasion, di/d h = 5 



EsP' ^sPcor 



1.0 



0.8 



0.6 



0.4 



0.2 

























10 
s. 












N 

'20 












\ 
























50 
\ 












100 
\ 






















200 






R,/R m / 





40 30 20 15 10 7.5 5 
h/d h 



EsP' EsPcor 



1.0 



0.8 



0.6 



0.4 



0.2 













^ 












"10 

s 












20 
\ 












\ 












RO 












\ 












100 












200, 
















R,/R m - 


500 . 



40 30 20 15 10 7.5 5 

h/d h 



:20 



EsP' Espcor 



1.0 



0.8 



0.6 



0.4 



0.2 













T-2: 

jo N 

20 
\ 












































50 
\ 
























100 , 












200 


















R,/R m — 


,000 



R.„ = 0.2R, 



I 1.0 



0.8 



0.6 



0.4 



0.2 





?> 


\ 














^ 


s 


"•^ 






X 


\\ 




•0.2 






V 




\ 


'or 


\ 










>,\ 




\ 








^ 




\ 


\ 






>\ 








\ s 




20\ 
50 N 














R xo/ R m —- 


• \ 

100 ■ 



1.0 



0.8 



0.6 



0.4 



0.2 

























,0.5 

1,\ 












\ N 












\ N 












& 












20 A 


































100 
200 . 






Rxo/ R m " 



1.0 



0.8 



0.6 



0.4 



0.2 













.0.5 
































10 N 
^ \ 












20 ' 












\\ 












50 
. \ 












100 












200 






Rxo/ R m ^ 





40 30 20 15 10 7.5 5 40 30 20 15 10 7.5 5 
h/d h h/d h 

1.0 1.0 



40 30 20 15 10 7.5 5 
h/d h 



0.8 



0.6 



0.4 



0.2 



1 


1 


\ 


S^ 




0.2 . 
0.5 




\\ 


> 


s N 


s 


\ 






\ 


s\ 


\ 


^ 






> 


s\ 


\ 


5— 






\ 




\ 












'10 s 












20 












'50 N 

J 00 
200 ■ 






Rxo/ R m — 















rj0.5. 


08 


























06 












10 














20 


04 












;\ 














50 


0? 












\\ 

100 

•» s 

-200 
'R00 ' 




















R xo/ R m 



1.0 



0.8 



0.6 



0.4 



0.2 













t 






















10 












20 












\ 












50 






















100 












200 
s 

500 , 






R xo/ R m -^ 



40 30 20 15 10 7.5 5 40 30 20 15 10 7.5 5 
h/d h h/d h 

1.0 1.0 



40 30 20 15 10 7.5 5 
h/d h 

















08 












-1 \ 
2 \ 














06 












5 
\ 














10 


04 












\ 

20 
\ 














09 












^50 














S 100 N 
200 ' 

500 '. 








Rxo/Rm^ 



0.8 



0.4 



0.2 













"2=!; 












5 \ 












10 












20 
\ 












s 












50 
\ 












s 












100 

> 












200 

•500 . 
,000 






R xo/ R m^ 



1.0 



0.8 



0.6 



0.4 



0.2 













r 4: 

10^" 

20 N 






















\ 












'50 












\ 












l ioo 












\ 












200 












500 






Rxo/Rn,- 1 ,.™- 



40 30 20 15 10 7.5 5 
h/d h 



40 30 20 15 10 7.5 5 40 30 20 15 10 7.5 5 
h/d h h/d h 



40 30 20 15 10 7.5 5 
h/d h 



5 Schlumberger 



< ► 



Back to Contents 



53 



Spontaneous Potential — Wireline 



Bed Thickness Correction — Open Hole (Empirical) 



Schlumberger 



SP-5 

(customary, former SP-4) 








100 










8-in. Hole; 3 3 /s-in. Tool, Centered 






1.0 
































i 

d s (in.) 


































^v 
















90 


























































V ( 


b 






Ri 






80 


















i\ 


^ 










R m 




















\* 






<§V 
















70 
60 


















* 














5 


_1.5 
















X 


j 




















^SSP 






































Correction 




(%) 






































factor 






50 


































20 


_2.0 








40 
































50 


12.5 












































Z3.0 








30 


































100 


_3.5 












































































_4.0 








20 
































" 


200 


1 5.0 
































v_ 




7 


] 50 


4 


D 3 


D 20 15 10 9 8 7 6 ! 


i 4 : 


















Bed thickness, h (ft) 








© Schlumberger 





















Purpose 

This chart is used to provide an empirical correction to the SP for 
the effects of invasion and bed thickness. The correction was obtained 
by averaging a series of thin-bed corrections in Reference 4. The 
resulting value of static spontaneous potential (Essp) can be used 
in Chart SP-1. 

Description 

This chart considers bed thickness (h) as a variable, and the ratio of 
the resistivity of the invaded zone to the resistivity of the mud (Ri/R m ) 
and the diameter of invasion (dj) as parameters of fixed value. The 
borehole diameter is fixed at 8 in. and the tool size at 3% in. 



To obtain the correction factor, enter the chart on the x-axis with 
the value of h. Move upward to the appropriate d; curve for the range 
of Ri/Rm- The correction factor on the y-axis corresponding to the 
intersection point is multiplied by the SP from the log to obtain the 
corrected SP. 



54 



Back to Contents 



Spontaneous Potential — Wireline 



Bed Thickness Correction — Open Hole (Empirical) 



Schlumberger 



SP-6 

(metric, former SP-4m) 



200-mm Hole; 86-mm Tool, Centered 



'-SSP 

(%) 




1.0 




.1.5 



Correction 
factor 



.2.0 



.2.5 

.3.0 

.3.5 
.4.0 

.5.0 



20 15 10 



5 3 2 

Bed thickness, h (m) 



© Schlumberger 



Purpose 

This chart is the metric version of Chart SP-5 for providing an empir- 
ical correction to the SP for the effects of invasion and bed thick- 
ness. The correction was obtained by averaging a series of thin-bed 
corrections in Reference 4. The resulting value of Essp can be used 
in Chart SP-1. 



Description 

This chart considers bed thickness (h) as a variable, and Ri/R m and 
di as parameters of fixed value. The borehole diameter is fixed at 
203 mm and the tool size at 86 mm. 



Back to Contents 



55 



Density — Wireline, LWD 



Porosity Effect on Photoelectric Cross Section 



Schlumberger 



Dens-1 




Pe k 
*- < 

1 2 3 4 5 6 0.5 0.4 0.3 0.2 0.1 




\ 1 Water' Gas \ 


Quartz Dolomite Calcite 

I I I 



Porosity Effect on Pe 


Matrix 


<t>, 


100% H 2 


100% CH 4 


Quartz 


0.00 


1.81 


1.81 


0.35 


1.54 


1.76 


Calcite 


0.00 


5.08 


5.08 


0.35 


4.23 


4.96 


Dolomite 


0.00 


3.14 


3.14 


0.35 


2.66 


3.07 


Specific 
gravity 





1.00 


0.10 



) Schlumberger 



Purpose 

This chart and accompanying table illustrate the effect that porosity, 
matrix, formation water, and methane (CH4) have on the recorded 
photoelectric cross section (Pe). 

Description 

The table lists the data from which the chart was made. As the 
porosity increases the effect is greater for each mineral. Calcite has 
the largest effect in the presence of gas or water as the porosity 
increases. 



Enter the chart with the total porosity (§ t ) from the log and move 
downward to intersect the angled line. From this point move 
to the left and intersect the line representing the appropriate matrix 
material: quartz, dolomite, or calcite minerals. From this intersection 
move upward to read the correct Pe. 



56 



Back to Contents 



Density — Wireline, LWD 



Apparent Log Density to True Bulk Density 



Schlumberger 



Dens-2 



Pb-Plog 

(g/cm 3 ) 



0.14 



0.12 



0.10 



0.08 



0.06 



0.04 



0.02 



-0.02 



-0.04 



Salt(NaCI) 
Sylvite (KCI) 



Magnesium 

<(> = 40% 




Add correction 

from y-axis to p| 0g 

to obtain true 

bulk density, p b 



Aluminum" 



cf» = 40% 



Limestone + water 
Dolomite + water 



Gypsum ( 
J 




© Schlumberger 



p to g(g/cm 3 : 



Purpose 

This chart is used to determine the true bulk density (pb) from the 
"apparent" recorded log value (piog). 

Description 

Enter the chart with the log density reading on the x-axis and move 
upward to intersect the mineral line that best represents the forma- 
tion. At this point, move horizontally left to read the value to be added 
to the log density. The individual mineral points reflect the log-derived 
density and the correction factor to be added or subtracted from the 
log value to obtain the true density of that mineral. 

The long diagonal lines representing zero porosity at the lower 
right and 40% porosity at the upper left are for dry gas in the forma- 
tion. The three points at the lower right of the diagonal lines rep- 
resent zero dry gas in the formation and are the endpoints for 



sandstone, limestone, and dolomite with water in the pores. This 
shows that there is a slight correction for water-filled formations 
from the log density value. 



Example 

Given: 

Find: 
Answer: 



Log density = 2.40 g/cm 3 in a sandstone formation 
(dry gas). 

Corrected bulk density. 

Enter the x-axis at 2.4 g/cm 3 and move upward to inter- 
sect the sandstone line. The correction from the y-axis is 
0.02 g/cm 3 . The correction value is added to the log den- 
sity to obtain the true value of the bulk density: 

2.40 + 0.02 = 2.42 g/cm 3 . 



Back to Contents 



57 



Neutron — Wireline 



Schlumberger 



Dual-Spacing Compensated Neutron Tool Charts 




This section contains interpretation charts to cover developments in 
compensated neutron tool (CNT) porosity transforms, environmental 
corrections, and porosity and lithology determination. 

CSU* software (versions CP-30 and later) and MAXIS* software 
compute three thermal porosities: NPHI, TNPH, and NPOR. 

NPHI is the "classic NPHI," computed from instantaneous near 
and far count rates, using "Mod-8" ratio-to-porosity transform with 
a caliper correction. 

TNPH is computed from deadtime-corrected, depth- and 
resolution-matched count rates, using an improved ratio-to-porosity 
transform and performing a complete set of environmental corrections 
in real time. These corrections may be turned on or off by the field 
engineer at the wellsite. For more information see Reference 32. 

NPOR is computed from the near-detector count rate and TNPH 
to give an enhanced resolution porosity. The accuracy of NPOR is 
equivalent to the accuracy of TNPH if the environmental effects on 
the near detector change less rapidly than the formation porosity. 
For more information on enhanced resolution processing, see 
Reference 35. 

Cased hole CNT logs are recorded on NPHI, computed from 
instantaneous near and far count rates, with a cased hole ratio-to- 
porosity transform. 



Using the Neutron Correction Charts 

For logs labeled NPHI: 

1. Enter Chart Neu-5 with NPHI and caliper reading to convert to 
uncorrected neutron porosity. 

2. Enter Charts Neu-1 and Neu-3 to obtain corrections for each 
environmental effect. Corrections are summed with the uncor- 
rected porosity to give a corrected value. 

3. Use crossplot Charts Por-11 and Por-12 for porosity and lithology 
determination. 

For logs labeled TNPH or NPOR, the CSU wellsite surface instru- 
mentation and MAXIS software have applied environmental correc- 
tions as indicated on the log heading. If the CSU and MAXIS 
software has applied all corrections, TNPH or NPOR can be used 
directly with the crossplot charts. In this case: 

1. Use crossplot Charts Por-11 and Por-12 to determine porosity 
and lithology. 



58 



Back to Contents 



Neutron — Wireline 



Compensated Neutron Tool 

Environmental Correction — Open Hole 



Schlumberger 



Purpose 

Chart Neu-1 is used to correct the compensated neutron log porosity 
index if the caliper correction was not applied. If the caliper correc- 
tion is applied, it must be "backed out" to use this chart. 

Description 

This chart is used only if the caliper correction was not applied 
to the logged data. The parameter section of the log heading lists 
whether correction was applied. 

Example 1: Backed-Out Correction of TNPH Porosity 

Given: Thermal neutron porosity (TNPH) from the log = 32 p.u. 
(apparent limestone units) and borehole size = 12 in. 

Find: Uncorrected TNPH with the correction backed out. 

Answer: Enter the top chart for actual borehole size at the inter- 
section point of the standard conditions 8-in. horizontal 
line and 32 p.u. on the scale above the chart. 

From this point, follow the closest trend line to intersect 
the 12-in. line for the borehole size. 

The intersection is the uncorrected TNPH value of 34 p.u. 

To use the uncorrected value on Chart Neu-1, draw a ver- 
tical line from this intersection through the remainder of 
the charts, as shown by the red line. 



Example 2: Environmentally Corrected THPH 

Given: Neutron porosity of 32 p.u. (apparent limestone units), 
without environmental correction, 12-in. borehole, Vi-m, 
thick mudcake, 100,000-ppm borehole salinity, 11-lbm/gal 
natural mud weight (water-base mud [WBM]), 150°F 
borehole temperature, 5,000-psi pressure (WBM), and 
100,000-ppm formation salinity. 

Find: Environmentally corrected TNPH porosity. 

Answer: If there is standoff (which is not uncommon), use Chart 
Neu-3. Then use Chart Neu-1 by drawing a vertical line 
through the charts for the previously determined 
backed-out (uncorrected) 34-p.u. neutron porosity 
value. 

On each environmental correction chart, enter the y-axis 
at the given value and move horizontally left to intersect 
the porosity value vertical line. 

For example, on the mudcake thickness chart the line 
extends from l A in. on the y-axis. 

At the intersection point, move parallel to the closest 
blue trend line to intersect the standard conditions, as 
indicated by the bullet. 

The point of intersection with the standard conditions 
for the chart is the value of porosity corrected for the 
particular environment. The change in porosity value 
(either positive or negative) is summed for the charts 
and referred to as delta porosity (A(|>). 

The A(|) net correction applied to the uncorrected log neutron 
porosity is listed in the table for the two examples. 




CNT Neutron Porosity Correction Examples 







Correction 




Example 1 


Example 2 


A(j) 


Log porosity 


32 p.u. 








Borehole size 


12 in. 


-2 






Mudcake thickness 


V,m. 









Borehole salinity 


100,000 ppm 




+1 




Mud weight 


11 Ibm/gal 




+2 




Borehole temperature 


150°F 




+4 




Wellbore pressure 


5,000 psi 




-1 




Formation salinity 


100,000 ppm 




-3 




Standoff (from Chart Neu-3) 


1 in. 




-4 




Net environmental correction 






-1 




Backed-out corrected porosity 




34 p.u. 






Environmentally corrected porosity 






33 p.u. 




Net correction 








-3 


Backed-out, environmentally corrected porosity 








31 p.u. 



< ► 



Back to Contents 



continued on next page 
59 



Neutron — Wireline 



Compensated Neutron Tool 

Environmental Correction — Open Hole 



Schlumberger 



Neu-1 

(customary, former Por-14c) 




Neutron log porosity index (appa 
10 20 


rent limestone porosity in p.u.) 

30 40 50 



71 




20 I / T 7 _ 




Actual borehole size 16 / / / S ,/ 




(in) _i2-_^i y y\ y ,y 


y i. ' ^' ^ y ^? 


s / ~7 2 TP* ~2* ' 


y "JZZ^ „*< ^ - . 


4 y _y y%_ ^ _«<>*_ 




1.0 




Mudcake thickness \j 1 1 1 J 




(m) t---J----t---t---t---i 


t \ X X 


t ___1 I Zt t [ 


t 1___^ . 


?50 




\ X X X X 


- X X- X~ X X - 


Borehole salinity \ \ \ i \ 


X X \ v a 


11 ,000 x ppml T \ t _t t. 


X J 3 \ \ 


X ^ \ a X 


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± ± \ _L \ 


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r '''j ^''"? ••t .y % "' % 


Oil hn^n muri 1 f " <"\ '••' / 


\~'\ Tv^y /■•■■' /! /. 


?fif) 


/ ... 


r i r r 


" \ A" X A \ " 


Limestone L L _) \_ 


Y % X V 


formatinn salinity / / / / 


.__/_ 1 ±11 


(1000 v DDm)' / /' y / 


"/ "& J / JL 


Ii,uuuxppm| o tL y y y * 


y ,<y\ y y / 






10 20 

© Schlumberger 


30 40 50 

• Standard conditions 



60 



< ► 



Back to Contents 



Neutron — Wireline 



Compensated Neutron Tool 

Environmental Correction — Open Hole 



Schlumberger 



Neu-2 

(metric, former Por-14cm) 



Neutron log porosity index (apparent limestone porosity) 

10 20 30 40 50 

I I I I I I 



600 
500 
Actual borehole size 400 
(mm) 300 

200 
100 




ludcake thickness 
(mm) 



Borehole salinity 
(g/kg) 



25 

12.5 


250 




1.5 



Mud density 1 -° 

(g/cm 3 ) 2.0 



149 

121 

Borehole temperature 93 

(°C) 66 

38 

10 

□ 172 

Pressure ,no 

(MPa) ]j£ 

Water-base mud °? 

34 
Oil-base mud J! 

250 

Limestone 

formation salinity 

(g/kg) 



LLim IXXX 


/ / / L l_l_l\ 




y v T 


I \ A- T \ 


\ 


\ 


4 4 V 


t L L V V 


\ 


\ 


4 4 4 


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4 4 4 


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1.0 _ 1 ± ± _ 


± \ \ \ \_ 


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a 



1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 

10 20 30 40 50 

• Standard conditions 



© Schlumberger 



Purpose 

This chart is the metric version of Chart Neu-1 for correcting the 
compensated neutron tool porosity index. 



< ► 



Back to Contents 



Neutron — Wireline 



Compensated Neutron Tool 

Standoff Correction — Open Hole 



Schlumberger 



Purpose 

Chart Neu-3 is used to determine the porosity change caused by 
standoff to the uncorrected thermal neutron porosity TNPH from 
Chart Neu-1. 

Description 

Enter the appropriate borehole size chart at the estimated neutron 
tool standoff on the y-axis. Move horizontally to intersect the uncor- 
rected porosity. At the intersection point, move along the closest 
trend line to the standard conditions line defined by the bullet to 
the right of the chart. This point is the porosity value corrected for 
tool standoff. The difference between the standoff-corrected porosity 
and the uncorrected porosity is the correction itself. 



Example 

Given: 

Find: 
Answer: 



TNPH = 34 p.u., borehole size = 12 in., and 
standoff =0.5 in. 

Porosity corrected for standoff. 

Draw a vertical line from the uncorrected neutron log 
porosity of 34 p.u. Enter the 12-in. borehole chart at 
0.5-in. standoff and move horizontally right to intersect 
the vertical porosity line. From the point of intersection 
move parallel to the closest trend line to intersect the 
standard conditions line (standoff = in.). The standoff- 
corrected porosity is 32 p.u. The correction is -2 p.u. 




62 



Back to Contents 



Neutron — Wireline 



Compensated Neutron Tool 

Standoff Correction — Open Hole 



Schlumberger 



Neu-3 

(customary, former Por-14d) 



Actual C 
borehole size 


Neutron log porosity index (apparent limestone 

10 20 30 



Dorosity in p.u.) 

40 50 









6 in. 




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5 

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10 

9 

8 

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5 

4 

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c 

© Schlumberger 


1 1 I 111 

10 20 30 


1 

40 \ 
• Standard conditions 


1 

)0 



< ► 



Back to Contents 



63 



Neutron — Wireline 



Compensated Neutron Tool 

Standoff Correction — Open Hole 



Schlumberger 



Neu-4 

(metric, former Por-14dm) 




Actual C 
borehole size 


Neutron log porosity index (apparent limestone porosity) 

10 20 30 40 50 








25 
150 mm 




J 










1 








1 








1 






















\ 
































/ 










J 








J 








J 






1 








1 






































1 








■ 


' 






/ 


' 






/ 


' 






, 










( 






1 






































50 

200 mm 25 








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175 

Standoff q 5Q 

(mm) 

125 

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75 

50 

25 




























































































-1 • 


















































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































250 

225 

200 

175 

150 
600 mm ^ 

100 

75 

50 

25 






















































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































( 

© Schlumberger 


1 1 1 1 

) 10 20 30 40 i 

• Standard conditions 


1 

so 



Purpose 

This chart is the metric version of Chart Neu-3 for determining the 
porosity change caused by standoff. 

64 

< ► Back to Contents 



Neutron — Wireline 



Compensated Neutron Tool 

Conversion of NPHI to TNPH— Open Hole 



Schlumberger 



Neu-5 

(former Por-14e) 





NPHI porosity index (apparent limestone porosity in p.u.) 

5 10 20 30 40 50 
.... 1 1 1 1 1 1 


24 






20 

Borehole size '° 

M » 

4 




































7 






/ 








/ 


' 








/ 


/ 








/ 


/ 








/ 


/ 








/ 


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/ 


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*>*' 
















© Schlumberger 


10 

TNPH porosity index ( 


20 30 40 50 
apparent limestone porosity in p.u.) 

• Standard conditions 




Purpose 

This chart is used to determine the porosity change caused by the 
borehole size to the neutron porosity NPHI and convert the porosity 
to thermal neutron porosity (TNPH). This chart corrects NPHI only 
for the borehole sizes that differ from the standard condition of 8 in. 
Refer to Chart Neu-1 to complete the environmental corrections for 
the TPNH value obtained. 

Description 

Enter the scale at the top of the chart with the NPHI porosity. 



Example 

Given: 

Find: 
Answer: 



NPHI porosity = 12.5% and borehole size = 16 in. 

Porosity correction for nonstandard borehole size. 

Enter the chart with the uncorrected porosity value 
of 12.5 at the scale at the top. Move down vertically 
to intersect the standard conditions line indicated by 
the bullet to the right. Enter the chart on the y-axis with 
the actual borehole size at the zone of interest and move 
horizontally right across the chart. 



At the point of intersection of the vertical line and the 
standard conditions line, move parallel to the closest 
trend line to intersect the actual borehole size line. 

At that intersection point move vertically down to the 
bottom scale to determine the TNPH porosity corrected 
only for borehole size. This value is also used to deter- 
mine the change in porosity as a result of tool standoff. 

TNPH = 12.5 + 5 = 17.5 p.u. 



Back to Contents 



65 



Neutron — Wireline 



Compensated Neutron Tool 

Formation £ Correction for Environmentally Corrected TNPH — Open Hole 



Schlumberger 




Purpose 

This chart is used to further correct the environmentally corrected 
TNPH porosity from Chart Neu-1 for the effect of the total forma- 
tion capture cross section, or sigma (£), of the formation of inter- 
est. This correction is applied after all environmental corrections 
determined with Chart Neu-1 have been applied. 

Description 

Enter the chart with £ for the appropriate formation along the y-axis 
and the corrected TNPH porosity along the x-axis. Where the lines 
drawn from these points intersect, move parallel to the closest trend 
line to intersect the appropriate fresh- or saltwater line to read the 
corrected porosity. 

The chart at the bottom of the page is used to correct the £- 
corrected porosity for salt displacement if the formation £ is due to 
salinity. However, this correction is not made if the borehole salinity 
correction from Chart Neu-1 has been applied. 



Example 

Given: 



Find: 



Answer: 



Corrected TNPH from Chart Neu-1 = 38 p.u., £ of the 
sandstone formation = 33 c.u., and formation salinity = 
150,000 ppm (indicating a freshwater formation). 

TNPH porosity corrected with Chart Neu-1 and for £ of 
the formation. 

Enter the appropriate chart with the £ value on the y-axis 
and the corrected TNPH value on the x-axis. At the inter- 
section of the sigma and porosity lines, parallel the clos- 
est trend line to intersect the freshwater line. (If the 
water in the formation is salty, the 250,000-ppm line 
should be used.) 

Move straight down from the intersection point to the 
formation salinity chart at the bottom. 

From the point where the straight line intersects the top 
of the salinity correction chart, parallel the closest trend 
line to intersect the formation salinity line. 

Draw a vertical line to the bottom scale to read the cor- 
rected formation sigma TNPH porosity, which is 35 p.u. 



66 



Back to Contents 



Neutron — Wireline 



Compensated Neutron Tool 

Formation £ Correction for Environmentally Corrected TNPH — Open Hole 



Schlumberger 



Neu-6 

(former Por-1 6) 



Neutron log porosity index 

10 20 30 
1 1 1 


40 50 
i 1 


70 






60 

Sandstone formation grj 
Formation! (c.u.) 

40 






















































































































' 


































. 








1 




















































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Back to Contents 



67 



Neutron — Wireline 



Compensated Neutron Tool 

Mineral I Correction for Environmentally Corrected TNPH — Open Hole 



Schlumberger 



Purpose 

This chart is used to further correct the environmentally corrected 
TNPH porosity from Chart Neu-1 for the effect of the mineral sigma 
(£). This correction is applied after all environmental corrections 
determined with Chart Neu-1 have been applied. 

Description 

Enter the chart for the formation type with the mineral £ value along 
the y-axis and the Chart Neu-1 corrected TNPH porosity along the 
x-axis. Where lines drawn from these points intersect, move parallel to 
the closest trend line to intersect the freshwater line to read the 
corrected porosity on the scale at the bottom. The choice of chart 
depends on the type of mineral in the formation. 



Example 

Given: 



Find: 



Answer: 



Corrected TNPH from Chart Neu-1 = 38 p.u., sandstone 
formation £ = 35 c.u., and formation salinity = 
150,000 ppm (indicating a freshwater formation). 

TNPH porosity corrected with Chart Neu-1 and for the 
mineral £. 

At the intersection of the £ and porosity value lines 
move parallel to the closest trend line to intersect the 
freshwater line. Move straight down to intersect the bot- 
tom prosify scale to read the TNPH porosity corrected 
for mineral £, which is 33 p.u. 




68 



Back to Contents 



Neutron — Wireline 



Compensated Neutron Tool 

Mineral I Correction for Environmentally Corrected TNPH — Open Hole 



Schlumberger 



Neu-7 

(former Por-17) 



Neutron log porosity index 

10 20 30 40 50 



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( 

© Schlumberger 


1 1 1 1 1 

) 10 20 30 40 50 




•* ► 



Back to Contents 



69 



Neutron — Wireline 



Compensated Neutron Tool 

Fluid £ Correction for Environmentally Corrected TNPH — Open Hole 



Schlumberger 




Purpose 

This chart is used to correct the environmentally corrected TNPH 
porosity from Chart Neu-1 for the effect of the fluid sigma (£) in 
the formation. This correction is applied after all environmental 
corrections determined with Chart Neu-1 have been applied. 

Description 

Enter the appropriate formation chart with the formation fluid £ 
value on the y-axis and the Chart Neu-1 corrected TNPH porosity on 
the x-axis. Where the lines drawn from these points intersect, move 
parallel to the closest trend line to intersect the appropriate fresh- 
or saltwater line. If the borehole salinity correction from Chart Neu-1 
has not been applied, from this point extend a line down to intersect 
the formation salinity chart at the bottom. Move parallel to the 
closest trend line to intersect the formation salinity line. Move 
straight down to read the corrected porosity on the scale below 
the chart. 



Example 

Given: 



Find: 
Answer: 



Corrected TNPH from Chart Neu-1 = 30 p.u. (without 
borehole salinity correction), fluid £ = 80 c.u., fluid 
salinity = 150,000 ppm, and sandstone formation. 

TNPH corrected with Chart Neu-1 and for fluid £. 

At the intersection of the fluid £ and Chart Neu-1 
corrected TNPH porosity (30-p.u.) line, move parallel 
to the closest trend line to intersect the freshwater line. 

From that point go straight down to the formation salinity 
correction chart at the bottom. 

Move parallel to the closest trend line to intersect the 
formation salinity line (150,000 ppm), and then draw a 
vertical line to the bottom scale to read the corrected 
TNPH value (26 p.u.). 



70 



Back to Contents 



Neutron — Wireline 



Compensated Neutron Tool 

Fluid £ Correction for Environmentally Corrected TNPH — Open Hole 



Schlumberger 



Neu-8 

(former Por-1 8) 



Neutron log porosity index 



L 



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Fluid Zlc.u.) 



160 

140 

120 

100 

80 

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20 
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10 



20 



30 



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40 



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50 



< ► 



Back to Contents 



Neutron — Wireline 



Compensated Neutron Tool 

Environmental Correction — Cased Hole 



Schlumberger 




Purpose 

This chart is used to obtain the correct porosity from the neutron 
porosity index logged with the compensated neutron tool in casing, 
where the effects of the borehole size, casing thickness, and cement 
sheath thickness influence the true value of formation porosity. 

Description 

Enter the scale at the top of the chart with a whole-number (not 
fractional) porosity value. Draw a straight line vertically through 
the three charts representing borehole size, casing thickness, and 
cement thickness. Draw a horizontal line on each chart from the 
appropriate value on the y-axis. At the intersection point of the verti- 
cal line and the horizontal line on each chart proceed to the blue 
dashed horizontal line by following the slope of the blue solid lines 
on each chart. At that point read the change in porosity index. The 
cumulative change in porosity is added to the logged porosity to obtain 
the corrected value. As can be seen, the major influences to the casing- 
derived porosity are the borehole size and the cement thickness. The 
same procedure applies to the metric chart. 

The blue dashed lines represent the standard conditions from 
which the charts were developed: 8 3 /4-in. open hole, 5'/2-in. 17-lbm 
casing, and 1.62-in. annular cement thickness. 

The neutron porosity equivalence nomographs at the bottom are 
used to convert from the log standard of limestone porosity to poros- 
ity for other matrix materials. 

The porosity value corrected with Chart Neu-9 is entered into 
Chart Neu-1 to provide environmental corrections necessaiy for 
determining the correct cased hole porosity value. 



Example 

Given: 



Find: 



Answer: 



Log porosity index = 27%, borehole diameter = 11 in., 
casing thickness = 0.304 in., and cement thickness = 
1.62 in. 

Cement thickness is defined as the annular space 
between the outside wall of the casing and the borehole 
wall. The value is determined by subtracting the casing 
outside diameter from the borehole diameter and divid- 
ing by 2. 

Porosity corrected for borehole size, casing thickness, 
and cement thickness. 

Draw a vertical line (shown in red) though the three 
charts at 27 p.u. 

Borehole-diameter correction chart: From the intersec- 
tion of the vertical line and the 11-in. borehole-diameter 
line (shown in red dashes) move upward along the 
curved blue line as shown on the chart. 

The porosity is reduced to 26% by -1 p.u. 

Casing thickness chart: The porosity index is changed 
by 0.3 p.u. 

Cement thickness chart: The porosity index is changed 
by 0.5 p.u. 

The resulting corrected porosity for borehole, casing, 
and cement is 27 - 1 + 0.3 + 0.5 = 26.8 p.u. 



72 



Back to Contents 



Neutron — Wireline 



Compensated Neutron Tool 

Environmental Correction — Cased Hole 



Schlumberger 



Neu-9 

(former Por-14a) 



Customary 

10 20 30 40 50 

Neutron log porosity index I ■ ■ ■ ■ i ■ ■ ■ ■ I ■ ■ ■ ■ i ■ ■ ■ ■ I ■ ■ ■ ■ i ■ ■ ■ ■ I ■ ■ ■ ■ i ■ ■ ■ ■ I ■ ■ ■ ■ i ■ ■ ■ ■ I 

(P-u.) 4 

6 

Diameter of borehole 8 

before running casing 10 

(in.) 12 

Casing thickness (in.) ^ 
9.5 x \0.2 

11.6.. 14 -- 



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weight 
(Ibm/ftl 



13.5.. 
15.1.. 



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20.. 26.. 



20 -■ 29.. 



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300 



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_l 



© Schlumberger 



• Standard conditions 



< ► 



Back to Contents 



73 



Neutron — Wireline 



APS* Accelerator Porosity Sonde 

Environmental Correction — Open Hole 



Schlumberger 




Purpose 

The Neu-10 charts pair is used to correct the APS Accelerator Porosity 
Sonde apparent limestone porosity for mud weight and actual bore- 
hole size. The charts are for the near-to-array and near-to-far poros- 
ity measurements. The design of the APS sonde resulted in a 
significant reduction in environmental correction. The answer deter- 
mined with this chart is used in conjunction with the correction 
from Chart Neu-11. 

Description 

Enter the appropriate chart pair (mud weight and actual borehole 
size) for the APS near-to-array apparent limestone porosity (APLU) 
or APS near-to-far apparent limestone porosity (FPLU) with the 
uncorrected porosity from the APS log by drawing a straight vertical 
line (shown in red) through both of the charts. At the intersection 
with the mud weight value, move parallel to the closest trend line to 
intersect the standard conditions line. This point represents a change 
in porosity resulting from the correction for mud weight. Follow the 
same procedure for the borehole size chart to determine that correc- 
tion change. Because the borehole size correction has a dependency 
on mud weight, even with natural muds, there are two sets of curves 
on the borehole size chart — solid for light muds (8.345 lbm/gal) and 
dashed for heavy muds (16 lbm/gal). Intermediate mud weights are 
interpolated. The two differences are summed for the total correc- 
tion to the APS log value. 

This answer is used in Chart Neu-11 to complete the environ- 
mental corrections for corrected APLU or FPLU porosity. 



Example 

Given: 

Find: 
Answer: 



APS neutron APLU uncorrected porosity = 34 p.u., 
mud weight = 10 lbm/gal, and borehole size = 12 in. 

Corrected APLU porosity. 

Draw a vertical line on the APLU mud weight chart from 
34 p.u. on the scale above. At the intersection with the 
10-lbm/gal mud weight line, move parallel to the trend 
line to intersect the standard conditions line. This point 
represents a change in porosity of -0.75 p.u. 

On the actual borehole size chart, move parallel to the 
closest trend line from the intersection of the 34-p.u. 
line and the actual borehole size (12 in.) to intersect 
the 8-in. standard conditions line. This point represents 
a change in porosity of -1.0 p.u. 

The total correction is -0.75 + -1.0 = -1.75 p.u., 
which results in a corrected APLU porosity of 
34 -1.75 = 32.25 p.u. 



74 



Back to Contents 



Neutron — Wireline 



APS* Accelerator Porosity Sonde 

Environmental Correction — Open Hole 



Schlumberger 



Neu-10 

(former Por-23a) 



APS near-to-array apparent limestone porosity uncorrected, APLU (p.u.! 



18 
16 

Mud weight 14 

(Ibm/gal) 12 

10 

8 

16 

14 

Actual ^2 

borehole size ^ 



t/lud weight 
(Ibm/gal) 



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borehole size 
(in.) 



14 
12 
10 





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APS near-to-far apparent limestone porosity uncorrected, FPLU (p.u.! 



2.0 
1.8 
1.6 
1.4 
1.2 
1.0 

400 
350 
300 
250 
200 



(g/cm 3 



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350 
300 
250 
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© Schlumberger 



| I I I I I I I I I | I I I I I I I I I | I I I I I I I I I | I I I I I I I I I | I I I I I I I I I | 

10 20 30 40 50 

• Standard conditions 



< ► 



Back to Contents 



75 



Neutron — Wireline 



APS* Accelerator Porosity Sonde Without Environmental Corrections 

Environmental Correction — Open Hole 



Schlumberger 



Neu-11 

(former Por-23b) 
























































Pressure 

(psi) (MPa) 



















































































































































































































































































































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5 i TlsS 


















































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IT'S- 4V N 




















































































































/ 
















































































































































































^* 






jr 


























SiTSNatHjI 












^ 








y 


s\ 


/ 






















v/N^J\wffl~T 










„ 


** 






" y 






































„ * 






X*"\, 




■•* 
























~^sl» 




















































^ 


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S 




y* 




























^. 


*^j 










r*\r 




























- I I I -f-p -p 


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r-* 


































.11 II. 



12 

11 

10 

9 

8 

7 

6 

5 

4 

3 

2 

1 



-1 



»F) 50 100 150 200 250 300 350 
>C) 10 38 66 93 121 149 177 
Formation temperature 



50 



150 



250 



Formation salinity 
(pptorg/kg) 



50 30 10 

Formation porosity 

(p.u.) 



Apparent 

porosity 

correction 

(p.u.) 



*Markof Schlumberger 
© Schlumberger 



Purpose 

This chart is used to complete the environmental correction for 
APLU and FPLU porosities from the APS log. 

Description 

Enter the left-hand chart on the x-axis with the temperature of the 
formation of interest. Move vertically to intersect the appropriate 
formation pressure line. From that point, move horizontally right to 
intersect the left edge of the formation salinity chart. Move parallel 
to the trend lines to intersect the formation salinity value. From that 
point move horizontally to intersect the left edge of the formation 
porosity chart. Move parallel to the trend lines to intersect the 
uncorrected APLU or FPLU porosity. At that intersection, move 
horizontally right to read the apparent porosity correction. 



Example 

Given: 



Find: 
Answer: 



APLU or FPLU porosity = 34 p.u., formation tempera- 
ture = 150°F, formation pressure = 5,000 psi, and for- 
mation salinity = 150,000 ppm. 

Environmentally corrected APLU or FPLU porosity. 

Enter the formation temperature chart at 150°F to inter- 
sect the 5,000-psi curve. From that point move horizon- 
tally right to intersect the left edge of the formation 
salinity chart. Move parallel to the trend lines to inter- 
sect the formation temperature of 150°F At this point, 
again move horizontally to the left edge of the next 
chart. Move parallel to the trend lines to intersect the 
34-p.u. porosity line. At that point on the y-axis, the 
change in porosity is +1.6 p.u. 

The total correction for a corrected APLU or FPLU 
from Charts Neu-10 and Neu-11 is 
34 + (-0.75 + -1) + 1.6 = 33.85 p.u. 



76 



Back to Contents 



Neutron— LWD 



Schlumberger 



CDN* Compensated Density Neutron, adnVISION* Azimuthal Density 
Neutron, and EcoScope* Integrated LWD Tools 

Mud Hydrogen Index Determination 



Purpose 

This chart is used to determine one of several environmental 
corrections for neutron porosity values recorded with the CDN 
Compensated Density Neutron, adnVISION Azimuthal Density 
Neutron, and EcoScope Integrated LWD tools. The value of hydrogen 
index (H m ) is used in the following porosity correction charts. 

Description 

To determine the H m of the drilling mud, the mud weight, tempera- 
ture, and hydrostatic mud pressure at the zone of interest must 
be known. 



Example 

Given: 

Find: 
Answer: 



Barite mud weight = 14 lbm/gal, mud temperature = 150°F, 
and hydrostatic mud pressure = 5,000 psi. 

Hydrogen index of the drilling mud. 

Enter the bottom chart for mud weight at 14 lbm/gal on 
the y-axis. Move horizontally to intersect the barite line. 

Move vertically to the bottom of the mud temperature 
chart and move upward parallel to the closest trend line 
to intersect the formation temperature. From the inter- 
section point move vertically to the bottom of the mud 
pressure chart. 

Move parallel to the closest trend line to intersect the 
formation pressure. Draw a line vertically to intersect 
the mud hydrogen index scale and read the result. 

Mud hydrogen index = 0.78. 




< ► 



Back to Contents 



continued on next page 
11 



Neutron— LWD 



CDN* Compensated Density Neutron, adnVISION* Azimuthal Density 
Neutron, and EcoScope* Integrated LWD Tools 

Mud Hydrogen Index Determination 



Schlumberger 



Neu-30 

(former Por-1 9) 




Mud hydrogen index, H m 

0.70 0.75 0.80 0.85 0.90 0.95 1 
1 i i i i 1 i i i i 1 i i i i 1 i i i i 1 i i i i 1 i i i i 




25 


t 






20 

Mud 
pressure 
(1,000 xpsi) 10 






















/ 




























































/ 


























































/ 


























































/ 
























































/ 


/ 




7 














































300 


i 






Mud 200 
temperature 
(°R 

100 

50 








S 


\ 


\ 






























































S 


\ 














































































































\ 




























































\ 


\ 
























1 




















16 




A 




14 

Mud 
weight 12 
(Ibm/gal) 

10 
8 






















































































































































































































v B 


arit 


e 


















































































































































































Bentoni 


te 






















































































0. 

*Markof Schlumberger 
© Schlumberger 


i i i i I i i i i I i i i i I i i i i I i i i i I i i i i 

70 0.75 0.80 0.85 0.90 0.95 1 





78 



< ► 



Back to Contents 



Neutron— LWD 



Schlumberger 



adnVISI0N475* Azimuthal Density Neutron— 4.75-in. Tool and 6-in. Borehole 

Environmental Correction — Open Hole 



Purpose 

This is one of a series of charts used to correct adnVISION475 
4.75-in. Azimuthal Density Neutron tool porosity for several environ- 
mental effects by using the mud hydrogen index (H m ) determined 
from Chart Neu-30 in conjunction with the parameters on the chart. 

Description 

This chart incorporates the parameters of borehole size, mud tem- 
perature, mud hydrogen index (from Chart Neu-30), mud salinity, 
and formation salinity for the correction of adnVISION475 porosity. 

The following charts are used with the same interpretation 
procedure as Chart Neu-31. The charts differ for tool size and 
borehole size. 



Example 

Given: 



Find: 
Answer: 



adnVISION475 uncorrected porosity = 34 p.u., borehole 
size = 10 in., mud temperature = 150°F, hydrogen 
index = 0.78, borehole salinity = 100,000 ppm, and forma- 
tion salinity = 100,000 ppm. 

Corrected adnVISION475 porosity. 

From the adnVISION475 porosity of 34 p.u. on the top 
scale, enter the borehole size chart to intersect the bore- 
hole size of 10 in. From the point of intersection move 
parallel to the closest trend line to intersect the stan- 
dard conditions line. 

From this intersection point move straight down to 
enter the mud temperature chart and intersect the mud 
temperature of 150°F. From the point of intersection 
move parallel to the closest trend line to intersect the 
standard conditions line. 

Continue this pattern through the charts to read the 
corrected porosity from the scale at the bottom of the 
charts. 

The corrected adnVISION475 porosity is 17 p.u. 




< ► 



Back to Contents 



continued on next page 
79 



Neutron— LWD 



Schlumberger 



adnVISI0N475* Azimuthal Density Neutron— 4.75-in. Tool and 6-in. Borehole 

Environmental Correction — Open Hole 



Neu-31 




adnVISI0N475 neutron porosity index (apparent limestone porosity) in 6-in. borehole 
10 20 30 40 50 


m 






























," 


^ 






«--■ 


**' 






















• 
* • 


Borehole 

o 






















** 


^ 




^ 


^* 


*>*' 


























size 

(in ) / 


















/ 


/ 






.'' 


rc 




-•' ' 


^" 


-"-' 




^ 


^ 






























/ 


/ 






/ 


y 


.'\. 


*' 




*"' 




*"' 






















6 














/ 






/ 




/ 


/ 




/ 




,' 
























300 














Mud 








\ 


, 












\ 


































temperature 200 










\ 
















































(°R 

100 






\ 




> 


v 


















































\ 






\ 












S \ 






































\ 








\ 












































07 






























































• 


Mud . 8 . 


















































1 








hydrogen 


















































1 








index, H m 0.9 


















































1 


























































1 








1.0 


















































1 












200 
















/ 








/ 




~_l 
















/ 
















Mud 








/ 








/ 






/ 


i 




f 




























/ 


salinity 100 








/ 






1 








/ 




. _i 


1 


























i 


/ 


(1,000 xppm) 








/ 






/ 






1 


' 




J 


























/ 


/ 













/ 






/ 






/ 






1 
























/ 


' 










200 


























































• 


Formation 
salinity 100 




















































































\ 




, 




, 












/ 








/ 


(1,000 xppm) 








/ 






1 








J 




/ _> 


1 




/ 




J 




i 


1 






/ 








/ 











/ 






/ 






/ 


/ 


/ 


J 




/ 




/ 


/ 


y 


/ 




y 


/ 






y 


/ 








I I 

10 

*Markof Schlumberger 
© Schlumberger 


11 1 1 1 1 

20 30 40 50 

• Standard conditions 



80 



< ► 



Back to Contents 



Neutron— LWD 



Schlumberger 



adnVISI0N475* BIP Neutron— 4.75-in. Tool and 6-in. Borehole 

Environmental Correction — Open Hole 



Neu-32 





adnVISI0N475 neutron porosity index (apparent limestone porosity) in 6-in. borehole 

10 20 30 40 50 



300 






Mud 2Q0 

temperature 

(°F) 

100 




























\ 


y 






\ 












\ 
























































\ 








\ 






\ 


































































\ 


i 






\ 








\ 


































































\ 






> 


v 






\ 


V 
















































1 
















\ 








\ 








\ 








































0.7 






Mud 0.8 
hydrogen 
index, H m ab 

1.0 




/ 






1 










i 










/ 








/ 














































/ 














I 










1 










/ 












































I 








I 


























/ 




























































i 


* 










1 








1 














































1 






/ 








/ 










1 








/ 






















































j 








r 








i 


i 






/ 


1 






















































Mud 200 
salinity 
(1,000 xppm) 10 ° 








/ 














i 


i 








/ 






1 


' 






/ 








1 


l 






i 


1 
























/ 






1 








1 








1 
















/ 
















/ 








/ 








1 








/ 






1 








1 










/ 








1 








/ 






1 


1 








/ 








/ 






, 








1 


/ 




1 


i 






/ 


i 








I 


f 






1 








/ 


















/ 








/ 














t 






J 








i 










i 








1 








/ 








f 










1 














i 














200 
Formation 

salinity 

(1,000 xppm) 








































































































































































) 






) 








j 
















1 
















1 


































/ 






! 








1 








j 








J 








/ 








I 








j 








/ 














y 


/ 




s 


/ 






/ 


/ 








/ 


/ 






/ 


/ 






/ 


' 






/ 


f 








/ 








/ 






) 


< 












( 

*Markof Schlumberger 
© Schlumberger 


) 10 20 30 40 50 




Purpose 

This chart is used similarly to Chart Neu-31 to correct 
adnVISION475 borehole-invariant porosity (BIP) measurements. 



Description 

Enter the top scale with the BIP neutron porosity (BNPH) to incor- 
porate corrections for mud temperature, mud hydrogen index, and 
mud and formation salinity. 



< ► 



Back to Contents 



Neutron— LWD 



Schlumberger 



adnVISI0N475* Azimuthal Density Neutron— 4.75-in. Tool 
and 8-in. Borehole 

Environmental Correction — Open Hole 



Neu-33 



adnVISI0N475 neutron porosity index (apparent limestone porosity) in 8-in. borehole 

10 20 30 40 50 

I i i i i I 



10 




Borehole 
size 
(in.) 



300 

Mud 
temperature 200 
(°F) 

100 



0.7 



8 
6 



r \ "\ s > \ x ^ s ^ ^ 


1 V \ \ Ss v ^ Ss, S ^^s ^ v ^ ^ V ^v, 


\ K \ \ ^^ s s s ^v^ Vs v^ ^ n v Nv 


t V V S s S ^ ^ v ^ ^ v ^ ^ v ^ ^ Nv 


5 V 2k ^ ^ S ^i. ^n. ^ V b*. ^ V *. 



























1 




















| 




































\ 


Mud 08 
























1 








































\ 








\ 








\ 


hydrogen 
























1 




















\ 












1 








\ 








\ 








\ 


index, H m 0.9 


































1 






























1 








\ 








n 


























1 




















' 




































\ 


1.0 . 












































1 




















\ 














\ 



200 
Mud 
salinity 100 

(1,000 xppm) 





J 7 J? y y /• y 


1 £ y' S' y 1 s* y* 


f / / / y 4 y 4 y* y 


Z Z Z z 7 Z /7 * y 


j L J Z Z Z jS* y y y 



200 
Formation 
salinity 100 

(1,000 xppm) 





1 T ___!_ __T__ 


4 i t i 


1. 4 -4- i t- 4- 


7 -4 / J / I j 


i / z z /As'± 



r 



*Markof Schlumberger 
© Schlumberger 



n~~i 

10 



Purpose 

This chart is used similarly to Chart Neu-31 to correct 
adnVISION475 porosity. 



20 



30 



40 



I 

50 

• Standard conditions 



82 



< ► 



Back to Contents 



Neutron— LWD 



Schlumberger 



adnVISI0N475* BIP Neutron— 4.75-in. Tool and 8-in. Borehole 

Environmental Correction — Open Hole 



Neu-34 



adnVISI0N475 neutron porosity index (apparent limestone porosity) in 8-in. borehole 
10 20 30 40 50 


3(10 














1 






\ 






\ 


\ 






\ 












\ 
































Mud 2Q0 














I 






\ 








\ 






\ 










































temperature 




















\ 


\ 






\ 








\ 








































100 






















\ 






\ 


V 






\ 


V 




























































\ 








\ 








s 






































0.7 




Mud 0.8 
hydrogen 
index, H m ab / 

1.0 . 


T^ 








/ 








1 










1 








/ 


























/ 














/ 








/ 








/ 








1 










/ 








































/ 








/ 
























/ 










































1 






/ 








l 


' 








I 








/ 
















































/ 








/ 








1 








/ 


' 
















































/ 






i 


/ 








1 








/ 
















































»„ j 200 _ 
















/ 




























1 








1 












/ 






/ 






Mud 












































1 


















1 


1 






/ 






salinity 










































/ 








1 






1 


1 




/ 








/ 






( l,uuu x ppm) 








































/ 


/ 






I 














/ 






1 








/ 








































/ 








/ 








I 






/ 
















200 














































































Formation 












































































Mn S nn lmltV , 100 




j 














i 








, 
















/ 


































(1,000 x ppm) 




1 






J 








J 








J 








/ 








/ 






I 








1 






/ 














n . 


/ 






• 


/ 






/ 


/ 






/ 


/ 






/ 


/ 






/ 


f 






J 








J 






/ 






/ 










10 20 30 40 50 

*Markof Schlumberger 
© Schlumberger 




Purpose 

This chart is used similarly to Chart Neu-32 to correct 
adnVISION475 borehole-invariant porosity (BIP) measurements. 



< ► 



Back to Contents 



83 



Neutron— LWD 



adnVISION675* Azimuthal Density Neutron— 6.75-in. Tool and 8-in. Borehole 

Environmental Correction — Open Hole 



Schlumberger 



Neu-35 

(former Por-26a) 



adnVISION675 neutron porosity indox (apparont limestone porosity in p.u.) 
10 20 30 40 50 

I I I I I I 



16 





































































































14 


































































































Borehole 




























































































































































































,in -' 10 


















































































































































































































































































8 


































































































300 



Mud 200 

temperature 
(°F) 

100 

50 











V \ S \ \ \ s s s s 








\ 


A \ S v \ \ \ S V S \ 










i V ^ \ V \ \ \ s s 










\ \ y \ \ \ s \ \ 










"1 >\>\Ks 








1 


: ±. _l_ l _l t. l ^l 



0.7 

Mud ° 8 

hydrogen 
index, H m 0.9 

1.0 



I I \ \ \ \ \ \ \ 


■-- 4- -I- -4- 4- -4- 4-4- XX- 


\ t 4 4 \ \ V \ V 


L _I_ ._[_ _i_ _1_ _\_. __L A _ V 


4 4 4 \ { \ V V t 


1 3 \ \ \ S S 



Mud 

salinity 

(1,000 xppm) 



250 
200 

100 



7 


t 


[ 


,_ _ h ._._ 


I ___! 



250 



Formation 

salinity 

(1,000 xppm) 



2.. ] T I \--l-X -X 


t t ^ 


,00 _ L 1 ,L i I -,- 4-4 


l i ijiit 


o LJ_L_z_L_z_a_J_ 



n -1 

10 



n -1 

20 



30 



H -1 

40 



n 

50 



*Markof Schlumberger 
© Schlumberger 



• Standard conditions 



Purpose 

This chart is used similarly to Chart Neu-31 to correct adnVISION675 
porosity. 



84 



< ► 



Back to Contents 



Neutron— LWD 



Schlumberger 



adnVISION675* BIP Neutron— 6.75-in. Tool and 8-in. Borehole 

Environmental Correction — Open Hole 



Neu-36 





adnVISI0N475 neutron porosity index (apparent limestone porosity) in 8-in. borehole 

] 10 20 30 40 50 



300 






Mud 200 
temperature 

<° F > 

100 
















1 






\ 






\ 


\ 






\ 












s 


















































I 






\ 








\ 






\ 


































































\ 


\ 






\ 








\ 


























































' 








\ 






\ 


\ 






\ 


V 
































































\ 








\ 








S 




































0.7 




Mud 0.8 
hydrogen 
index, H m °- 9 

1.0 




/ 










/ 


















1 








/ 












































/ 










/ 








I 








1 










/ 










































I 












/ 
























/ 






















































/ 








1 


< 








1 








/ 












































1 


















/ 








1 








1 
























































! 








/ 








1 








1 


















































R/l A 200 

Mud 
salinity 
(1,000 x ppm) 10 ° 






















/ 




























/ 








1 








































































/ 




















1 


1 






/ 


















































/ 








1 






1 


1 














/ 
















































/ 


/ 






1 






















1 


















































/ 








/ 








1 








1 


















200 
Formation 

Mnnn linity s ™ 
(1,000 x ppm) 








































































































































































j 










/ 






l 








i 
















/ 








































1 








i 








J 
















/ 








/ 






) 








1 








I 














y 


/ 








/ 


/ 






/ 


/ 






/ 


/ 






/ 


/ 






/ 


/ 






J 








J 














/ 














( 

*Markof Schlumberger 
© Schlumberger 


1 1 1 1 1 

1 10 20 30 40 50 




Purpose 

This chart is used similarly to Chart Neu-32 to correct 
adnVISION675 borehole-invariant porosity (BIP) measurements. 



< ► 



Back to Contents 



85 



Neutron— LWD 



adnVISION675* Azimuthal Density Neutron— 6.75-in. Tool and 10-in. Borehole 

Environmental Correction — Open Hole 



Schlumberger 



Neu-37 

(former Por-26b) 




[ 


adnVISI0N675 neutron porosity index (apparent limestone porosity in p.u.) 

10 20 30 40 50 


16 






14 
Borehole 
size 12 

(in -> 10 

8 
































































































































































































































































































































































































































































































































300 
















Mud 200 
temperature 
(°F) 

100 

50 




\ 


1 




\ 


\ 
































































\ 




\ 
























































, 




\ 






\ 






















































\ 




\ 


L 




\ 


i 


























































\ 






\ 


























































1 






\ 














































0.7 
















Mud °- 8 
hydrogen 
index, H m 0.9 

1.0 
















\ 










\ 


































\ 


\ 




















\ 










\ 
































A 


V 




















\ 










\ 


i 
































V 


\ 


















\ 












\ 












































\ 


I 






\ 


\ 










> 


\ 












































L 








\ 












\ 


* 
































250 














200 

Mud 
salinity 
(1,000 xppm) luu 








1 
































































j 








' 












/ 


















































i 












i 


» 










/ 








f 






/ 






, 




















i 












1 










j 


/ 






/ 


/ 






/ 




j 


/ 




I 








1 








i 










i 












/ 








/' 






/ 


/ 




/' 






/ 






250 














200 

Formation 
salinity 
(1,000 xppm) luu 




































, 










L_ 
























































, 








, 
























































i 








/ 












, 




















































, 






/ 






/ 






























i 


























/ 






1 






/ 












C 

*Markof Schlumberger 
© Schlumberger 


i i i i 

10 20 30 40 5 

• Standard conditions 






Purpose 

This chart is used similarly to Chart Neu-31 to correct 
adnVISION675 porosity. 



86 



< ► 



Back to Contents 



Neutron— LWD 



Schlumberger 



adnVISION675* BIP Neutron— 6.75-in. Tool and 10-in. Borehole 

Environmental Correction — Open Hole 



Neu-38 



adnVISI0N675 neutron porosity index (apparent limestone porosity) in 10-in. borehole 
10 20 30 40 50 


snn 






































\ 








\ 


\ 








\ 
















\ 


















Mud 200 




















\ 








\ 










\ 








\ 










\ 






























temperature 




















1 


1 








\ 








\ 










\ 








N 


\ 




























(°F) 

100 






























\ 










\ 








> 


\ 








\ 


\ 
























































\ 










\ 










\ 










\ 


























0.7 r 






Mud 0.8 
hydrogen 
index, H m °- 9 / 

1.0 . 












/ 








/ 




























/ 








/ 






























/ 








I 


r 








/ 
















I 


1 








1 










/ 








/ 


1 








/ 




















1 








/ 


















1 










1 








/ 


f 








/ 










/ 












1 






/ 








/ 


















/ 










/ 










/ 








; 


1 








/ 








/ 












/ 






/ 


/ 
















I 


1 








/ 


f 








/ 










/ 










/ 








/ 












T 






/ 


















/ 










1 










/ 








/ 


1 










/ 








1 














m a 200 \ 






















































































Mud 






















































































salinity 






















































































I i,uuu x ppm| 



















































































































































































200 


























\ 


1 








\ 








\ 








\ 


v 
















\ 
















Formation 












\ 








\ 








\ 








\ 


\ 








\ 








\ 
































Mnnn inity , 100 












\ 








\ 








\ 










\ 








\ 


\ 








\ 






























(1,000 xppm) 














I 






1 


1 








\ 








\ 


\ 








\ 










\ 



























































\ 










\ 










\ 










\ 




























I I I I I I 

10 20 30 40 50 

*Markof Schlumberger 
© Schlumberger 



Purpose 

This chart is used similarly to Chart Neu-32 to correct 
adnVISION675 borehole-invariant porosity (BIP) measurements. 



< ► 



Back to Contents 



87 



Neutron— LWD 



Schlumberger 



adnVISION825* Azimuthal Density Neutron— 8.25-in. Tool 
and 12.25-in. Borehole 

Environmental Correction — Open Hole 



Neu-39 




°F) 



Standoff = 0.25 in. 
adnVISI0N825 neutron porosity index (apparent limestone porosity) in 12.25-in. borehole 



1.5 

1.0 
Standoff 

(in.) 0.5 



16 

Borehole u 

size 



12 

10 

300 



Mud 200 

temperature 

(°F) 100 



10 



20 



30 
i_l_i 



40 



50 
jj 











/ 


























/ 


/ 










/ 


/ 










/ 










/ 


7- 








/ 


r 








/ 


r- 














/ 


/ 


























/ 












y 










y 


/ 








y 


y 








/ 


/ 








/ 


y 








/ 








/ 


t 
























s 










/ 


y 










y 


s 








y 


/ 








f 


y 








/■ 


y 








S 


y 








/ 
























y 










y 


y 








/■ 


y 










y 


y 








y 


y 








y 


y 








y 


y 






y 


I 




- 














y 


y 


y 










s 




y 


y 


w* 


y 


y 










y 






y 


y 


y 




y 


y 


y 


y 






w» 


y 


y 
















y' 







lll l lllillllill] 



iliiilii 



0.7 
Mud 08 

hydrogen 
index, H m 0.9 

1 

20 




























/ 












/ 


































































Pressure 10 
























/ 










/ 


r 


































































,000 x psi) 






















/ 










/ 


/ 



























































































/ 








_ 


/ 







































































200 


















\ 








\ 








\ 








\ 


V 
























































Mud 


















\ 








\ 










\ 








s 
























































salinity 100 


















' 


1 








\ 








\ 


V 








\ 






















































OOOxppm) 




















1 








\ 










\ 










\ 





































































































\ 





















































200 
Formation 
salinity 100 

(1,000 xppm) 





*Markof Schlumberger 
© Schlumberger 



i~~n 

10 



20 



30 



n~~i 

40 



n 

50 



• Standard conditions 



Purpose 

This chart is used similarly to Chart Neu-31 to correct 
adnVISION825 porosity. 



< ► 



Back to Contents 



Neutron— LWD 



CDN* Compensated Density Neutron and adnVISION825s* 
Azimuthal Density Neutron — 8-in. Tool and 12-in. Borehole 

Environmental Correction — Open Hole 



Schlumberger 



Neu-40 

(former Por-24c) 



Neutron porosity index (apparent limestone porosity) in 12-in. borehole 

10 20 30 40 50 
i i i i i i 


18 
















































































































































Borehole 






































































(in.) 14 






































































































































12 i 
































































350 










• 

• 
• 


300 




\ 




\ 


































































) 


\ 




\ 




























































Mud 






\ 




\ 




























































(°F) 






\ 




\ 




























































100 _ 






\ 




\ 


L 


























































50 " 






4 






\~ 


























































07 














I 








\ 


" 


\ 






























































1 








\ 






\ 


V 












































Mud 














\ 






\ 






\ 












































index, H m 0.9 




















\ 








\ 






















































| 


\ 








\ 






\ 


^ 








































1.0 
















L 






\ 








\ 








































250 








200 






































































Mud 










































































































































(1,000 x ppm) 





























































































































, 
















250 


200 




























1 








\ 


















1 
















Formation 


















1 


















■ 








/ 
























Mn S nn inity I "» 








I 


1 
















1 


/ 








1 










/ 
























(1,000 x ppm) 


/ 










/ 




/ 


/ 








I 








/ 


f 






/ 


/ 


























/ 


/ 






/ 




/ 




/ ; 








/ 








/ 








/ 


/ 






























1 1 1 1 1 

10 20 30 40 ! 

™„i.n.hi,,.h.„.. • Standard conditio 
Mark of Schlumberger 

© Schlumberger 


1 

50 

ns 




Purpose 

This chart is used similarly to Chart Neu-31 to correct 
CDN Compensated Density Neutron tool and adnVISION825s 
Azimuthal Density Neutron porosity. 



Back to Contents 



89 



Neutron— LWD 



CDN* Compensated Density Neutron and adnVISION825s* 
Azimuthal Density Neutron — 8-in. Tool and 14-in. Borehole 

Environmental Correction — Open Hole 



Schlumberger 



Neu-41 

(former Por-24d) 




Neutron porosity index (apparent limestone porosity) in 14-in. borehole 
10 20 30 40 50 


is A 














































































• 


16 












































































Borehole 












































































(in.) 14 






















































































































































12 L 


































































350 










c 




300 


\ 






















\ 






















































\ 


L 




















^ 


\ 


v 
















































Mud 
temperature 200 




\ 
























\ 
















































(°F) 




\ 
























,r n 
















































100 




























! 
















































50 " 














r 














r _> 


y A 














































07 


E 




\ 










































































0.8 


-\ 


























V 
















































•1 • 

« 


Mud 


\ 


\ 








































































index, H m 09 




\ 












































































\ 








































































1 n 




1 


\ 






































































250 


G 


200 
















i 






















1 








\ 






























Mud 














i 


1 






| 








/ 






i 


I 








1 






























salinity 

(1 nnn v nnml 100 _j 






















I 






\ 








/ 








/ 


I 


\ 


> 


' 






















1 


\ 






I 


' 






1 

i 








1 






1 






1 


f 








/ ; 




i 


/ 






















/ 


/ 


J 














i 






/ 








1 




1 


1 








/ 






& 




















/ 


/ 


> 




?5n 




200 
















l 








f 


































1 


















Formation 
























{ 






\ 








1 


1 






i 


\ 










1 


















salinity 
(1 000 x DDm) 100 


1 






1 
















1 






1 








1 








1 










! 




















_i 


I 






/ 






1 








I 






I 








/ 








/ 


1 


J 




i 


/ 




















/ 


.1 






1 


1 












/ 


1 






/ 




/ 


/ 








> 


i 




/ 


' 


/ 
















y 


/ 


/ 


/ 


K 




10 20 30 40 

"Mark of Schlumberger •Standard conditio 
© Schlumberger 


1 

50 

ns 



90 



< ► 



Back to Contents 



Neutron— LWD 



CDN* Compensated Density Neutron and adnVISION825s* 
Azimuthal Density Neutron — 8-in. Tool and 16-in. Borehole 

Environmental Correction — Open Hole 



Schlumberger 



Neu-42 

(former Por-24e) 



c 


Nautron porosity index (apparent limestone porosity) in 16-in. borehole 

10 20 30 40 \ 


10 

J 


18 






16 
Borehole 

size 

(in.) 14 

12 






































































































































































































































































































































































































































































350 


















• 


300 

Mud 
temperature 200 
(°F) 

100 
50 


"\ 














































































\ 












































































\ 












































































\ 


L 












































































\ 








































































_. 


-. 


J 


■ - 


-- J 




































































0.7 










0.8 
Mud 

hydrogen 

index, H m 09 

1 


























































































































































• 
• 


















































































































































































































































































































250 
















200 

Mud 
salinity 
(1,000 xppm) 10° 






| 






I 
















1 




















i 














































1 


l 






1 




















/ 


i 


































J 




/ 


1 






1 








1 


















1 


f 


































/ 






/ 






I 


1 






j 


1 
















/ 


r 




































L 






/ 




/ 


1 






/ 


/ 














/ 


/ 


/ 






































250 










200 

Formation 
salinity 
(1,000 xppm) 10° 












































i 




















j 






























' 














1 


1 








1 


1 




































i_ 












j 








1 


















j 
j 












































f 






1 








1 






J 


1 








J 


/ 




































/ 


1 






1 




1 








/ 


1 




/ 


1 








/ 


/ 
































/ 


/ 


/ 










C 

*Markof Schlumberger 
© Schlumberger 


i i i i 

10 20 30 40 ! 

• Standard conditio 


1 

50 

ns 



< ► 



Back to Contents 



Neutron— LWD 



Schlumberger 



EcoScope* Integrated LWD Neutron Porosity — 6.75-in. Tool 

Environmental Correction — Open Hole 



Purpose 

Charts Neu-43 through Neu-46 show the environmental corrections 
that are applied to EcoScope 6.75-in. Integrated LWD Tool neutron 
porosity measurements. These charts can be used to estimate the 
correction that is normally already applied to the field logs. 

Description 

The charts incorporate the parameters of borehole size, mud tem- 
perature, mud hydrogen index (from Chart Neu-30), mud salinity, 
and formation salinity for the correction of EcoScope 6.75-in. 
neutron porosity. 

Select the appropriate chart based on both the hole size and 
the measurement type: thermal neutron porosity (TNPH) or best 
thermal neutron porosity (BPHI). 



Enter the charts with the uncorrected neutron porosity data. 
Charts Neu-43 and Neu-44 are for use with BPHIJJNC, and Charts 
Neu-45 and Neu-46 are for use with TNPH_UNC. Because the bore- 
hole size correction is applied to the field logs, including the _UNC 
channels, do not include the borehole size correction, which is in the 
charts for illustrative purposes only. 

A correction for eccentricity effects is normally also applied to 
the field BPHI measurement. Because this correction is not included 
in these charts, there may be a small difference between the correc- 
tion estimated from the charts and that actually applied to the field 
data, depending on the tool position in the borehole. 

The charts are used with a similar procedure to that described 
for Chart Neu-31. 




92 



Back to Contents 



Neutron— LWD 



Schlumberger 



EcoScope* Integrated LWD BPHI Porosity — 6.75-in. Tool and 8.5-in. Borehole 

Environmental Correction — Open Hole 



Neu-43 



EcoScope uncorrected BPHI porosity (apparent limestone porosity in p.u.) in 8.5-in. borehole 

10 20 30 40 50 
i i i i i i 


14 
































4 










/ 




-1 • 


13 . 






























1 




/ 






' 


/ 
































t 








i 






12 






































/ 






Borehole 






































/ 










































_, 


1 




/ 












































/ 


(m.) io 










































/ 






































/ 




1 




9 . 




































J 












































/ 




' 




8.' 




































t 






























n 




, 






































260 . 










\ 








































\ 




\ 


































210 . 


















































\ 




\ 


































loci 160 . 










1 


































( H 






' 






































110 . 








. 


] 














































\ 
































60 












1 
































70 






















1 


























0.75 _ 




















1 












































1 
























0-80 - 
















L 




1 
























Mud 




















1 
















































































































index, H m .90 " 






































































1 


















0.95 


























: 


























. 




































1.00 












































250 












. 






















7 






























200 
















7 




1 






, 


































7 




I 






j 


















Mud 150 
















t 




I 






7 




1 






























r 




1 






7 




1 






























r 










7 




_7 














(1,000 xppm) 


























f 




_f 














50 . 








_ 




± 














r 




_f 






1 
















_ 



































































__ 














250 


200 

Formation 150 
salinity 1f)n 
(1,000 xppm) 

50 






























V 




L 




\ 




Y 




























1 




1 




\ 




\ 




> 




















1 






\ 








\ 




1 


I 




























\ 




, 




) 






\ 




























\ 




\ 






\ 




\ 
































\ 






\ 






I 


























i 




\ 






\ 






\ 


















i 




\ 




\ 




\ 






\ 






\ 


















1 




\ 






\ 




1 




\ 






\ 




























\ 




\ 




\ 






\ 






1 1 1 1 1 

10 20 30 40 ! 

*Markof Schlumberger 

©Schlumberger • Standard conditi 


1 
so 

ns 




Purpose 

This chart is used similarly to Chart Neu-31 to estimate the correc- 
tion applied to EcoScope 6.75-in. Integrated LWD Tool best thermal 
neutron porosity (BPHI) measurements. 



Use this chart only with EcoScope BPHI neutron porosity; use 
Chart Neu-45 with EcoScope thermal neutron porosity (TNPH) 
measurements. 



Back to Contents 



93 



Neutron— LWD 



Schlumberger 



EcoScope* Integrated LWD BPHI Porosity — 6.75-in. Tool and 9.5-in. Borehole 

Environmental Correction — Open Hole 



Neu-44 




EcoScope uncorrected BPHI porosity (apparent limestone porosity in p.u.) in 9.5-in. borehole 

10 20 30 40 50 
i i i i i i 


14 












































1 








• 


13 . 




























































































/ 








12 










































f 


r 




Borehole 








































, 




j 














































/ 




/ 


















































/ 






(m.) io 












































/ 














































/ 




7 






9 . 






































/ 






/ 












































/ 






t 






R / 






































/ 






' 


























T 




\ 


" - 1 








i 


































260 _ 


1 




\ 




\ 














































\ 




\ 








































210 






\ 




\ 












































, 


^ 




\ 








































loci 160 _ 






h 




\ 








































In 






1 




\ 








































110 _ 






1 


I 


\ 




















































\ 






































60 












] 






































70 
















1 














































0.75 _ 




r 


















































1 














































0-80 - 




1 






















1 
























Mud 




1 






1 




1 












1 


















































j 




























T 








" 




" 










1 
























index, H m .90 " 




3 






















1 




























j 








r 




r 










1 
























0.95 




n 








I 




I 






































J 














































1.00 


















































PRO 




































I 












:t 










1 






• 


200 




















T 












j 




































| 












1 






i 










Mud 150 
































1 












i 


























T 












4 


















Mnnn I 100 




















r 












t 


















(1,000 xppm) 




















r 












i 


















50 . 




















1 












± 












/ 


















. 























































„_ 
1 






















j 












250 












































i 








\ 






\ 










200 . 


























\ 




} 




\ 






\ 




























1 








\ 








\ 






\ 










Formation 150 . 




















_ 






\ 




i 




i 






\ 
























1 












I 




\ 






\ 






\ 








salinity m 
















L 




\ 










\ 






\ 






\ 








(1,000 xppm) 












t 




L 




\ 










\ 






\ 






\ 








50 
















H 




\ 






\ 




\ 






\ 






\ 




























\ 






\ 






i 




' 


i 




\ 





























_L 






i 






v_ 






\ 




\ 










1 1 1 1 1 

10 20 30 40 ! 

*Markof Schlumberger 

©Schlumberger • Standard conditi 


1 
SO 

ns 



Purpose 

This chart is used similarly to Chart Neu-31 to estimate the correc- 
tion applied to EcoScope 6.75-in. Integrated LWD Tool best thermal 
neutron porosity (BPHI) measurements. 



Use this chart only with EcoScope BPHI neutron porosity; use 
Chart Neu-46 with EcoScope thermal neutron porosity (TNPH) 
measurements. 



94 



Back to Contents 



Neutron— LWD 



Schlumberger 



EcoScope* Integrated LWD TNPH Porosity — 6.75-in. Tool and 8.5-in. Borehole 

Environmental Correction — Open Hole 



Neu-45 



EcoScope uncorrected TNPH porosity (apparent limestone porosity in p.u.) in 8.5-in. borehole 

10 20 30 40 50 
i i i i i 


14 






13 

12 
Borehole 

size 11 

(m.) 10 

9 
8 






























r 














■i • 






























-I 


\ 








































/ 


\ 

1 






1 


































/ 








1 










































1 




































j 






1 




































/ 






1 




































/ 


1 




1 


































/ 




7 




1 


































/ 




I 






































/ 




/ 






































L 




































260 

210 

Temperature 

{op) 160 

110 

60 






r 


\ 




. 




































t 


\ 




\ 




































I 






\ 




































I 


\ 




\ 




































1 


\ 




\ 




































1 






\ 








































, 


i 


\ 




























































































































































0.70 






















0.75 

Mud °- 8 ° 
hydrogen 0.85 
index, H m n.grj 

0.95 

1.00 




















1 




T 








v_ 




1 
























i_ 




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r 




1 






























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1 




















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250 
























200 

Mud 150 

nnnn" mty i 100 
(1,000 xppm) 

50 























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j • 
































































T 


f 














f 


























r 


f 










































f 














r 










































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250 






















200 
Formation 150 

Mnnn initV , 100 

(1,000 xppm) 

50 
























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( 

*Markof Schlumberger 
© Schlumberger 


... . 

) 10 20 30 40 50 

• Standard conditions 




Purpose 

This chart is used similarly to Chart Neu-31 to estimate the correc- 
tion applied to EcoScope 6.75-in. Integrated LWD Tool thermal neu- 
tron porosity (TNPH) measurements. 



Use this chart only with EcoScope TNPH measurements. Use 
Chart Neu-43 with EcoScope best thermal neutron porosity (BPHI) 
measurements. 



Back to Contents 



95 



Neutron— LWD 



Schlumberger 



EcoScope* Integrated LWD TNPH Porosity — 6.75-in. Tool and 9.5-in. Borehole 

Environmental Correction — Open Hole 



Neu-46 




EcoScope uncorrected TNPH porosity (apparent limestone porosity in p.u.) in 9.5-in. borehole 

10 20 30 40 50 
i i i i i i 


14 






























i 






n 














-l • 


13 . 


































f 
















































I 














12 
































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(m.) io 






































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loci 160 _ 








L 


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110 _ 
































































































60 












t 




































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0.75 _ 
































































































0-80 - 
















































Mud 
















































































































































index, H m .90 " 
































































































0.95 
































































































1.00 
















































250 




























i 


































J • 


200 












4 
















































t 




7 












j 




















Mud 150 
















T 












j 






. 




. 




_, 






















T 












T 




















Mnnn I 100 
















f 












T 




J 
















(1,000 xppm) 
















f 












J 










r 










50 








T 








r 












J 




I 




1 
















































■ 

















X 












































250 














































J 












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200 














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i 




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Formation 150 . 


















\ 








\ 




\ 






























r 


1 




I 








\ 






I 
















salinity 100 ; 












L 














\ 






\ 
















(1,000 xppm) 








„ 








; 










\ 






\ 
















50 












I 








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1 




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3 








\ 






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> 


















1 1 1 1 1 1 

10 20 30 40 50 

*Markof Schlumberger 

© Schlumberger • Standard conditions 



Purpose 

This chart is used similarly to Chart Neu-31 to estimate the correc- 
tion applied to EcoScope 6.75-in. Integrated LWD Tool thermal neu- 
tron porosity (TNPH) measurements. 



Use this chart only with EcoScope TNPH neutron porosity; use 
Chart Neu-44 with EcoScope best thermal neutron porosity (BPHI) 
measurements. 



96 



Back to Contents 



Neutron— LWD 



EcoScope* Integrated LWD — 6.75-in. Tool 

Formation Sigma Environmental Correction — Open Hole 



Schlumberger 



Purpose 

This chart is used to environmentally correct the raw sigma (RFSA) 
measurement for porosity, borehole size, and mud salinity. The fully 
corrected sigma (SIFA) measurement is normally presented on the 
logs. 

Description 

Chart Neu-47 includes (from top to bottom) the moments sigma 
transform, diffusion correction based on porosity, and borehole 
correction. 

Example 

Given: Raw sigma (24 c.u.), porosity (30 p.u.), borehole size 

(10 in.), and mud salinity (200,000 ppm). 
Find: Corrected sigma (SIFA). 
Answer: Enter the chart from the scale at the top with the raw 

sigma value of 24 c.u. 

Moments Sigma Transform 

Move parallel to the closest trend line to intersect the x-axis of the 
moments sigma transform chart. The difference between the x-axis 
value and the raw sigma value is the moments sigma transform 
correction (19.8 - 24 = -4.2 c.u.). 



Diffusion Correction 

Move down vertically from the scale at the top to intersect the 
30-p.u. line on the porosity chart. At the intersection point, move 
parallel to the closest trend line to intersect the x-axis of the 
porosity chart. 

The difference between the x-axis value and the raw sigma value 
is the diffusion correction (25.3 - 24 = +1.3 c.u.). 

Borehole Correction 

Move down vertically from the scale at the top to intersect the 10-in. 
borehole size line. At the intersection point, move parallel to the 
closest trend line corresponding to the mud salinity to intersect 
the x-axis of the borehole correction chart. 

The difference between the x-axis value and the raw sigma value 
is the borehole correction (22.8 - 24 = -1.2 c.u.). 

Net Correction 

The net correction to apply to the raw sigma value is the sum the 
three corrections (-4.2 + 1.3 + -1.2 = -4.1 c.u.). The environmentally 
corrected sigma is the sum of the net correction and the raw sigma 
value (24 + -4.1 = 19.9 c.u.). 




EcoScope Sigma Correction Example 




Correction 


Raw sigma 


24 c.u. 




Porosity 


30 p.u. 




Borehole size 


10 in. 




Mud salinity 


200,000 ppm 




Moments sigma transform 




-4.2 c.u. 


Porosity correction 




+1.3 c.u. 


Borehole correction 




-1.2 c.u. 


Net correction 




-4.1 c.u. 


Environmentally corrected sigma 




19.9 c.u. 



< ► 



Back to Contents 



continued on next page 
97 



Neutron— LWD 



Schlumberger 



EcoScope* Integrated LWD — 6.75-in. Tool 

Formation Sigma Environmental Correction — Open Hole 



Neu-47 




Momonts 

sigma 
transform 

Porosity 
(p.u.) 

Boreholo 
sizo (in.) 

*Markof Schlumberger 
© Schlumberger 


1 


) 


10 20 
1 , , , , 1 , 


Raw sigma (c.u.) 

30 40 50 60 


















/ 






/ 


A 


/ 


/ 


X 






y 


^ 


s 


^ 


S 














so 












40 
30 
20 
10 













































































































































































































































































































































































































































































1 
























































I 
























































1 
























































I 
























































1 
























































1 
























































I 
























































I 
























































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1 
























































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11 










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9 
R 
























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Mud salinity 

ppm 

50,000 ppm 

100,000 ppm 

150,000 ppm 
200,000 ppm 














/ 
















V 








V 








































i 








\tt 






































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| i i i i | i 

10 20 


30 40 50 60 

• Standard conditions 



98 



< ► 



Back to Contents 



Nuclear Magnetic Resonance — Wireline 



CMR*Tool 

Hydrocarbon Effect on NMR/Density Porosity Ratio 



Schlumberger 



CMR-1 



Pb 
(g/cm 3 



1.4 
1.6 
1.8 
2.0 
2.2 
2.4 
2.6 



1.0 



0.8 



0.6 



0.4 



0.2 









Ph = 0.8 










^06 
^0.5 










v^a4 










\02 










\0.1 ^ 



0.2 



Fresh Mud and Dry Gas at 700 psi 

p ma = 2.65,p f =1,l,= 1,p gas = 0.25, 
PT = 4, T, gas = 4, l H = 0.5 



0.4 0.6 

1-S V „ 







0% 


20% 




1 1 
Porosity = 50 p. u. 












40% 
dn 


60% 

).U. — 


" 80% 






G 


as / 






30 p. u 






100% 






_20[ 










^xo~ 




-10 p 








^Wa 


ter 
















































Pb 

(g/cm 3 



0.8 1.0 



Fresh Mud and Dry Gas at 700 psi 

p ma = 2.71, Pf = 1,l f =1, Pgas = 0.25, 
PT = 4,T ig as = 4,l gas = 0.5 





0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 



0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 



*Markof Schlumberger 
© Schlumberger 



Purpose 

This chart is used to determine the saturation of the flushed zone 
(Sxo) and hydrocarbon density (ph) by using density (p) and CMR 
Combinable Magnetic Resonance data. 

Description 

The top chart has three components: ratio of total CMR porosity 
to density porosity (<])tcMRA]>D) on the y-axis, (1 - Sxo) values on the 
x-axis, and ph defined by the radiating lines from the value of unity 
on the y-axis. Enter the chart with the values for (1 - Sxo) and the 
<|)tcMR/<j)D ratio. The intersection point indicates the hydrocarbon 



density value. The bottom charts are used to determine the Sxo value 
in sandstone (left) and limestone (right). 

Example 

Given: CMR porosity = 25 p.u., §v = 30 p.u., and S xo = 80%. 

Find: Hydrocarbon density of the fluid in the formation. 

Answer: <|>tcMR/<|>D ratio = 25/30 = 0.83. 

1 - Sxo = 1 - 0.8 = 0.20 or 20%. 

For these values, ph = 0.40. 



Back to Contents 



99 



This page intentionally left blank. 



< ► 



Back to Contents 



Resistivity Laterolog — Wireline 



ARI* Azimuthal Resistivity Imager 

Environmental Correction — Open Hole 



Schlumberger 



RLI-1 

(former Rcor-14) 



3 5 /a-in. Tool Centered, Active Mode, Thick Beds 



1.5 































































































































































































































































6__ 




























R,/R a 1.0 






















/< 


<Z 


/ 


? 


" 














-- J0__ 








































A 


/ 


& 


** 
















\ 


- \L 

ole diameter (in 


r 


























/ 














































































































0.5 

























































10 



100 
FL/FL 



*Markof Schlumberger 
© Schlumberger 



1,000 



10,000 




Purpose 

This chart is used to environmentally correct the ARI Azimuthal 
Resistivity Imager high-resolution resistivity (LLhr) curve for the 
effect of borehole size. 

Description 

For a known value of resistivity of the borehole mud (R m ) at the zone 
of interest, a correction for the recorded log azimuthal resistivity (R a ) 
is determined by using this chart. The resistivity measured by the 
ARI tool is equal to or higher than the corrected resistivity (Rt) for 
borehole sizes of 8 to 12 in. However, the measured ARI resistivity 
is lower than Rt in 6-in. boreholes and for values of R a /R m between 
6 and 600. 



Example 

Given: 



Find: 
Answer: 



ARI LLhr resistivity (R a ) = 20 ohm-m, mud resistivity 
(R m ) = 0.02 ohm-m, and borehole size at the zone of 
interest = 10 in. 

True resistivity (Rt). 

Enter the chart at the x-axis with the ratio R a /R m = 
20/0.02 = 1,000. 

Move vertically upward to intersect the 10-in. line. Move 
horizontally left to read the Rt/R a value on the y-axis 
of 0.86. 

Multiply the ratio by R a to obtain the corrected LLhr 

resistivity: 

Rt = 0.86 x 20 = 17.2 ohm-m. 



Back to Contents 



101 



Resistivity Laterolog — Wireline 



High-Resolution Azimuthal Laterolog Sonde (HALS) 

HLLD Borehole Correction — Open Hole 



Schlumberger 



RLI-2 




R./HLLD 



R t /HLLD 



1.2 



1.1 



1.0 



0.9 



0.8 



0.7 



0.6 



10- 



1.5 



10° 



HLLD Tool Centered (R m =0.1ohm-m) 



10° 



10' 



10 2 
HLLD/R m 



10 3 









































5 ir 


. 












4 


* * 


:■---- 


t>. 


■•^: 


















3 in. 
3 in. 




10 in. 






12 in. 

14 in. 

16 in. 










* 


































y 




^7*~ 






















<> 
















































•^8 


^ 


2^fc 








'in 
in 





































10" 



10= 



Borohole Effect, HLLD Tool Centered (R m = 0.1 ohm-m) 









































c 


b 


1 3 




































f in. 
.8 in. 












































10 in. 
12 in. 


1 1 


































- 


14 in. 

16 in. 








•"S 




■::=-=n 
























- 


18 in. 

9H in 






> ' 


















■«. 














nq 


































^<^ 
















0.7 
































^^_ 


='i^ 
















































0.5 











































10' 



10 2 10 3 10 4 

HLLD/R m 



10= 



© Schlumberger 



Purpose 

This chart is used to correct the HALS laterolog deep resistivity 
(HLLD) for borehole and drilling mud effects. 

Description 

Enter the chart on the x-axis with the value of HLLD divided by 
the mud resistivity (R m ) at formation temperature. Move upward 
to intersect the curve representing the borehole diameter (dh), and 
then move horizontally left to read the value of the ratio Rt/HLLD on 
the y-axis. Multiply this value by the HLLD value to obtain Rt. Charts 



RL1-3 through RL1-14 are similar to Chart RL1-2 for different resistivity 
measurements and values of tool standoff. 



Example 

Given: 

Find: 
Answer: 



HLLD = 100 ohm-m, R m = 0.02 ohm-m at formation 
temperature, and borehole size = 10 in. 

Rt. 

Ratio of HLLD/R m = 100/0.02 = 5,000. 

Rt = 0.80 x 100 = 80 ohm-m. 



102 



Back to Contents 



Resistivity Laterolog — Wireline 



High-Resolution Azimuthal Laterolog Sonde (HALS) 

HLLS Borehole Correction — Open Hole 



Schlumberger 



RLI-3 



HLLS Tool Centered (FL = 0.1 ohm-m) 



3.0 
2.5 
2.0 

R./HLLS 1-5 

1.0 

0.5 





10- 







5 in 


























1 
1 






1 
1 










8 in 

. 10 i 

12i 

14i 

16i 


n. 






















i 


1 
1 
1 




1 












n. 
n. 
n. 






















/ 
/ 




1 
1 
1 


1 






1 
1 


1 










1 


S5. 




s_= 


..'■---- 


-" 






• 
#• 


_ 





/ 
s 






s 










f 


ii"** 






































-..::: 

















































10° 



10' 



10 2 
HLLS/R, 



10 3 



10" 



10= 



) Schlumberger 



3.0 



Borehole Effect, HLLS Tool Centered (R m = 0.1 ohm-m) 



2.5 




c 
6 
8 


h 

in. 












1 
1 






1 

1 

J 






I 
1 

1 

L 














10 in. 

12 in. 

1/1 \n 












1 
1 
1 
1 




/ 


1 

i' 




1 

1 








1 

1 
1 




2.0 





R./HLLS 1.5 


16 in. 

18 in. 

?n in 










1 
1 
1 
/ 






1 

1 
/ 




/ 


1 






/ 
/ 










■ - 


- 


~'.: 


* 


* 




-- 




_ 




-- 


/ 
/ 








1.0 




<* 


«s 


s; ^ 


b'S:%i 


0.5 






















































































10° 



10' 



10 2 10 3 

HLLS/R m 



Purpose 

This chart is used similarly to Chart RL1-2 to correct HALS laterolog 
shallow resistivity (HLLS) for borehole and drilling mud effects. 



10 4 



10= 



< ► 



Back to Contents 



103 



Resistivity Laterolog — Wireline 



High-Resolution Azimuthal Laterolog Sonde (HALS) 

HRLD Borehole Correction — Open Hole 



Schlumberger 



RLI-4 



HRLD Tool Centered (R m = 0.1 ohm-m) 




) Schlumberger 



R t /HRLD 



R t /HRLD 



1.1 

1.0 
0.9 
0.8 
0.7 
0.6 
0.5 
0.4 



10- 



1.4 



10° 









j in. 


































bin. 

8 in. 

10 ir 

1 2 ir 

14 ir 

16 ir 












-/-' 


- >. 






X*-* 














- ~^. 








/ 


'- 


'/' 




•s 


V 
N 


> 


"V 


V 








. 




r 'it 
i / 












































r 

Jr 






















s 




X 


■«. 



















































































10° 



10 1 



10 2 
HRLD/R m 



10 3 



10" 



10 5 



Borehole Effect, HRLD Tool Centered (R m = 0.1 ohm-m) 









































c 


h 




1 ? 




































8 in. 












































10 in. 
_. 12 in. 


1 n 


































-- 


_. 14 in. 
. 16 in 












^r 


„. 




w i,T 


" '" -TT 1 
















-- 


_. 18 in. 
20 in. 




-■ ,_ ^ 














f— 


- 




---.. 


^ 




--. 


..."- 










OR 




















w *' 












- 


- 


"■* „, 


"■■»., 


^ 






--. 


• .. 








Ofi 








/ 


















■ „ > ■*■ 


-. 




* .„ 


"-- 


*■ 


- 




■-.. 






































_ 








n.4 













































10' 



10 2 10 3 

HRLD/R m 



10 4 



10= 



Purpose 

This chart is used to similarly to Chart RL1-2 to correct the HALS 
high-resolution deep resistivity (HRLD) for borehole and drilling 
mud effects. 



104 



< ► 



Back to Contents 



Resistivity Laterolog — Wireline 



High-Resolution Azimuthal Laterolog Sonde (HALS) 

HRLS Borehole Correction — Open Hole 



Schlumberger 



RLI-5 



HRLS Tool ContorGd (R m = 0.1 ohm-m) 



R./HRLS 



3.0 



2.5 



2.0 



1.5 



1.0 



0.5 



10-' 



10° 



10' 



10 2 
HRLS/R, 









5 i r 

i ir 


. 
























1 
1 

J . 












3 in. 

Oin. 

in 
























1 

1 
1 

,1 




1 








14in. 

16 in. 
























1 
1 

1 
1 


1 
1 


1 




































1 


• • 


1 
1 






















_^*^, 


:"■■-' 





































































10 3 



10 4 



10 5 



© Schlumberger 



3.0 



R t /HRLS 



Borehole Effect, HRLS Tool Centered (R m = 0.1 ohm-m) 



?R 




d, 

6 
8 


n. 
n 














\ 








1 

1 






1 






?n 





10 in. 

12 in. 

1 A in 
















1 
1 
1 






1 
1 
1 

1 












1 5 


IE 

1£ 

2C 


in. 
in. 
in. 
















1 

1 
1 
1 


1 


1 

1 
1 




1 
1 


1 
1 














- 








^ 


/ 


/ 


> 




,. 


/ 
/ 

* 








p „ ■ 


1.0 










05 


4 


^ 


- 


e 


!:S= 












































































10" 



10' 



10 2 10 3 

HRLS/R m 



Purpose 

This chart is used to similarly to Chart RL1-2 to correct the HALS 
high-resolution shallow resistivity (HRLS) for borehole and drilling 
mud effects. 



10 4 



10= 



< ► 



Back to Contents 



105 



Resistivity Laterolog — Wireline 



High-Resolution Azimuthal Laterolog Sonde (HALS) 

HLLD Borehole Correction — Eccentered in Open Hole 



Schlumberger 



RLI-6 



HLLD Tool Ecconterod at Standoff = 0.5 in. (R m = 0.1 ohm-m) 




) Schlumberger 



1.2 



1.1 



1.0 



R./HLLD 09 
0.8 

0.7 



0.6 



10-' 



R t /HLLD 



1.2 
1.1 

1.0 
0.9 
0.8 
0.7 
0.6 



10-' 











































d h 

5 in. 

6 in. 
8 in 












































10 in. 














* 


_j--s 

























- \L III. 




14 in. 

16 in. 






































% 














/ 


/j 


1 
























^ 


H 


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ft 
1 
































'V 





10" 



10' 



10 2 
HLLD/R m 



10 3 



10 4 



10= 



HLLD Tool Eccentored at Standoff = 1.5 in. (R m =0.1 ohm-m) 











































d h 
Bin. 




in in 














*■-" 


-■ — -» 






















12 in. 

14 in. 

16 in. 










4 


/ 
* 


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N 






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10" 



10' 



10 2 
HLLD/R m 



10 3 



10 4 



10 5 



Purpose 

This chart is used to similarly to Chart RL1-2 to correct the HALS 
laterolog deep resistivity (HLLD) for borehole and drilling mud effects 
at 0.5- and 1.5-in. standoffs. 



106 



< ► 



Back to Contents 



Resistivity Laterolog — Wireline 



High-Resolution Azimuthal Laterolog Sonde (HALS) 

HLLS Borehole Correction — Eccentered in Open Hole 



Schlumberger 



RLI-7 



3.0 


HLLS Tool Eccontorod at Standoff = 0.5 in. (R m = 0.1 ohm-m) 




2.5 
2.0 

R t /HLLS 1 - 5 
1.0 

0.5 




d h 

5 in. 

6 in. 

8 in. 

10 in 

12 in 

14 in 

16 in 














1 
1 






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, 






































































10-' 10° 10 1 10 2 10 3 

HLLS/R m 

HLLS Tool Eccontored at Standoff = 1 .5 in. (R m = 0.1 ol 
3.0 


10" 
lm-m) 


10= 


2.5 
2.0 
R./HLLS 1.5 
1.0 
0.5 



d h 

8 in. 

10 ir 

1 2 ir 

14 ir 

16 ir 


















i 
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© Schlumberger 


0-' 


10° 


10 1 

H 


10 2 
LLS/R m 


10 3 


10" 


10= 



Purpose 

This chart is used to similarly to Chart RL1-2 to correct the HALS 
laterolog shallow resistivity (HLLS) for borehole and drilling 
mud effects at 0.5- and 1.5-in. standoffs. 



< ► 



Back to Contents 



107 



Resistivity Laterolog — Wireline 



Schlumberger 



High-Resolution Azimuthal Laterolog Sonde (HALS) 

HRLD Borehole Correction — Eccentered in Open Hole 



RLI-8 



HRLD Tool Eccontered at Standoff = 0.5 in. (R m = 0.1 ohm-m) 




) Schlumberger 



R./HRLD 



R./HRLD 



1.1 

1.0 
0.9 
0.8 
0.7 
0.6 
0.5 
0.4 







d 
5 


h 

in. 






































bin. 

8 in. 

10 in 

12 in 

14 in 

16 in 


















































































/ / y f 

f f / 


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10- 



10° 



10' 



10 2 
HRLD/R m 



10 3 



10 4 



10= 



HRLD Tool Eccentored at Standoff =1.5 in. (R m =0.1 ohm-m) 



1.1 
1.0 
0.9 
0.8 
0.7 
0.6 
0.5 
0.4 





c 


in 














































10 in 

12 in 

14 in 

16 in 










































. 








i s 
f / 


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X 


X 






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1 









































10-' 



10" 



10 1 



10 2 
HRLD/R m 



10 3 



10" 



10 5 



Purpose 

This chart is used to similarly to Chart RL1-2 to correct the HALS 
high-resolution deep resistivity (HRLD) for borehole and drilling 
mud effects at 0.5- and 1.5-in. standoffs. 



108 



< ► 



Back to Contents 



Resistivity Laterolog — Wireline 



High-Resolution Azimuthal Laterolog Sonde (HALS) 

HRLS Borehole Correction — Eccentered in Open Hole 



Schlumberger 



RLI-9 



HRLS Tool Eccentered Standoff = 0.5 in. (R_ = 0.1 ohm-m) 



3.0 



2.5 



2.0 



R./HRLS 1 - 5 
1.0 

0.5 



10-' 



10° 



10 1 







d h 
5 ir 


. 






























. 8 in. 
10 in. 






























iz in. 

14 in. 

16 in. 














/ 
/ 

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k 1 






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10 2 
HRLS/R m 



10 3 



10 4 



10= 



) Schlumberger 



HRLS Tool Eccentered Standoff = 1.5 in. (R m =0.1 ohm-m) 



3.0 



R./HRLS 



10-' 



10" 









R in 
































1 
1 








25 




m i 


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12i 

14 i 

16 i 


1. 
1. 






















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1 
1 




























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1 
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y 


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f 


1 




1 
/ 


1 












05 
































































































10' 



10 2 
HRLS/R m 



Purpose 

This chart is used to similarly to Chart RL1-2 to correct the HALS 
high-resolution shallow resistivity (HRLS) for borehole and drilling 
mud effects at 0.5- and 1.5-in. standoffs. 



10 3 



10 4 



10 5 



< ► 



Back to Contents 



109 



Resistivity Laterolog — Wireline 



HRLA* High-Resolution Laterolog Array 

Borehole Correction — Open Hole 



Schlumberger 



RLI-10 



3.0 
2.5 
2.0 
R t /RLA1 1-5 
1.0 
0.5 



Tool Centered 




10-' 




3.0 
2.5 
2.0 
R./RLA1 1.5 
1.0 
0.5 



10- 



3.0 

2.5 

2.0 

R t /RLA1 1.5 

1.0 
0.5 




10-' 



*Markof Schlumberger 
© Schlumberger 























1 
1 

1 


1 
1 












1 


































































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1 
1 


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10° 



10' 



10 2 10 3 

RLA1/R m 

Standoff = 0.5 in. 



W 



10 5 



10° 



10' 



10 2 10 3 

RLA1/R m 
Standoff = 1.5 in. 



10 4 



10 5 



10 6 











i r / 


i 
i 

i 
























l_ 


f ' / 


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if i 
















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n. 


















/ ' 


i / 

r / 
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6 in. 
. 8 in. 






















ii 

ii 


' I ' 
/ 1 


/ I 

1 I 


I 
I 








































bin. 
10 in. 

12 in. 

14 in. 

16 in. 

18 in. 
__ 20 in. 

22 in. 












A 




/i 


* 


* 








































-- 








v 


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10° 



10' 



10 2 



10 3 



10 4 



10= 



10 6 



RLA1/R m 



Purpose effects. RLA1 is the apparent resistivity from computed focusing 

This chart is used to similarly to Chart RL1-2 to correct HRLA High- mode 1. 

Resolution Laterolog Array resistivity for borehole and drilling mud 

110 

< ► Back to Contents 



Resistivity Laterolog — Wireline 



HRLA* High-Resolution Laterolog Array 

Borehole Correction — Open Hole 



Schlumberger 



RLI-11 



3.0 
2.5 
2.0 
R,/RLA2 1.5 
1.0 
0.5 



Tool Centered 

























/, 


1 








1 
1 












i 
i 

i 
























































/ / 








1 
1 














i 
i 
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1 

> / 
/ 




/ 


1 
1 


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1 
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V 


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'/ 







































































10-' 



10° 



10' 



3.0 
2.5 
2.0 

R t /RLA2 1 - 5 
1.0 

0.5 



10 2 10 3 

RLA2/R m 

Standoff = 0.5 in. 



10" 



10 5 



10 6 




10-' 















1 ' / 
1 ' / 
1 ' / 


1 


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1 
/ 

1 




































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10° 



10' 



3.0 
2.5 

2.0 

R t /RLA2 1-5 
1.0 

0.5 



10 2 10 3 

RLA2/R m 

Standoff =1.5 in. 



10 4 



10 5 



10 6 



























1 1 

/ J 

1 / 




1 
1 
1 




1 


1 


1 




































































1 


1 1 
1 


1 
1 










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1 
1 


































































1 / 


/ / 
/ 
/ 


1 








1 
1 
1 




























































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10 ' 



10° 



10' 



10 2 



10 3 



10 4 



10= 



10 6 



*Markof Schlumberger 
© Schlumberger 



5 in. 

6 in. 

8 in. 

9 in. 

10 in. 

12 in. 

14 in. 

16 in. 

18 in. 

20 in. 

22 in. 




RLA2/R m 



Purpose effects. RLA2 is the apparent resistivity from computed focusing 

This chart is used to similarly to Chart RL1-2 to correct HRLA High- mode 2. 

Resolution Laterolog Array resistivity for borehole and drilling mud 



< ► 



Back to Contents 



in 



Resistivity Laterolog — Wireline 



HRLA* High-Resolution Laterolog Array 

Borehole Correction — Open Hole 



Schlumberger 



RLI-12 



R t /RLA3 



3.0 
2.5 
2.0 
1.5 
1.0 
0.5 



Tool Centered 



10- 



10° 




R t /RLA3 



3.0 
2.5 
2.0 
1.5 
1.0 
0.5 




10- 



10° 



R t /RLA3 



3.0 
2.5 
2.0 
1.5 
1.0 
0.5 




10-' 



















1 






7 
I 
1 


















i j 




1 

i 1 
r 






1 
1 
/ 
















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:::::: 




' ' f t 



























10' 



10 2 10 3 

RLA3/R m 

Standoff = 0.5 in. 



10 4 



10 5 



10 6 





























1 

1 
/ 








; 
/ 
; 




/ 








/ 
/ 
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10' 



10 2 10 3 

RLA3/R m 

Standoff = 1.5 in. 



10 4 



10= 



10 6 



























1 


1 
1 
1 






1 

1 

1 
















1 
1 
1 
























































1 
1 


1 






/ 














/ 


/ 






















































/ / 

* / 


1 

/ 






/ 


1 

; 

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f< 


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- 


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■.■• 


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■'■■' 















































































































































10" 



10' 



*Markof Schlumberger 
© Schlumberger 



10 2 10 3 

RLA3/R m 



10 4 



10= 



10 6 







d h 


— 


— 


5 in. 


— 


— 


6 in. 

8 in. 

9 in. 










10 in. 


-- 


-- 


12 in. 

14in. 


-- 


-- 


16 in. 
18 in. 


— 


— 


20 in. 
22 in. 



Purpose effects. RLA3 is the apparent resistivity from computed focusing 

This chart is used to similarly to Chart RL1-2 to correct HRLA High- mode 3. 

Resolution Laterolog Array resistivity for borehole and drilling mud 

112 

< ► Back to Contents 



Resistivity Laterolog — Wireline 



HRLA* High-Resolution Laterolog Array 

Borehole Correction — Open Hole 



Schlumberger 



RLI-13 



R t /RLA4 



3.0 
2.5 
2.0 
1.5 
1.0 
0.5 



Tool Centered 




10-' 

















































i 
i 
i 
















1 


































































i 




) 












i 
i 
/ 
































































/ 


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i 






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i 

i 








































































_ — - 


.' 


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' 




.. — — 


— 








— 




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^ 


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-z 






























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V 















































































10° 



10' 



R t /RLA4 



3.0 
2.5 
2.0 
1.5 
1.0 
0.5 



10 2 10 3 

RLA4/R m 

Standoff = 0.5 in. 



10 4 



10= 




10-' 



10° 



10 1 



R t /RLA4 



3.0 
2.5 
2.0 
1.5 
1.0 
0.5 



10 2 10 3 

RLA4/R m 

Standoff =1.5 in. 



10 4 



10= 




10-' 



10° 



10 1 



10 2 



10 3 



10 4 



10 5 



*Markof Schlumberger 
© Schlumberger 



RLA4/R, 



10 6 









































/ 
/ 






















































































i 








1 


1 














1 
/ 
1 


























































/ 


/ 
/ 






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1 
1 


1 
















1 
1 
1 


















































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/ 
















s 


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10 6 





















1 ' 

1 ' 
/ 








1 




/ 






r 




























/ 
1 




f 




1 

1 
/ 




/ 






/ 

r 


























' .< 


1 






/ 
/ 


/ 










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1 
1 




















<*-■;[ 


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^ 


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/ 








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TWMTiT 











































































10 6 



5 in. 

6 in. 

8 in. 

9 in. 

10 in. 

12 in. 

14 in. 

16 in. 

18 in. 

20 in. 

22 in. 




Purpose 



effects. RLA4 is the apparent resistivity from computed focusing 



This chart is used to similarly to Chart RL1-2 to correct HRLA High- mode 4. 

Resolution Laterolog Array resistivity for borehole and drilling mud 



< ► 



Back to Contents 



113 



Resistivity Laterolog — Wireline 



Schlumberger 



HRLA* High-Resolution Laterolog Array 

Borehole Correction — Open Hole 



RLI-14 



R t /RLA5 



3.0 
2.5 
2.0 
1.5 
1.0 
0.5 



Tool Centered 




10-' 

























































































































































































































































































_ - 




• 




- 


'<, 


^ 














=='== 


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s= 






::= = 


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S=S= 


■:.= 




J ' 


11 


11! '. 


v, 






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-LLL 


'=='= 


' ' ' 


11. 






1 








/ 




































































R t /RLA5 



3.0 
2.5 
2.0 
1.5 
1.0 
0.5 




10-' 



R t /RLA5 



3.0 
2.5 
2.0 
1.5 
1.0 
0.5 



10- 



*Markof Schlumberger 
© Schlumberger 



10° 



10' 



10 2 10 3 

RLA5/R m 

Standoff = 0.5 in. 



10" 



10= 



10 6 

















































i 
1 

1 






























































1 
1 




























































1 
1 
1 
















/ 












































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1 










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r 


















w 




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i = i"iS 


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5 in. 

6 in. 

8 in. 

9 in. 

10 in. 

1 2 in. 

14 in. 

16 in. 

18 in. 

20 in. 

22 in. 



10° 



10' 



10 2 10 3 

RLA5/R m 

Standoff =1.5 in. 



10 4 



10= 



10 6 



























































\ 






! 
1 
1 






































































I 




/ 


1 








































































1 

/ 
/ 


/ 








































































/ 

/ 
















.. 


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^f 




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VJW'tt 








fl 


. J - 


t*fl 




































- 


r 


r.T-r.- 















































































10° 



10' 



10 2 



10 3 



10' 



10= 



10 6 



RLA5/R m 



Purpose effects. RLA5 is the apparent resistivity from computed focusing 

This chart is used to similarly to Chart RL1-2 to correct HRLA High- mode 5. 

Resolution Laterolog Array resistivity for borehole and drilling mud 

114 

< ► Back to Contents 



Resistivity Laterolog — LWD 



Schlumberger 



GeoSteering* Bit Resistivity — 6.75-in. Tool 

Borehole Correction — Open Hole 



RLI-20 



*Markof Schlumberger 
© Schlumberger 


R t /R a 
R t /R a 


1 f 
















1.1 
1.0 
0.9 
0.8 
0.7 
0.5 

n 




































































































24-in. bit 
18-in. bit 
12-in. bit 












1 

1 ? 


o- 2 


1 


0-' 10° 


10' 10 2 
R a /R m 


10 3 


10" 10 5 


1.1 
1.0 
0.9 
0.8 
0.7 
0.6 
OR 
































































































24-in. bit 

18-in. bit 
12-in. bit 












1 


o- 2 


1 


0"' 10° 


10' 10 2 
R a /R m 


10 3 


10 4 1 


D 5 




Purpose 

This chart is used to derive the borehole correction for the GeoSteering 
bit-measured resistivity. The bit resistivity corrected to the true 
resistivity (Rt) is then used in the calculation of water saturation. 

Description 

Enter the chart on the x-axis with the ratio of the bit resistivity and 
mud resistivity (R a /R m ) at formation temperature. Move upward to 



intersect the appropriate bit size. Move horizontally left to intersect 
the correction factor on the y-axis. Multiply the correction factor by 
the R a value to obtain Rt. Charts RL1-21, RL1-23, and RL1-24 are simi- 
lar to Chart RLI-20 for different tools and bit sizes. 

Chart RL1-22 differs in that it is for reaming-down mode as 
opposed to drilling mode. 



Back to Contents 



115 



Resistivity Laterolog-LWD 



GeoSteering* arcVISION675* Resistivity— 6.75-in. Tool 

Borehole Correction — Open Hole 



Schlumberger 



RLI-21 



1.2 




Rt/R. 



Rt/Ra 



1.2 



1.1 
































I.U 












0.9 
















0.8 
















07 
































OR 


24-in. bit 















18-in. bit 
12-in. bit 



10- 2 10-' 10° 10 1 10 2 10 3 10 4 10 5 

R a /R m 



1.1 
1 n 






























(19 
















OR 
















07 
































OR 


■) 


4-in. bit 


OR 












1 
1 


8-in. bit 
2-in. bit 



10" : 



10" 1 10° 10 1 10 2 10 3 10 4 10 5 



*Markof Schlumberger 
© Schlumberger 



Purpose 

This chart is used similarly to Chart RL1-20 to derive the borehole 
correction for the GeoSteering bit-measured arcVISION675 
resistivity. 



116 



< ► 



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Resistivity Laterolog — LWD 



Schlumberger 



GeoSteering* Bit Resistivity in Reaming Mode — 6.75-in. Tool 

Borehole Correction — Open Hole 



RLI-22 



1.5 






1.4 
1.3 
1.2 
1.1 

Rt/R. i.o 

0.9 
0.8 
0.7 

0.6 
05 
























Bit / 


























































^^arcVISION*tool 




























































10 -2 10-1 1Q 1f Jl 1Q 2 1 3 1Q4 10= 

R a /Rm 

*Markof Schlumberger 
© Schlumberger 




Purpose 

This chart is used similarly to Chart RL1-20 to derive the borehole 
correction for the GeoSteering bit-measured resistivity while ream- 
ing down. 



< ► 



Back to Contents 



117 



Resistivity Laterolog — LWD 



geoVISION* Resistivity Sub— 6.75-in. Tool 

Borehole Correction — Open Hole 



Schlumberger 



RLI-23 



Ring Resistivity (with 8V$-in. bit) 



Rt/R. 




10° 10 1 10 2 10 3 10 4 10= 

R a /Rm 

Medium Button Resistivity (with 8V2-in. bit) 




Rt/R. 



Be 


re 


h 


Die 


Jiame 

i 

13 


te 


r 
/ 


ir 


.) 






/ 








I 
















/ 




• 


/ 

2 


















1 




























1 










I 
































U 


.5 










































( 


15 






































8 "5 









































10° 10 1 10 2 10 3 10 4 10= 

Ra/Rm 

Bit Resistivity (with 814-in. bit) 
ROP to Bit Face = 4 ft 



R,/R a 



Bt 


>re 


nole 


dia 


ne 


in 
er (i 


l.) 
1 


/ 
























22 1 


20 


/ 


























_ 18 






























■1 16 




i\ 






__.. 


















































1 


i 


























llL'lQ 




























B.5— 





























10° 10' 



*Markof Schlumberger 
© Schlumberger 



10 2 10 3 

R a /R m 



10 4 10= 



Rt/R. 



Deep Button Resistivity (with 81/2-in. bit) 

TTTTTl 1 — I llllll 




Shallow Button Resistivity (with 8'/2-in. bit) 



R./R. 



Be 


>r 


9h 


ole 


diam 


3t 


ar( 


n.) 
/ 




1 






















1 

10 










/ 




























9.5 


/ 
































9.2 


/ 

5 
































9 1- 






























































S.\) 













10° 10 1 10 2 10 3 10 4 10 5 

R./Rm 

Bit Resistivity (with 81/2-in. bit) 
ROP to Bit Face = 35 ft 



R,/R. 



E 


>or( 


jhok 


di 


an 


le 


ter 


in. 




1/ 




























1/ 






1 


/ 




















22 

\\\ ? 


j 






I 
























Ifi 


























"ffl — 


— 1 


4^ 


9 _ 


















■TTT 






^0- 




























— ; a.sw 



10" 10' 



10 2 10 3 

R./R m 



10 4 10 5 



Purpose sub of the geoVISION 6.75-in. tool. The bottom row of charts 

This chart is used similarly to Chart RL1-20 to derive the borehole specifies the bit readout point (ROP) to the bit face, 

correction for the bit-measured resistivity from the GVR* resistivity 

118 

< ► Back to Contents 



Resistivity Laterolog — LWD 



geoVISION* Resistivity Sub— 8.25-in. Tool 

Borehole Correction — Open Hole 



Schlumberger 



RLI-24 



Ring Resistivity (with 1 2V4-in. bit) 



R,/R a 




Deep Button Resistivity (with 12!/4-in. bit) 



10° 10' 



10 2 10 3 10 4 

R a /R m 



Medium Button Resistivity (with 12!/4-in. bit) 



R,/R a 



B( 


jre 


iole 


dia 


1 

ne1 

/ 


er ( 


1 
n.) 

rl 
























/ 


1 








J 
















1 


7 


16 






/ 


























1 


5 








/ 


























14- 




























■13.5- 


-19 9R- 































10° 10 1 



10 2 10 3 

Ra/Rm 



10 4 10= 



Bit Resistivity (with 12V4-in. bit) 
ROP to Bit Face = 4 ft 



R,/R a 



B 


Dre 


rrrm 
iole 


dia 


m 


Bt( 


irl 


n.) 




























26 


/ 


J 










/ 


















24' 


* 


111 


































!0- 






















1 


8 


























1R 






























14 




























m 12 


2R 



































10" 10' 



*Markof Schlumberger 
© Schlumberger 



10 2 10 3 

Ra/Rm 



10 4 10 5 



Rt/Ra 



Bort 


h 


ole 


1 1 \l 
diameter (in.) 


























/ 


/ 






/ 










/ 














20 


19 




/ 

8 






' 






/ 


























17 




Ifi' 






























IR 














































14 
































Tf 12.25 "" 



10° 10' 



10 2 103 

Ra/Rm 



10 4 10 5 



Shallow Button Resistivity (with 1 2V4-in. bit) 



R/Ra 



E 





e 


lole 


dif 


rr 


e 


1 

ter 

f 


in.) 










\ 






















1 

4 






/ 








j 






















1 

13.; 










1 


































1 

13 






































J2.75 


2.25 





































10° 10 1 10 2 10 3 10 4 10 5 

R a /R m 

Bit Resistivity (with 12/4-in. bit) 
ROP to Bit Face = 35 ft 



R,/R a 



Borehole diameter (in. 




Purpose sub of the geoVISION 8.25-in. tool. The bottom row of charts 

This chart is used similarly to Chart RL1-20 to derive the borehole specifies the bit readout point (ROP) to the bit face, 

correction for the bit-measured resistivity from the GVR* resistivity 



< ► 



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119 



Resistivity Laterlog — LWD 



GeoSteering* Bit Resistivity — 6.75-in. Tool 

Distance Out of Formation — Open Hole 



Schlumberger 



RLI-25 



Distance (ft) 




600 



500 



400 



300 



200 



100 



lOohm- 
lOOohrr 
Iflnhm- 


m/4° BUR 
-m/4°BUR 
m/5° BUR 












100ohm-m/5°BUR 
10ohm-m/10°BUR 


























/$ 
































/ * 









10 



12 



Dip angle I 



*Markof Schlumberger 
© Schlumberger 



Purpose 

This chart is used to calculate the distance the GeoSteering bit must 
travel to return to the target formation. 

Description 

When drilling is at very high angles from vertical, the bit may wander 
out of formation. If this occurs, how far the bit must travel to get 
back into the formation must be determined. 

Enter the chart with the known dip angle of the formation on 
the x-axis. Move upward to intersect the appropriate "buildup rate" 
(BUR) curve. Move horizontally left from the intersection point to 
the y-axis and read the distance back into the formation. 



Example 

Given: 

Find: 
Answer: 



Formation dip angle = 6° formation resistivity during 
drilling = 10 ohm-m, and buildup rate = 4°. 

Distance to return to the target formation. 

Enter the chart at 6° on the x-axis. Move upward to the 
10 ohm-m/4° BUR curve. Move horizontally left to the 
y-axis to read approximately 290 ft. 



120 



Back to Contents 



Resistivity Laterolog — Wireline 



CHFR* Cased Hole Formation Resistivity Tool 

Cement Correction — Cased Hole 



Schlumberger 



RLI-50 



CHFR Cement Correction Chart (4.5-in.-0D casing) 



1.6 



1.4 




No cement 
3.5 in. 
3.75 in. 


















































1.2 


1.5 in. 

3 in. 

5 in. 
































-•- 














■• 


































. 


••- 
• 

— * 


i — 




. -• 


















1.0 

Rt/Rchfr °' 8 

0.6 


\ i 














i 


1 


i 




— « 


►- 




-O 1 


*— 




/ 
i 


It 

/ 


/ 
/ 




9«^==^ 






— » 


►- 






-<» — < 


» — 












"•— 
















' 


/ 
/ 
/ 

i , 


i 

i 
i 
i 


i 




































0.4 














J i 


i 
i 

i 

+ : 
i 


m 
i 

i 








































0.2 














T i 
1 i 
1 i 

/ • 


m 

i 
i 
i 

t 






































































































io- 2 



*Markof Schlumberger 
© Schlumberger 




10-' 



10° 

■'chfr/'*cem 



10' 



10 2 



Purpose 

This chart is used to correct the raw cased hole resistivity measure- 
ment of the CHFR Cased Hole Formation Resistivity tool (R C Mr) for 
the thickness of the cement sheath. The resulting value of true resis- 
tivity (Rt) is used to calculate the water saturation. 



Description 

Enter the chart on the x-axis with the ratio of R C h& and the resistivity 
of the cement sheath (R C em)- The value of R ce m is obtained with labo- 
ratory measurements. Move upward to the appropriate cement 
sheath thickness curve, which represents the annular space between 
the outside of the casing and the borehole wall. Move horizontally 
left to the y-axis and read the Rt/RcMt value. Multiply this value by 
RcMr to obtain Rt. 

Charts RL1-51 and RL1-52 are for making the correction in larger 
casing sizes. 



Back to Contents 



121 



Resistivity Laterolog — Wireline 



CHFR* Cased Hole Formation Resistivity Tool 

Cement Correction — Cased Hole 



Schlumberger 



RLI-51 



CHFR Cement Correction Chart (7-in.-0D casing) 



1.6 



1.4 



1.2 



1.0 



R,/Rch,r °- 8 




0.6 



0.4 



0.2 



10- 2 



10-' 



10° 

■■chfr' ricem 





\lo cement 
3 5 in 
































































3.75 in. 
1.5 in. 

3 in. 
5 in. 







































































































1 


-Z.'. 


-• 


-• 


- 


- 


- 


• 
-II 


•- 














• 

— H 




4 


i 




— < 


»— 








ii i 


>— 




— < 

/ 

/ 


>— 

• 
/ 






•/ 


















(1 1 
















41 




















> 
i 
i 


/ 
/ 

' / 
/ 

• 


/ 
/ 
t 






























































/ f 

i 

' i 


i 
i 

f / 

* 


/ 




























































i 


/ 


i • 
/ / 


/ 


































































* i 
* 





















































10 1 



10 2 



*Markof Schlumberger 
© Schlumberger 



Purpose 

This chart is used similarly to Chart RL1-50 to obtain the cased hole 
resistivity of the CHFR Cased Hole Formation Resistivity tool cor- 
rected for the thickness of the cement sheath in 7-in.-OD casing. 



122 



< ► 



Back to Contents 



Resistivity Laterolog — Wireline 



CHFR* Cased Hole Formation Resistivity Tool 

Cement Correction — Cased Hole 



Schlumberger 



RLI-52 



1.6 


CHFR Cement Correction Chart (9.625-in.-0D casing) 




1.4 
1.2 
1.0 

R,/Rch,r °- 8 

0.6 

0.4 

0.2 




No cement 

0.5 in. 

0.75 in. 

1.5 in. 

3 in. 

5 in. 












































































































































• 


• 
/ 






,'- 




<b— 




-•" 


i — • 












-• 




i 


1 




— 1 


►— 






» 1 


» — 


/ 


> 




* > 
















-it — < 


» — 


































• 


* 


/ 


























































/ / 
/ • 
[ / 
/ 
/ 

,' » 




























































II 




9 ' 

a 

i > 
































































* 


















































1 

*Markof Schlumberger 
© Schlumberger 


D- 2 10-' 10° 10 1 10 2 

"chfr' "cem 






Purpose 

This chart is used similarly to Chart RL1-50 to obtain the cased hole 
resistivity of the CHFR Cased Hole Formation Resistivity tool cor- 
rected for the thickness of the cement sheath in 9.625-in.-OD casing. 



< ► 



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123 



Resistivity Induction — Wireline 



AIT* Array Induction Imager Tool 

Operating Range — Open Hole 



Schlumberger 




Purpose 

This chart is used to determine the limit of application for the AIT 
Array Induction Imager Tool measurement in a salt-saturated borehole. 

Description 

When the AIT tool logs a large salt-saturated borehole, the 10- and 
20-in. induction curves may well be unusable because of the large 
conductive borehole. In a borehole with a diameter (dh) of 8 in., 
the 10- and 20-in. curve data are usable if Rt < 300R m . The ratio 
of the true resistivity to the mud resistivity (Rt/R m ) is proportional 
to (d h /8) 2 . 

A general rule is that a 12-in. borehole must have a ratio of Rt/R m 
< 133 to have usable shallow log data. Additional requirements are 
that the borehole must be round and the AIT tool standoff is 2.5 in. 
The value of Rt/R m is further reduced if the borehole is irregular or 
the standoff requirement is not met. 

Chart RInd-1 summarizes these requirements. The expected 
values of Rt, R m , borehole size, and standoff size are entered to 
accurately determine the usable resolution in a smooth hole. The 
lower chart summarizes which AIT resistivity tools typically provide 
the most accurate deep resistivity data. 

Example: Salt-Saturated Borehole 

Given: Borehole size = 10 in., Rt = 5 ohm-m, R m = 

0.0135 ohm-m, and standoff (so) = 2.5 in. 
Find: Which, if any, of the AIT curves are valid. 

Answer: From the x-axis equation: 



Enter the chart on the x-axis at 346 and move upward 
to intersect Rt = 5 ohm-m on the y-axis. The intersection 
point is in an error zone for which the shallow induction 
curves are not valid even in a round borehole. The 
deeper induction curves are valid only with a 2-ft or 
larger vertical resolution. 

The limits for the 1-, 2-, and 4-ft curves are integral to the chart. 
As illustrated, a 1-ft 90-in. curve is not usable in a large salt-saturated 
borehole. Also, under these conditions, the 1-, 2-, and 4-ft curves can- 
not have the same resistivity response. 

Example: Freshwater Mud Borehole 

Given: Borehole size = 10 in., Rt = 5 ohm-m, R m = 0.135 ohm-m, 
and standoff (so) = 1.5 in. 

Which, if any, of the AIT curves are valid. 

Rt/Rm = 37.0, (d h /8) 2 = (10/8) 2 = 1.5625, and (1.5/so) = 
1.5/1.5 = 1. The resulting value from the x-axis equation 
is 37.0 x 1.5625 x 1 = 57.9. 

Enter the chart at 57.9 on the x-axis and intersect 
Rt = 5 ohm-m on the y-axis. The intersection point is 
within the limit of the 1-ft vertical resolution boundary. 
All the AIT induction curves are usable. 



Find: 
Answer: 



Rt 

V R my 



1.5 



^10Yfl.5 A 



0.0135 



2.5 



(370)(l.5625)(0.6)=346. 



124 



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Resistivity Induction — Wireline 



AIT* Array Induction Imager Tool 

Operating Range — Open Hole 



Schlumberger 



Rlnd-1 



(ohm-m) 



R, 
(ohm-m) 



innn 






Limit of 4-ft logs 






















■■»■■"»• '"a 




















































100 






Limit of 1-ft logs 

1 
































— range (compute standoff 












































.Salt- 
saturated 


10 


method 


torsmoot 


n noies) 


















Freshwat 
mud exan 


?.r =j= 




/ / borehole 












/ example 
















i 




















































/ on an iuy; 







0.01 0.1 



10 100 1,000 10,000 100,000 

mm 



10,000 



































































inon 


AIT 4-ft lir 


nit 






• 








:AIT2-ft limit = 


















— y — 












AIT 1 -ft li 
















100 


Tilt 




• 
























































































• 
































• 




























1 


AIT 


V> Al 1 and 

fj=HHLA*=^ 






HRLA : 
= tools — 


^^^^ 






ifi tools ^/— 














ll 





























0.01 0.1 1 10 100 1,000 10,000 100,000 

R t /R m 



*Markof Schlumberger 
© Schlumberger 



< ► 



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125 



Resistivity Induction — Wireline 



AIT* Array Induction Imager Tool 

Borehole Correction — Open Hole 



Schlumberger 




Introduction 

The AIT tools (AIT-B, AIT-C, AIT-H, AIT-M, Slim Array Induction 
Imager Tool [SAIT], Hostile Environment Induction Imager Tool 
[HIT], and SlimXtreme* Array Induction Imager Tool [QAIT]) do not 
have chartbook corrections for environmental effects. The normal 
effects that required correction charts in the past (borehole correc- 
tion, shoulder effect, and invasion interpretation) are now all made 
using real-time algorithms for the AIT tools. In reality, the charts for 
the older dual induction tools were inadequate for the complexity of 
environmental effects on induction tools. The very large volume of 
investigation required to obtain an adequate radial depth of investiga- 
tion to overcome invasion makes the resulting set of charts too exten- 
sive for a book of this size. The volume that affects the logs can be tens 
of feet above and below the tool. To make useful logs, the effects of the 
volume above and below the layer of interest must be carefully removed. 
This can be done only by either signal processing or inversion-based 
processing. This section briefly describes the wellsite processing and 
advanced processing available at computing centers. 

Wellsite Processing 

Borehole Correction 

The first step of AIT log processing is to correct the raw data from 
all eight arrays for borehole effects. Borehole corrections for the AIT 
tools are based on inversion through an iterative forward model to 
find the borehole parameters that best reproduce the logs from the 
four shortest arrays — the 6-, 9-, 12-, and 15-in. arrays (Grove and 
Minerbo, 1991). The borehole forward model is based on a solution 
to Maxwell's equations in a cylindrical borehole of radius r with the 
mud resistivity (R m ) surrounded by a homogeneous formation of 
resistivity Rf. The tool can be located anywhere in the borehole, but 
is parallel to the borehole axis at a certain tool standoff (so). The 
borehole is characterized by its radius (r). In this model, the signal 
in a given AIT array is a function of only these four parameters. 

The four short arrays overlap considerably in their investigation 
depth, so only two of the borehole parameters can be uniquely deter- 
mined in an inversion. The others must be supplied by outside mea- 
surements or estimates. Because the greatest sensitivity to the 
formation resistivity is in the contrast between R m and Rf, no external 
measurement is satisfactory for fitting to Rf. Therefore, Rf is always 
solved for. This leaves one other parameter that can be determined. 
The three modes of the borehole correction operation depend on 
which parameter is being determined: 

■ compute mud resistivity: requires hole diameter and standoff 

■ compute hole diameter: requires a mud resistivity measurement 
and standoff 

■ compute standoff: requires hole diameter and mud resistivity 
measurement. 



Because the AIT borehole model is a circular hole, either axis 
from a multiaxis caliper can be used. If the tool standoff is adequate, 
the process finds the circular borehole parameters that best match 
the input logs. Control of adequate standoff is important because 
the changes in the tool reading are very large for small changes in 
tool position when the tool is veiy close to the borehole wall. Near 
the center of the hole the changes are very small. A table of rec- 
ommended standoff sizes is as follows. 



AIT Tool Recommended Standoff 


Hole Size (in.) 


Recommended Standoff (in.) 




AIT-B, AIT-C, AIT-H, AIT-M, HIT 


SAIT, QAIT 


<5.0 


- 


0.5 


5.0 to 5.5 


- 


1.0 


5.5 to 6.5 


0.5 


1.5 


6.5 to 7.75 


1.0 


2.0 


7.75 to 9.5 


1.5 


2.5 


9.5 to 11.5 


2.0 + bowspring' 


2.5 


>11.5 


2.5 + bowspring' 


2.5 



Note: Do not run AIT tools £ 
* Only for AIT-H tool 



Each type of AIT tool requires a slightly different approach to 
the borehole correction method. For example, the AIT-B tool requires 
the use of an auxiliary R m measurement (Environmental 
Measurement Sonde [EMS]) to compute R m or to compute hole 
size by using a recalibration of the mud resistivity method internal 
to the borehole correction algorithm. The Platform Express* 
SlimAccess* and Xtreme* AIT tools have integral R m sensors that 
meet the accuracy requirements for the compute standoff mode. 

Log Formation 

AIT tools are designed to produce a high-resolution log response 
with reduced cave effect in comparison with the induction log deep 
(ILD) in most formations. The log processing (Barber and Rosthal, 
1991) is a weighted sum of the raw array data: 



N z-z max * \ 

o log (z)=Z Z w I (i')o[ , )(.-4 



where Oi g (z) is the output log conductivity in mS/m, a a w is the 
skin-effect-corrected conductivity from the rath array, and the 
weights (w) represent a deconvolution filter applied to each of the 
raw array measurements. The log depth is z, and z' refers to the 
distance above or below the log depth to where the weights are 
applied. The skin effect correction consists of fitting the X-signal 
to the skin-effect-error signal (Moran, 1964; Barber, 1984) at high 
conductivities and the R-signal to the error signal at low conductivi- 



126 



Back to Contents 



Resistivity Induction — Wireline 



AIT* Array Induction Imager Tool 

Borehole Correction — Open Hole 



Schlumberger 



ties, with the crossover occurring between 100 and 200 mS/m. The 
use of the R-signal at low conductivities overcomes the errors in 
the X-signal associated with the normal magnetic susceptibilities 
of sedimentary rock layers (Barber et al, 1995). 

The weights w in the equation can profit from further refine- 
ment. The method used to compute the weights introduces a small 
amount of noise in the matrix inversion, so the fit is about ±1% to 
±2% to the defined target response. A second refinement filter is 
used to correct for this error. The AIT wellsite processing sequence, 
from raw, calibrated data to corrected logs, is shown in Fig. 1. 



(Freedman and Minerbo, 1991, 1993; Zhang et al., 1994). Maximum- 
Entropy Resistivity Log Inversion (MERLIN) processing (Barber et 
al, 1999) follows Freedman and Minerbo (1991) closely, and that 
paper is the basic reference for the mathematical formulation. The 
problem is set up as the simplest parametric model that can fit the 
data: a thinly layered formation with each layer the same thickness 
(Fig. 2). The inversion problem is to solve for the conductivity of 
each layer so that the computed logs from the layered formation 
are the closest match to the measured logs. 



R-signals only 



A(H)IFC 



L 




1 > 


28 channels ^B 


28 


(AIT-B,-C,and-D)^ 
16 channels 


Borehole 
► correction 


or 
16 


(all others) A 








V 




Caliper j 


►• 




R m i 


►■ 




Stanrinff , 


►■ ' 





14 
or 



Multichannel 

signal 
processing 

and 2D 
processing 



Five depths 
(10 to 90 in.) 



G> 





Skin 

effect 

correction 


A 


28 
or 


16 


Five depths 
(10 to 90 in.) 





R-signals 
X-signals 



Figure 1. Block diagram of the real-time log processing chain from raw, calibrated array data to finished logs. 



Exception 
handling and 

environmentally 
compensated 

log processing 



AAA 

R 

Caliper 
Raw BHC signals 



.+. 10 in. 

.+. 20 in. 

->. 30 in. 

->. 60 in. 

->. 90 in. 




There are only two versions of this processing — one for AIT-B, 
AIT-C, and AIT-D tools and one for all other AIT tools (AIT-H, AIT-M, 
SAIT, HIT, and QAIT) (Anderson and Barber, 1995). Only two ver- 
sions are required because the tools were carefully designed with 
the same coil spacings to produce the same two-dimensional (2D) 
response to the formation. 

Advanced Processing 

Logs in Deviated Wells or Dipping Formations 

The interpretation of induction logs is complicated by the large vol- 
ume of investigation of these tools. The AIT series of induction tools 
is carefully focused to limit the contributions from outside a rela- 
tively thin layer of response (Barber and Rosthal, 1991). In beds 
at high relative dip, the focused response cuts across several beds, 
and the focusing developed for vertical wells no longer isolates the 
response to a single layer. The effect of the high relative dip angle is 
to blur the response and to introduce horns at the bed boundaries. 

Maximum Entropy Inversion: MERLIN Processing 

The maximum entropy inversion method was first applied by Dyos 
(1987) to induction log data. For beds at zero dip angle, it has been 
shown to give well-controlled results when applied to deep induction 
(ID) and medium induction (IM) from the dual induction tool 



Well path 




Figure 2. The parametric model used in MERLIN inversion. All layers are the 
same thickness, and the inversion solves for the conductivity of each layer 
with maximum-entropy constraints. 



Back to Contents 



127 



Resistivity Induction — Wireline 



AIT* Array Induction Imager Tool 

Borehole Correction — Open Hole 



Schlumberger 



The flow of MERLIN processing is shown in Fig. 3. The borehole- 
corrected raw resistive and reactive (R- and X-) signals are used as 
a starting point. The conductivity of a set of layers is estimated from 
the log values, and the iterative modeling is continued until the logs 
converge. The set of formation layer conductivity values is then con- 
verted to resistivity and output as logs. 

28 or 16 channels 



Borehole-corrected 
R- andX-signals 



> Initial guess 



lodel parameters 



Invasion Processing 

The wellsite interpretation for invasion is a one-dimensional (ID) 
inversion of the processed logs into a four-parameter invasion model 
(Rxo, Rt, ri, and n, shown in Fig. 4). The forward model is based on 
the Born model of the radial response of the tools and is accurate for 
most radial contrasts in which induction logs should be used. The 
inversion can be run in real time. The model is also available in the 
Invasion Correction module of the GeoFrame* Invasion 2 application, 
which also includes the step-invasion model and annulus model (Fig. 4). 



Step Profile 



Forward model 



Compute 

Lagrangian 




Computed log 




Sensitivity 
matrix 



Update model 
parameters 



L 




Distance from wellbore . 



Formation 

resistivity 

profile 



Exit 

Write model 

parameters 

as log 





Slope Profile 


Rxo 


>^ R, 


— r,_>! N 

r. i 


I 




I 



Distance from wellbore . 



Figure 3. Data flow in the MERLIN inversion algorithm. The output is the 
final set of model parameters after the iterations converge. 







Annulus Profile 












Rxo 

r 1 




■"■ann 




r„ 




R« 









Figure 4. Parametric models used in AIT invasion processing. The slope 
profile model is used for real-time processing; the others are available 
at the computing centers. R xo = resistivity of the flushed zone, R t = true 
resistivity, n = radius of invasion, R an n = resistivity of the annulus. 



128 



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Resistivity Induction — Wireline 



AIT* Array Induction Imager Tool 

Borehole Correction — Open Hole 



Schlumberger 



Another approach is also used in the Invasion 2 application mod- 
ule. If the invaded zone is more conductive than the noninvaded 
zone, some 2D effects on the induction response can complicate 
the ID inversion. Invasion 2 conducts a full 2D inversion using a 
2D forward model (Fig. 5) to produce a more accurate answer for 
situations of conductive invasion and in thin beds. 




Figure 5. The parametric 2D formation model used in Invasion 2. 



References 

Anderson, B., and Barber, T.: Induction Logging, Sugar Land, TX, 
USA, Schlumberger SMP-7056 (1995). 

Barber, T.D.: "Phasor Processing of Induction Logs Including 
Shoulder and Skin Effect Correction," US Patent No. 4,513,376 
(September 11, 1984). 

Barber, T., et al: "Interpretation of Multiarray Induction Logs in 
Invaded Formations at High Relative Dip Angles," The Log Analyst, 
(May-June 1999) 40, No. 3, 202-217. 

Barber, T., Anderson, B., and Mowat, G.: "Using Induction Tools to 
Identify Magnetic Formations and to Determine Relative Magnetic 
Susceptibility and Dielectric Constant," The Log Analyst 
(July-August 1995) 36, No. 4, 16-26. 

Barber, T., and Rosthal, R.: "Using a Multiarray Induction Tool to 
Achieve Logs with Minimum Environmental Effects," paper SPE 22725 
presented at the SPE Annual Technical Conference and Exhibition, 
Dallas, Texas, USA (October 6-9, 1991). 

Dyos, C. J.: "Inversion of the Induction Log by the Method of Maximum 
Entropy," Transactions of the SPWLA 28th Annual Logging 
Symposium, London, UK (June 29-July 2, 1987), paper T. 

Freedman, R., and Minerbo, G.: "Maximum Entropy Inversion of the 
Induction Log," SPE Formation Evaluation (1991), 259-267; also 
paper SPE 19608 presented at the SPE Annual Technical Conference 
and Exhibition, San Antonio, TX, USA (October 8-11, 1989). 

Freedman, R., and Minerbo, G.: "Method and Apparatus for 
Producing a More Accurate Resistivity Log from Data Recorded by an 
Induction Sonde in a Borehole," US Patent 5,210,691 (January 1993). 

Grove, G.R, and Minerbo, G.N.: "An Adaptive Borehole Correction 
Scheme for Array Induction Tools," Transactions of the SPWLA 32nd 
Annual Logging Symposium, Midland, Texas, USA (June 16-19, 
1991), paper P. 

Moran, J.H.: "Induction Method and Apparatus for Investigating 
Earth Formations Utilizing Two Quadrature Phase Components of 
a Detected Signal," US Patent No. 3,147,429 (September 1, 1964). 

Zhang, Y-C, Shen, L., and Liu, C: "Inversion of Induction Logs Based 
on Maximum Flatness, Maximum Oil, and Minimum Oil Algorithms," 
Geophysics (September 1994), 59, No. 9, 1320-1326. 




Back to Contents 



129 



Resistivity Electromagnetic — LWD 



arcVISI0N475* and ImPulse* 4 3 /4-in. Array 
Resistivity Compensated Tools — 2 MHz 

Borehole Correction — Open Hole 

Purpose 

This chart is used to determine the borehole correction applied 
by the surface acquisition system to arcVISION475 and ImPulse 
phase-shift (R ps ) and attenuation resistivity (R a d) curves on the 
log. The value of Rt is used in the calculation of water saturation. 

Description 

Enter the appropriate chart for the borehole environmental condi- 
tions and tool used to measure the various formation resistivities 
with the either the uncorrected phase-shift or attenuation resistivity 
value (not the resistivity shown on the log) on the x-axis. Move upward 
to intersect the appropriate resistivity spacing line, and then move 
horizontally left to read the ratio value on the y-axis. Multiply the 
ratio value by the resistivity value entered on the x-axis to obtain Rt. 

Charts REm-12 through REm-38 are used similarly to Chart 
REm-11 for different borehole conditions and arcVISION* and 
ImPulse tool combinations. 



Schlumberger 



Example 

Given: 



Find: 
Answer: 



Rps = 400 ohm-m (uncorrected) from arcVISION475 
(2-MHz) phase-shift 10-in. resistivity, borehole size = 
6 in., and mud resistivity (R m ) = 0.02 ohm-m at forma- 
tion temperature. 

Formation resistivity (Rt). 

Enter the top left chart at 400 ohm-m on the x-axis 
and move upward to intersect the 10-in. resistivity 
curve (green). 

Move left and read approximately 1.075 on the y-axis. 

Rt = 1.075 x 400 = 430 ohm-m. 




130 



Back to Contents 



Resistivity Electromagnetic — LWD 



arcVISI0N475* and ImPulse* 4 3 /4-in. Array 
Resistivity Compensated Tools — 2 MHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-11 



2.0 



R/Rp 



arcVISI0N475 and ImPulse BoreholG Correction for 2 MHz, d h = 6 in., R m = 0.02 ohm-m 

2.0 



1 R 


























1.0 


























OR 























R,/Ra 



1 ") 


















\ 








1 














'. " 


y 


J 








OR 



























10-' 10° 10' 10 2 10 3 

R ps (ohm-m) 



10-' 10° 10' 10 2 

R ad (ohm-m) 



10 3 



2.0 



Rt/Rps 



arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 6 in., R m = 0.1 ohm-m 

2.0 



1 R 


























10 


























(1R 



























R,/Ra 



1 R 






























1(1 




























0.R 





























10-' 10° 10' 10 2 10 3 

R ps (ohm-m) 



10-' 10° 10' 10 2 

R ad (ohm-m) 



10 3 




2.0 



R,/R P 



arcVISI0N47R and ImPulse Borehole Correction for 2 MHz, d h = 6 in., R m = 1.0 ohm-m 

2.0 



1 R 


























10 


























OR 



























R,/Ra 



1.R 
































1 
























f 






OR 































10- 1 10° 10 1 10 2 10 3 

Rps (ohm-m) 



10-' 10° 



10 1 
R ad (ohm-m) 



10 2 10 3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 10 16 22 28 34 



< ► 



Back to Contents 



131 



Resistivity Electromagnetic — LWD 



arcVISI0N475* and ImPulse* 4 3 /4-in. Array 
Resistivity Compensated Tools — 2 MHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-12 



2.0 



R t /R p , 



10- 1 10" 



arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 7 in., R m = 0.02 ohm-m 

2.0 



1 Ft 




























i n 




























OF 





























Pit/ Pi a 



1.5 



1.0 



0.5 




10' 
R ps (ohm-m) 



10 2 



10 3 



10- 1 10° 10' 10 2 10 3 

R arl (ohm-m) 



Rt/Rp 



2.0 



1.5 



1.0 



0.5 




2.0 



Rt/Rp 



10- 



10-' 10° 



arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 7 in., R m = 0.1 ohm-m 

2.0 






















































































































Rt/Rai 



10' 
Rps (ohm-m) 



10 2 



10 3 



10- 



10" 



10' 
R a „ (ohm-m) 



arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 7 in., R m = 1 .0 ohm-m 

2.0 



1 5 




























1 n 




























05 


























' 



10° 10 1 

R,,,. (ohm-m) 



10 2 



R,/R a 



1.5 



1.0 



0.5 



10 3 



10- 



1 5 




























1.0 


























05 



























10 2 



10° 10' 10 2 

R a(i (ohm-m) 



10 3 



10 3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 


10 


16 


■)■> 


28 


34 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION475 and ImPulse resistivity measurements. Uncorrected 
resistivity is entered on the x-axis, not the resistivity shown on the log. 



132 



< ► 



Back to Contents 



Resistivity Electromagnetic — LWD 



arcVISI0N475* and ImPulse* 4 3 /4-in. Array 
Resistivity Compensated Tools — 2 MHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-13 



2.0 



Rt/Rp 



10-' 10° 



arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 8 in., R m = 0.02 ohm-m 

2.0 



1 5 




















































1 










OF 












■^s: 


= !i ^ 


^ 


**; 


^ 







Rt/Rai 



1.5 



1.0 



0.5 







1 





















10' 
R ps (ohm-m) 



10 2 



10 3 



10- 



10° 



10 1 



10 2 



10 3 



Rt/Rp 



2.0 



1.5 



1.0 



0.5 



10- 



R t /R p 



2.0 



1.5 



1.0 



0.5 



10" 



10-' 10° 



arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 8 in., R m = 0.1 ohm-m 

2.0 



j j 


^_,Jy 





R t /R a 



1.5 




















I 






1 n 
















— - 


L 


]•/ 






05 



























10' 
Rps (ohm-m) 



10 2 



10 3 



arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 8 in., R m = 1.0 ohm-m 

2.0 






R./R. 



10' 
R ps (ohm-m) 



10 2 



10 3 



10-' 10° 10' 

R ad (ohm-m) 



10-' 10° 10 1 10 2 

R ad (ohm-m) 



10 2 



10 3 




1.5 






























in 






















1 






05 





























10 3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 10 16 



22 28 



34 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION475 and ImPulse resistivity measurements. Uncorrected 
resistivity is entered on the x-axis, not the resistivity shown on the log. 



< ► 



Back to Contents 



133 



Resistivity Electromagnetic — LWD 



arcVISI0N475* and ImPulse* 4 3 /4-in. Array 
Resistivity Compensated Tools — 2 MHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-14 



2.0 



R t /R p 



arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 10 in., R m = 0.02 ohm-m 

2.0 



1 R 


/ 


























1 n 




























or 








■"■■^ 


S5 


-5:: 


^ 


5 


fc 


N 









R t /R a 



1 R 


























10 


























OR 



























10-' 10° 10 1 10 2 

R DS (ohm-m) 



10 3 



10- 1 10° 10' 10 2 

R ad (ohm-m) 



10 3 



2.0 



Rt/Rp 




Rt/Rp 



2.0 



1.5 



1.0 



0.5 



arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 10 in., R m = 0.1 ohm-m 

2.0 



1 5 










/ 








1 


i n 




















05 





















R,/Ra 



1.5 



1.0 



0.5 




10-' 10" 



10 1 10 2 

R ps (ohm-m) 



10 3 



10-' 10° 



arcVISI0N475 and ImPulse Borehole Correction for 2 MHz, d h = 10 in., R m = 1.0 ohm-m 

2.0 






10' 
R ps (ohm-m) 



10 2 



1.5 



R,/R a 



1.0 = 



0.5 



10 3 



10- 



10° 10 1 

R ad (ohm-m) 



10-' 10° 10' 10 2 10 3 

R ad (ohm-m) 



I 


_Jf 





10 2 10 3 



*M a rkof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 10 16 22 28 34 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION475 and ImPulse resistivity measurements. Uncorrected 
resistivity is entered on the x-axis, not the resistivity shown on the log. 



134 



< ► 



Back to Contents 



Resistivity Electromagnetic — LWD 



arcVISION675* 6 3 /4-in. Array Resistivity Compensated Tool— 400 kHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-15 



R,/R P 



2.0 



1.5 



1.0 



0.5 



arcVISI0N675 Borehole Correction for 400 kHz, d h = 8 in., R m = 0.02 ohm-m 

2.0 













/ 




















•«!!53 


5 == 


^ 



R,/R a 



1.5 



1.0 



0.5 



10-' 10° 10 1 10 2 

R ps (ohm-m) 



10 3 











I 

J 















































10-' 10° 10 1 10 2 10 3 

R arl (ohm-m) 



Rt/R„ 



2.0 



1.5 



1.0 



0.5 



arcVISION675 Borehole Correction for 400 kHz, d h = 8 in., R m = 0.1 ohm-m 

2.0 













1 










-«£ 


11/ 















R,/Ra 



1 5 






























1.0 
















..^ 


^ 


/ 










05 































10-' 10° 10 1 10 2 

Rps (ohm-m) 



10 3 



10-' 10° 10 1 10 2 

R ari (ohm-m) 



10 3 




2.0 



R/Rps 



1.5 


























1.0 


























0.5 



























10- 1 10° 



arcVISI0N675 Borehole Correction for 400 kHz, d h = 8 in., R m = 1 .0 ohm-m 

2.0 



R t /R a 



1.5 



1.0 



0.5 































....> 


/ 



















10 1 10 2 



10 3 



10- 



R ps (ohm-m) 



10° 10 1 10 2 

R ari (ohm-m) 



10 3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 16 22 28 34 40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION675 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



< ► 



Back to Contents 



135 



Resistivity Electromagnetic — LWD 



arcVISION675* 6 3 /4-in. Array Resistivity Compensated Tool— 400 kHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-16 



2.0 



Rt/Rp 



arcVISION675 Borehole Correction for 400 kHz, d h = 10 in., R m = 0.02 ohm-m 

2.0 



1 "i 




























1 n 




























05 





























R,/Ra 



1.5 



1.0 



0.5 


















































































10-' 10° 10' 10 2 10 3 

R ps (ohm-m) 



10-' 10° 10' 10 2 10 3 



2.0 



Rt/Rp 




arcVISI0N675 Borehole Correction for 400 kHz, d h = 10 in., R m = 0.1 ohm-m 

2.0 



1 5 
























il 


1.0 


















— - 


-> 


{ 


f ; 


05 



























R,/Ra 



10- 1 10° 10' 10 2 10 3 

Rps (ohm-m) 



1 5 


















lj 








1 














,,^ 


; 


I 1 








05 



























10- 1 10° 10 1 10 2 10 3 

R ad (ohm-m) 



2.0 



Rt/Rp 



1 5 






























1.0 






























05 































arcVISI0N675 Borehole Correction for 400 kHz, d h = 10 in., R m = 1.0 ohm-m 

2.0 



Rt/R. 



1 5 
























I 




1 n 






















..J 


1 




05 


















— . 




:: ~< 


\ 





10- 1 10° 10' 10 2 

Rps (ohm-m) 



10 3 



10-' 10° 10 1 10 2 10 3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 16 22 28 34 40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION675 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



136 



< ► 



Back to Contents 



Resistivity Electromagnetic — LWD 



arcVISION675* 6 3 /4-in. Array Resistivity Compensated Tool— 400 kHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-17 



2.0 



Rt/Rp 



arcVISION675 Borehole Correction for 400 kHz, d h = 12 in., R m = 0.02 ohm-m 

2.0 



1 5 


























in 


























OR 










=a 


"tf 


t S 


^ 


\ 


V 







Rt/Ra 



1 F 










I 
















in 








/ 


1 


/ 














OF 












"°==: 


•U 


~^ 


^N 


\ 







10-' 10° 10 1 

Rps (ohm-m) 



10 2 



10 3 



10-' 10" 10' 10 2 

Rad (ohm-m) 



10 3 



Rt/Rp 



2.0 



1.5 



1.0 



0.5 



2.0 



Rt/Rp 



10-' 10° 



arcVISION675 Borehole Correction for 400 kHz, d h = 12 in., R m = 0.1 ohm-m 

2.0 



/ / 


:: yy' 


"~~~T^\- 



Rt/Rai 



10' 
Rps (ohm-m) 



102 1Q3 



1.5 


























1.0 


























05 



























arcVISI0N675 Borehole Correction for 4H0 kHz, d h = 1 2 in., R m = 1.0 ohm-m 

2.0 



10-1 100 ioi 

Rps (ohm-m) 



Rt/R. 



10 2 10 3 



10-' 



10" 



10' 
Rad (ohm-m) 



15 


















J 










in 














--€ 


^ 


I 










05 





























10-1 100 101 102 

R ad (ohm-m) 



10 3 




1 5 






















1 




1.0 




















> 


I 


1 


05 



























102 1Q3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 16 22 28 34 40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION675 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



< ► 



Back to Contents 



137 



Resistivity Electromagnetic — LWD 



arcVISION675* 6 3 /4-in. Array Resistivity Compensated Tool— 400 kHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-18 



2.0 



R t /R p 



arcVISION675 BoreholG Correction for 400 kHz, d h = 14 in., R m = 0.02 ohm-m 

2.0 



1 5 


























in 


























OF 



























R t /R a 



1 s 










1 




i 














1 


rf= 


^ 


^ 


1 


1 


/ 


I 














OR 





























10-' 10° 10 1 10 2 

R ps (ohm-m) 



10 3 



10-' 



10° 10 1 10 2 

R ad (ohm-m) 



10 3 



Rt/Rp 



2.0 



1.5 



1.0 



0.5 




arcVISI0N675 Borehole Correction for 400 kHz, d h = 14 in., R m = 0.1 ohm-m 

2.0 















f 


/ 






























' 



































R t /R ai 



10-' 10° 10' 10 2 

R ps (ohm-m) 



10 3 



1 5 


















\ 










1 n 




















f f 








05 





























10-' 10° 10' 10 2 10 3 

R ad (ohm-m) 



2.0 



R,/R P 



1 5 






















\ 


1.0 
























05 

























arcVISI0N675 Borehole Correction for 400 kHz, d h = 14 in., R m = 1.0 ohm-m 

2.0 



10-' 10° 10' 10 2 

R ps (ohm-m) 



Rt/Ra 



10 3 



1.5 | 


,.. _ Jl 


HR 



10-' 10° 10' 10 2 



10 3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 


Ifi 


22 


28 


34 


40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION675 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



138 



< ► 



Back to Contents 



Resistivity Electromagnetic — LWD 



arcVISION675* 6 3 /4-in. Array Resistivity Compensated Tool— 2 MHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-19 



2.0 



Rt/Rp 



1 S 


























i n 


























or 



























arcVISI0N67B Borehole Correction for 2 MHz, d h = 8 in., R m = 0.02 ohm-m 

2.0 



R,/R a 



1 R 


























i n 
















= 


s== : 


J 






OF 



























10-' 10° 10 1 

R„„ (ohm-m) 



10 2 



10 3 



10-' 10° 10' 

R ari (ohm-m) 



10 2 



10 3 



2.0 



R,/R P 



1 R 


























1.0 


























OF 




















Hi^ 


^ 


^ 



io- 1 



2.0 



Rt/R„ 



10° 



arcVISI0N67F Borehole Correction for 2 MHz, d h = 8 in., R m = 0.1 ohm-m 

2.0 



R,/Ra 



10' 
R ps (ohm-m) 



10 2 



10 3 



10- 



10° 



10' 



1.F 




























1 n 




























OR 





























arcVISI0N67F Borehole Correction for 2 MHz, d h = 8 in., R m = 1.0 ohm-m 

2.0 



10-' 10° 10 1 

R n „ (ohm-m) 



10 2 



R,/Ra 



10 3 



1 F 




















J 








10 


















ii 


') 






OF 



























10 2 



10- 1 10° 10' 10 2 

R ad (ohm-m) 



10 3 




1 R 


























1.0 


























OR 



























10 3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.! 



.16 22 28 34 



.40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION675 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



< ► 



Back to Contents 



139 



Resistivity Electromagnetic — LWD 



arcVISION675* 6 3 /4-in. Array Resistivity Compensated Tool— 2 MHz 

Bed Thickness Correction — Open Hole 



Schlumberger 



REm-20 



2.0 



R/Rp 



arcVISION675 BoreholG Correction for 2 MHz, d h = 10 in., R m = 0.02 ohm-m 

2.0 



1.5 




























1 n 




























OF 





























R,/Ra 



1 5 
















I 








1 
























on 














•«^ 


^ 


5 k 







10-' 10° 10' 10 2 10 3 

R ps (ohm-m) 



10-' 10° 10' 10 2 10 3 

R ar] (ohm-m) 



2.0 



R t /R p 




2.0 



Rt/Rp 



arcVISI0N675 Borehole Correction for 2 MHz, d h = 10 in., R m = 0.1 ohm-m 

2.0 



1 F 
























1 
























OF 












r 


= 


T 


^ 


ss 


^ 



R,/Ra 



1.5 



1.0 



0.5 



111 

M 



10-' 10° 10' 10 2 10 3 

Rps (ohm-m) 



arcVISI0N675 Borehole Correction for 2 MHz, d h = 10 in., R m = 1.0 ohm-m 

2.0 



1 5 


























1.0 


























OR 



























R,/Ra 



10-' 10° 10 1 10 2 10 3 

Rps (ohm-m) 



10-' 10° 10 1 10 2 

R ar] (ohm-m) 



10-' 10° 10' 10 2 10 3 

R ari (ohm-m) 



1 5 


























1.0 


















—' 


/ 






0.5 



























10 3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 16 22 28 34 40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION675 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



140 



< ► 



Back to Contents 



Resistivity Electromagnetic — LWD 



arcVISION675* 6 3 /4-in. Array Resistivity Compensated Tool— 2 MHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-21 



2.0 



Rt/Rp 



arcVISI0N675 Borehole CorrGction for 2 MHz, d h = 12 in., R m = 0.05 ohm-m 

2.0 



1 F 
























i n 
























OR 

























Rt/Ra 



1 R 




















| 






10 


















.--'' 


; 






05 

























10-' 10" 10' 102 103 

Rps (ohm-m) 



10-' 10° 10' 10 2 

Rad (ohm-m) 



103 



Rt/Rp 



2.0 



1.5 



1.0 



0.5 



10-' 



2.0 



Rt/Rp 



arcVISI0N675 Borehole Correction for 2 MHz, d h = 12 in., R m = 0.1 ohm-m 

2.0 

















( 



































Rt/Ra 



1.5 



1.0 



0.5 



10" 10' 102 103 

Rps (ohm-m) 



1.5 
















/ 




10 




















05 



















arcVISI0N675 Boreholo Correction for 2 MHz, d h = 12 in., R m = 1.0 ohm-m 

2.0 



Rt/Ra 



10-' 10° 10' 10 2 10 3 



10-' 10° 



10' 
Rad (ohm-m) 



_. _. 1 


ML 





10-' 10" 10' 102 103 

Rad (ohm-m) 




1.5 






















1 






i n 














































0.5 





























102 1Q3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 16 22 28 34 40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION675 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



< ► 



Back to Contents 



141 



Resistivity Electromagnetic — LWD 



arcVISION675* 6 3 /4-in. Array Resistivity Compensated Tool— 2 MHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-22 



2.0 



Rt/Rp 



arcVISI0N675 Borehole Correction for 2 MHz, d h = 14 in., R m = 0.02 ohm-m 

2.0 



1F 


























1 n 


\ 


V 


N, 




















OR 


•*B 


*a^S 


■^ 


= 


t 


? 


^ 


:v 


:n 







Rt/Ra 



1F 


























1 


























OF 



























10- 1 10° 10' 10 2 10 3 

R ps (ohm-m) 



10-' 10° 10 1 10 2 10 3 

R arl (ohm-m) 



2.0 



Rt/Rp 



arcVISI0N675 Borehole Correction for 2 MHz, d h = 14 in., R m = 0.1 ohm-m 

2.0 



IF 
























i n 
























0.F 

























R,/R a 



1 F 
































10 
































0.E 


































10-' 10° 10 1 10 2 

Rps (ohm-m) 



10 3 



10-' 10" 10 1 10 2 10 3 

R ar] (ohm-m) 



Rt/Rps 



2.0 



1.F 



1.0 



0.E 



arcVISI0N67E Borehole Correction for 2 MHz, d h = 14 in., R m = 1.0 ohm-m 

2.0 



-i=_j» ■ — ~-™^~===:::: z: 



R,/Ra 



1 F 




























10 
















-* 


J 


I 






0.F 





















10-' 10° 10' 

R n , (ohm-m) 



10 2 10 3 



10-' 10" 10' 10 2 

R afi (ohm-m) 



10 3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 16 22 28 34 40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION675 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



142 



< ► 



Back to Contents 



Resistivity Electromagnetic — LWD 



arcVISION825* 81/4-in. Array Resistivity Compensated Tool— 400 kHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-23 



Rt/R„ 



2.0 



1.5 



1.0 



0.5 



10- 1 



arcVISI0N825 Borehole Correction for 400 kHz, d h = 10 in., R m = 0.02 ohm-m 

2.0 




R,/Ra 



1.5 



1.0 



0.5 

















































J 


I 































10-' 



10° 10' 10 2 

R ad (ohm-m) 



10 3 



R t /R p 



2.0 



1.5 



1.0 



0.5 



10-' 



10" 



arcVISI0N825 Borehole Correction for 400 kHz, d h = 10 in., R m = 0.1 ohm-m 

2.0 




R t /R a 



1.5 



1.0 



0.5 




10' 
R ps (ohm-m) 



10 2 



10 3 



10- 



10° 10 1 10 2 

R ari (ohm-m) 



10 3 




2.0 



R,/R P 



arcVISI0N825 Borehole Correction for 400 kHz, d h = 10 in., R m = 1.0 ohm-m 

2.0 



1 5 


























1 n 


























05 



























R,/Ra 



1 5 


























i n 


























05 














,,!a ^ 


^ 


1 


^ 


* 


>s 



10-' 10° 10 1 10 2 10 3 

Rps (ohm-m) 



10- 1 



10° 10' 



10 2 10 3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 


16 


22 


98 


34 


40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION825 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



< ► 



Back to Contents 



143 



Resistivity Electromagnetic — LWD 



arcVISION825* 8!/4-in. Array Resistivity Compensated Tool— 400 kHz 

Bed Thickness Correction — Open Hole 



Schlumberger 



REm-24 




2.0 






arcVISION825 Borehole Correction for 400 kHz, d h = 12 in., R 

?n 


„ = 0.02 ohm-m 






1.5 

R,/R ps 

1.0 

05 
























1.5 














/ 




































R t /R ad 

1 








,^ 


I 


'l 


































OR 












=:: ^ 


^ 


^ 


:\ 








1( 
2.0 


H 


10" 

Rps 


10' 
(ohm-m) 

arcVISI0N82 


10 2 10 3 io- 1 

5 Borehole Correction for 400 kHz, d h = 12 in., F 

20 


10° 10 1 

R ad (ohm-m) 

m = 0.1 ohm-m 


10 2 


IO 3 


1.5 
R t /R ps 

1.0 

0.5 


















Y 


) 


/ 


1.5 




















I 




















^ 


4:. 


1 


/ 




R t /R ad 

1 












-■=: 



...^ 


<f 


/ 
































0.5 












; x 


X 


\ 










1( 
2.0 


)-' 


10° 

Rps 


10 1 
(ohm-m) 

arcVISION82 


10 2 
5 Borehole Co 


10 3 10-' 

rrection for 400 kHz, d h = 12 in., F 
?n 


10" 10' 

R ad (ohm-m) 

m = 1.0 ohm-m 


10 2 


10 3 


1.5 

Rt/Rps 

1.0 
05 
























1.5 


















































Rt/Rad 

1 


















































5 














■«^5 


^ 


; '; 


k 


fc 


s 




1 


]-' 


10" 


Rps 


10' 
(ohm-m) 


10 2 


10 3 io- 1 


10" 

Rad 


10' 
ohrr 


-m) 


10 2 


10 3 




F 


psistiwity sparing (in) 1fi 2? 2R 34 40 




© Schlumberger 



























Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION825 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



144 



< ► 



Back to Contents 



Resistivity Electromagnetic — LWD 



arcVISION825* 8!/4-in. Array Resistivity Compensated Tool— 400 kHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-25 



R,/R P 



2.0 



1.5 



1.0 



0.5 



10-' 



10° 



arcVISION825 Borehole Correction for 400 kHz, d h = 14 in., R m = 0.02 ohm-m 

2.0 



R,/R a 



10' 



R ps (ohm-m) 



10 2 10 3 




10" 10 1 10 2 

R ad (ohm-m) 



10 3 



Rt/Rp 



2.0 



1.5 



1.0 



0.5 



arcVISI0N825 Borehole Correction for 400 kHz, d h = 14 in., R m = 0.1 ohm-m 

2.0 



















I 































































R«/Ra 



1.5 



1.0 



0.5 




10- 1 10° 10' 10 2 

R ps (ohm-m) 



10 3 



10- 



10° 10 1 10 2 

R ad (ohm-m) 



10 3 




2.0 



Rt/Rp 



arcVISI0N825 Borehole Correction for 400 kHz, d h = 14 in., R m = 1.0 ohm-m 

2.0 



1 5 


























i n 


























05 



























10- 1 10° 10 1 10 2 

R ps (ohm-m) 



R«/Ra 



1.5 



1.0 



0.5 




10 3 



10-' 10° 10 1 10 2 

R ad (ohm-m) 



10 3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 16 22 28 34 40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION825 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



< ► 



Back to Contents 



145 



Resistivity Electromagnetic — LWD 



arcVISION825* 81A-in. Array Resistivity Compensated Tool— 400 kHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-26 



R t /R„ 



2.0 



1.5 



1.0 



0.5 



arcVISION825 Borehole Correction for 400 kHz, d h = 18 in., R m = 0.02 ohm-m 

2.0 



/ , 























R t /R a 



1.5 



1.0 



0.5 



1/ 


1 












k 





























10-' 10" 10' 102 

R ps (ohm-m) 



10 3 



10-' 



10° 10' 10 2 

R ad (ohm-m) 



10 3 



2.0 



Rt/Rps 




arcVISION825 Borehole Correction for 400 kHz, d h = 18 in., R m = 0.1 ohm-m 

2.0 



1 5 


























1 n 


























05 



























Rt/Ra 



1 5 














i 


I 










1 n 












U: 


>i 


I 


1 








05 



























10-' 10° 10 1 10 2 

R ps (ohm-m) 



10 3 



10-' 10° 10' 10 2 10 3 

R ad (ohm-m) 



2.0 



R t /R„ 



arcVISION825 Borehole Correction for 400 kHz, d h = 18 in., R m = 1.0 ohm-m 

2.0 



1 5 




























1 n 




























05 





























Rt/Ra 



1.5 



1.0 



0.5 



_nirik 



10-' 10° 10' 10 2 10 3 

Rps (ohm-m) 



10-' 10° 10' 10 2 

R ad (ohm-m) 



10 3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 


1fi 


22 


28 


34 


40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION825 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



146 



< ► 



Back to Contents 



Resistivity Electromagnetic — LWD 



arcVISION825* 8!/4-in. Array Resistivity Compensated Tool— 2 MHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-27 



2.0 



Rt/R„ 



10-' 



10° 



arcVISION825 BoreholG Correction for 2 MHz, d h = 10 in., R m = 0.02 ohm-m 

2.0 



1 R 


























1 n 


























OR 



























R,/Ra 



1 R 


























1 n 


























OR 














-^ 




? 


s 


x 


\ 



10' 
R ps (ohm-m) 



10 2 10 3 



10-' 10° 10' 10 2 

R ad (ohm-m) 



10 3 



2.0 



Rt/Rp 



1 R 




























1 n 




























OR 





























10- 



10" 



arcVISI0N82R Borehole Correction for 2 MHz, d h = 10 in., R m = 0.1 ohm-m 

2.0 



Rt/Ra 



1 R 
















J I 








1 


















! 






OR 

























10' 
Rps (ohm-m) 



10 2 



10 3 



10- 



10° 10' 10 2 

R ad (ohm-m) 



10 3 




Rt/Rp 



2.0 



1.5 



1.0 



0.5 



10-' 



10° 



arcVISION825 Borehole Correction for 2 MHz, d h = 10 in., R m = 1.0 ohm-m 

2.0 



10' 
R ps (ohm-m) 



10 2 



Rt/Ra 



1.5 



1.0 



0.5 



10 3 



10-i 10 o 10 1 

R ad (ohm-m) 



10 2 



- - - -f 



10 3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 


Ifi 


?■) 


28 


34 


40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION825 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



< ► 



Back to Contents 



147 



Resistivity Electromagnetic — LWD 



arcVISION825* 8!/4-in. Array Resistivity Compensated Tool— 2 MHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-28 




2.0 






arcVISI0N825 Borehole Correction for 2 MHz, d h = 12 in., R„ 


= 0.02ohm-rr 








1.5 
Rt/Rps 

1.0 

05 


























1.5 


















I 
































Rt/Rad 

1 


















i 














■ ~ 




T 


»'■*, 


^ 


> 


^ 


s 




OR 












— >. 


""^ 


N 


^ 








11 

2.0 


)-' 


10" 

Rps 


101 

ohm-m) 
arcVISION82 


102 103 10-1 

5 Borehole Correction for 2 MHz, d h = 12 in., R 
20 


10" 

Rad 

m = 0.1 ohm-m 


10i 
ohm-m) 


102 


103 


1.5 
Rt/Rps 

1.0 

05 


























1.5 
















1 


|l 
































Rt/Rad 

1 


















































I! 5 


























1( 
2.0 


H 


10» 

Rps 


10' 
ohm-m) 

arcVISION82 


102 

5 Borehole Cc 


103 10-1 

irrection for 2 MHz, d h = 12 in., R 
20 


10" 

Rad 

a = 1.0 ohm-m 


10i 
ohm-m) 


102 


103 


1.5 
Rt/Rps 

1.0 

05 


























1.5 






















| 




























Rt/Rad 

- 1.0 


























^ 
























5 


^ 














--=: 


^ 


\ 


\ 




1 


h 1 


10" 


Rps 


10' 
ohm-m) 


102 


103 1Q-, 


10" 

Rad 


10' 
ohm 


-m) 


102 


103 




R 


Rsistivity sparing (in) 1fi 22 28 3d 40 




© Schlumberger 



























Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION825 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



148 



< ► 



Back to Contents 



Resistivity Electromagnetic — LWD 



arcVISION825* 8!/4-in. Array Resistivity Compensated Tool— 2 MHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-29 



2.0 



Rt/Rp 



arcVISI0N825 Borehole Correction for 2 MHz, d h = 14 in., R m = 0.02 ohm-m 

2.0 



1 5 


























i n 


— — — 


— — 






















05 








..1^ 


^ 


^ 


^ 


^ 


^ 


:::n 







Rt/Ra 



1.5 



1.0 



0.5 





7 r 















10-' 10° 10' 102 

R ps (ohm-m) 



103 



10-' 10 o ioi 102 

R ad (ohm-m) 



103 



2.0 



Rt/Rp 



1 5 


























1 


























05 



























arcVISION825 Borehole Correction for 2 MHz, d h = 14 in., R m = 0.1 ohm-m 

2.0 



Rt/Ra 



1 5 
















/ 




I 








1 n 




























05 


























J 



10-' 10° 10' 10 2 

Rps (ohm-m) 



10 3 



10-' 100 ioi 102 

R ad (ohm-m) 



10 3 




Rt/Rp 



2.0 



1.5 



1.0 



0.5 



arcVISION825 Borehole Correction for 2 MHz, d h = 14 in., R m = 1.0 ohm-m 

2.0 



/ 


jy 


w ~ ===::::: 



Rt/Ra 



1.5 



1.0 



0.5 



-Tit 1 



10-' 10° 10' 

R DS (ohm-m) 



102 1Q3 



10-' 10° 10' 102 

Rad (ohm-m) 



103 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 16 22 28 34 40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION825 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



< ► 



Back to Contents 



149 



Resistivity Electromagnetic — LWD 



arcVISION825* 8!/4-in. Array Resistivity Compensated Tool— 2 MHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-30 



2.0 



Rt/Rp 



arcVISION825 Borehole Correction for 2 MHz, d h = 18 in., R m = 0.02 ohm-m 

2.0 



1 F 


























1 n 


























OR 



























Rt/Rp 



1 F 






























1 n 






























OF 



























10-' 10" 10' 102 103 

Rps (ohm-m) 



10' 10" 10' 

Rad (ohm-m) 



102 1Q3 



Rt/Rp 



2.0 



1.5 



1.0 



0.5 




2.0 



Rt/Rp 



arcVISI0N825 Borehole Correction for 2 MHz, d h = 18 in., R m = 0.1 ohm-m 

2.0 















1 



































Rt/Rp 



1 F 


























1 


























OF 























10-' iqo iQi 1Q2 



10 3 



1 F 


























1 






""* 




















DF 


6 


2 





















arcVISI0N825 Borehole Correction for 2 MHz, d h = 18 in., R m = 1.0 ohm-m 

2.0 



10-' ioo 101 

R ps (ohm-m) 



Rt/R 



t/nps 



102 1Q3 



10-1 1Q0 



10' 
Rad (ohm-m) 



10-' 10° 10' 10 2 

Rad (ohm-m) 



10 3 



1 F 








1 


1 


>- 




— ,asi : 


m 


OF 









102 1Q3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 16 22 28 34 40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION825 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



150 



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Resistivity Electromagnetic — LWD 



arcVISION900* 9-in. Array Resistivity Compensated Tool— 400 kHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-31 



2.0 






arcVISI0N900 Borehole Correction for 400 kHz, d h = 12 in., R 

9 n 


„ = 0.02 ohm-m 






1.5 
R t /R ps 

1.0 
05 






















1.5 










/ 


' 




































Rt/Rad 

1 








J 


/ 


y 




































OR 




























1( 
2.0 


H 


10° 

Rps 


10' 
(ohm-m) 

arcVISI0N90 


10 2 10 3 10-' 

3 Borehole Correction for 400 kHz, d h = 12 in., F 

?n 


10° 10' 

R ad (ohm-m) 

m = 0.1 ohm-m 


10 2 


10 3 


1.5 

Rt/Rps 

1.0 
05 


















r 


/ 


1.5 
















J 


}) 




















,..,-ssS 


< 


6 


'j 




Rt/Rad 

1 












— « s 


A 


/ 
































5 


























1( 
2.0 


)-' 


10° 

Rps 


10' 
(ohm-m) 

arcVISI0N90 


10 2 
] Borehole Cc 


10 3 10-' 
rrection for 400 kHz, d h = 12 in., F 


10° 10' 

R ad (ohm-m) 

m = 1.0 ohm-m 


10 2 


10 3 


1.5 

Rt/Rps 

1.0 
05 






















1.5 
















































Rt/Rad 

1 














































^> 5 




























1 


h' 


10° 


Rps 


10' 
(ohm-m) 


10 2 


10 3 10- 1 


10° 

Rad 


w 

ohm 


-m) 


10 2 


10 3 




F 


lesistivity spacing (in.) 


1R ?? n 


■14 40 




... , ,. .. . 




© Schlumberger 




























Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION900 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



< ► 



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151 



Resistivity Electromagnetic — LWD 



arcVISION900* 9-in. Array Resistivity Compensated Tool— 400 kHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-32 



Rt/Rp 




arcVISION900 Borehole Correction for 400 kHz, d h = 15 in., R m = 0.02 ohm-m 

2.0 



Rt/R a 



10 3 




10 2 10 3 



R t /R p 



2.0 



1.5 



1.0 



0.5 




Rt/Rp 



2.0 



1.5 



1.0 



0.5 



10- 



arcVISI0N900 Borehole Correction for 400 kHz, d h = 15 in., R m = 0.1 ohm-m 

2.0 



R./R. 



1.5 



1.0 



0.5 



10-' 10° 10 1 10 2 

R ps (ohm-m) 



10 3 



10-' 




arcVISI0N900 Borehole Correction for 400 kHz, d h = 15 in., R m = 1.0 ohm-m 

2.0 




R,/R a 



1.5 



1.0 



0.5 



10° 10 1 10 2 10 3 



R ps (ohm-m) 



10- 




10 3 



10 3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 16 22 28 34 40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION900 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



152 



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Resistivity Electromagnetic — LWD 



arcVISION900* 9-in. Array Resistivity Compensated Tool— 400 kHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-33 



2.0 



Rt/Rp 



arcVISI0N900 Borehole Correction for 400 kHz, d h = 18 in., R m = 0.02 ohm-m 

2.0 



1 5 


/ 


/ 
















































i n 












OR 



























Rt/Ra 



1.5 



1.0 



0.5 



/ 


1 1 










M-- 

























10-' 10" 10 1 10 2 10 3 

R D s (ohm-m) 



10-' 10" 10i 102 

Rad (ohm-m) 



10 3 



2.0 



Rt/Rp 



2.0 



Rt/Rp 



arcVISION900 Borehole Correction for 400 kHz, d h = 18 in., R m = 0.1 ohm-m 

2.0 



1 5 




















/ 






1.0 
05 



















































Rt/Ra 



1.5 



1.0 



0.5 




10- 1 10" 10' 102 

R ps (ohm-m) 



103 



arcVISI0N900 Borehole Correction for 400 kHz, d h = 18 in., R m = 1.0 ohm-m 

2.0 



1 5 


























1.0 
05 



















































Rt/Ra 



10-1 io" 101 102 

R DS (ohm-m) 



10 3 



10-i 10" 



101 
Rad (ohm-m) 



10-' 10" 101 102 

Rad (ohm-m) 



10 3 




1 5 




























1 












"■■1 
















05 






"'■^ 


l| 


^ 


^ 


\ 







10 2 10 3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 16 22 28 34 40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION900 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



< ► 



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153 



Resistivity Electromagnetic — LWD 



arcVISION900* 9-in. Array Resistivity Compensated Tool— 400 kHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-34 



2.0 



Rt/Rp 



arcVISION900 BoreholG Correction for 400 kHz, d h = 22 in., R m = 0.02 ohm-m 

2.0 



1 5 


























1 


























OR 



























R t /R a 



1 5 


I 


























y 
























1 






(15 



























10-' 10" 10' 102 103 

R ps (ohm-m) 



10-' 10" 10' 10 2 

R ad (ohm-m) 



10 3 



Rt/Rp 



2.0 



1.5 



1.0 



0.5 




Rt/Rp 



2.0 



1.5 



1.0 



0.5 



arcVISI0N900 Borehole Correction for 400 kHz, d h = 22 in., R m = 0.1 ohm-m 

2.0 



/ 


// 


/ 




i; 


^ 


/ 













Rt/Ra 



1 5 














J 


' 














i n 








i"'*^ 


£ 


i 




/ 














05 































10-' 10° 10 1 10 2 10 3 

Rps (ohm-m) 



arcVISI0N900 Borehole Correction for 400 kHz, d h = 22 in., R m = 1.0 ohm-m 

2.0 







1 ' 


' / 



















1.5 



R,/Ra 



1.0 & 



0.5 



10-' 10° 10' 

R n<! (ohm-m) 



10 2 10 3 



10- 



10" 10' 

R ad (ohm-m 




10-' 10° 10' 10 2 10 3 

R ad (ohm-m) 



10 3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 16 22 28 34 40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION900 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



154 



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Resistivity Electromagnetic — LWD 



arcVISION900* 9-in.Array Resistivity Compensated Tool— 2 MHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-35 



2.0 



Rt/Rp 



arcVISION900 Borehole Correction for 2 MHz, d h = 1 2 in., R m = 0.02 ohm-m 

2.0 



1 Pi 


























i n 


























n5 










■-• 


— ■•■ 


"■'^ 


^ 


^ 


% 


N 





Rt/Ra 



1 s 


























1 n 


























(15 












— ■■! 


"^ 


^ 


^ 


iiSN 







10-' 10° 10' 10 2 

R ps (ohm-m) 



10 3 



10-' 10° 10' 10 2 



10 3 



Rt/Rp 



2.0 



1.5 



1.0 



0.5 



Rt/Rp 



2.0 



1.5 



1.0 



0.5 



10-' 10" 



arcVISI0N900 Borehole Correction for 2 MHz, d h = 12 in., R m = 0.1 ohm-m 

2.0 




Rt/Ra 



1.5 



1.0 



0.5 



10- 1 



arcVISION900 Borehole Correction for 2 MHz, d h = 12 in., R m = 1.0 ohm-m 

2.0 



















■f 






\ 



Rt/Ra 



1.5 



1.0 



0.5 



10-' 10° 10' 10 2 

Rps (ohm-m) 



10 3 




10-' 10° 10' 10 2 



10° 10 1 10 2 10 3 










1 








; 


^ 




■■"■^58= 


\^ 



10 3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 16 22 28 34 40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION900 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



< ► 



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155 



Resistivity Electromagnetic — LWD 



arcVISION900* 9-in. Array Resistivity Compensated Tool— 2 MHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-36 



2.0 



Rt/Rp 



arcVISION900 BorGhole Correction for 2 MHz, d h = 1 R in., R m = 0.02 ohm-m 

2.0 



1 R 


























1 


^^ 
























OR 




-=Sai 


:=,^ 


^ 


4: 


'1 


^ 


S? 


::x 







Rt/Ra 



1 R 














/ 












1 


























OR 





















10-' 10° 10' 102 

R ps (ohm-m) 



103 



10- 1 10° 10' 102 

Rad (ohm-m) 



103 



2.0 



Rt/Rp 



1 R 


























i n 


























OR 




























Rt/Rp 



2.0 



1.R 



1.0 



0.R 



arcVISI0N900 Borehole Correction for 2 MHz, d h = 1R in., R m = 0.1 ohm-m 

2.0 



Rt/Ra 



1.R 



1.0 



0.R 









1 





































10-' 10° 10' 10 2 

Rps (ohm-m) 



10 3 



arcVISION900 Borehole Correction for 2 MHz, d h = 1R in., R m = 1.0 ohm-m 

2.0 









/ 










^ 









Rt/Ra 



10' 10° 10' 

Rps (ohm-m) 



1Q2 1Q3 



10-' 10° 10' 

Rad (ohm-m) 



10-' 10° 10' 102 

R ad (ohm-m) 



103 



1 R 


























1 n 


























OR 














■<= 


=::: 


; § 


\ 


^v 



10 2 1Q3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.] 



.16 22 28 34 40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION900 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



156 



< ► 



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Resistivity Electromagnetic — LWD 



arcVISION900* 9-in. Array Resistivity Compensated Tool— 2 MHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-37 



2.0 



Rt/Rp 




arcVISI0N900 Borehole Correction for 2 MHz, d h = 18 in., R m = 0.02 ohm-m 

2.0 



Rt/Ra 



1.5 



1.0 



0.5 



/ 












^-- 












— 


"^ 


^S 


V 







103 



10-' 10" 10' 102 103 

Rad (ohm-m) 



2.0 



Rt/Rp 



1 5 




















































1.0 
05 





































arcVISI0N900 Borehole Correction for 2 MHz, d h = 18 in., R m = 0.1 ohm-m 

2.0 



Rt/Ra 



1.5 



1.0 



0.5 



/ / / / 


j/jj 


^"\ 



10-' 10" 10' 102 

Rps (ohm-m) 



103 



10-' 10° 10' 102 103 

Rad (ohm-m) 




Rt/Rp 



2.0 



1.5 



1.0 



0.5 



arcVISI0N900 Borehole Correction for 2 MHz, d h = 18 in., R m = 1.0 ohm-m 

2.0 























1 












































4 


% 




5=* 



























Rt/Ra 



1.5 



1.0 



0.5 




10-' 10" 10' 

Rps (ohm-m) 



102 1Q3 



10' 10° 



10' 
Rad (ohm-m) 




10 2 1Q3 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 16 22 28 34 40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION900 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



< ► 



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157 



Resistivity Electromagnetic — LWD 



arcVISION900* 9-in. Array Resistivity Compensated Tool— 2 MHz 

Borehole Correction — Open Hole 



Schlumberger 



REm-38 



Rt/Rp 



2.0 



1.5 



1.0 



0.5 



arcVISION900 BorGhole Correction for 2 MHz, d h = 22 in., R m = 0.02 ohm-m 

2.0 



















































■<^ 



































Rt/Ra 



1.5 



1.0 



0.5 



t 









































































10-' 10" ioi 102 

R ps (ohm-m) 



103 



10-1 ioo ioi 102 

R ad (ohm-m) 



103 



2.0 



Rt/Rp 



1 fi 




























i 
































05 




























Rt/Rp 



2.0 



1.5 



1.0 



0.5 



10-1 



arcVISI0N900 Borehole Correction for 2 MHz, d h = 22 in., R m = 0.1 ohm-m 

2.0 



Rt/R a 



1 5 






/ 




) 


1 
















*s2 


^ 


4 


Y 


i 
















1 










05 



























10-' 10" 10' 102 

Rps (ohm-m) 



10 3 



arcVISION900 Borehole Correction for 2 MHz, d h = 22 in., R m = 1.0 ohm-m 

2.0 







/ 


h r 

















1.5 



Rt/Ra 



1.0 S 



0.5 



10° 10' 10 2 10 3 



10-' 10° 




10' 
Rad (ohm-m 



10-' io» ioi 102 

R ad (ohm-m) 



TO 3 



103 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 16 22 28 34 40 



Purpose 

This chart is used similarly to Chart REm-11 to determine the 
borehole correction applied by the surface acquisition system 



to arcVISION900 resistivity measurements. Uncorrected resistivity 
is entered on the x-axis, not the resistivity shown on the log. 



158 



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Resistivity Electromagnetic — LWD 



arcVISION675* arcVISION825*, and arcVISION900* 
Array Resistivity Compensated Tools — 400 kHz 

Bed Thickness Correction — Open Hole 

Purpose 

This chart is used to determine the correction factor applied by the 
surface acquisition system for bed thickness to the phase-shift and 
attenuation resistivity on the logs of arcVISION675, arcVISION825, 
and arcVISION900 tools. 

Description 

The six bed thickness correction charts on this page are paired for 
phase-shift and attenuation resistivity at different values of true (Rt) 
and shoulder bed (R s ) resistivity. Only uncorrected resistivity values 
are entered on the chart, not the resistivity shown on the log. 

Chart REm-56 is also used to find the bed thickness correction 
applied by the surface acquisition system for 2-MHz arcVISION* and 
ImPulse* logs. 



Schlumberger 



Example 

Given: 

Find: 
Answer: 



Rt/Rs = 10/1, R ps uncorrected = 20 ohm-m (34 in.), and 
bed thickness = 6 ft. 

Rt. 

The appropriate chart to use is the phase-shift resistivity 
chart in the first row, for Rt = 10 ohm-m and R s = 1 ohm-m. 

Enter the chart on the x-axis at 6 ft and move upward 
to intersect the 34-in. spacing line. The corresponding 
value of Rt/Rp S is 1.6; Rt = 20 x 1.6 = 32 ohm-m. 




< ► 



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continued on next page 
159 



Resistivity Electromagnetic — LWD 



arcVISION675* arcVISION825* and arcVISION900* 
Array Resistivity Compensated Tools — 400 kHz 

Bed Thickness Correction — Open Hole 



Schlumberger 



REm-55 



arcVISI0N675, arcVISION825, and arcVISI0N900 400-kHz 
Bed Thickness Correction for R t = 10 ohm-m and R s = 1 ohm-m at Center of Bed 





?n 






Pha 


se-Shift Resistivity 








1.5 
1.0 
0.5 

n 


















Rt/Rps 























































2.0 






Attenuation Resistivity 






1.5 


















Rt/Rad 1.0 


















0.5 






































2 4 6 8 10 12 14 16 

Bed thickness (ft) 



2 4 6 8 10 12 14 16 

Bed thickness (ft) 




arcVISI0N675, arcVISI0N825, and arcVISI0N900 400-kHz 
Bed Thickness Correction for R, = 1 ohm-m and R s =10 ohm-m at Center of Bed 



2.0 






Pha 


;e-Shift Resistivity 






1.5 


















Rt/Rps 1.0 


















0.5 


/ 


* 


S^ 















V 

















2.0 






Attenuation Resistivity 






1.5 


















Rt/Rad 1.0 


















0.5 




^ 


^ 


^= 













/ 


^r 















2 4 6 8 10 12 14 16 

Bed thickness (ft) 



2 4 6 8 10 12 14 16 

Bed thickness (ft) 



*Markof Schlumberger 
© Schlumberger 



arcVISI0N675, arcVISION825, and arcVISI0N900 400-kHz 
Bed Thickness Correction for R t = 100 ohm-m and R s =10 ohm-m at Center of Bed 



2.0 






Phase-Shift Resistivity 






1.5 


















Rt/Rps 1.0 


















0.5 






































2 4 6 8 10 12 14 16 

Bed thickness (ft) 



Resistivity spacing (in.) 16 22 28 34 40 



160 



< ► 



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Resistivity Electromagnetic — LWD 



arcVISION* and ImPulse* Array Resistivity Compensated Tools — 2 MHz 

Bed Thickness Correction — Open Hole 



Schlumberger 



REm-56 



arcVISION and ImPulse 2-MHz Bed Thickness Correction for 
R, = 10 ohm-m and R s =1 ohm-m at Center of Bed 



2.0 






Pha 


se-Shift Resistivity 






1.5 




\ 


s. 












R,/Rps 1.0 




\Nj 


^ 


^ 










0.5 




































2.0 






Attenuation Resistivity 






1.5 






\^ 


v\ 










Rt/Rad i.o 








^ 


^ 








0.5 






































2 4 6 8 10 12 14 16 

Bed thickness (ft) 



2 4 6 8 10 12 14 16 

Bed thickness (ft) 



arcVISION and ImPulse 2-MHz Bed Thickness Correction for 
R, = 1 ohm-m and R, =10 ohm-m at Center of Bed 



2.0 






Pha 


se-Shift Resistivity 






1.5 


















R t /Rps i.o 


















0.5 






































2.0 






Attenuation Resistivity 






1.5 


















Rt/Rad 1-0 


















0.5 


J 


^ 


^ 


ss** 













f 


















2 4 6 8 10 12 14 16 

Bed thickness (ft) 



2 4 6 8 10 12 14 16 

Bed thickness (ft) 



arcVISION and ImPulse 2-MHz Bed Thickness Correction for 
R.= 100 ohm-m and R, =10 ohm-m at Center of Bed 



2.0 






Phas 


;e-Shift Resistivity 






1.5 


















Rt/Rps i.o 


















0.5 






































2.0 






Attenuation Resistivity 






1.5 












^ 


k 




Rt/Rad 10 














^S 


1 


0.5 






































2 4 6 8 10 12 14 16 

Bed thickness (ft) 



2 4 6 8 10 12 14 16 

Bed thickness (ft) 



*Markof Schlumberger 
© Schlumberger 



Resistivity spacing (in.) 


16 


22 


?R 


34 


40 



< ► 



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161 



Resistivity Electromagnetic — LWD 



arcVISION675* and ImPulse* Array Resistivity 
Compensated Tools — 2 MHz and 16-in. Spacing 

Dielectric Correction — Open Hole 



Schlumberger 



REm-58 



I.60 



8.55 



i.50 



8.45 



I.40 



Attenuation g 35 
(dBJ 



I.30 




8.25 



I.ZO 



8.15 



:.10 



77777 




° Dielectric assumption 
e r = 5 + 108.5R- 035 



*Markof Schlumberger 
© Schlumberger 



3 4 

Phase shift! 



Purpose 

This chart is used to estimate the true resistivity (Rt) and dielectric 
correction (e r ). Rt is used in water saturation calculation. 

Description 

Enter the chart with the uncorrected (not those shown on the log) 
phase-shift and attenuation values from the arcVISION675 or 
ImPulse resistivity tool. The intersection point of the two values is 
used to determine Rt and the dielectric correction. Rt is interpolated 
from the subvertical lines described by the dots originating at the 



listed Rt values. The e r is interpolated from the radial lines originating 
from the e r values listed on the left-hand side of the chart. Charts 
REm-59 through REm-62 are used to determine Rt and e r at larger 
spacings. 

Example 

Given: Phase shift = 2° and attenuation = 8.45 dB for 16-in. 
spacing. 

Find: Rt and e r . 

Answer: Rt = 26 ohm-m and e r = 70 dB. 



162 



Back to Contents 



Resistivity Electromagnetic — LWD 



arcVISION675* and ImPulse* Array Resistivity 
Compensated Tools — 2 MHz and 22-in. Spacing 

Dielectric Correction — Open Hole 



Schlumberger 

REm-59 



6.9 



6.8 



6.7 



Attenuation 
(dB) 



6.6 



6.5 



6.4 



6.3 



TTT 
//// 




° Dielectric assumption 
e r = 5 + 108.5R" 035 



*Markof Schlumberger 
© Schlumberger 



Phase shift! 



Purpose 

Charts REm-59 through REm-62 are identical to Chart REm-58 
for determining Rt and e r at larger spacings of the arcVISION675 
and ImPulse 2-MHz tools. 

< ► 



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163 



Resistivity Electromagnetic — LWD 



arcVISION675* and ImPulse* Array Resistivity 
Compensated Tools — 2 MHz and 28-in. Spacing 

Dielectric Correction — Open Hole 



Schlumberger 



REm-60 



5.5 



Attenuation 
(dB) 




5.4 



5.3 



5.2 



5.1 



5.0 



4.9 



4.8 




o Dielectric assumption 
E r = 5 + 108.5R- 035 



*Markof Schlumberger 
© Schlumberger 



Phase shift! 



Purpose 

Charts REm-59 through REm-62 are identical to Chart REm-58 
for determining Rt and e r at larger spacings of the arcVISION675 
and ImPulse 2-MHz tools. 

164 



Back to Contents 



Resistivity Electromagnetic — LWD 



arcVISION675* and ImPulse* Array Resistivity 
Compensated Tools — 2 MHz and 34-in. Spacing 

Dielectric Correction — Open Hole 



Schlumberger 



REm-61 



4.7 



4.6 



4.5 



4.4 



Attenuation 4.3 
(dB) 



4.2 



4.1 



4.0 



3.9 



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*Markof Schlumberger 
© Schlumberger 



3 4 5 

Phase shift (°) 



Purpose 

Charts REm-59 through REm-62 are identical to Chart REm-58 
for determining Rt and e r at larger spacings of the arcVISION675 
and ImPulse 2-MHz tools. 

< ► 



Back to Contents 



165 



Resistivity Electromagnetic — LWD 



arcVISION675* and ImPulse* Array Resistivity 
Compensated Tools — 2 MHz and 40-in. Spacing 

Dielectric Correction — Open Hole 



Schlumberger 



REm-62 



4.0 



Attenuation 
(dB) 




3.9 



3.8 



3.7 



3.6 



3.5 



3.4 



3.3 



3.2 



3.1 




°Dielectric assumption 
e r = 5 + 108.5R- 035 



*Markof Schlumberger 
© Schlumberger 



Phase shift (") 



Purpose 

Charts REm-59 through REm-62 are identical to Chart REm-58 for 
determining Rt and e r at larger spacings of the arcVISION675 and 
ImPulse 2-MHz tools. 



166 



Back to Contents 



Resistivity Electromagnetic — LWD 



arcVISION675* and ImPulse* Array Resistivity 
Compensated Tools — 2 MHz with Dielectric Assumption 

Dielectric Correction — Open Hole 



Schlumberger 



REm-63 



3.5 



10-' 



Dielectric Effects of Standard Processed arcVISI0N675 or ImPulse Log 
at 2 MHz with Dielectric Assumption 



10° 



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*Markof Schlumberger 
© Schlumberger 



Resistivity 
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< ► 



Back to Contents 



167 



Formation Resistivity — Wireline 



Resistivity Galvanic 

Invasion Correction — Open Hole 



Schlumberger 



Rt-1 

(former Rint-1) 



Purpose 

The charts in this chapter are used to determine the correction for 
invasion effects on the following parameters: 

■ diameter of invasion (di) 

■ ratio of flushed zone to true resistivity (R xo /Rt) 

■ Rt from laterolog resistivity tools. 

The Rxo/Rt and Rt values are used in the calculation of water 
saturation. 

Description 

The invasion correction charts, also referred to as "tornado" or "but- 
terfly" charts, assume a step-contact profile of invasion and that all 
resistivity measurements have already been corrected as necessaiy 
for borehole effect and bed thickness by using the appropriate chart 
from the "Resistivity Laterolog" chapter. 

To use any of these charts, enter the y-axis and x-axis with the 
required resistivity ratios. The point of intersection defines di, 
Rxo/Rt, and Rt as a function of one resistivity measurement. 

Saturation Determination in Clean Formations 

Either of the chart-derived values of Rt and R xo /Rt are used to find 
values for the water saturation of the formation (Sw). The first of two 
approaches is the S w - Arc hie (Swa), which is found using the Archie 
saturation formula (or Chart SatOH-3) with the derived Rt value and 
known values of the formation resistivity factor (Fr) and the resistiv- 
ity of the water (R w ). The Sw- ratio (Swr) is found by using R xo /Rt and 
Rmf/Rw as in Chart SatOH-4. 



If Swa and Swr are equal, the assumption of a step-contact inva- 
sion profile is indicated to be correct, and all values determined 
(Sw, Rt, Rxo, and di) are considered good. 

If Swa > Swr, either invasion is very shallow or a transition-type 
invasion profile is indicated, and Swa is considered a good value for Sw. 

If Swa < Swr, an annulus-type invasion profile may be indicated, 
and a more accurate value of water saturation may be estimated 
by using 

1 

'wA 



V wR / 

The correction factor of (Swa/Swr) 174 is readily determined from 
the scale. 

For more information, see Reference 9. 














SwA'SwR 
















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168 



Back to Contents 



Formation Resistivity — Wireline 



High-Resolution Azimuthal Laterolog Sonde (HALS) 

Formation Resistivity and Diameter of Invasion — Open Hole 



Schlumberger 



Rt-2 





Thick Beds, 8-in. Hole, R xo /R m = 10 




10 3 

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10° 10' 10 2 

HLLD/HLLS 






Purpose 

The resistivity values of HALS laterolog deep resistivity (HLLD), 
HALS laterolog shallow resistivity (HLLS), and resistivity of the 
flushed zone (R xo ) measured by the High-Resolution Azimuthal 
Laterolog Sonde (HALS) are used with this chart to determine 
values for diameter of invasion (di) and true resistivity (Rt). 

Description 

The conditions for which this chart is used are listed at the top. The 
chart is entered with the ratios of HLLD/HLLS on the x-axis and 
HLLD/Rxo on the y-axis. The intersection point defines dj on the 
dashed curves and the ratio of Rt/R xo on the solid curves. 



Example 

Given: 

Find: 
Answer: 



HLLD = 50 ohm-m, HLLS = 15 ohm-m, R xo = 2.0 ohm-m, 
and R m = 0.2 ohm-m. 

Rt and diameter of invasion. 

Enter the chart with the values of HLLD/HLLS = 50/15 = 
3.33 and HLLD/R X0 = 50/2 = 25. 

The resulting point of intersection on the chart indicates 
that Rt/R X o = 35 and di = 34 in. 
Rt = 35 x 2.0 = 70 ohm-m. 



Back to Contents 



169 



Formation Resistivity — Wireline 



Schlumberger 



High-Resolution Azimuthal Laterolog Sonde (HALS) 

Formation Resistivity and Diameter of Invasion — Open Hole 



Rt-3 






Thick Beds, 8-in. Hole, R xo /R m = 10 




10 3 

10 2 

HRLD/R X0 

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10° 

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10° 10 1 10 2 

HRLD/HRLS 





Purpose 

The resistivity values of high- resolution deep resistivity (HRLD), high- 
resolution shallow resistivity (HRLS), and R xo measured by the HALS 
are used similarly to Chart Rt-2 to determine values for di and Rt. 



Description 

The conditions for which this chart is used are listed at the top. The 
chart is entered with the ratios of HRLD/HRLS on the x-axis and 
HRLD/Rxo on the y-axis. The intersection point defines di on the 
dashed curves and the ratio of Rt/R X o on the solid curves. 



170 



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Formation Resistivity — LWD 



geoVISION675* Resistivity 

Formation Resistivity and Diameter of Invasion — Open Hole 



Schlumberger 



Rt-10 





Ring, Deep, and Medium Button Resistivity (6.75-in. tool) 




10 
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*Markof Schlumberger 
© Schlumberger 


1 2 3 

Rring/Rbd 




Purpose Example 

This chart is used to determine the correction applied to the log Given: 

presentation of Rt and di determined from geoVISION675 ring (Rring) 

and deep (Rbd) and medium button (Rbm) resistivity values. pj n( j. 

Description Answer: 

Enter the chart with the ratios of R r i n g/Rbd on the x-axis and 

Rrmg/Rbm on the y-axis. The intersection point defines di on the blue 

dashed curves, Rt/Rring on the red curves, and Rt/R xo on the black 

curves. Charts Rt-11 through Rt-17 are similar to Chart Rt-10 for 

different tool sizes, configurations, and resistivity terms. 



vnng 



= 30 ohm-m, R X o/Rn 
6 ohm-m. 



50, Rbd = 15 ohm-m, and 



Rt, di, and R xo . 

Enter the chart with values of Rring/Rbd = 30/15 = 2 on 
the x-axis and Rring/Rbm = 30/6 = 5 on the y-axis to find 
di = 22.5 in., Rt/Rrmg = 3.1, and Rt/R X o = 50. From these 
ratios, R t = 3.1 x 30 = 93 ohm-m and R xo = 93/50 = 
1.86 ohm-m. 



Back to Contents 



171 



Formation Resistivity — LWD 



geoVISION675* Resistivity 

Formation Resistivity and Diameter of Invasion — Open Hole 



Schlumberger 



Rt-11 








Deep, Medium, and Shallow Button Resistivity (6.75-in. tool) 




Rxo/R m = 50 




















































Rbd/Rb S 


30 
20 

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9 
8 
7 
6 
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© Schlumberger 









Purpose 

This chart is used similarly to Chart Rt-10 to determine the 
correction applied to the log presentation of Rt and di determined 
from geoVISION675 deep (Rbd), medium (Rbm), and shallow 
button (Rbs) resistivity values. 



172 



< ► 



Back to Contents 



Formation Resistivity — LWD 



geoVISION675* Resistivity 

Formation Resistivity and Diameter of Invasion — Open Hole 



Schlumberger 



Rt-12 



Bit, Ring, and Deep Button Resistivity (6.75-in. tool) with ROP to Bit Face = 4ft 



Rbit/Rb, 





R„/R m = so 

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© Schlumberger 



Purpose 

This chart is used similarly to Chart Rt-10 to determine the correc- 
tion applied to the log presentation of Rt and di determined from 
geoVISION675 R r i n g, bit (Rwt), and Rbd resistivity values. 



Rbit/Rri 



< ► 



Back to Contents 



173 



Formation Resistivity — LWD 



geoVISION675* Resistivity 

Formation Resistivity and Diameter of Invasion — Open Hole 



Schlumberger 



Rt-13 






Bit, Ring, and Deep Button Resistivity (6.75-in. tool) with ROPto Bit Face = 35 ft 




20 

10 
9 
8 
7 

6 

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b 

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3 
2 

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R xo /R m = 50 
d h - 8.5 in. 












































34 


Z0 2.4 












































1 C 




O 5[ 


) 






























Rt/R- 










?a 




7 «» / 1/ 


* / 


I 


































1. 


4 






**> 




y^, 


7^ X A 


100 


7C 
































2 
>*> 






• 










-70- 


































1 . 




*^5 




*r* 








50 






























99 -** 


r 4 


• 










* 


f \ 




4? 




































^S 














• .. : - ; ' 


* 






































* 










j f 




3 


D 


































r * 










































2( 


) 










f^S 


4t 








20 
























rii 
















^* 




j5' ; ^j 


































/»[/ 






/ 


.^v 








• 


• 


15 






































/ - 








■V 






































~?[ ]/ 


<W 


+4 

10 








Rf/Rxn 






















18 / 


v 




'Ws 






'v\V 






































//ft t 






/^Jr 


































1 


2 / 




r / 






f or 


r\* 





I 


































16 






* 


t * 


> 


E 










































I A 


/th/f/t 
















































i 






3 
















































i/ 
























































2 




















































M* 
























































1 






















































*Markof Schlumberger 
© Schlumberger 


1 2 3456789 10 20 

nbit'r»ring 





Purpose 

This chart is used similarly to Chart Rt-10 to determine the correc- 
tion applied to the log presentation of Rt and di determined from 
geoVISION675 R r i n g, Rbit, and Rbd resistivity values. 



174 



< ► 



Back to Contents 



Formation Resistivity — LWD 



geoVISION825* 8 1 /4-in. Resistivity-at-the-Bit Tool 

Formation Resistivity and Diameter of Invasion — Open Hole 



Schlumberger 



Rt-14 





Ring, Deep, and Medium Button Resistivity (81/4-in. tool) 




10 
9 

8 

7 

6 
5 

4 

"ring' ''bm 

3 
2 

1 


Rxo/R m = 50 

d h = 12.25 in. 






























































































1 R 


— 1.8 


2^ 


























22- 




































.- 


. * 




















01 






00 ^~4^ 






«** 


**■ V 1 




3.0 














di 


1 A 




* 
** 




<^ 


^ 


' s 




















*f** 




• y' 










>>• y 


'26 










20 <+ 


"***^ -^ 


* 




/^ x 


* S^ 


* 
* 






















1 3 ^S "^ 




>*'** ^* 


^r *» 


X V 


* 


^r^ 


^/x 




















' '" ?~ 


^*s/ 




* 






"** -^^ 






















/ r 4 - >^ 


s / 




^ ' 










30 
















19 




£s"^ . 








^ 
* > 




rs> 


100 


















/ 1 / 


Sr 




,*^. 






if * 




70 




















/ '/ 


/¥ f 

7 <^ 


7' ' 






^ 30 






















18 / 


//# 




*£*<7j 




/J'' 


























'!//// 




• ' './— 


y *N jfi 


' on 




MK 






















1.2 U. 


/iff 


<7>< 






zU 
























It' / 

Iv / ' 


' /V/ 


'<T''t 


/ * s 


' 15 




























ff/i 


M'/?/ 




































y '^f' 


j7 S' 


10 




























1/ 


/i j/>// 




































i/* &•<. 


/ jf 


































r'f —£' 


' 7 
































ill/ jrb 


Jr^jy' 


































111 / J^s 


y / 5 
































16 1 


w 


'• 






































3 






































































W 2 


































1 


































*Markof Schlumberger 
© Schlumberger 


1 2 

"ring/ribd 






Purpose 

This chart is used similarly to Chart Rt-10 to determine the correc- 
tion applied to the log presentation of Rt and di determined from 
geoVISION825 R r i n g, Rbd, and Rbm resistivity values. 



< ► 



Back to Contents 



175 



Formation Resistivity — LWD 



geoVISION825* 8 1 /4-in. Resistivity-at-the-Bit Tool 

Formation Resistivity and Diameter of Invasion — Open Hole 



Schlumberger 



Rt-15 






Deep, Medium, and Shallow Button Resistivity (8'/4-in. tool) 




20 

10 
9 
8 
7 

6 

FL/Rbs 5 

4 

3 

2 
1 


Rx /R m = 50 
d h = 12.25 in. 










































19 


































R 


/Rb 




















1 4 


1 R 
































n 








I ■■ 




































IB 










y ' 








>. ; 














































* 




y 








2.4 






























s 


< 








^ 




-" 

•' 






^ > 




















1.2. 










y "■ 


/ , 










di 














• 












^ 








/> 


■■ ** 




•V 






























/ 












*-* 


• / 














































>>*» 




.> 


* 




X 
*• 


«" > 








**■ 


?7 


jr** 




24 


















16 




tj 






* 
• 


* 




• 
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^ 


y* 


• 
• 


y 










^ 




/ ««* 


70- 


10 


] 


















/i 








• 










•• 








^/ 






^ 


y 


50 
























f '/ 




if 




/ 




s 




s 








«* >■ 




/^ 


.* 


































V 






/ • 




/> 












30 


































A / 


il 




/ 


A 


/^ 








• 


Jr * 


* 








































/ 






X^ 






* 


•>• 


2 n 




































1. 


1 




• / 


' 1 
'Is' 


*7 




'/ 


7 
















i/R 


XD 


































/ i 


K J* 






/., 


* 




* 


IE 








h 




































/ijf 


Si 

i 

lySP 


f ' 


/• 

























































/ 


i Jr7 
'si's 






• 


7 






















































/'/ 




v7 


!A 






























































ff 




























































11/ 1 




3 
























































14 




/ 1 


r • 






























































Y* 






























































1 




























































*Markof Schlumberger 
© Schlumberger 


1 2 3 4 E 

Rbd'Hbm 





Purpose 

This chart is used similarly to Chart Rt-10 to determine the correc- 
tion applied to the log presentation of Rt and di determined from 
geoVISION825 Rbd, Rbm, and Rbs resistivity values. 



176 



< ► 



Back to Contents 



Formation Resistivity — LWD 



geoVISION825* 8 1 /4-in. Resistivity-at-the-Bit Tool 

Formation Resistivity and Diameter of Invasion — Open Hole 



Schlumberger 



Rt-16 





Bit, Ring, and Doop Button Resistivity (8V4-in. tool) with ROP to Bit Face = 4 ft 




10 
9 

8 

7 

6 
5 

4 

r>bit/"bd 

3 

2 
1 


fUR m = 50 
d h = 12.25 in. 




































^t/Rw 






2.4: 


3n 


35 












































3U 




















































i 




V 




^4U 












































2.0 . 












J-50 








































1.8 






*>"f** 






*/ 


• 










































28 






fs 




""^ / 


• 






50 














































/ • 




• 




•/ 






































/^// 










^-•—1 


^V 


"-n/ 


^2/ 60 


























(J; 




.6 






*■ z 


/ 


"V 






"-*7* 


/• 




I 


'HOOj 






























2b 








' • 


s 






SJ 






/d- 


































^^4 


» 


>5* 






• 


• 


(^ 


sf 


SJ^t 


• 


bU 


























1.5 








S 




' 




/ 




• ' 


S 

f y 




^"3 







































^ 


s/ 




/ y* 


/ 








7 

• 


' ?n 






























y 








f / 
f 


^, 




..-"-' 


-^ 




"^ 


• 


- 

"1 


5 
























_1.4 




/ 1 


l/ 


y/ 




A 


/ 


/ 


> 




^^? 

• y 


•J 


? s 


s 










































^v 




• ^ 


''V 


1? 


IU 
































/l/i 




'// 


• 


v""! 


> 




f • 








































22 






^■v ' 


•^ 




// 




*> 


-7 






































r'\s'l 


// 












>^ 




































li 


/ // // 
i' rs 






* 

ss 


7/ 


-y 




^5 










































/7Ur 




S,* 










































1.3 / 


if I 1 




y 






/s 










































i / 




'/ L 


*;si'. 


''X,} 




















!«/R, 






















20 It 




'A, 




^A £r 


















h 
































s 




-\ 














































Wu 






/ (' 






















































•Y 
























































i 




















































If'' 


V 
























































* 


























































" 1 
























































*Markof Schlumberger 
© Schlumberger 


1 2 3 4 5 6 7 8 

"bit/firing 





Purpose 

This chart is used similarly to Chart Rt-10 to determine the correc- 
tion applied to the log presentation of Rt and di determined from 
geoVISION825 R r i n g, Rbit, and Rbd resistivity values. 



< ► 



Back to Contents 



177 



Formation Resistivity — LWD 



geoVISION825* 8 1 /4-in. Resistivity-at-the-Bit Tool 

Formation Resistivity and Diameter of Invasion — Open Hole 



Schlumberger 



Rt-17 






Bit, Ring, and Deep Button Resistivity (8V4-in. tool) with ROP to Bit Face = 35 ft 




20 

10 
9 
8 
7 

6 

Rbit/Rbd r 

a 
4 
3 

2 
1 


R,/Rxo = 50 
d h = 12.25 in. 












































40 


2.0 


50 












































35 


1 6 -r 




S/ 


3.0 














































^ i 


i / 


• y 


s. , 


ID 






























R t /R b it 






J 










s^ 


7 * 

r • 


V)'' iuu 


































3C 

Si 

s 




. 




• 1^ 






S4 


• 70 
































9« 








s 


/ 






i 


w 5C 
































1.3 _ 




**• 










t> 


*£ 


*~"? r 


30 
























A 


















/ 


s 






**/ 


i s 
































?fi 






' i^ 




' s 


s 


' .,'■■*' 




s 










































j/' 


/ 4 




/ 








* L 


































s 


? 


s 


'/ySf 






s 




"^4* 


*fi 






































*i 




i 


■>" i 


^sfi 






/,, 




r b 






ri t /n xo 
































/ 






* y 






































?4 




A 




V 


i 






X" •, 


/' 


i 






































' iy 


i 








"%/* 




ls*s 


' 10 






























1.2 j 




/i 










• / 


s<> 


Y S 


' 






































St 

r f 






'j 


/ 


/ 






' 7 




































>2 / 






i/ 


sf 




• 


/ 


'5 


's 






































li/l 


?s* 


* A 




/ 
if 


s 
* 








































1 r i. 


'/, 






' 














































20 ill A/ 


r / 




\ 














































^U0Z' 


// 
























































1 




















































J/S 
























































1 






















































*Markof Schlumberger 
© Schlumberger 


1 2 3 4 5 6 7 8 9 10 20 

■'bit'r'ring 





Purpose 

This chart is used similarly to Chart Rt-10 to determine the correc- 
tion applied to the log presentation of Rt and di determined from 
geoVISION825 R r i n g, Rbit, and Rbd resistivity values. 



178 



< ► 



Back to Contents 



Formation Resistivity — LWD 



arcVISION* Array Resistivity Compensated Tool— 400 kHz 

Resistivity Anisotropy Versus Shale Volume — Open Hole 



Schlumberger 



Rt-31 



(ohm-m) 



Response Through Sand and Shale Layers at 90° Relative Dip 
for R sh = 1 ohm-m and R sand = 5 ohm-m 



10' 



Phase-Shift Resistivity 



10° 



Ok^ "---^^ 

** ^^^^- ^^ * »»^. 

■»» ^^^%»^ ^^^ 



0.2 0.4 0.6 0.8 1.0 



Response Through Sand and Shale Layers at 90° Relative Dip 
for R sh = 1 ohm-m and R sand = 20 ohm-m 



10 2 



R ps 10' 
(ohm-m) 



10° 



Phase-Shift Resistivity 



vv 



0.2 0.4 0.6 0.8 1.0 



R B d 

(ohm-m) 



10' 



10° 



Attenuation Resistivity 



v>v 

N^^^ — ~^^ 

"* ^^^^ — ^^^^ 



*Markof Schlumberger 
© Schlumberger 



Rad 

(ohm-m) 



0.2 



0.4 0.6 

V,„ 



0.8 



1.0 



10 2 



10' 



10° 



Attenuation Resistivity 



vv 

s — '■ 

\ ^vj^ - — "^ - v^ — 

s r 1 **^ ^*-^s^ 



0.2 



0.4 0.6 



0.8 



1.0 




Resistivity spacing 



16 in. 



22 in. 



28 in. 



34 in. 



40 in. 



Purpose 

This chart illustrates the resistivity response, as affected by sand 
and shale layers, of the arcVISION tool in horizontal wellbores. 
The chart is used to determine the values of Rh and R v . These 
corrections are already applied to the log presentation. 

Description 

The chart is constructed for shale layers at 90° relative dip to the 
axis of the arcVISION tool. That is, both the layers of shale and the 
tool are horizontal to the vertical. Other requirements for use of this 
chart are that the shale resistivity (R S h) is 1 ohm-m and the sand 
resistivity is 5 or 20 ohm-m. 



Select the appropriate chart for the attenuation (R ar j) or phase- 
shift (Rps) resistivity and values of resistivity of the shale (R S h) and 
sand (Rsand)- Enter the chart with the volume of shale (V sn ) on the 
x-axis and the resistivity on the y-axis. At the intersection point of 
these two values move straight downward to the dashed blue curve 
to read the value of Rh. Move upward to the solid green curve to read 
the value of R v . 

Chart Rt-32 is used to determine Rh and R v values for the 2-MHz 
resistivity. 



Back to Contents 



179 



Formation Resistivity — LWD 



arcVISION* and ImPulse* Array Resistivity Compensated Tools — 2 MHz 

Resistivity Anisotropy Versus Shale Volume — Open Hole 



Schlumberger 



Rt-32 



Response Through Sand and Shale Layers at 90° Relative Dip 
for R sh = 1 ohm-m and R sand = 5 ohm-m 



10 2 




PhasG-Shift Resistivity 












































































Rp S 10' 












ohm-m) 


•*— 












^ "■ 














^''^SSfe, """"•s^. 








■*» 












** 


•* ^ 












"* - *. ^ 






10" 






"* "* — ^ 


~~o^. 



Response Through Sand and Shale Layers at 90° Relative Dip 



10 2 



Phase-Shift Resistivity 



R ps 
(ohm-m) 



10 1 



0.2 0.4 0.6 0.8 1.0 

V., 



10° 



v^^ :^s»— < =r — — 



0.2 0.4 0.6 0.8 1.0 

V h 



10 2 



Attenuation Resistivity 



R„d 10' 
(ohm-m) 



10° 



s ^^^ ^*'-»*»^ 
*. ^V> ^---. 

N— ^Sw "''- » v w = 

*i ^ ■■■ w^ — — \ — 

** — ^*"^^ — — ^-"ii 

*» ^^^. ^" m ^. 

** — ^ ^ ^^^ — — >v — 

*• — ^^^ s^- — — X. — 



Rad 

(ohm-m) 



in 2 




Attenuation Resistivity 
























































































m 1 














— * — ~^^^ 




































N. 
























*>» 














^, 






w° 






~~~ 


---___ 


— — ^\ 




0.2 0.4 0.6 0.8 



1.0 



Resistivity spacing 



16 in. 
ft, 



22 in. 

R„ 



*Markof Schlumberger 
© Schlumberger 



Purpose 

This chart is used similarly to Chart Rt-31 for arcVISION and 
ImPulse 2-MHz resistivity. These corrections are already applied 
to the log presentation. 



28 in. 



0.2 0.4 0.6 0.8 1.0 

V.„ 



34 in. 



40 in. 



180 



< ► 



Back to Contents 



Formation Resistivity — LWD 



arcVISION* Array Resistivity Compensated Tool— 400 kHz 

Resistivity Anisotropy Versus Dip — Open Hole 



Schlumberger 



Rt-33 



10 3 



Aniostropy Response for R h = 1 ohm-m and V(R V /RJ = 5 
Phase-Shift Resistivity 



(ohm-m) 







































in 2 








































































10' 










/-^ 


























10° 













10' 



Aniostropy Response for R h = 1 ohm-m and V(R V /RJ = 2 
Phase-Shift Resistivity 



Rp S 
(ohm-m) 



10 20 30 40 50 60 70 80 90 
Relative dip angle (°) 



































































































10° 













10 20 30 40 50 60 70 80 90 
Relative dip angle (°) 



(ohm-m) 



in 3 




Attenuation Resistivity 
































































in 2 








































































10' 


























































m° 













R B d 

(ohm-m) 



10' 




Attenuation Resistivity 




































































































m° 













10 20 30 40 50 60 70 80 90 
Relative dip angle (°) 



10 20 30 40 50 60 70 80 90 
Relative dip angle (°) 




Resistivity spacing 



16 in. 



22 in. 



28 in. 



34 in. 



40 in. 



*Markof Schlumberger 
© Schlumberger 



Purpose 

This chart is used to determine arcVISION R ps and R a d for relative 
dip angles from to 90°. These corrections are already applied to 
the log presentation. 



Description 

Enter the appropriate chart with the value of relative dip angle and 
move to intersect the known resistivity spacing. Move horizontally 
left to read R ps or R a d for the conditions of the horizontal resistivity 
(Rh) = 1 ohm-m and the square root of the R v /Rh ratio. 



< ► 



Back to Contents 



181 



Formation Resistivity — LWD 



arcVISION* and ImPulse* Array Resistivity Compensated Tools — 2 MHz 

Resistivity Anisotropy Versus Dip — Open Hole 



Schlumberger 



Rt-34 



10 3 



Aniostropy Response for R h = 1 ohm-m and V(R„/RJ = 5 
Phase-Shift Resistivity 



(ohm-m) 

































m 2 


















III 1 S^ 




















flsl 






























in' 


















































m° 






^0z 





10' 



Aniostropy Rosponse for R h = 1 ohm-m and V(R„/RJ = 2 
Phase-Shift Resistivity 



R PS 

(ohm-m) 



































































































m° 




.—- * 









10 20 30 40 50 60 70 80 90 
Relative dip angle (°) 



10 20 30 40 50 60 70 80 90 
Relative dip angle (°) 



Rad 

(ohm-m) 




10 3 




Attenua 


ion Resistivi 


ty 




















































in 2 






































































in 1 








































































10° 











Rad 

(ohm-m) 



10' 




Attenuation Resistivity 




































































































1(1° 











10 20 30 40 50 60 70 80 90 
Relative dip angle (°) 



10 20 30 40 50 60 70 80 90 
Relative dip angle (°) 



Resistivity spacing 



16 in. 



22 in. 



28 in. 



34 in. 



40 in. 



*Markof Schlumberger 
© Schlumberger 



Purpose 

This chart is used similarly to Chart Rt-33 for arcVISION and 
ImPulse 2-MHz resistivity. These corrections are already applied 
to the log presentation. 



182 



< ► 



Back to Contents 



Formation Resistivity — LWD 



arcVISION* Array Resistivity Compensated Tool— 400 kHz 

Resistivity Anisotropy Versus Square Root of R v /Rh — Open Hole 



Schlumberger 



Rt-35 



10 3 



Aniostropy Response at 85° dip for R h = 1 ohm-m 
Phase-Shift Resistivity 



(ohm-m) 





























































































in 2 












































































































in 1 








































































10° 



















10 1 



Rps 

(ohm-m) 



Aniostropy Response at 65° dip for R h = 1 ohm-m 
Phase-Shift Resistivity 



















































































































































10° 



















1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 

VfrvRj 



1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 

VfRJPJ 



(ohm-m) 



in 3 






Attenuation Resistivity 














































































in 2 








































































10 1 
















































= ' 




in° 











R B d 

(ohm-m) 



10' 






Attenuation Resistivity 














































































































































in° 



















1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 
V(R V /R h ) 



1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 



VfrvRT 




Resistivity spacing 


Ifiin 


??in 


?Rin 


34 in 


40 in 



*Markof Schlumberger 
© Schlumberger 



Purpose 

This chart and Chart Rt-36 reflect the effect of anisotropy on the 
arcVISION resistivity response. These corrections are already 
applied to the log presentation. As the square root of the R ¥ /Rh 
ratio increases, the effect on the resistivity significantly increases. 



Description 

Enter the appropriate chart with the value of the phase-shift or 
attenuation resistivity on the y-axis. Move horizontally to intersect 
the resistivity spacing curve. At the intersection point read the value 
of the square root of the R v /Rh ratio on the x-axis. 



< ► 



Back to Contents 



183 



Formation Resistivity — LWD 



arcVISION* and ImPulse* Array Resistivity Compensated Tools — 2 MHz 

Resistivity Anisotropy Versus Square Root of R v /Rh — Open Hole 



Schlumberger 



Rt-36 



10 3 



Aniostropy Response at 85° dip for R h = 1 ohm-m 
Phase-Shift Resistivity 



(ohm-m) 









































































1fl 2 












































































































in' 








































































m° 



















10 1 



Aniostropy Rosponse at 65° dip for R h = 1 ohm-m 
Phase-Shift Resistivity 



Rp S 
(ohm-m) 



















































































































































in° 



















1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 



1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 

VirvRJ 



(ohm-m) 




in 3 






Attenuation Resistivity 














































































in 2 


































































in 1 
















. 


































































m° 













R B d 
(ohm-m) 



in> 






Attenuation Resistivity 










































































































































m° 















1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 



1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 



VirvRT 



VlRA 



Resistivity spacing 


Ifiin 


??in 


9Rin 


34 in 


40 in 



*Markof Schlumberger 
© Schlumberger 



Purpose 

This chart is used similarly to Chart Rt-35 for arcVISION and 
ImPulse for 2-MHz resistivity. These corrections are already 
applied to the log presentation. 



184 



< ► 



Back to Contents 



Formation Resistivity — LWD 



arcVISION675* Array Resistivity Compensated Tool— 400 kHz 

Conductive Invasion — Open Hole 



Schlumberger 

Rt-37 



1 


R xo and d; for R, ~ 10 ohm-m 








16-in. R ps /40-in. R ad 01 
0.01 


































ilH 






























































































Wt/'/I'l/Jlli 




























m¥ / 'i i /M\\ 


























9S&^'''''/y/HI\l\ 






















64>^y^| 


WMf' 'A/M/j 






















60> 


r*j7/jffmL 




111 






















^r7rf-*0.8 Y W , 
^±j0.75/i// / 

-5T~ Vmrllf/ /J 




16 




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0.3 ^o.t 

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40 




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/ j 


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dilin.P 


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i 


ill/ ' " 


= 0.1 o 


im 


-m 






















28 ' 


r24 


















































0. 

*Markof Schlumberger 
© Schlumberger 


31 0.1 1.0 

28-in. Rp S /40-in. R ad 




Purpose 

This log-log chart is used to determine the correction applied to 
the log presentation of the 40-in. arcVISION675 resistivity measure- 
ments, diameter of invasion (di), and resistivity of the flushed zone 
(Rxo). These data are used to evaluate a formation for hydrocarbons. 

Description 

Enter the chart with the ratio of the 16-in. R ps /40-in. R a d on the y-axis 
and 28-in. R ps /40-in. Radon the x-axis. The intersection point defines 
the following: 

■ di 

■ Rxo 

■ correction factor for 40-in. attenuation resistivity. 



Chart Rt-38 is used for 2-MHz resistivity values. The corresponding 
charts for resistive invasion are Charts Rt-39 and Rt-40. 



Example 

Given: 

Find: 
Answer: 



16-in. R ps /40-in. R ad = 0.2 and 28-in. R ps /40-in. R ad = 0.4. 
Rxo, di, and correction factor for 40-in. R a d- 
At the intersection point of 0.2 on the y-axis and 0.4 on 
the x-axis, di = 31.9 in., R xo = 1.1 ohm-m, and correction 
factor = 0.955. 

The value of the 40-in. R a d is reduced by the correction 
factor: 40-in. R a d x 0.955. 



Back to Contents 



185 



Formation Resistivity — LWD 



Schlumberger 



arcVISION675* and ImPulse* Array Resistivity Compensated Tools — 2 MHz 

Conductive Invasion — Open Hole 



Rt-38 








R xo and d : for R t - 10 ohm-m 


1.0 






































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f 2 WM 


























48,7 




























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d, (in. 








































































































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0.1 1 









28-in. R nq /40-in. R art 


*Markof Schlumberger 






© Schlumberger 







Purpose 

This chart is used similarly to Chart Rt-37 for arcVISION675 and 
ImPulse 2-MHz resistivity. The corrections are already applied to 
the log presentation. 



186 



< ► 



Back to Contents 



Formation Resistivity — LWD 



arcVISION* Array Resistivity Compensated Tool— 400 kHz 

Resistive Invasion — Open Hole 



Schlumberger 

Rt-39 



FL and dfor R, ~10ohm-m 



10 



16-in. R ps / 
40-in. R„ H 




R xn = 300ohm-m 




10 



*Markof Schlumberger 
© Schlumberger 



28-in. R ps /40-in. R„ 



Purpose 

This chart is used similarly to Chart Rt-37 to determine the correc- 
tion applied to the arcVISION log presentation of di, R xo , and 40-in. 
Rati for resistive invasion. 



< ► 



Back to Contents 



187 



Formation Resistivity — LWD 



Schlumberger 



arcVISION* and ImPulse* Array Resistivity Compensated Tools — 2 MHz 

Resistive Invasion — Open Hole 



Rt-40 



R lo and d; for R, ~10ohm-m 



2.4 



2.2 



2.0 



16-in. R ps / 
40-in. R„ ri 





300ohm-m 



*Markof Schlumberger 
© Schlumberger 



28-in. R ps /40-in. R ai 



1.4 



Purpose 

This chart is used similarly to Chart Rt-39 to determine the correc- 
tion applied to the arcVISION and ImPulse log presentation for 
2-MHz resistivity. 



< ► 



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Formation Resistivity — LWD 



arcVISION* Array Resistivity Compensated Tool— 400 kHz in Horizontal Well 

Bed Proximity Effect — Open Hole 



Schlumberger 



Purpose 

Charts Rt-41 and Rt-42 are used to calculate the correction applied 
to the log presentation of Rt from the arcVISION tool at the 
approach to a bed boundary. The value of Rt is used to calculate 
water saturation. 

Description 

There are two sets of charts for differing conditions: 



Example 

Given: 

Find: 
Answer: 



shoulder bed resistivity (Rshouider) = 10 ohm-m and Rt : 
Rshouider = 10 ohm-m and Rt =100 ohm-m. 



1 ohm-m 



Rshouider = 10 ohm-m, Rt = 1 ohm-m, and 
16-in. R ps = 1.5 ohm-m. 

Bed proximity effect. 

The top set of charts is appropriate for these resistivity 
values. The ratio R ps /Rt = 1.5/1 = 1.5. 

Enter the y-axis of the left-hand chart at 1.5 and move 
horizontally to intersect the 16-in. curve. The corre- 
sponding value on the x-axis is 1 ft, which is the distance 
of the surrounding bed from the tool. At 2 ft from the 
bed boundaiy, the value of 16-in. R ps = 1 ohm-m. 




< ► 



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continued on next page 

189 



Formation Resistivity — LWD 



arcVISION* Array Resistivity Compensated Tool— 400 kHz in Horizontal Well 

Bed Proximity Effect — Open Hole 



Schlumberger 



Rt-41 



Rps/Rt 



o 



Bed Proximity Effect for Horizontal Well: R sh0U | der = lOohm-m and R,= 1 ohm-m 

3 























1 




















tt 


k 




















1 


^a*. 

























































Rad/Rt 





\1 




















? 












































1 










































n 























01 23456789 10 
Distanco to bod boundary (ft) 



1 2 3 4 5 6 7 8 9 10 
Distance to bed boundary (ft) 



Rps/R« 



Bed Proximity Effect for Horizontal Well: R sh0U | der = 10 ohm-m and R t = 100 ohm-m 

3 

























? 












































1 












































n 





















Rad/Rt 

























? 












































1 










































n 






















1 2 3 4 5 6 7 8 9 10 
Distance to bed boundary (ft) 



1 2 3 4 5 6 7 8 9 10 
Distance to bed boundary (ft) 



Resistivity spacing 



16 in. 



22 in. 



28 in. 



34 in. 



40 in. 



*Markof Schlumberger 
© Schlumberger 



190 



< ► 



Back to Contents 



Formation Resistivity — LWD 



arcVISION* and ImPulse* Array Resistivity Compensated Tools — 2 MHz 
in Horizontal Well 

Bed Proximity Effect — Open Hole 



Schlumberger 



Rt-42 



R ps /R t 



Bed Proximity Effect for Horizontal Well: R sh0U | der = lOohm-m, Rt= 1 ohm-m 

3 







1 


















? 


























i\ 


















1 












































n 























1 2 3 4 5 6 7 8 9 10 
Distance to bed boundary (ft) 



Rad/Rt 























? 










































1 












































n 























12 3 4 5 6 7 

Distance to bed boundary (ft) 



10 



Rps/Rt 



Bed Proximity Effect for Horizontal Well: R shoU | dor = 10 ohm-m, R, = 100 ohm-m 

3 

























? 
























[ 




















1 


I 






















^ 


^ 


stf* 


^ 


^v 




































Rad/Rt 

























? 












































1 








































n 



















1 2 3 4 5 6 7 8 9 10 
Distance to bed boundary (ft) 



1 2 3 4 5 6 7 8 9 10 
Distance to bed boundary (ft) 



Resistivity spacing 



16 in. 



22 in. 



28 in. 



34 in. 



40 in. 




*Markof Schlumberger 
© Schlumberger 



Purpose 

This chart is used similarly to Chart Rt-41 for arcVISION and 
ImPulse 2-MHz resistivity. The correction is already applied 
to the log presentation. 



< ► 



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191 



Lithology — Wireline 



Density and NGS* Natural Gamma Ray Spectrometry Tool 

Mineral Identification — Open Hole 



Schlumberger 



Purpose Example 

This chart is a method for identifying the type of clay in the wellbore. Given: 

The values of the photoelectric factor (Pe) from the Litho-Density* 

log and the concentration of potassium (K) from the NGS Natural 

Gamma Ray Spectrometry tool are entered on the chart. p m( j. 

Description Answer: 

Enter the upper chart with the values of Pe and K to determine the 
point of intersection. On the lower chart, plotting Pe and the ratio 
of thorium and potassium (Th/K) provides a similar mineral evalua- 
tion. The intersection points are not unique but are in general areas 
defined by a range of values. 



Environmentally corrected thorium concentration 
(ThNGScorr) = 10.6 ppm, environmentally corrected 
potassium concentration (KNGScorr) = 3.9%, and Pe = 3.2. 

Mineral concentration of the logged clay. 

The intersection points from plotting values of Pe and K 
on the upper chart and Pe and Th/K ratio = 10.6/3.9 = 2.7 
on the lower chart suggest that the clay mineral is illite. 




192 



Back to Contents 



Lithology — Wireline 



Density and NGS* Natural Gamma Ray Spectrometry Tool 

Mineral Identification — Open Hole 



Schlumberger 



Lith-1 

(former CP-18) 



10 



Photoelectric 
factor, Pe 



4 6 

Potassium concentration, K (%) 













Chlorite 

=1 




Glauconite 




Biotite 




O 




i n 






















Montmorillonite 






mite 




O 1 








Muscovite 






ft 1 


O 


O 1 Kaolmite 











10 



10 



Photoelectric 
factor, Pe 



0.1 0.2 0.3 



*Markof Schlumberger 
© Schlumberger 



8 




































jlauconite 


3iotite 


1 




Chlori 


te 










O 




R 


K 


i 




U 


4 


















Mixe 


d layer 






















I 


lite 


. 












d 






M 
K 


uscovit 

1 


e 
1 




V 






<"> 














1 1 












I 


lontmorilk 


nite 


Kaolini 


te 






























0.6 1 2 3 6 10 

Thorium/potassium ratio, Th/K 



20 30 60 100 



< ► 



Back to Contents 



193 



Lithology — Wireline 



NGS* Natural Gamma Ray Spectrometry Tool 

Mineral Identification — Open Hole 



Schlumberger 



Lith-2 

(former CP-19) 



Thorium 
(ppm) 



100% illite point . 




Feldspar 



Th/K = 0.3 



Potassium evaporites, -30% feldspar 



2 3 

Potassium (%) 




*Markof Schlumberger 
© Schlumberger 



Purpose 

This chart is used to determine the type of minerals in a shale 
formation from concentrations measured by the NGS Natural 
Gamma Ray Spectrometry tool. 

Description 

Entering the chart with the values of thorium and potassium locates 
the intersection point used to determine the type of radioactive min- 
erals that compose the majority of the clay in the formation. 



A sandstone reservoir with varying amounts of shaliness and 
illite as the principal clay mineral usually plots in the illite segment 
of the chart with Th/K between 2.0 and 3.5. Less shaly parts of the 
reservoir plot closer to the origin, and shaly parts plot closer to the 
70% illite area. 



194 



Back to Contents 



Lithology — Wireline 



Platform Express* Three-Detector Lithology Density Tool 

Porosity and Lithology — Open Hole 



Schlumberger 



Purpose 

This chart is used to determine the lithology and porosity of a forma- 
tion. The porosity is used for the water saturation determination and 
the lithology helps to determine the makeup of the logged formation. 

Description 

Note that this chart is designed for fresh water (fluid density 
[Pf] = 1.0 g/cm 3 ) in the borehole. Chart Lith-4 is used for saltwater 
(Pf = 1.1 g/cm 3 ) formations. 

Values of photoelectric factor (Pe) and bulk density (Pb) from the 
Platform Express Three-Detector Lithology Density (TLD) tool are 
entered into the chart. At the point of intersection, porosity and 
lithology values can be determined. 



Example 

Given: 



Find: 
Answer: 



Freshwater drilling mud, Pe = 3.0, and bulk density : 
2.73 g/cm 3 . 

Freshwater drilling mud, Pe = 1.6, and bulk density : 
2.24 g/cm 3 . 

Porosity and lithology. 

For the first set of conditions, the formation is a 
dolomite with 8% porosity. 

The second set is for a quartz sandstone formation 
with 30% porosity. 




< ► 



Back to Contents 



continued on next page 
195 



Lithology — Wireline 



Platform Express* Three-Detector Lithology Density Tool 

Porosity and Lithology — Open Hole 



Schlumberger 



Lith-3 

(former CP-16) 



Fresh Water (p f = 1.0g/cm 3 ), Liquid-Filled Borehole 



1.9 



Bulk density, p h 
(g/cm 3 ) 




















































































































































































































































































































































v 




























































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2 3 4 

Photoelectric factor, Pe 



*Markof Schlumberger 
© Schlumberger 



196 



< ► 



Back to Contents 



Lithology — Wireline 



Platform Express* Three-Detector Lithology Density Tool 

Porosity and Lithology — Open Hole 



Schlumberger 



Lith-4 

(former CP-17) 



Salt Water (p f = 1.1 g/cm 3 ), Liquid-Filled Borehole 



1.9 



Bulk density, p b 
(g/cm 3 ) 



























































































































































































































































































































































































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*Markof Schlumberger 
© Schlumberger 



3 4 

Photoelectric factor, Pe 



This chart is used similarly to Chart Lith-3 for lithology and poros- bulk density (pb) from the Platform Express TLD tool in saltwater 

ity determination with values of photoelectric factor (Pe) and borehole fluid. 



< ► 



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197 



Lithology — Wireline, LWD 



Density Tool 

Apparent Matrix Volumetric Photoelectric Factor — Open Hole 



Schlumberger 



Lith-5 

(former CP-20) 










3.0 
2.5 
2.0 

Bulk density, p b 

(g/cm 3 ) 




















































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10 

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1 r 








6 

© Schlumberger 


5 4 3 2 1 4 6 8 10 12 14 

Photoelectric factor, Pe Apparent matrix 

volumetric photoelectric factor, U maa 



Purpose 

This chart is used to determine the apparent matrix volumetric 
photoelectric factor (U ma a) for the Chart Lith-6 percent lithology 
determination. 

Description 

This chart is entered with the values of bulk density (pb) and Pe from 
a density log. The value of the apparent total porosity (cpta) must also 
be known. The appropriate solid lines on the right-hand side of the 
chart that indicate a freshwater borehole fluid or dotted lines that 
represent saltwater borehole fluid are used depending on the salinity 
of the borehole fluid. Uf is the fluid photoelectric factor. 



Example 

Given: 

Find: 
Answer: 



Pe = 4.0, pb = 2.5 g/cm 3 , <|)ta = 25%, and freshwater 
borehole fluid. 

Apparent matrix volumetric photoelectric factor (U ma a). 

Enter the chart with the Pe value (4.0) on the left-hand 
x-axis, and move upward to intersect the curve for 
pb = 2.5 g/cm 3 . 

From that intersection point, move horizontally right to 
intersect the <|)ta value of 25%, using the blue freshwater 
curve. 

Move vertically downward to determine the U maa value 
on the right-hand x-axis scale: U ma a = 13. 



198 



Back to Contents 



Lithology — Wireline, LWD 



Density Tool 

Lithology Identification — Open Hole 



Schlumberger 



Purpose Example 

This chart is used to identify the rock mineralogy through comparison Given: 
of the apparent matrix grain density (pmaa) and apparent matrix volu- 
metric photoelectric factor (U ma a). Find: 

Description Answer: 

The values of p maa and U ma a are entered on the y- and x-axis, respec- 
tively. The rock mineralogy is identified by the proximity of the point 
of intersection of the two values to the labeled points on the plot. 
The effect of gas, salt, etc., is to shift data points in the directions 
shown by the arrows. 



pmaa 
Umaa 



2.74 g/cm 3 (from Chart Lith-9 or Lith-10) and 
13 (from Chart Lith-5). 

Matrix composition of the formation. 

Enter the chart with pmaa = 2.74 g/cm 3 on the y-axis and 
Umaa = 13 on the x-axis. The intersection point indicates 
a matrix mixture of 20% dolomite and 80% calcite. 




< ► 



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continued on next page 

199 



Lithology — Wireline, LWD 



Density Tool 

Lithology Identification — Open Hole 



Schlumberger 



Lith-6 

(former CP-21) 




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© Schlumberger 


10 12 14 16 
: photoelectric factor, U maa 



200 



< ► 



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Lithology — Wireline, LWD 



Environmentally Corrected Neutron Curves 

M-N Plot for Mineral Identification— Open Hole 



Schlumberger 



Purpose 

This chart is used to help identify mineral mixtures from sonic, 
density, and neutron logs. 

Description 

Because M and N slope values are practically independent of porosity 
except in gas zones, the porosity values they indicate can be corre- 
lated with the mineralogy. (See Appendix E for the formulas to calcu- 
late M and N from sonic, density, and neutron logs.) 

Enter the chart with M on the y-axis and N on the x-axis. The 
intersection point indicates the makeup of the formation. Points for 
binary mixtures plot along a line connecting the two mineral points. 
Ternary mixtures plot within the triangle defined by the three con- 
stituent minerals. The effect of gas, shaliness, secondary porosity, 
etc., is to shift data points in the directions shown by the arrows. 



The lines on the chart are divided into numbered groups by poros- 
ity range as follows: 

1. tj> = (tight formation) 

2. <j) = to 12 p.u. 

3. <> = 12 to 27 p.u. 

4. c> = 27 to 40 p.u. 

Example 

Given: M = 0.79 and N = 0.51. 

Find: Mineral composition of the formation. 

Answer: The intersection of the M and N values indicates dolomite 
in group 2, which has a porosity between to 12 p.u. 




< ► 



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continued on next page 
201 



Lithology — Wireline, LWD 



Environmentally Corrected Neutron Curves 

M-N Plot for Mineral Identification— Open Hole 



Schlumberger 



Lith-7 

(former CP-8) 




© Schlumberger 


1.1 






c 

1.0 
0.9 

0.8 

M 

0.7 
0.6 
0.5 
































oFreshwater mud 

p ( = 1.0Mg/m 3 ,t, = 620|as/m 




I 


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■ 


, = 1.0g/cm 3 ,t,= 189u.s/ft 


/ Gypsum 
























Saltwater mud 
































p, = 1.1 Mg/m 3 ,t, = 607ns/m 
p f = 1.1 g/cm 3 ,t f =185u.s/ft 
























































t 




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r 










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0. 


3 0.4 0.5 0.6 0.7 

N 


8 



202 



< ► 



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Lithology — Wireline 



Environmentally Corrected APS* Curves 

M-N Plot for Mineral Identification— Open Hole 



Schlumberger 



Purpose 

This chart is used to help identify mineral mixtures from APS 
Accelerator Porosity Sonde neutron logs. 

Description 

Because M and N values are practically independent of porosity 
except in gas zones, the porosity values they indicate can be corre- 
lated with the mineralogy. (See Appendix E for the formulas to cal- 
culate M and N from sonic, density, and neutron logs.) 

Enter the chart with M on the y-axis and N on the x-axis. The 
intersection point indicates the makeup of the formation. Points for 
binary mixtures plot along a line connecting the two mineral points. 
Ternary mixtures plot within the triangle defined by the three con- 
stituent minerals. The effect of gas, shaliness, secondary porosity, 
etc., is to shift data points in the directions shown by the arrows. 



The lines on the chart are divided into numbered groups by poros- 
ity range as follows: 

1. tj> = (tight formation) 

2. <j) = to 12 p.u. 

3. <> = 12 to 27 p.u. 

4. c> = 27 to 40 p.u. 

Because the dolomite spread is negligible, a single dolomite point 
is plotted for each mud. 

Example 

Given: M = 0.80 and N = 0.55. 

Find: Mineral composition of the formation. 

Answer: Dolomite. 




< ► 



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continued on next page 
203 



Lithology — Wireline 



Environmentally Corrected APS* Curves 

M-N Plot for Mineral Identification— Open Hole 



Schlumberger 



Lith-8 

(former CP-8a) 



1.1 




M 





































o Freshwater muc 












i 


» 






























p f =1.0Mg/m 3 ,t f = 620u,s/m 
p f = 1.0g/cm 3 ,t f = 189ns/ft 




i 
i 


































• Saltwater mud 

p, = 1.1 Mg/m 3 ,t f = 607u.s/m 

p f = 1.1 g/cm 3 ,t f = 185u.s/ft 




1 Gypsum 


























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0.3 



0.4 



0.5 



0.6 



0.7 



0.8 



*Markof Schlumberger 
© Schlumberger 



204 



< ► 



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Lithology — Wireline, LWD 



Bulk Density or Interval Transit Time and Apparent Total Porosity 

Apparent Matrix Parameters — Open Hole 



Schlumberger 



Purpose 

Charts Lith-9 (customary units) and Lith-10 (metric units) provide 
values of the apparent matrix internal transit time (t maa ) and appar- 
ent matrix grain density (pmaa) for the matrix identification (MID) 
Charts Lith-11 and Lith-12. With these parameters the identification 
of rock mineralogy or lithology through a comparison of neutron, 
density, and sonic measurements is possible. 

Description 

Determining the values of t ma a and p maa to use in the MID Charts 
Lith-11 and Lith-12 requires three steps. 

First, apparent crossplot porosity is determined using the appro- 
priate neutron-density and neutron-sonic crossplot charts in the 
"Porosity" section of this book. For data that plot above the sand- 
stone curve on the charts, the apparent crossplot porosity is denned 
by a vertical projection to the sandstone curve. 

Second, enter Chart Lith-9 or Lith-10 with the interval transit 
time (t) to intersect the previously determined apparent crossplot 
porosity. This point defines t maa . 

Third, enter Chart Lith-9 or Lith-10 with the bulk density (Pb) 
to again intersect the apparent crossplot porosity and define p maa . 

The values determined from Charts Lith-9 and Lith-10 for t maa and 
pm aa are cross plotted on the appropriate MID plot (Charts Lith-11 
and Lith-12) to identify the rock mineralogy by its proximity to the 
labeled points on the plot. 



Example 

Given: 



Find: 
Answer: 



Apparent crossplot porosity from density-neutron = 20%, 
Pb = 2.4 g/cm 3 , apparent crossplot porosity from 
neutron-sonic = 30%, and t = 82 \is/ft. 

pm aa and tm aa . 

pnm = 2.75 g/cm 3 and t maa = 



46(is/ft. 




< ► 



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continued on next page 
205 



Lithology — Wireline, LWD 



Bulk Density or Interval Transit Time and Apparent Total Porosity 

Apparent Matrix Parameters — Open Hole 



Schlumberger 



Lith-9 

(customary, former CP-14) 




Fluid Density = 1.0 g/cm 3 

Apparent matrix transit time, t maa (u.s/ft) 
?n 130 120 110 100 90 80 70 60 50 40 30 nf) 


2.9 
2.8 
2.7 
2.6 

Bulk density, 2 5 
p„(g/cm 3 ) 

2.4 
2.3 
2.2 
2.1 
2.0 


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110 
100 

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2 

© Schlumberger 


.0 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2. 

Apparent matrix density, p maa (g/cm 3 ) 


] 



206 



< ► 



Back to Contents 



Lithology — Wireline, LWD 



Bulk Density or Interval Transit Time and Apparent Total Porosity 

Apparent Matrix Parameters — Open Hole 



Schlumberger 



Lith-10 

(metric, former CP-14m) 



Fluid Density = 1.0 g/cm 3 

Apparent matrix transit time, t maa (u.s/m) 

?n 350 325 300 275 250 225 200 175 150 125 1 00 qRn 


2.9 

2.8 

2.7 

2.6 

Bulk density, 2.5 
p„(g/cm 3 ) 

2.4 
2.3 
2.2 
2.1 
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v>\ 


3 

© Schlumberger 


2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2. 

Apparent matrix density, p maa (g/cm 3 ) 






Purpose 

Charts Lith-9 (customary units) and Lith-10 (metric units) provide 
values of the apparent matrix internal transit time (t ma a) and appar- 
ent matrix grain density (pmaa) for the matrix identification (MID) 
Charts Lith-11 and Lith-12. With these parameters the identification 
of rock mineralogy or lithology through a comparison of neutron, 
density, and sonic measurements is possible. 



< ► 



Back to Contents 



207 



Lithology — Wireline, LWD 



Density Tool 

Matrix Identification (MID)— Open Hole 



Schlumberger 



Purpose 

Charts Lith-11 and Lith-12 are used to establish the type of mineral 
predominant in the formation. 

Description 

Enter the appropriate (customaiy or metric units) chart with 
the values established from Charts Lith-9 or Lith-10 to identify the 
predominant mineral in the formation. Salt points are defined for 
two tools, the sidewall neutron porosity (SNP) and the CNL* 
Compensated Neutron Log. The presence of secondary porosity 
in the form of vugs or fractures displaces the data points parallel 
to the apparent matrix internal transit time (t maa ) axis. The presence 
of gas displaces points to the right on the chart. Plotting some shale 
points to establish the shale trend lines helps in the identification 
of shaliness. For fluid density (pf) other than 1.0 g/cm 3 use the table 
to determine the multiplier to correct the apparent total density 
porosity before entering Chart Lith-11 or Lith-12. 



pf 


Multiplier 


1.00 


1.00 


1.05 


0.98 


1.10 


0.95 


1.15 


0.93 



Example 

Given: 

Find: 
Answer: 



pmaa = 2.75 g/cm 3 , t maa = 56 us/ft (from Chart Lith-9), 
and pf = 1.0 g/cm 3 . 

The predominant mineral. 

The formation consists of both dolomite and calcite, 
which indicates a dolomitized limestone. The formation 
used in this example is from northwest Florida in the 
Jay field. The vugs (secondary porosity) created by the 
dolomitization process displace the data point parallel 
to the dolomite and calcite points. 




208 



Back to Contents 



Lithology — Wireline, LWD 



Density Tool 

Matrix Identification (MID)— Open Hole 



Schlumberger 



Lith-11 

(customary, former CP-15) 



20 






2.1 
2.2 
2.3 
2.4 
2.5 

Hmaa 

(g/cm 3 ) 2 6 
2.7 
2.8 
2.9 
3.0 
3.1 












































































Salt O 
(CNL* log 


































































































































































































































































































































































Salt t 




























































































KMP 




























































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































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*Markof Schlumberger 
© Schlumberger 


30 40 50 60 70 

tmaa (^S/ft) 





^ ► 



Back to Contents 



209 



Lithology — Wireline, LWD 



Density Tool 

Matrix Identification (MID)— Open Hole 



Schlumberger 



Lith-12 

(metric, former CP-15m) 






























































































































Salt L. 
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1 
































































































































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2.4 






























































































































































































































































































































































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100 120 



140 



160 180 

t maa (u.s/m) 



200 220 



240 



*Markof Schlumberger 
© Schlumberger 



Purpose 

Chart Lith-12 is used similarly to Chart Lith-11 to establish the mineral 
type of the formation. 



210 



< ► 



Back to Contents 



Porosity — Wireline, LWD 



Sonic Tool 

Porosity Evaluation- 



-Open Hole 



Schlumberger 



Purpose 

This chart is used to convert sonic log slowness time (At) values 
into those for porosity (c|)). 

Description 

There are two sets of curves on the chart. The blue set for matrix 
velocity (v ma ) employs a weighted-average transform. The red set 
is based on the empirical observation of lithology (see Reference 
20). For both, the saturating fluid is assumed to be water with 
a velocity (v f ) of 5,300 ft/s (1,615 m/s). 

Enter the chart with the slowness time from the sonic log on the 
x-axis. Move vertically to intersect the appropriate matrix velocity 
or lithology curve and read the porosity value on the y-axis. For rock 
mixtures such as limy sandstones or cherty dolomites, intermediate 
matrix lines may be interpolated. 

To use the weighted-average transform for an unconsolidated sand, 
a lack-of-compaction correction (B cp ) must be made. Enter the chart 
with the slowness time and intersect the appropriate compaction 
correction line to read the porosity on the y-axis. If the compaction 
correction is not known, it can be determined by working backward 
from a nearby clean water sand for which the porosity is known. 



Example: Consolidated Formation 

Given: At = 76 \xs/ft in a consolidated formation with 

V ma = 18,000 ft/S. 

Find: Porosity and the formation lithology (sandstone, 

dolomite, or limestone). 

Answer: 15% porosity and consolidated sandstone. 

Example: Unconsolidated Formation 

Given: Unconsolidated formation with At = 100 (is/ft in 

a nearby water sand with a porosity of 28%. 

Find: Porosity of the formation for At = 110 (is/ft. 

Answer: Enter the chart with 100 \is/ft on the x-axis and move 
vertically upward to intersect 28-p.u. porosity. This 
intersection point indicates the correction factor curve 
of 1.2. Use the 1.2 correction value to And the porosity for 
the other slowness time. The porosity of an unconsoli- 
dated formation with At = 110 us/ft is 34 p.u. 



Lithology 


Vma (ft/S) 


At ma (us/ft) 


Vma (m/s) 


At ma (|is/m) 


Sandstone 


18,000-19,500 


55.5-51.3 


5,486-5,944 


182-168 


Limestone 


21,000-23,000 


47.6-43.5 


6,400-7,010 


156-143 


Dolomite 


23,000-26,000 


43.5-38.5 


7,010-7,925 


143-126 




< ► 



Back to Contents 



continued on next page 
211 



Porosity — Wireline, LWD 



Sonic Tool 

Porosity Evaluation — Open Hole 



Schlumberger 



Por-1 

(customary, former Por-3) 




50 


v, = 5,300 ft/s 


50 


40 

30 

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3 

© Schlumberger 


40 50 60 70 80 90 100 110 120 13 

1 nterval transit time. At (|is/ft) 






212 



< ► 



Back to Contents 



Porosity — Wireline, LWD 



Sonic Tool 

Porosity Evaluation — Open Hole 



Schlumberger 



Por-2 

(metric, former Por-3m) 



50 


v f = 1,615 m/s 


50 


40 

30 

Porosity, 
<j>(p.u.j 

20 

10 




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1C 

© Schlumberger 


150 200 250 300 350 400 

Interval transit time. At (|is/m) 






Purpose 

This chart is used similarly to Chart Por-1 with metric units. 



< ► 



Back to Contents 



213 



Porosity — Wireline, LWD 



Density Tool 

Porosity Determination — Open Hole 



Schlumberger 



Por-3 

(former Por-5) 



P,(g/cm 3 


) 1.0 0.9 0.8 




1.1/ 


- 


- 


































































/ 






































































// 










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10 























































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*Markof Schlumberger 
© Schlumberger 


2.8 2.6 2.4 2.2 ! 

, 2.31 
Bulk density, p b (g/cm ) 


.0 




Purpose 

This chart is used to convert grain density (g/cm 3 ) to density porosity. 

Description 

Values of log-derived bulk density (pb) corrected for borehole size, 
matrix density of the formation (pma), and fluid density (pf) are used 
to determine the density porosity ((|)d) of the logged formation. The 
pf is the density of the fluid saturating the rock immediately sur- 
rounding the borehole — usually mud filtrate. 

Enter the borehole-corrected value of pb on the x-axis and move 
vertically to intersect the appropriate matrix density curve. From the 
intersection point move horizontally to the fluid density line. Follow 
the porosity trend line to the porosity scale to read the formation 



porosity as determined by the density tool. This porosity in combina- 
tion with CNL* Compensated Neutron Log, sonic, or both values of 
porosity can help determine the rock type of the formation. 



Example 

Given: 



Find: 
Answer: 



pb = 2.31 g/cm 3 (log reading corrected for borehole 
effect), p ma = 2.71 g/cm 3 (calcite mineral), and 
pt = 1.1 g/cm 3 (salt mud). 

Density porosity. 

(|)d = 25 p.u. 



214 



Back to Contents 



Porosity — Wireline 



Schlumberger 



APS* Near-to-Array (APLC) and Near-to-Far (FPLC) Logs 

Epithermal Neutron Porosity Equivalence — Open Hole 



Purpose 

This chart is used for the apparent limestone porosity recorded by the 
APS Accelerator Porosity Sonde or sidewall neutron porosity (SNP) 
tool to provide the equivalent porosity in sandstone or dolomite for- 
mations. It can also be used to obtain the apparent limestone poros- 
ity (used for the various crossplot porosity charts) for a log recorded 
in sandstone or dolomite porosity units. 

Description 

Enter the x-axis with the corrected near-to-array apparent limestone 
porosity (APLC) or near-to-far apparent limestone porosity (FPLC) 
and move vertically to the appropriate lithology curve. Then read the 
equivalent porosity on the y-axis. For APS porosity recorded in sand- 
stone or dolomite porosity units enter that value on the y-axis and 
move horizontally to the recorded lithology curve. Then read the 
apparent limestone neutron porosity for that point on the x-axis. 

The APLC is the epithermal short-spacing apparent limestone 
neutron porosity from the near-to-array detectors. The log is auto- 
matically corrected for standoff during acquisition. Because it is 
epithermal this measurement does not need environmental correc- 
tions for temperature or chlorine effect. However, corrections for 
mud weight and actual borehole size should be applied (see Chart 
Neu-10). The short spacing means that the effect of density and 
therefore the lithology on this curve is minimal. 

The FPLC is the epithermal long-spacing apparent limestone neu- 
tron porosity acquired from the near-to-far detectors. Because it is 
epithermal this measurement does not need environmental correc- 
tions for temperature or chlorine effect. However, corrections for 
mud weight and actual borehole size should be applied (see Chart 
Neu-10). The long spacing means that the density and therefore 
lithology effect on this curve is pronounced, as seen on Charts Por-13 
and Por-14. 



The HPLC curve is the high- resolution version of the APLC curve. 
The same corrections apply. 



Resolution 


Short Spacing 


Long Spacing 


Normal 


APLC 

Epithermal neutron porosity ( E N P 1 ) t 


FPLC 


Enhanced 


HPLC 
HNPI f 


HFLC 



T Not formation-salinity corrected. 

Example: Equivalent Porosity 

Given: APLC = 25 p.u. and FPLC = 25 p.u. 

Find: Porosity for sandstone and for dolomite. 

Answer: Sandstone porosity from APLC = 28.5 p.u. and sandstone 
porosity from FPLC = 30 p.u. 

Dolomite porosity = 24 and 20 p.u., respectively. 

Example: Apparent Porosity 

Given: Clean sandstone porosity = 20 p.u. 

Find: Apparent limestone neutron porosity. 

Answer: Enter the y-axis at 20 p.u. and move horizontally to 
the quartz sandstone matrix curves. Move vertically 
from the points of intersection to the x-axis and read 
the apparent limestone neutron porosity values. 
APLC = 16.8 p.u. and FPLC = 14.5 p.u. 




< ► 



Back to Contents 



continued on next page 
215 



Porosity — Wireline 



APS* Near-to-Array (APLC) and Near-to-Far (FPLC) Logs 

Epithermal Neutron Porosity Equivalence — Open Hole 



Schlumberger 



Por-4 

(former Por-13a) 



40 






30 

True porosity 
for indicated 20 
matrix material, 
<j> (pu.) 

10 



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FPLC 

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*Markof Schlumberger 
© Schlumberger 


10 20 30 40 

Apparent limestone neutron porosity, ^ SNPl . 01 .(p,u.) 
Apparent limestone neutron porosity, cj> A p St . or (p.u.) 




216 



< ► 



Back to Contents 



Porosity — Wireline 



Thermal Neutron Tool 

Porosity Equivalence — Open Hole 



Schlumberger 



Por-5 

(former Por-13b) 



40 






30 

True porosity 
for indicated 20 
matrix material, 
<Kp.u.) 

10 



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*Markof Schlumberger 
© Schlumberger 


10 20 30 40 
Apparent limestone neutron porosity, <4> CNLcor (p.u.) 



Purpose 

This chart is used to convert CNL* Compensated Neutron Log porosity 
curves (TNPH or NPHI) from one lithology to another. It can also be 
used to obtain the apparent limestone porosity (used for the various 
crossplot porosity charts) from a log recorded in sandstone or dolomite 
porosity units. 

Description 

To determine the porosity of either quartz sandstone or dolomite 
enter the chart with the either the TNPH or NPHI corrected 
apparent limestone neutron porosity (<|>cNLcor) on the x-axis. Move 
vertically to intersect the appropriate curve and read the porosity 
for quartz sandstone or dolomite on the y-axis. The chart has a 
built-in salinity correction for TNPH values. 



NPHI Thermal neutron porosity (ratio method) 

NPOR Neutron porosity (environmentally corrected and 

enhanced vertical resolution processed) 

TNPH Thermal neutron porosity (environmentally corrected) 




Example 

Given: 



Find: 
Answer: 



Quartz sandstone formation, TNPH = 18 p.u. (apparent 
limestone neutron porosity), and formation salinity = 
250,000 ppm. 

Porosity in sandstone. 

From the TNPH porosity reading of 18 p.u. on the x-axis, 
project a vertical line to intersect the quartz sandstone 
dashed red curve. From the y-axis, the porosity of the 
sandstone is 24 p.u. 



Back to Contents 



217 



Porosity — Wireline 



Thermal Neutron Tool— CNT-D and CNT-S 2 1 /2-in. Tools 

Porosity Equivalence — Open Hole 



Schlumberger 



Por-6 




True porosity 

for indicated 

matrix material, 

tt> (p.u.) 

© Schlumberger 


40 






30 

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-10 10 20 30 40 

Apparent limestone neutron porosity (p.u.) 



Purpose 

This chart is used similarly to Chart Por-5 to convert 2!/2-in. compen- 
sated neutron tool (CNT) porosity values (TNPH) from one lithology 
to another. Fresh formation water is assumed. 



218 



< ► 



Back to Contents 



Porosity— LWD 



adnVISI0N475* 4.75-in. Azimuthal Density Neutron Tool 

Porosity Equivalence — Open Hole 



Schlumberger 



Por-7 



40 






35 
30 

25 

True porosity 
for indicated 20 
matrix material, 
<|>(p.u.) 

15 

10 

5 














































































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*Markof Schlumberger 
© Schlumberger 


5 5 10 15 20 25 30 35 40 
Corrected apparent limestone neutron porosity, (]> A oNcor (P u -) 



Purpose 

This chart is used to determine the porosity of sandstone, limestone, 
or dolomite from the corrected apparent limestone porosity measured 
with the adnVISION475 4.75-in. tool. 



Description 

Enter the chart on the x-axis with the corrected apparent limestone 
porosity from Chart Neu-31 to intersect the curve for the appropriate 
formation material. Read the porosity on the y-axis. 




< ► 



Back to Contents 



219 



Porosity— LWD 



Schlumberger 



adnVISION675* 6.75-in. Azimuthal Density Neutron Tool 

Porosity Equivalence — Open Hole 



Por-8 



40 






35 
30 

25 

Truo porosity 
for indicated 20 
matrix material, 
<t>(p.u.) 

15 

10 

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*Markof Schlumberger 
© Schlumberger 


5 5 10 15 20 25 30 35 40 
Corrected apparent limestone neutron porosity, <t> A DN.;or (P u -) 




Purpose 

Chart Por-8 is used similarly to Chart Por-7 for determining 
porosity from the corrected apparent limestone porosity from 
the adnVISION675 6.75-in. tool. 



220 



< ► 



Back to Contents 



Porosity— LWD 



Schlumberger 



adnVISION825* 8.25-in. Azimuthal Density Neutron Tool 

Porosity Equivalence — Open Hole 



Por-9 



40 






35 
30 

25 

True porosity 
(p.u.) 20 

15 

10 

5 




















































































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*Markof Schlumberger 
© Schlumberger 


5 5 10 15 20 25 30 35 40 
Corrected apparent limestone neutron porosity, (t>ADN Cor (P- u -) 



Purpose 

Chart Por-9 is used similarly to Chart Por-7 for determining 
porosity from the corrected apparent limestone porosity from 
the adnVISION825 8.25-in. tool. 




< ► 



Back to Contents 



221 



Porosity— LWD 



Schlumberger 



EcoScope* 6.75-in. Integrated LWD Tool, BPHI Porosity 

Porosity Equivalence — Open Hole 



Por-10 



40 






35 
30 

25 

True porosity 
for indicated 20 
matrix material, 
<j>(P-U.) 

15 

10 

5 
















































































































































































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*Markof Schlumberger 
© Schlumberger 


5 5 10 15 20 25 30 35 40 

Corrected apparent limestone BPHI porosity (p.u.) 




Purpose 

This chart is used to determine the porosity of sandstone, limestone, 
or dolomite from the corrected apparent limestone BPHI porosity 
measured with the EcoScope 6.75-in. LWD tool. 

Use this chart only with EcoScope best thermal neutron porosity 
(BPHI) measurements; use Chart Por- 10a with EcoScope thermal 
neutron porosity (TNPH) measurements. 



Description 

Enter the chart on the x-axis with the corrected apparent limestone 
BPHI porosity from Chart Neu-43 or Neu-44 to intersect the curve for 
the appropriate formation material. Read the porosity on the y-axis. 



222 



< ► 



Back to Contents 



Porosity— LWD 



EcoScope* 6.75-in. Integrated LWD Tool, TNPH Porosity 

Porosity Equivalence — Open Hole 



Schlumberger 



Por-10a 



40 






35 
30 

25 

True porosity 
for indicated 20 
matrix material, 

<Kp-u.) 

15 

10 

5 








































































































































































s 
















































































































































































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* 












































































*Markof Schlumberger 
© Schlumberger 


5 5 10 15 20 25 30 35 40 
Corrected apparent limestone TNPH porosity (p.u.) 



Purpose 

This chart is used to determine the porosity of sandstone, limestone, 
or dolomite from the corrected apparent limestone TNPH porosity 
measured with the EcoScope 6.75-in. LWD tool. 

Use this chart only with EcoScope thermal neutron porosity 
(TNPH) measurements; use Chart Por-10 with EcoScope best 
thermal neutron porosity, average (BPHI) measurements. 



Description 

Enter the chart on the x-axis with the corrected apparent limestone 
TNPH porosity from Chart Neu-45 or Neu-46 to intersect the curve for 
the appropriate formation material. Read the porosity on the y-axis. 




< ► 



Back to Contents 



223 



Porosity — Wireline 



CNL* Compensated Neutron Log and Litho-Density 4 
(fresh water in invaded zone) 

Porosity and Lithology — Open Hole 



Schlumberger 



Tool 



Purpose 

This chart is used with the bulk density and apparent limestone 
porosity from the CNL Compensated Neutron Log and Litho-Density 
tools, respectively, to approximate the lithology and determine the 
crossplot porosity. 

Description 

Enter the chart with the environmentally corrected apparent neu- 
tron limestone porosity on the x-axis and bulk density on the y-axis. 
The intersection of the two values describes the crossplot porosity 
and lithology. 

If the point is on a lithology curve, that indicates that the forma- 
tion is primarily that lithology. If the point is between the lithology 
curves, then the formation is a mixture of those lithologies. The posi- 
tion of the point in relation to the two lithology curves as composi- 
tion endpoints indicates the mineral percentages of the formation. 

The porosity for a point between lithology curves is determined 
by scaling the crossplot porosity by connecting similar numbers on 
the two lithology curves (e.g., 20 on the quartz sandstone curve to 
20 on the limestone curve). The scale line closest to the point repre- 
sents the crossplot porosity. 

Chart Por-12 is used for the same purpose as this chart for salt- 
water-invaded zones. 



Example 

Given: 

Find: 
Answer: 



Corrected apparent neutron limestone porosity = 
16.5 p.u. and bulk density = 2.38 g/cm 3 . 

Crossplot porosity and lithology. 

Crossplot porosity = 18 p.u. The lithology is approxi- 
mately 40% quartz and 60% limestone. 




224 



< ► 



Back to Contents 



Porosity — Wireline 



CNL* Compensated Neutron Log and Litho-Density*Tool 
(fresh water in invaded zone) 

Porosity and Lithology — Open Hole 



Schlumberger 



Por-11 

(former CP-1e) 



1.9 


Liquid-Filled Borehole (p, = 1.000 g/cm 3 and C f = ppm) 




2.0 
2.1 
2.2 
2.3 

2.4 

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density, 
p„(g/cm 3 ) 2 - 5 

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2.7 
2.8 
2.9 
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*Markof Schlumberger 
© Schlumberger 


10 20 30 40 
Corrected apparent limestone neutron porosity, <|) CNLcor (p.u.) 






< ► 



Back to Contents 



225 



Porosity — Wireline 



CNL* Compensated Neutron Log and Litho-Density*Tool 
(saltwater in invaded zone) 

Porosity and Lithology — Open Hole 



Schlumberger 



Por-12 

(former CP-11) 




1.9 


Liquid-filled borehole (p, = 1.190 g/cm 3 and C, = 250,000 ppm) 




2.0 
2.1 
2.2 
2.3 

2.4 

Bulk 
density, 
p b (g/cm 3 ) 2 - 5 

2.6 
2.7 
2.8 
2.9 
3.0 






































































































45 
40 
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( 


5 


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*Markof Schlumberger 
© Schlumberger 


10 20 30 40 
Corrected apparent limestone neutron porosity, <t>cNLcor(P- u -) 





Purpose 

This chart is used similarly to Chart Por-11 with CNL Compensated 
Neutron Log and Litho-Density values to approximate the lithology 
and determine the crossplot porosity in the saltwater-invaded zone. 



Example 

Given: 

Find: 
Answer: 



Corrected apparent neutron limestone porosity = 
16.5 p.u. and bulk density = 2.38 g/cm 3 . 

Crossplot porosity and lithology. 

Crossplot porosity = 20 p.u. The lithology is approxi- 
mately 55% quartz and 45% limestone. 



226 



< ► 



Back to Contents 



Porosity — Wireline 



APS* and Litho-Density* Tools 

Porosity and Lithology — Open Hole 



Schlumberger 



Por-13 

(former CP-1g) 



1.9 


Liquid-Filled Borehole (p f = 1.000 g/cm 3 and C f = ppm) 




2.0 
2.1 
2.2 
2.3 

2.4 

Bulk density, 
p b (g/cm 3 ) 25 

2.6 
2.7 
2.8 
2.9 
3.0 


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*Markof Schlumberger 
© Schlumberger 


10 20 30 40 
Corrected APS apparent limestone neutron porosity, <t> APS ,, or (p.u.) 





Purpose 

This chart is used to determine the lithology and porosity from the 
Litho-Density bulk density and APS Accelerator Porosity Sonde porosity 
log curves (APLC or FPLC). This chart applies to boreholes filled 
with freshwater drilling fluid; Chart Por-14 is used for saltwater fluids. 

Description 

Enter either the APLC or FPLC porosity on the x-axis and the bulk 
density on the y-axis. Use the blue matrix curves for APLC porosity 
values and the red curves for FPLC porosity values. Anhydrite plots 
on separate curves. The gas correction direction is indicated for for- 
mations containing gas. Move parallel to the blue correction line if 
the APLC porosity is used or to the red correction line if the FPLC 
porosity is used. 



Example 

Given: 

Find: 
Answer: 




APLC porosity = 8 p.u. and bulk density = 2.2 g/cm 3 . 

Approximate quartz sandstone porosity. 

Enter at 8 p.u. on the x-axis and 2.2 g/cm 3 on the y-axis 
to find the intersection point is in the gas-in-formation 
correction region. Because the APLC porosity value was 
used, move parallel to the blue gas correction line until 
the blue quartz sandstone curve is intersected at approx- 
imately 19 p.u. 



Back to Contents 



227 



Porosity — Wireline 



APS* and Litho-Density* Tools (saltwater formation) 

Porosity and Lithology — Open Hole 



Schlumberger 



Por-14 

(former CP-1h) 




1.9 


Liquid-Filled Borehole (p, = 1.190 g/cm 3 and C, = 250,000 ppm) 




2.0 
2.1 
2.2 
2.3 

2.4 

Bulk density, 
p b (g/cm 3 ) 25 

2.6 
2.7 
2.8 
2.9 
3.0 


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*Markof Schlumberger 
© Schlumberger 


10 20 30 40 
Corrected APS apparent limestone neutron porosity, <t> A pscor (P u -) 





Purpose 

This chart is used similarly to Chart Por-13 to determine the lithology 
and porosity from Litho-Density* bulk density and APS* porosity log 
curves (APLC or FPLC) in saltwater boreholes. 



Example 

Given: 

Find: 
Answer: 



APLC porosity = 8 p.u. and bulk density = 2.2 g/cm 3 . 

Approximate quartz sandstone porosity. 

Enter 8 p.u. on the x-axis and 2.2 g/cm 3 on the y-axis to 
And the intersection point is in the gas-in-formation cor- 
rection region. Because the APLC porosity value was 
used, move parallel to the blue gas correction line until 
the blue quartz sandstone curve is intersected at approx- 
imately 20 p.u. 



228 



Back to Contents 



Porosity— LWD 



adnVISI0N475* 4.75-in. Azimuthal Density Neutron Tool 

Porosity and Lithology — Open Hole 



Schlumberger 



Por-15 



1.9 


FreshWater, Liquid-Filled Borehole (p,= 1.0g/cm 3 ) 




2.0 
2.1 
2.2 

2.3 

Bulk density, 

Pb(g/cm 3 ) u 

2.5 
2.6 
2.7 
2.8 
2.9 
3.0 








































































































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_ 

*Markof Schlumberger 
© Schlumberger 


5 5 10 15 20 25 30 35 40 45 
Corrected apparent limestone neutron porosity, (|> AUNcor (p.u.) 



Purpose 

This chart is used to determine the crossplot porosity and lithology 
from the adnVISION475 4.75-in. density and neutron porosity. 

Description 

Enter the chart with the adnVISION475 corrected apparent lime- 
stone neutron porosity (from Chart Neu-31) and bulk density. The 
intersection of the two values is the crossplot porosity. The position 
of the point of intersection between the matrix curves represents the 
relative percentage of each matrix material. 



Example 

Given: (|)ADNcor = 20 p.u. and pb = 2.24 g/cm 3 . 

Find: Crossplot porosity and matrix material. 

Answer: 25 p.u. in sandstone. 




< ► 



Back to Contents 



229 



Porosity— LWD 



adnVISION675* 6.75-in. Azimuthal Density Neutron Tool 

Porosity and Lithology — Open Hole 



Schlumberger 



Por-16 




1.9 


FreshWater, Liquid-Filled Borehole (p f = 1.0g/cm 3 ) 




2.0 
2.1 
2.2 

2.3 

Bulk density, 
p„(g/cm 3 ) 

2.5 
2.6 
2.7 
2.8 
2.9 
3.0 
















































































































































































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_ 

*Markof Schlumberger 
© Schlumberger 


5 5 10 15 20 25 30 35 40 45 
Corrected apparent limestone neutron porosity, (|> ADNcor (p.u.) 



Purpose Example 

This chart uses the bulk density and apparent limestone porosity from Given: 

the adnVISION 6.75-in. Azimuthal Density Neutron tool to determine 

the lithology of the logged formation and the crossplot porosity. p m( j. 

Description Answer: 

This chart is applicable for logs obtained in freshwater drilling 
fluid. Enter the corrected apparent limestone porosity and the bulk 
density on the x- and y-axis, respectively. Their intersection point 
determines the lithology and crossplot porosity. 



Corrected adnVISION675 apparent limestone porosity = 
20 p.u. and bulk density = 2.3 g/cm 3 . 

Porosity and lithology type. 

Entering the chart at 20 p.u. on the x-axis and 2.3 g/cm 3 
on the y-axis corresponds to a crossplot porosity of 
21.5 p.u. and formation comprising approximately 
60% quartz sandstone and 40% limestone. 



230 



Back to Contents 



Porosity— LWD 



adnVISION825* 8.25-in. Azimuthal Density Neutron Tool 

Porosity and Lithology — Open Hole 



Schlumberger 



Por-17 



1.9 


FreshWater, Liquid-Filled Borehole (p f = 1.0g/cm 3 ) 




2.0 
2.1 
2.2 

2.3 

Bulk density, 

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_ 

*Markof Schlumberger 
© Schlumberger 


5 5 10 15 20 25 30 35 40 4 
Corrected apparent limestone neutron porosity, <|> ADNcor (p.u.) 


5 




Purpose 

This chart is used similarly to Chart Por-15 to determine the lithology 
and crossplot porosity from adnVISION825 8.25-in. Azimuthal Density 
Neutron values. 



< ► 



Back to Contents 



231 



Porosity— LWD 



EcoScope* 6.75-in. Integrated LWD Tool 

Porosity and Lithology — Open Hole 



Schlumberger 



Por-18 



1.9 


FreshWater, Liquid-Filled Borehole (p f = 1.0g/cm 3 ) 








2.0 

2.1 

2.2 

2.3 

2.4 
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2.7 

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_ 

*Markof Schlumberger 
© Schlumberger 


5 5 10 15 20 25 30 35 40 45 
Corrected apparent limestone BPHI porosity (p.u.) 




Purpose 

This chart is used similarly to Chart Por-15 to determine the lithol- 
ogy and crossplot porosity from EcoScope 6.75-in. density and best 
thermal neutron porosity (BPHI) values. 

Use this chart only with EcoScope BPHI neutron porosity; use 
Chart Por-19 with EcoScope thermal neutron porosity (TNPH) 
measurements. 



232 



< ► 



Back to Contents 



Porosity— LWD 



EcoScope* 6.75-in. Integrated LWD Tool 

Porosity and Lithology — Open Hole 



Schlumberger 



Por-19 



1.9 


FreshWater, Liquid-Filled Borehole (p f = 1.0g/cm 3 ) 








2.0 
2.1 
2.2 

2.3 

Bulk density, 
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2.6 
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_ 

*Markof Schlumberger 
© Schlumberger 


5 5 10 15 20 25 30 35 40 45 
Corrected apparent limestone TNPH porosity (p.u.) 



Purpose 

This chart is used similarly to Chart Por-15 to determine the lithol- 
ogy and crossplot porosity from EcoScope 6.75-in. density and ther- 
mal neutron porosity (TNPH) values. 

Use this chart only with EcoScope TNPH neutron porosity; use 
Chart Por-18 with EcoScope best thermal neutron porosity (BPHI) 
measurements. 




< ► 



Back to Contents 



233 



Porosity — Wireline 



Sonic and Thermal Neutron Crossplot 

Porosity and Lithology — Open Hole, Freshwater Invaded 



Schlumberger 



Purpose 

This chart is used to determine crossplot porosity and an approxi- 
mation of lithology for sonic and thermal neutron logs in freshwater 
drilling fluid. 

Description 

Enter the corrected neutron porosity (apparent limestone porosity) 
on the x-axis and the sonic slowness time (At) on the y-axis to find 
their intersection point, which describes the crossplot porosity and 
lithology composition of the formation. Two sets of curves are drawn 
on the chart. The blue set of curves represents the crossplot porosity 
values using the sonic time-average algorithm. The red set of curves 
represents the field observation algorithm. 



Example 

Given: 



Find: 
Answer: 



Thermal neutron apparent limestone porosity = 20 p.u. 
and sonic slowness time = 89 |as/ft in freshwater 
drilling fluid. 

Crossplot porosity and lithology. 

Enter the neutron porosity on the x-axis and the sonic 
slowness time on the y-axis. The intersection point is at 
about 25 p.u. on the field observation line and 24.5 p.u. 
on the time-average line. The matrix is quartz sandstone. 




234 



< ► 



Back to Contents 



Porosity — Wireline 



Sonic and Thermal Neutron Crossplot 

Porosity and Lithology — Open Hole, Freshwater Invaded 



Schlumberger 



Por-20 

(customary, former CP-2c) 



t f =190u_s/ftandC ( = 0ppm 



Sonic transit time, 
At (us/ft) 



110 






































































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1 II11H HV/HTHIJH 

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10 20 30 40 

Corrected CNL* apparent limestone neutron porosity, 4> CNLcor (p.u.) 



*Markof Schlumberger 
© Schlumberger 



< ► 



Back to Contents 



235 



Porosity — Wireline 



Sonic and Thermal Neutron Crossplot 

Porosity and Lithology — Open Hole, Freshwater Invaded 



Schlumberger 



Por-21 

(metric, former CP-2cm) 



t, = 620 u.s/m and C f = ppm 



Sonic transit time. 
At (u.s/m) 




sro 










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*Markof Schlumberger 
© Schlumberger 



10 20 30 40 

Corrected CNL* apparent limestone neutron porosity, <() CNLcor (p.u.) 



Purpose 

This chart is used similarly to Chart Por-20 for metric units. 



236 



< ► 



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Porosity — Wireline, LWD 



Density and Sonic Crossplot 

Porosity and Lithology — Open Hole, Freshwater Invaded 



Schlumberger 



Purpose 

This chart is used to determine porosity and lithology for sonic and 
density logs in freshwater-invaded zones. 

Description 

Enter the chart with the bulk density on the y-axis and sonic slow- 
ness time on the x-axis. The point of intersection indicates the type 
of formation and its porosity. 



Example 

Given: Bulk density = 2.3 g/cm 3 and sonic slowness 
time = 82 us/ft. 

Find: Crossplot porosity and lithology. 

Answer: Limestone with a crossplot porosity = 24 p.u. 




< ► 



Back to Contents 



continued on next page 
237 



Porosity — Wireline, LWD 



Density and Sonic Crossplot 

Porosity and Lithology — Open Hole, Freshwater Invaded 



Schlumberger 



Por-22 

(customary, former CP-7) 



t, = 189 us/ft and p, = 1.0 g/cm 3 



1.8 



Bulk density, 
p b (g/cm 3 ) 



40 50 60 70 80 90 100 

Sonic transit time. At (u.s/ft) 











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110 120 



© Schlumberger 



238 



< ► 



Back to Contents 



Porosity — Wireline, LWD 



Density and Sonic Crossplot 

Porosity and Lithology — Open Hole, Freshwater Invaded 



Schlumberger 



Por-23 

(metric, former CP-7m) 



Bulk density, 
p b (g/cm 3 ) 

© Schlumberger 


1 R 




t f = 620 u,s/m a nd p f = 1 .0 g/c m 3 




1.9 
2.0 
2.1 
2.2 
2.3 
2.4 
2.5 
2.6 
2.7 
2.R 
2.9 
3.0 


Tirrm averarjp 

Field observation 


































































































































































C 


) Sylvite 


























































































































































































































































































































































































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f 




























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150 200 


250 300 350 400 
Sonic transit time. At (u,s/m) 





Purpose 

This chart is used similarly to Chart Por-22 for metric units. 



< ► 



Back to Contents 



239 



Porosity — Wireline, LWD 



Density and Neutron Tool 

Porosity Identification — Gas-Bearing Formation 



Schlumberger 



Purpose Example 

This chart is used to determine the porosity and average water satu- Given: 
ration in the flushed zone (S xo ) for freshwater invasion and gas com- 
position of C1.1H4.2 (natural gas). p m( j. 

Description Answer: 

Enter the chart with the neutron- and density-derived porosity values 
((|)n and (|)d, respectively). On the basis of the table, use the blue curves 
for shallow reservoirs and the red curves for deep reservoirs. 



<|)d = 25 p.u. and (|)n = 10 p.u. in a low-pressure, shallow 
(4,000-ft) reservoir. 

Porosity and S xo . 

Enter the chart at 25 p.u. on the y-axis and 10 p.u. on the 
x-axis. The point of intersection identifies (on the blue 
curves for a shallow reservoir) § = 20 p.u. and Sxo = 62%. 



Depth 


Pressure 


Temperature 


p w (g/cm 3 ) 


Ihw 


p g (g/cm 3 ) 


'Hg 


Shallow reservoir 


-2,000 psi [-14,000 kPa] 


~120°F[~50°C] 


1.00 


1.00 








Deep reservoir 


-7,000 psi [-48,000 kPa] 


~240°F[~120°C] 


1.00 


1.00 


0.25 


0.54 



Pw = density of water, p g = density of gas, l Hw = hydrogen index of water, and l Hg = hydrogen index of gas 




240 



< ► 



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Porosity — Wireline, LWD 



Density and Neutron Tool 

Porosity Identification — Gas-Bearing Formation 



Schlumberger 



Por-24 

(former CP-5) 



50 






40 

30 

Density-derived porosity, 
D (p.u.) 

20 

10 






\ 






























V 


V 


•J 
































\ 






































7 


^n 







































s 


































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/ 
























































































































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100 
















































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M0 „ 


















































































































































































































































For shallow reservoirs, use blue curves. 
For deep reservoirs, use red curves. 




































































h 












































//b^ 




















































































































































































































































































































































































































































































© Schlumberger 


10 20 30 4( 
Neutron-derived porosity, <j) N (p. u.) 


) 




< ► 



Back to Contents 



241 



Porosity — Wireline 



Density and APS* Epithermal Neutron Tool 

Porosity Identification — Gas-Bearing Formation 



Schlumberger 



Purpose Example 

This chart is used to determine the porosity and average water satu- Given: 
ration in the flushed zone (S xo ) for freshwater invasion and gas com- 
position of CH4 (methane). Find: 

Description Answer: 

Enter the chart with the APS Accelerator Porosity Sonde neutron- and 
density-derived porosity values (<|)n and (|)d, respectively). On the basis 
of the table, use the blue curves for shallow reservoirs and the red 
curves for deep reservoirs. 



<|)d = 15 p.u. and APS $$ = 8 p.u. in a normally pressured 
deep (14,000-ft) reservoir. 

Porosity and S xo . 

<S> = 11 p.u. and S xo = 39%. 



Depth 


Pressure 


Temperature 


pw 


Ihw 


Pg 


S 


Shallow reservoir 


-2,000 psi [-14,000 kPa] 


~120°F[-50°C] 


1.00 


1.00 


0.10 


0.23 


Deep reservoir 


-7,000 psi [-48,000 kPa] 


~240°F[~120°C] 


1.00 


1.00 


0.25 


0.54 



p w = density of water, p g = density of gas, l Hw = hydrogen index of water, and ! Hg = hydrogen index of gas 




242 



< ► 



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Porosity — Wireline 



Density and APS* Epithermal Neutron Tool 

Porosity Identification — Gas-Bearing Formation 



Schlumberger 



Por-25 

(former CP-5a) 



50 






40 

30 

Density-derived porosity, 
<t> D (p.u.) 

20 
10 
























































40 














































































































































40 

























































































































































































































































































































































































































2t 






























?5 










































) 




















Porosity 


















































































































































































































'40 


























































































6U 




































































30 
































































60 





































































































































































































































9^ 






80 


























































































































20~ 








lb 


























































































ipn 
















































4C 
























s 


















































fin 




















°xo 


















































20 






















































































80 


































































20 J\ 


















































































IUU 


^xo 












































































































































































































































































lb/' 






















































































































































































































































































































































































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F 


"or shallow reservoirs, use blue curves. 


















w* 






















- For deep reservoirs, use red curves. 



































































































































































































































































































































































































































































































































( 

*Markof Schlumberger 
© Schlumberger 


) 10 20 30 4 
APS epithermal neutron-derived porosity, <)> N (p.u.) 


3 




< ► 



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243 



Porosity — Wireline 



Density, Neutron, and R xo Logs 

Porosity Identification in Hydrocarbon-Bearing Formation — Open Hole 



Schlumberger 



Purpose 

This nomograph is used to estimate porosity in hydrocarbon-bearing 
formations by using density, neutron, and resistivity in the flushed 
zone (Rxo) logs. The density and neutron logs must be corrected for 
environmental effects and lithology before entry to the nomograph. 
The chart includes an approximate correction for excavation effect, 
but if hydrocarbon density (ph) is <0.25 g/cm 3 (gas), the chart may 
not be accurate in some extreme cases: 

■ very high values of porosity (>35 p.u.) coupled with medium 
to high values of hydrocarbon saturation (Shi) 

■ Shi- = 100% for medium to high values of porosity. 

Description 

Connect the apparent neutron porosity value on the appropriate 
neutron porosity scale (CNL* Compensated Neutron Log or sidewall 
neutron porosity [SNP] log) with the corrected apparent density 
porosity on the density scale with a straight line. The intersection 
point on the (])i scale indicates the value of ty\. 

Draw a line from the <|)i value to the origin (lower right corner) 
of the chart for Aty versus Shi- 
Enter the chart with Shr from (Shi = 1 - S xo ) and move vertically 
upward to determine the porosity correction factor (A(|)) at the inter- 
section with the line from the §1 scale. 

This correction factor algebraically added to the porosity <|)i gives 
the corrected porosity. 



Example 

Given: 



Find: 
Answer: 



Corrected CNL apparent neutron porosity = 12 p.u., 
corrected apparent density porosity = 38 p.u., and 
Shi- = 50%. 
Hydrocarbon-corrected porosity. 

Enter the 12-p.u. ty mi value on the CNL scale. A line from 
this value to 38 p.u. on the <|)Dcor scale intersects the (|)i 
scale at 32.2 p.u. The intersection of a line from this 
value to the graph origin and Shr = 50% is A§ = -1.6 p.u. 
Hydrocarbon-corrected porosity: 32.2 - 1.6 = 30.6 p.u. 




244 



Back to Contents 



Porosity — Wireline 



Density, Neutron, and R xo Logs 

Porosity Identification in Hydrocarbon-Bearing Formation — Open Hole 



Schlumberger 



Por-26 

(former CP-9) 



Tcor Tcor 

(CNL*) (SNP) 
50 50 



H fDcor 




> 



-4 



A0 
(p.u.l 







100 80 60 40 20 



*Markof Schlumberger 
© Schlumberger 



< ► 



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245 



Porosity — Wireline 



Hydrocarbon Density Estimation 



Schlumberger 



Por-27 

(former CP-10) 




s hr (%) 





*Markof Schlumberger 
© Schlumberger 



s hr (%) 



Purpose 

This chart is used to estimate the hydrocarbon density (ph) within 
a formation from corrected neutron and density porosity values. 

Description 

Enter the ratio of the sidewall neutron porosity (SNP) or 
CNL* Compensated Neutron Log neutron porosity and density 
porosity corrected for lithology and environmental effects 
OsNPcor or <])cNLcor A]>Dcor, respectively) on the y-axis and the 



hydrocarbon saturation on the x-axis. The intersection point of the 
two values defines the density of the hydrocarbon. 

Example 

Given: Corrected CNL porosity = 15 p.u., corrected density 

porosity = 25 p.u., and Shr = 30% (residual hydrocarbon). 

Find: Hydrocarbon density. 

Answer: Porosity ratio = 15/25 = 0.6. ph = 0.29 g/cm 3 . 



246 



Back to Contents 



Saturation — Wireline, LWD 



Porosity Versus Formation Resistivity Factor 

Open Hole 



Schlumberger 



SatOH-1 

(former Por-1) 



50 
40 

30 
25 

20 
15 

10 

9 

8 
Porosity, -, 

<Mp.u.) 

6 

5 
4 



2.5 



10 



20 



50 



100 



200 



500 1,000 



2,000 5,000 



10,000 



2.5 



10 













N 


V 




















































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^ 
























































^— 


^ — 


V. 



















































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s s 






















































s 




V. 
























































N 


\ 






















































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1 
























































¥ 




































































































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v. 












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s 




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)2.15 








7 Fractures 1 ^ 












s?5 - 


-fe- ::! 


























































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^s^ 














































^^S 








s-2 2 


^ 


























































s 














































v 












^s, 














































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\ 






















































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\ 














































l"B - a2 








X 


^ 














































V 










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1.4 











































































20 



50 100 200 500 1,000 

Formation resistivity factor, F R 



2,000 5,000 



10,000 



© Schlumberger 



Purpose 

This chart is used for a variety of conversions of the formation 
resistivity factor (Fr) to porosity. 

Description 

The most appropriate conversion is best determined by laboratory 
measurement or experience in the area. In the absence of this 
knowledge, recommended relationships are the following: 

■ Soft formations (Humble formula): F R = 0.62/c> 2 - 51 or F r = 0.81A]) 2 

■ Hard formations: Fr = l/(]) m with the appropriate cementation 
factor (m). 



Example 






Given: 


Soft formation with 


Hard formation (m = 2) with 




if = 25 p.u. 


i) = 8 p.u. 


Find: 


Fr. 


Fr. 


Answer: 


Fr = 13 (from chart). 


Fr = 160 (from chart). 




Fr = 12.96 (calculated). 


Fr = 156 (calculated). 




< ► 



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247 



Saturation — Wireline, LWD 



Spherical and Fracture Porosity 

Open Hole 



Schlumberger 



SatO H -2 

(former Por-1a) 



Cementation 
exponent, m 




0.5 0.8 1 



Isolated 
pores 



Fractures 



4 6 

Porosity, <)> (p.u. I 



40 50 



© Schlumberger 




Purpose 

This chart is used to identify how much of the measured porosity 
is isolated (vugs or moldic) or fractured porosity. 

Description 

This chart is based on a simplified model that assumes no contribu- 
tion to formation conductivity from vugs and moldic porosity and the 
cementation exponent (m) of fractures is 1.0. 

When the pores of a porous formation have an aspect ratio close 
to 1 (vugs or moldic porosity), the value of m of the formation is usu- 
ally greater than 2. Fractured formations typically have a cementa- 
tion exponent less than 2. 



Enter the chart with the porosity ((])) on the x-axis and m on the 
y-axis. The intersection point gives an estimate of either the amount 
of isolated porosity (c|)iso) or the amount of porosity resulting from 
fractures (§&). 



Example 

Given: 

Find: 
Answer: 



tj> = 10 p.u. and cementation exponent = 2.5. 

Intergranular (matrix) porosity. 

Entering the chart with 10 p.u. and 2.5 gives an intersec- 
tion point of tpiso = approximately 4.5 p.u. 
Intergranular porosity = 10 - 4.5 = 5.5 p.u. 



248 



Back to Contents 



Saturation — Wireline, LWD 



Saturation Determination 

Open Hole 



Schlumberger 



Purpose 

This nomograph is used to solve the Archie water saturation 
equation: 





s -K- 
w V R t \ 


F R R w 


where 




Sw = 


water saturation 




R = 


resistivity of clean-water formation 


Rt = 


true resistivity of the formation 




Fr = 


formation resistivity factor 




Kw — 


formation water resistivity. 





Description 

If R is known, a straight line from the known R value through the 
measured Rt value indicates the value of Sw. If Ro is unknown, it may 
be determined by connecting R w with Fr or porosity ((])). 



Example 

Given: 

Find: 
Answer: 



It should be used in clean (nonshaly) formations only. 



R w = 0.05 ohm-m at formation temperature, ty = 20 p.u. 
(Fr = 25), and R t = 10 ohm-m. 

Water saturation. 

Enter the nomograph on the R w scale at R w = 0.05 ohm-m. 

Draw a straight line from 0.05 through the porosity scale 
at 20 p.u. to intersect the R scale. 

From the intersection point of R = 1, draw a straight line 
through Rt = 10 ohm-m to intersect the Sw scale. 

Sw = 31.5%. 




< ► 



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continued on next page 
249 



Saturation — Wireline, LWD 



Saturation Determination 

Open Hole 



Schlumberger 



SatO H -3 

(former Sw-1) 



Clean Formations, m = 2 



R w 

(ohm-m) 
_ 0.01 



J 1 0.02 



0.03 
0.04 

J L 0.05 

0.06 
0.07 
0.08 
0.09 
0.1 



0.2 

0.3 

0.4 

0.5 

0.6 
0.7 
0.8 
0.9 
1 

1.5 

2 



(%) 



^ 2,000 



2.5 _ 




3 _ 


1 1,000 




1 800 


4_ 


1 600 


5 _ 


1 400 


6 - 


- 300 


7 _ 


. 200 


8 _ 




9 _ 
10 - 


1 100 




1 80 




I 60 


15 J 


50 
40 


20 J 


30 




1 20 


25 J 




30 J 


1 10 


35 J 


8 


40 _ 


6 


45 


: 5 


50 J 


L 4 



m = 2.0 



Ro 
(ohm-m) 

30 __ 



20 
18 
16 
14 

12 

10 

9 

8 

7 

6 
5 

4 



3 _. 



2 
1.8 
1.6 
1.4 
1.2 

1.0 
0.9 
0.8 
0.7 
0.6 
0.5 

0.4 
0.3 _. 



0.2 
0.18 
0.16 
0.14 
0.12 
0.10 _L 



R, 
(ohm-m) 

10,000 _ 
8,000 I 

6,000 JL 

5,000 _- 

4,000 -- 

3,000 _. 

2,000 _. 



1,000 
800 

600 
500 
400 
300 

200 

100 
80 

60 
50 
40 
30 

20 

10 
8 

6 
5 

4 
3 



1.0 
0.8 
0.6 
0.5 
0.4 
0.3 

0.2 ± 



0.1 J_ 



(%) 
5 

6 _. 



9 _. 

10 
11 
12 
13 
14 
15 
16 

18 
20 



25 
30 

40 

50 

60 
70 

80 

90 

100 



© Schlumberger 



FrR« 



250 



< ► 



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Saturation — Wireline, LWD 



Saturation Determination 

Open Hole 



Schlumberger 



Purpose 

This chart is used to determine water saturation (Sw) in shaly or 
clean formations when knowledge of the porosity is unavailable. It 
may also be used to verify the water saturation determination from 
another interpretation method. The large chart assumes that the 
mud filtrate saturation is 



IS 



The small chart provides an Sxo correction when S xo is known. 
However, water activity correction is not provided for the SP portion 
of the chart (see Chart SP-2). 

Description 

Clean Sands 

Enter the large chart with the ratio of the resistivity of the flushed 
zone to the true formation resistivity (R xo /Rt) on the y-axis and the 
ratio of the resistivity of the mud filtrate to the resistivity of the for- 
mation water (Rmf /R w ) on the x-axis to find the water saturation at 
average residual oil saturation (Sw a ). If Rmf/Rw is unknown, the chart 
may be entered with the spontaneous potential (SP) value and the 
formation temperature. If S xo is known, move diagonally upward, 
parallel to the constant-Swa curves, to the right edge of the chart. 
Then, move horizontally to the known S xo (or residual oil saturation 
[ROS], S or ) value to obtain the corrected value of Sw. 



Example 

Given: 

Find: 
Answer: 



R xo = 12 ohm-m, Rt = 2 ohm-m, Rmf/Rw = 20, and 

Sor — 20/o. 

Sw (after correction for ROS). 

Enter the large chart at R xo /Rt = 12/2 = 6 on the 
y-axis and Rmf/Rw = 20 on the x-axis. From the point of 
intersection (labeled A), move diagonally to the right to 
intersect the chart edge and directly across to enter the 
small chart and intersect S or = 20%. 
Sw = 43%. 



Description 

Shaly Sands 

Enter the chart with R xo /Rt and the SP in the shaly sand (Epsp). The 
point of intersection gives the Swa value. Draw a line from the chart's 
origin (the small circle located at R xo /Rt = Rmf/Rm = 1) through this 
point to intersect with the value of static spontaneous potential (Essp) 
to obtain a value of R xo /Rt corrected for shaliness. This value of R xo /Rt 
versus Rmf/Rw is plotted to find Sw if Rmf/Rw is unknown because the 
point defined by R xo /Rt and Essp is a reasonable approximation of Sw. 
The small chart to the right can be used to further refine Sw if S or is 
known. 

Example 

Given: R xo /R t = 2.8, Rmf/Rw = 25, E PS p = -75 mV, Essp = -120 mV, 
and electrochemical SP coefficient (Kc) = 80 (formation 
temperature = 150°F). 

Find: Sw and corrected value for S or = 10%. 

Answer: Enter the large chart at R xo /Rt = 2.8 and the intersection 
of Epsp = -75 mV at Kc = 80 from the chart below. A line 
from the origin through the intersection point (labeled B) 
intersects the -120-mV value of Essp at Point C. Move 
horizontally to the left to intersect Rmf/Rw = 25 at Point D. 
Then move diagonally to the right to intersect the right 
y-axis of the chart. Move horizontally to the small chart to 
determine S xo = 0.9%, Sw = 38%, and corrected Sw = 40%. 

For more information, see Reference 12. 




< ► 



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continued on next page 
251 



Saturation — Wireline, LWD 



Saturation Determination 

Open Hole 



Schlumberger 



SatO H -4 

(former Sw-2) 





























































s or (%) 




Rmf/Rw 


10 20 30 40 




0.6 U.8 l.U l.b 


1 2.b 3 4 b 6 8 10 lb 


2U 2b 30 40 bO 60 






2 


$>' 


/ 




50 
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10 
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6 
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R xc, „ 

R, 

1 
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0.6 
0.5 

0.4 
0.3 

0.2 

0.1 
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75 

100 . 
Temperature 150 

(°F) 200 ; 

300 : 

© Schlumberger 
























































80 
70 

60 




































































































































































4>' 
























































y \y 

y \ 

' \ 

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R.n 










































fc PSP = -Mog-^-2 


K c log ^ 








































™t 


50 


S>' 


\ 
\ 


Sxo = V^w 




























































































40 

30 
25 

20 
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, 






















































































































































































































































































































































































































































































































































































0.6 


8 

r 

7 

1 
8 

r 


1.0 1.5 


2 2.5 3 4 5 6 8 

Rmf/Rw 


10 15 


20 25 30 


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/ / / / / s* 




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\ 1 1 i /;////////x/^<y>'^ 


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20 10 




c 


-20 -40 -60 -80 -100 -120 -140 
Ep SP orE SS p(mV) 















252 



< ► 



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Saturation — Wireline, LWD 



Graphical Determination of S w from S w t and S W b 

Open Hole 



Schlumberger 



SatOH-5 

(former Sw-14) 



100 






90 
80 
70 
60 
S wt (%) 50 
40 
30 
20 
10 













































































































































































































































































































































































































































^wb 
















































































































































































70% 

| 














































































































































































































































































60% 






























































































"* 






























































































% 
































































































bU 
































































































































































































40% 






























































































































































































1 . 
30% 




























































































































































































































































































20% 

r 1 






























































































































































































10% 


































































































































































































































































































u 


































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































C 

© Schlumberger 


10 20 30 40 50 60 70 80 90 100 

s w (%) 



Purpose 

This chart is used to drive a value of water saturation (Sw) corrected 
for the bound-water volume in shale. 

Description 

This is a graphical determination of Sw from the total water satura- 
tion (Swt) and the saturation of bound water (Swb): 



"wt ^wb 



Enter the y-axis with Swt and move horizontally to intersect 
the appropriate Swb curve. Read the value of Sw on the x-axis. 

Example 

Given: Swt = 45% and Swb = 10%. 

Find: Sw. 

Answer: Sw = 39.5%. 




1-S 



">yi • 



Back to Contents 



253 



Saturation — Wireline, LWD 



Porosity and Gas Saturation in Empty Hole 

Open Hole 



Schlumberger 



SatO H -6 

(former Sw-11) 



Us8 if no 
shale present 



Neutron 

porosity 

index 

(corrected 

for lithology) 



/latrix density, 2.75 
Pma(g/cm 3 ) 



Density and Hydrogen Index of Gas Assumed Zero 
Porosity, <]) (p.u.) 

10 12 14 16 18 20 22 24 26 



28 30 




Use if no 
oil present 



_ 10,000 
IC 4,000 
-- 2,000 
zz 1,000 

II 400 
-- 300 

II 200 
__ 150 

100 

70 
-L 60 

:: 50 

II 40 
__ 30 



:: 20 



II 15 
X 14 
13 

__ 12 

__ 11 



Sandstone 
Limy sandstone 
Limestone 



Dolomite 



© Schlumberger 



2.7 2.6 2.5 2.4 2.3 2.2 2.1 
Apparent bulk density from density log, p b (g/cm 3 ) 




Purpose 

This chart is used to determine porosity ((])) and gas saturation (Sg) 
from the combination of density and neutron or from density and 
resistivity measurements. 



Example 

Given: 



Find: 
Answer: 



S„ = 

Sw : 



Sh-Sg 

100 - s h . 



Description 

Enter from the point of intersection of the matrix density (pma) and 
apparent bulk density (pb). Move vertically upward to intersect 
either neutron porosity ((|)n, corrected for lithology) or the ratio of 
true resistivity to connate water resistivity (Rt/R w ). This point defines 
the actual porosity and Sg on the curves. 

Oil saturation (S ) can also be determined if all three measure- 
ments (density, neutron, and resistivity) are available. Find the values 
of § and Sg as before, and then find the intersection of Rt/R w with (]) 
to read the value of the total hydrocarbon saturation (Sh) on the 
saturation scale for use in the following equations: 
254 

a ► Back to Contents 



Limy sandstone (p ma = 2.68 g/cm 3 ), pb = 2.44 g/cm 3 , 

<|>n = 9 p.u., Rt = 74 ohm-m, and R w = 0.1 ohm-m. 

§, S g , S h , So, and Sw. 

First, find R t /R w = 74/0.1 = 740. 

c> = 12 p.u. and S g = 25%. 

Sh = 70% (total hydrocarbon saturation). 

So = 70 - 25 = 45%. 

Sw = 100 - 70 = 30%. 



Saturation — Wireline 



EPT* Propagation Time 

Open Hole 



Schlumberger 



SatO H -7 

(former Sxo-1) 



21 
20 
19 
18 
17 
16 
15 
14 



tp.lns/m) 13 



12 

11 

10 

9 



10.9. 



6 

5 

Sandstone 



tpma (ns/m) 

8 9 10 
■ l.l.i 



tpm= (ns/m) 

8 9 
■ l.l 



10 

_l 



\\\ 


\ 


\\\ 


\ 


\\\ 


\ 

\ 




\ 


^A 


\ 
\ 


\\\ 


\ 
\ 


\\\ 


\ 
\ 


V\> 


\ 


\\\ 


\ 
\ 


\\\ 






\ 


\\\ 


\ 
\ 


\N\ 


\ 




\ 
\ 


\\\ 


\ 
\ 


^ 


\ 


olomitG 






Limestone 



Sandstone 



Dolomite 



S„ 

%) 
100 

_90 

_80 



_60 




_40 



_30 



_ 20 



I— 



Limestone 



*Markof Schlumberger 
© Schlumberger 



Purpose 

This nomograph is used to define flushed zone saturation (S xo ) in 
the rock immediately adjacent to the borehole by using the EPT 
Electromagnetic Propagation Tool time measurement (t p i). 

Description 

Use of this chart requires knowledge of the reservoir lithology or 
matrix propagation time (t pma ), saturating water propagation time 
(t pw ), porosity ((])), and expected hydrocarbon type. Enter the far- left 
scale with t p i and move parallel to the diagonal lines to intersect the 
appropriate t pma value. From this point move horizontally to the right 



edge of the scale grid. From this point, extend a straight fine through 
the porosity scale to the center scale grid; again, move parallel to the 
diagonal lines to the appropriate t pma value and then horizontally to 
the right edge of the grid scale. From this point, extend a straight 
line through the intersection of t pw and the hydrocarbon type point 
to intersect the S xo scale. For more information, see Reference 25. 




Back to Contents 



255 



Saturation — Wireline 



EPT* Attenuation 

Open Hole 



Schlumberger 



SatO H -8 

(former Sxo-2) 









c 


xo 








(%) 










5 




A„ 






_ 6 




(dB/m) 






_ 7 




6,000 






_ 8 




5,000 _ 






"EPTcor 

(dB/m) 


_ 9 
_ 10 




4,000 _ 






1 






3,000 _ 


















* 




.._ 2 










(p.u.) 






- 




2,000 _ 








.._ 3 


_ 20 










.1 




.._ 4 
















I 6 

'"" 8 












2 




_ 30 




1,000 _ 






3 


J 


- 10 






900 _ 






4 






_ 40 




800 _ 






.5 








700 _ 










20 






600 _ 












_ 50 








\ — 


.10 




30 






500 _ 
400 _ 




\^ 


.15 
.20 




40 yT 
60 y^ 


_ 60 
_ 70 
_ 80 




300 _ 






^30 
140 




80 y^ 

"— 100/ 


_ 90 
_ 100 




200 _ 








200 

300 
400 






100 _ 








600 






90 _ 








800 




*Markof Schlumberger 


80 _ 








-— 1,000 




© Schlumberger 












Purpose 

This nomograph is used to determine the flushed zone saturation 
(Sxo) in the rock immediately adjacent to the borehole by using the 
EPT Electromagnetic Propagation Tool attenuation measurement. It 
requires knowledge of the saturating fluid (usually mud filtrate) 
attenuation (A w ), porosity ((])), and the EPT EATT attenuation 
(Aeptcoi) corrected for spreading loss. 

Description 

The value of A w must first be determined. Chart Gen- 16 is used to 
estimate A w by using the equivalent water salinity and formation 
temperature. EPT-D spreading loss is determined from the inset on 
Chart Gen-16 based on the uncorrected EPT propagation time (t p i) 
measurement. The spreading loss correction algebraically added to 
the EPT-D EATT attenuation measurement gives the corrected EPT 
attenuation (Aeptcoi). These values are used with porosity on the 
nomograph to determine S xo . 



Example 

Given: 

Find: 
Answer: 



EATT = 250 dB/m, t p i = 10.9 ns/m, (b = 28 p.u., water salin- 
ity = 20,000 ppm, and bottomhole temperature = 150°F. 

Spreading loss (from Chart Gen-16 inset) and S xo . 

The spreading loss determined from the inset on 
Chart Gen-16 is -82 dB/m. 

Aeptcoi- = 250 - 82 = 168 dB/m. 

A w (from Chart Gen-16) = 1,100 dB/m. 

Enter the far- left scale at A w = 1,100 dB/m and draw 
a straight line through § = 28 p.u. on the next scale to 
intersect the median line. From this intersection point, 
draw a straight line through Aeptcoi = 168 dB/m on the 
next scale to intersect the S xo value on the far-right 
scale. Sxo = 56 p.u. 



256 



Back to Contents 



Saturation — Wireline 



Capture Cross Section Tool 

Cased Hole 



Schlumberger 



Purpose 

This chart is used to determine water saturation (Sw) from capture 
cross section, or sigma (E), measurements from the TDT* Thermal 
Decay Time pulsed neutron log. 

Description 

This chart uses sigma water (E w ), matrix capture cross section (E ma ), 
and porosity ((])) to determine water saturation in clean formations. 
The chart may be used in shaly formations if sigma shale (E S h), the 
volume fraction of shale in the formation (Vsh), and the porosity cor- 
rected for shale are known. 

Thermal decay time (t and t S h in shale) is also shown on some 
of the chart scales because it is related to E. 

Procedure 

Clean Formation 

The Sw determination for a clean formation requires values known 
for E ma (based on lithology), ty, E w from the NaCl salinity (see Chart 
Gen-12 or Gen-13), and sigma hydrocarbon (Eh) (see Chart Gen-14). 
Enter the value of E ma on Scale B and draw a line to Pivot Point B. 
Enter Ei g on Scale B and draw Line b through the intersection of 
Line a and the value of § to intersect the sigma of the formation 
fluid (Ef) on Scale C. Draw Line 5 from Ef through the intersection 
of Eh and E w to determine the value of Sw on Scale D. 

Example: Clean Formation 

Given: Ei og = 20 c.u., E ma = 8 c.u. (sandstone) from TDT tool, 
E h = 18 c.u., E„ = 80 c.u. (150,000 ppm or mg/kg), and 
<j> = 30 p.u. 

Find: Sw. 

Answer: Following the procedure for a clean formation, Sw = 43%. 



Procedure 

Shaly Formation 

The Sw determination in a shaly formation requires additional infor- 
mation: sigma shale (E S h) read from the TDT log in adjacent shale, 
V S h from porosity-log crossplot or gamma ray, shale porosity ((|) S h) read 
from a porosity log in adjacent shale, and the porosity corrected for 
shaliness ((])shcor) with the relation for neutron and density logs 
in liquid-filled formations of (|)shcor = <|>iog - V S h(|)sh. 

Enter the value of E ma on Scale B and draw Line 1 to intersect 
with Pivot Point A. From the value of E S h on Scale A, draw Line 2 
through the intersection of Line 1 and V S h to determine the shale- 
corrected E cor on Scale B. Draw Line 3 from E CO r to the value of E ma 
on the scale to the left of Scale C. Enter Ei og on Scale B and draw 
Line 4 through the intersection of Line 3 and the value of (]) to deter- 
mine Ef on Scale C. From Ef on Scale C, draw Line 5 through the 
intersection of Eh and Ew to determine Swon Scale D. 



Example 




Given: 


Eiog = 25 c.u. 




E ma = 8 c.u. 




Eh = 18 c.u. 




E w = 80 c.u. 




E S h = 45 c.u. 




(|>iog = 33 p.u. 




c>sh = 45 p.u. 




V sh = 0.2. 


Find: 


(|)shcor and Sw. 


Answer: 


First find the porosity corrected for shaliness, 




(|>shcor = 33 p.u. - (0.2 x 45 p.u.) = 24 p.u. This value 




is used for the (]) point between Scales B and C. 




Sw = 43%. 




< ► 



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continued on next page 
257 



Saturation — Wireline 



Capture Cross Section Tool 

Cased Hole 



Schlumberger 



SatCH-1 

(former Sw-1 2) 




25 <h(p.u.) 



Qf Pivot point B / 

f/ 

5 1Q. '15 20 30 40 .50 60 70 80 90 100 110 120 
C *x„„\ i i i i i . f i i i i i i i i i i i i i i i 



*0 



So 





e \ £ w (cu.) 


*^£&9&: 


X?<fc 


^^<^ 


nKa/(? 


&^* 


o^>^?^ 


V 


^<$*&> 


Formation water 




salinity (ppm x 1,000) 



2h(c.u' 




S w (%) \ 
100 90 80 70 60 50 \ 40 30 20 10 

D I I I I | I I I I I | l M I I I I I I I I 



Igtog ~ Z ma ) - <t>(S h - 2 ma ) - V sh (Z sh - 2 n 
<|)(2w-2h) 



© Schlumberger 
258 



< ► 



Back to Contents 



Saturation — Wireline 



Capture Cross Section Tool 

Cased Hole 



Schlumberger 



Purpose 

This chart is used to graphically interpret the TDT* Thermal Decay 
Time log. In one technique, applicable in shaly as well as clean 
sands, the apparent water capture cross section (E wa ) is plotted 
versus bound-water saturation (Swb) on a specially constructed grid to 
determine the total water saturation (Swt). 

Description 

To construct the grid, refer to the example chart on this page. Three 
fluid points must be located: free-water point (Ewt), hydrocarbon 
point (Eh), and a bound-water point (Ewb). The free- (or connate for- 
mation) water point is located on the left y-axis and can be obtained 
from measurement of a formation water sample, from Charts Gen-12 
and Gen-13 if the water salinity is known, or from the TDT log in 
a clean water-bearing sand by using the following equation: 



(1) 



<\> 



The hydrocarbon point is also located on the left y-axis of the grid. 
It can be determined from Chart Gen-14 based on the known or 
expected hydrocarbon type. 

The bound-water point (Swb) can be obtained from the TDT log 
in shale intervals also by using the E wa equation. It is located on the 
right y-axis of the grid. 

The distance between the free-water and hydrocarbon points is 
linearly divided into lines of constant water saturation drawn parallel 
to a straight line connecting the free-water and bound-water points. 
The Swt = 0% line originates from the hydrocarbon point, and the 
Swt = 100% line originates from the free-water point. 

The value of E wa from the equation is plotted versus Swb to give 
Swt- The value of Swb can be estimated from the gamma ray or other 
bound-water saturation estimator. 

Once Swt and Swb are known, the water saturation of the reservoir 
rock exclusive of shale can be determined using 



wt 



K- !_ s 



J \b 



(2) 



wb 



Example 

Given: 



Find: 
Answer: 



Ewt = 61 c.u. and Eh = 21 c.u. (medium-gravity oil with 
modest GOR from Chart Gen-14), and £ W b = 76 c.u. 
(from TDT log in a shale interval and the preceding Eq. 1). 

Swt and Sw for Point 4. 

Zwa = 54 c.u. (from Eq. 1) and Swb = 25% (from 
gamma ray). 

Swt = 72% and Sw = 63% (from the preceding Sw 
equation). 



■^wa 

(c.u.: 




40 



*Markof Schlumberger 
© Schlumberger 



40 60 

s„„(%) 
- 1 — i — i — i — i — i — i — i — i — i 

44 48 52 56 60 64 68 72 76 80 
Gamma Ray 
(gAPl) 



The grid can also be used to graphically determine water 
saturation (Sw) in clean formations by crossplotting Ei g on the 
y-axis and porosity (<|>) on the x-axis. The values of E ma and Sw need 
not be known but must be constant over the interval studied. There 
must be some points from 100% water zones and a good variation in 
porosity. These water points define the Sw = 100% line; when extrap- 
olated, this line intersects the zero-porosity axis at E ma . The Sw = 0% 
line is drawn from E ma at tj) = p.u. to E = Eh at ty = 100 p.u. (or 
E = Vt(Ema + Eh) at <|> = 50 p.u.). The vertical distance from Sw = 0% 
to Sw = 100% is divided linearly to define lines of constant water 
saturation. The water saturation of any plotted point can thereby 
be determined. 




< ► 



Back to Contents 



continued on next page 
259 



Saturation — Wireline 



Capture Cross Section Tool 

Cased Hole 



Schlumberger 



SatCH-2 

(former Sw-17) 



■Hog 

or 
























































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































<t> or S wh 

i 







































































































© Schlumberger 



260 



< ► 



Back to Contents 



Saturation — Wireline 



Schlumberger 

RST* Reservoir Saturation Tool — 1.6875 in. and 2.5 in. 

Carbon/Oxygen Ratio — Open Hole 



Purpose consistently outside the trapezoid, the interpretation model may 

Charts SatCH-3 through SatCH-8 are presented for illustrative require revision. 

purposes only. They are used to ensure that the measured near- and The rectangle within each chart is constructed from four distinct 

far-detector carbon/oxygen (C/O) ratio data are consistent with the points determined by the intersection of the near- and far-detector 

interpretation model. These example charts are drawn for specific C/O ratios: 

cased and open holes and tool sizes to provide trapezoids for the WW = water/water point 

to determination of oil saturation (S ) and oil holdup (y ). WO = water/oil point 

Description ow = oil/water point 

Known formation and borehole data define the expected C/O ratio 00 = oil/oil point. 

values, which are determined in water saturation and borehole RST Reservoir Saturation Tool processing then determines the water 

holdup values ranging from to 1. All log data for formations with saturation (S*) of the formation. 

porosity ((])) greater than 10 p.u. should be within the trapezoidal 

area bounded by the limits of the S and y values. If data plot 




Back to Contents 



continued on next page 
261 



Saturation — Wireline 



RST* Reservoir Saturation Tool — 1.6875 in. and 2.5 in. 
in 6.125-in. Borehole 

Carbon/Oxygen Ratio — Open Hole 



Schlumberger 



SatCH-3 

(former RST-3) 



<(> = 30%, 6.125-in. Open HoIg 



Far-detector 
carbon/oxygen 0A 
ratio 



f)R 


RST-A and RST-C, limestone 

RST-A, quartz sandstone 












RST-B and RST-D, limestone 

RST-B, quartz sandstone 






00 




or 
























<»00 


0.4 




WO 




^ ^*oo 


00 
















n? 




WO __-> 


>^JT0W 


• 

ow 


+* 
*" 








/wwTWW 










n 


WV^ 




- *~ 












WW 











0.5 
Near-detector carbon/oxygen ratio 



1.0 



(|) = 20%, 6.125-in. Open Hole 



Far-detector 
carbon/oxygen 0.4 
ratio 




OR 


RST-A and RST-C, limestone 

RST-A, quartz sandstone 












RST-B and RST-D, limestone 

RST-B, quartz sandstone 










06 










^00 


















04 








■^\j*m 


• 00 








wo* 




•oo 


00 




0? 




W0- 
WW /£ 




• 
ow 


• 








W0 # # 0^'' 

W0 -.''''WW 




•ow 









4 


Y"WN 












WW 













0.5 



Near-detector carbon/oxygen ratio 



1.0 



*Markof Schlumberger 
© Schlumberger 



262 



< ► 



Back to Contents 



Saturation — Wireline 



RST* Reservoir Saturation Tool — 1.6875 in. and 2.5 in. 
in 9.875-in. Borehole 

Carbon/Oxygen Ratio — Open Hole 



Schlumberger 



SatCH-4 



c|) = 30%, 9.875-in. Open Hole 



Far- detector 

carbon/oxygen 

ratio 



1.5 








RST-AandRST-C, limestone 
RST-A, quartz sandstone 
RST-B and RST-D, limestone 














RST-B, quartz sandstone 










00 


1 n 




















^-^Z^\m 


00 




n^i 




















WO 

/WO 


























V\ 

g 














n 














WW 1 


"tow 













0.5 1.0 

Near-detector carbon/oxygen ratio 



1.5 



4> = 20%, 9.875-in. Open Hole 



Far-detector 

carbon/oxygen 

ratio 



1.5 





RST-AandRST-C, limestone 

RST-A, quartz sandstone 

RST-Band RST-D, limestone 

RST-B, quartz sandstone 












1 n 






















^^•oo 




05 








J,^' „» ^ 


. + ' oo 










wo 











. — •-"ow 


n 


wv 


u.-^- - " " " 
















WW 













0.5 1.0 

Near-detector carbon/oxygen ratio 



1.5 



*Markof Schlumberger 
© Schlumberger 



< ► 



Back to Contents 



263 



Saturation — Wireline 



RST* Reservoir Saturation Tool — 1.6875 in. and 2.5 in. 
in 8.125-in. Borehole with 4.5-in. Casing at 11.6 Ibm/ft 

Carbon/Oxygen Ratio — Cased Hole 



Schlumberger 



SatCH-5 

(former RST-5) 



ctj = 30%, 6.125-in. Borehole, 4.5-in. Casing at 11. 6 Ibm/ft 



0.8 



0.6 



RST-AandRST-C, limestone 
RST-A, quartz sandstone 
RST-B and RST-D, limestone 
RST-B, quartz sandstone 



Far-detector 
carbon/oxygen 0.4 
ratio 



0.2 




Near-detector carbon/oxygen ratio 



<|> = 20%, 6.125-in. Borehole, 4.5-in. Casing at 1 1.6 Ibm/ft 



Far-detector 
carbon/oxygen 0.4 
ratio 




OR 


RST-A and RST-C, limestone 

RST-A, qnart7 sanrktnnp 












RST-B and RST-D, limestone 

RST-B, quartz sandstone 




















or 
























04 








^•oo 










WO 


— pr^^jtfm/ 


?»00 






n? 




WO/JP 


-wfl__*1)W 














ow ,'' 








n 


WW 


F 


-■•bw 










WW 













0.5 
Near-detector carbon/oxygen ratio 



1.0 



*Markof Schlumberger 
© Schlumberger 



264 



< ► 



Back to Contents 



Saturation — Wireline 



RST* Reservoir Saturation Tool — 1.6875 in. and 2.5 in. 
in 7.875-in. Borehole with 5.5-in. Casing at 17 Ibm/ft 

Carbon/Oxygen Ratio — Cased Hole 



Schlumberger 



SatCH-6 



Far-detector 

carbon/oxygen 

ratio 

Far-detector 

carbon/oxygen 

ratio 

*Markof Schlumberger 
© Schlumberger 


0.8 
0.6 
0.4 
0.2 


0.8 
0.6 
0.4 
0.2 



q) = 30%, 7.875-in. Borehole, 5.5-in. Casing at 17 Ibm/ft 






RST-A and RST-C, limestone 

RST-A, quartz sandstone 

RST-B and RST-D, limestone 

RST-B, quartz sandstone 






















00 






























^/^0W 




>00 






WO* 




S £ 








pmy^ 


*^- * ^owl— — 


nw j- ' 






V 


wo^/yp^^; 

WO Ifc^f^' 

A/V 'WW 


m 


• 
• 
• 






WW ( 


'/*' ----- 




ow 






wwf 

1 










0.5 

Near-detector carbon/oxygen ratio 

<]> = 20%, 7.875-in. Borehole, 5.5-in. Casing at 17 Ibm/ft 


1.0 




RST-A and RST-C, limestone 

RST-A, quartz sandstone 

RST-B and RST-D, limestone 

RST-B, quartz sandstone 










































J»00 












^Tow 










^^f^uv 


. — - — 37*00 








wo^^--^; 

W0/^<^< 


s^'1*Wi 

" ^'l— — . 


— -«™ nn 








WW \^f^""' " 




• 
s 
s 
• 






W 
WW, 


V U *» s ^ * 

0/*>' ----- 

if-"' 


- - — 


ow 








WW 










0.5 

Near-detector carbon/oxygen ratio 


1.0 





-* ► 



Back to Contents 



265 



Saturation — Wireline 



RST* Reservoir Saturation Tool — 1.6875 in. and 2.5 in. 
in 8.5-in. Borehole with 7-in. Casing at 29 Ibm/ft 

Carbon/Oxygen Ratio — Cased Hole 



Schlumberger 



SatCH-7 

(former RST-1) 



$ = 30%, 8.5-in. Borehole, 7-in. Casing at 29 Ibm/ft 



Far-detector 
carbon/oxygen 0.4 
ratio 



OR 


RST-Aand RST-C, limestone 

RST-A, quartz sandstone 








00 




RST-B and RST-D, limestone 

RST-B, quartz sandstone 
















^o 




OR 




















* * 


00 


0.4 








* "^ 1 


/ 00 


















0? 




W0« — " s 






">^)W 












•'OW 






n 


WW <^ " 
wwir'""" 


*■ 










WW 













0.5 
Near-detector carbon/oxygen ratio 

: 20%, 8.5-in. Borehole, 7-in. Casing at 29 Ibm/ft 



1.0 



Far-detector 
carbon/oxygen 0-4 
ratio 




08 


RST-Aand RST-C, limestone 

RST-A, qnart7 sanrktnnp 












RST-B and RST-D, limestone 

RST-B, quartz sandstone 






00 














or 


















^^<*» 


ow 




04 








^S^-'*' 00 

<>"'-«'nw ■ 


00 












««•_, — .. — — — —"~ 


ow^X 


00 

A — 




n? 










* 










WW/ ir^r<r: 
W0*2^^-"" 






* 




n 


WW 


*",-— 

{'-'"' 


--"""" 










WW* 


WW 











0.5 
Near-detector carbon/oxygen ratio 



1.0 



*Markof Schlumberger 
© Schlumberger 



266 



< ► 



Back to Contents 



Saturation — Wireline 



RST* Reservoir Saturation Tool — 1.6875 in. and 2.5 in. 
in 9.875-in. Borehole with 7-in. Casing at 29 Ibm/ft 

Carbon/Oxygen Ratio — Cased Hole 



Schlumberger 



SatCH-8 

(former RST-2) 



4> = 30%, 9.875-in. Borehole, 7-in. Casing at 29 Ibm/ft 



Far-detector 
carbon/oxygen 0.4 
ratio 



OR 


RST-A and RST-C, limestone 

RST-A, quartz sandstone 

RST-B and RST-D, limestone 

RST-B, quartz sandstone 






nn 
























OR 


















^S"^ ^t^S 


1\A 


*00 

' 03 


04 




















-?*^ow 


/ 00 

/-- -* 




0? 




wo — -^y" 








ow y 






WO 


wo/v^: 








• 

ow 




n 


W\ 

WW 


■ —"■""" 


^ *" ' ' " 










WW 


9 











0.5 
Near-detector carbon/oxygen ratio 

<s> = 20%, 9.875-in. Borehole, 7-in. Casing at 29 Ibm/ft 



1.0 



Far-detector 
carbon/oxygen 0-4 
ratio 



08 


RST-A and RST-C, limestone 

RST-A, quartz sandstone 

RST-B and RST-D, limestone 

RST-B, quartz sandstone 
















jp00 














OR 


















>/ ^0^\ «■»■• 


[ow 

00 




04 










^00 


















n i 




wo ^--^T^s 


* ■* ,11' — ■"* 




•ow jt oo 






V 


\Xwoxv^--, 
vwPj|£f^T- 


^. — , ,. • ■* ■""■ 




* 

ow 







w 

WW, 




- — — -" 










1 


WW 











0.5 
Near-detector carbon/oxygen ratio 



1.0 



*Markof Schlumberger 
© Schlumberger 



< ► 



Back to Contents 



267 



Permeability 



Permeability from Porosity and Water Saturation 

Open Hole 



Schlumberger 



Purpose 

Charts Perm-1 and Perm-2 are used to estimate the permeability of 
shales, shaly sands, or other hydrocarbon-saturated intergranular 
rocks at irreducible water saturation (Swi). 

Description 

The charts are based on empirical observations and are similar in 
form to a general expression proposed by Wyllie and Rose (1950) 
(see Reference 49): 



1/2 






-c. 



(1) 



Chart Perm-1 presents the results of one study for which the 
observed relation was 



f 



1/2 



lOO^) 



2.25 ^ 



(2) 



Chart Perm-2 presents the results of another study: 



k 1/2 70(b 2 : 



1-S„ 



\ 



(3) 



The charts are valid only for zones at irreducible water saturation. 
Enter porosity (§) and S™ on a chart. Their intersection defines 
the intrinsic (absolute) rock permeability (k). Medium-gravity oil is 
assumed. If the saturating hydrocarbon is other than medium-gravity 
oil, a correction factor (C) based on the fluid densities of water and 
hydrocarbons (p w and ph, respectively) and elevation above the free- 
water level (h) should be applied to the Swi value before it is entered 
on the chart. The chart on this page provides the correction factor 
based on the capillary pressure: 



P, 



h (pw"Ph) 



2.3 



(4) 



Charts Perm-1 and Perm-2 can be used to recognize zones at irre- 
ducible water saturation, for which the product c^S™ from levels within 
the zone is generally constant and plots parallel to the c^S™ lines. 



Example 

Given: (]) = 23 p.u., Swi = 30%, gas saturation with ph = 0.3 g/cm 3 
and p w = 1.1 g/cm 3 , and h = 120 ft. 

Find: Correction factor and k. 

Answer: First, find p c to determine the correction factor if the 
zone of interest is not at irreducible water saturation: 



h(pw-Ph) 120(1.1-0.3) 



2.3 



2.3 



:42. 



Enter the correction factor chart with S™ = 30% to inter- 
sect the curve for p c = 40 (nearest to 42), for which the 
correction factor is 1.08. The corrected Swi value is Swi = 
1.08 x 30% = 32.4%. 

Chart Perm-1: (])S'wi = 0.072% and k = 130 mD. 
Chart Perm-2: c^S'™ = 0.072% and k = 65 mD. 



2.0 



1.6 



Correction 1.4 
factor, C 

1.2 



1.0 



0.8 













n ?nn 


ILL Mr tuu 


.«■" 


,* 


,/' 


f 


4 r 


J 


f 




1 


r 




,r 




" I n p,„ — p„ ' ' 




- : - - Pc JO 






J 






















,i' "">« p c - IUU 


















•"" n 1(1 


,1 . Pc lu . 


— .-.,,,,,,,,,,,,,..— p _Q 

















20 40 60 80 

Irreducible water saturation, S wi (%) 



100 




) Schlumberger 



268 



Back to Contents 



Permeability 



Permeability from Porosity and Water Saturation 

Open Hole 



Schlumberger 



Perm-1 

(former K-3) 



60 






50 

40 

Irreducible 

water 
saturation ,n 

above 
transition 

zone, 

s wi (%> 

20 

10 














I 




































































1 




P 




0.5 


































































1 




I 


i 




































































ft 




/ 


p \l i r 






































































/ 










































































1 

0.1 








































































In 


m \ 










2 














































S w 


































































/* 










































































/ 




































r 






































/ 




































































0.12 










































1(1 










































































































0.10 
















































?n 


V 












































































l> 












































































50 


> 


>rf 












u.ua 






























































00 


*J 

















































































3 






































































200 


























































































































































n n 


4 




" bl 


JU 




j±{ 








































































. 







1, 


300 














s' 




































































-^ 




































































5,uuu 


































^ 


.02 
































































•^ 


01. 


























































































































































































































































































































































C 

© Schlumberger 


5 10 15 20 25 30 35 40 

Porosity, <|> (p.u.) 




< ► 



Back to Contents 



269 



Permeability 



Permeability from Porosity and Water Saturation 

Open Hole 



Schlumberger 



Perm-2 

(former K-4) 



40 




35 

30 

25 

Porosity, 20 

(j)(p.U.) 

15 

10 

5 






































































































































































































































































































































































































































































































































































































































































































































































,ui 


JU 




















































































, 






























































































/ 






























































































1 


























































































, 










2,000 














































































/ 
















■0 


















































































f\ /| / 






V 


\ 


















































































V 1,000 j 






























































































% 


f. 






















































































) 
















































<| 






































dU 








































































/ 






















1 








































/ 


t 


























/ 














20 


n 








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■ 




































































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v if 


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Rfl 
































nnp 
























































































































































20 






















nr 


6 




















































A / J 


























































































/ 




















5 










04 




























































































































































































































































n 


n' 








1 






























































































































































nni 






























n n 
























































































































































































. 


























































































































( 

© Schlumberger 






1 


] 








2( 


) 






Ir 


3( 
re 


) 


;ib 


le 


w 


4 
aft 


] 
>r ; 


at 


ur 


at 


5 

on 


] 

a 


30 


je 


m 


6 
n 



.it 


on 


zc 


>n 


7 

3, 



5 


(°/ 


») 




8 


] 








90 




100 



This chart is used similarly to Chart Perm-1 for the relation 



k 1/2 70A 2 



'l-S ^ 

o 
V wi J 




270 



< ► 



Back to Contents 



Permeability 



Schlumberger 



Fluid Mobility Effect on Stoneley Slowness 

Open Hole 



Perm-3 



10,000 


Fresh Mud at 600 Hz 




1,000 

Mobility 
(mD/cp) 10 n 

10 
0.1 




















































































































































































| 


















































1 
















































1 








































lUlc 


mbr 


ane 


im 




in 


c 






































pe 
/ 






























50 








10/ 




5 










\// 


/ OGPa/cm 
(no mudcake) 




























i 






/ 












































/ 


















































I 


















































/ 


















































/ 


















































/ 


















































/ 


















































/ 




















































































































































































































































































































































1 


















































/ 


















































/ 
















































I 


/ 
















































/ 


















































1 


















































1 


















































/ 


















































/ 


















































/ 
















































/ 


















































/ 


















































/ 
















































© Schlumberger 


1 1 10 100 

Mobility-added slowness, S - S e (u,s/ft) 



Purpose 

This chart is used to estimate ease of movement through a formation 
by a fluid. 

Description 

The mobility-added slowness, which is the difference between the 
Stoneley slowness and the calculated elastic Stoneley slowness, is 
plotted on the x-axis and the mobility of the fluid is on the y-axis. The 
membrane impedance curves represent the effect that the mudcake 
has on the determination of the mobility of the fluid in the formation. 
The membrane impedance is scaled in gigapascal per centimeter. 




Back to Contents 



271 



Cement Evaluation — Wireline 



Cement Bond Log — Casing Strength 

Interpretation — Cased Hole 



Schlumberger 



Purpose 

This chart is used to determine the decibel attenuation of casing 
from the measured cement bond log (CBL) amplitude and convert 
it to the compressive strength of bonded cement (either standard 
or foamed). 

Description 

The amplitude of the first casing arrival is recorded by an acoustic 
signal-measuring device such as a sonic or cement bond tool. This 
amplitude value is a measure of decibel attenuation that can be 
translated into a bond index (an indication of the percent of casing 
cement bonding) and the compressive strength (psi) of the cement 
at the time of logging. 

Enter the chart on the y-axis with the log value of CBL amplitude 
and move upward parallel to the 45° lines to intersect the appropri- 
ate casing size. At that point, move horizontally right to the attenua- 
tion scale on the right-hand y-axis. From this point, draw a line 
through the appropriate casing thickness value to intersect the com- 
pressive strength scale. The casing wall thickness is calculated by 
subtracting the nominal inside diameter (ID) from the outside 
diameter (OD) listed on the table for threaded nonupset casing 
and dividing the difference by 2. 



Example 

Given: Log amplitude reading = 3.5 mV in zone of interest 

and 1.0 mV in a well-bonded section (usually the lowest 
millivolt value on the log), casing size = 7 in. at 
29 lbm/ft, casing thickness = 0.41 in., and neat cement 
(not foamed). 

Find: Compressive strength and bond index of the cement at 

the time of logging. 

Answer: Enter the 3.5-mV reading on the left y-axis of Chart 
Cem-1 and proceed to the 7-in. casing line. 

Move horizontally to intersect the right-hand y-axis at 
8.9 dB/ft. 

Determine the casing thickness as (7 - 6.184)/2 = 0.816/2 
= 0.41 in. Draw a line from 8.9 dB/ft through the 0.41-in. 
casing thickness point to the compressive strength scale. 

Cement compressive strength = 2,100 psi. 

To find the bond index, determine the decibel attenuation of the 
lowest recorded log value by entering 1.0 mV on the left-hand y-axis 
and proceeding to the 7-in. casing line. Move horizontally to intersect 
the right-hand y-axis at 12.3 dB/ft. 

Divide the precisely determined decibel attenuation for the CBL 
amplitude in the zone of interest by this value for the lowest millivolt 
value: 8.9/12.3 = 72% bond index. 

A 72% bond index means that 72% of the casing is bonded. This 
is not a well-bonded zone because a value of 80% bonding over a 10-ft 
interval is historically considered well bonded. Although the logging 
scale is a linear millivolts scale, the decibel attenuation scale is loga- 
rithmic. The millivolts log scale for the CBL value cannot rescaled 
in percent of bonding. If it were, the apparent percent bonding 
would be 65% because most bond log scales are from to 100 mV 
reading from left to right, over 10 divisions of track 1, or conversely 
100% to 0% cement bonding for mV = 100% bonding and 
100 mV = 0% bonding. 




272 



Back to Contents 



Cement Evaluation — Wireline 



Schlumberger 



Cement Bond Log — Casing Strength 

Interpretation — Cased Hole 



Threaded 


Nonupset Casing 
























OD 

(in.) 


Weight 
per ft* 
(Ibm) 


Nominal 
ID 

(in.) 


Drift 

Diameter* 

(in.) 




OD 

(in.) 


Weight 

perft T 

(Ibm) 


Nominal 
ID 

(in.) 


Drift 
Diameter* 

(in.) 




OD 

(in.) 


Weight 
per ft* 
(Ibm) 


Nominal 

ID 

(in.) 


Drift 

Diameter* 
(in.) 


4 


11.60 


3.428 


3.303 


7 


17.00 
20.00 
22.00 
23.00 
24.00 
26.00 
28.00 
29.00 
30.00 
32.00 
35.00 
38.00 
40.00 


6.538 
6.456 
6.398 
6.366 
6.336 
6.276 
6.214 
6.184 
6.154 
6.094 
6.004 
5.920 
5.836 


6.413 
6.331 
6.273 
6.241 
6.211 
6.151 
6.089 
6.059 
6.029 
5.969 
5.879 
5.795 
5.711 


10 


33.00 


9.384 


9.228 


4K 


9.50 
11.60 
13.50 


4.090 
4.000 
3.920 


3.965 
3.875 
3.795 


10% 


32.75 
40.00 
40.50 
45.00 
45.50 
48.00 
51.00 
54.00 
55.50 


10.192 
10.054 
10.050 
9.960 
9.950 
9.902 
9.850 
9.784 
9.760 


10.036 
9.898 
9.894 
9.804 
9.794 
9.746 
9.694 
9.628 
9.604 


4 3 / 


16.00 


4.082 


3.957 


5 


11.50 
13.00 
15.00 
17.70 
18.00 
21.00 


4.560 
4.494 
4.408 
4.300 
4.276 
4.154 


4.435 
4.369 
4.283 
4.175 
4.151 
4.029 


11 3 / 


38.00 
42.00 
47.00 
54.00 
60.00 


11.150 
11.084 
11.000 
10.880 
10.772 


10.994 
10.928 
10.844 
10.724 
10.616 


5X 


13.00 
14.00 
15.00 
15.50 
17.00 
20.00 
23.00 


5.044 
5.012 
4.974 
4.950 
4.892 
4.778 
4.670 


4.919 
4.887 
4.849 
4.825 
4.767 
4.653 
4.545 


n 


20.00 
24.00 
26.40 
29.70 
33.70 
39.00 


7.125 
7.025 
6.969 
6.875 
6.765 
6.625 


7.000 
6.900 
6.844 
6.750 
6.640 
6.500 


12 


40.00 


11.384 


11.228 


13 


40.00 


12.438 


12.282 


13 3 / 


48.00 


12.715 


12.559 


8% 


24.00 
28.00 
32.00 
36.00 
38.00 
40.00 
43.00 
44.00 
49.00 


8.097 
8.017 
7.921 
7.825 
7.775 
7.725 
7.651 
7.625 
7.511 


7.972 
7.892 
7.796 
7.700 
7.650 
7.600 
7.526 
7.500 
7.386 


5 3 / 


14.00 
17.00 
19.50 
22.50 


5.290 
5.190 
5.090 
4.990 


5.165 
5.065 
4.965 
4.865 


16 


55.00 


15.375 


15.187 


18 5 / 


78.00 


17.855 


17.667 


20 


90.00 


19.190 


19.002 


6 


15.00 
16.00 
18.00 
20.00 
23.00 


5.524 
5.500 
5.424 
5.352 
5.240 


5.399 
5.375 
5.299 
5.227 

5.115 


21 % 


92.50 
103.00 
114.00 


20.710 
20.610 
20.510 


20.522 
20.422 
20.322 


9 


34.00 
38.00 
40.00 
45.00 
55.00 


8.290 
8.196 
8.150 
8.032 
7.812 


8.165 
8.071 
8.025 
7.907 
7.687 


2VA 


100.50 
113.00 


23.750 
23.650 


23.562 
23.462 


6% 


17.00 
20.00 
22.00 
24.00 
26.00 
26.80 
28.00 
29.00 
32.00 


6.135 
6.049 
5.989 
5.921 
5.855 
5.837 
5.791 
5.761 
5.675 


6.010 
5.924 
5.864 
5.796 
5.730 
5.712 
5.666 
5.636 
5.550 




t Weight per foot in pounds is given for plain pipe (no threads 

or coupling) 

t Drift diameter is the guaranteed minimum inside diameter of 


5% 


29.30 
32.30 
36.00 
40.00 
43.50 
47.00 
53.50 


9.063 
9.001 
8.921 
8.835 
8.755 
8.681 
8.535 


8.907 
8.845 
8.765 
8.679 
8.599 
8.525 
8.379 


any part of the casing. Use drift diameter to determine the 
largest-diameter equipment that can be safely run inside the 
casing. Use inside diameter for volume capacity calculations. 















< ► 



Back to Contents 



continued on next page 
273 




Cement Evaluation — Wireline 



Cement Bond Log — Casing Strength 

Interpretation — Cased Hole 



Schlumberger 



Cem-1 

(former M-1) 




1 

70 

50 
40 
30 

20 
15 

10 
9 
8 
7 
6 

5 
CRI amplitndp ^ 


i/ 

5 


Casi 

10 
V 


ng 

IS 

6 


size 

)4 
2" 


m 

3 

3' 


■0 


Centered tool only, 3-ft [0.91 4-m] spacing 
Attenuation 








y 


/ 




1 ' Compressive strength 
_ 1 , {p f, 








/ 






I (m 


ra) 








/ 


/ 




2 


30 

_ 4,000 

25 

3,000 
= — 20 

15 

_ 2,000 

10 

- 1,000 Standard 

cement 

5 

_ 500 

3 

2 














R 














3 










/ 




1? 














4 














c 16 














5 




—/. 




<< 






5 20 Casing thickness 


A 


// 


/ 


y A 


' 




(mm) (in.) 
7 15 ^° 6 


// 




/ 








24 V 














Tt- ° 5 Tjoa^S^^^l 








/ 


' 




28 ^-^^T H4 




/l 


i- 


/ 




— ►< 


**^~^™\ 


// 


/ 










- 32 b __V 


/ < 












10 \_0 3 


(mV) 3 
2 

1 
0.5 

0.2 
4' 

© Schlumberger 














7 — t 1,000 I 

11- 36 V_ 








/ 


/ 




12 .„ r snn 




























5 J- 0.2 

13 c 














44 














14 














4 _ 
48 














MM) 




" 250 

1 

_ 100 

05 














Foamed cement 
ic- 52 3 — 














IB 














17 56 qnn 


/ 


/ 










2 _ 

18 


_ 50 
0.3 


V 
h 

5' 


h 
Cas 


nc 


1C 

h 

size 


13 
(in 


3 /b 

) 


(dB/ft) 200 

1 _ 
100 



274 



< ► 



Back to Contents 



Appendix A 



Linear Grid 











































































































































































































< ► Back to Contents 



275 



Appendix A 



Log-Linear Grid 



7 _ : 

4 =========================================================== 

3 ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ 

2 EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE 

5 El 

4 EE: 

3 zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz 
2 EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE 



276 



-* ► 



Back to Contents 



Appendix A 



Water Saturation Grid for Resistivity Versus Porosity 



For F R : 



0.62 



5,000 



4,000 



3,000 



2,500 



2,000 



Conductivity 
(mmho/m) 



1,500 



1,000 



500 
400 
300 

200 

150 

100 
50 

25 

10 











Res 
mul 
in a 


stivit 
tipliet 
highe 


/sea 
by 1 

r ran 


e ma 
3 for i 


/ bo 
jse 





































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































0.20 



0.25 



0.30 



0.35 

0.40 

0.45 
0.50 

0.60 

0.70 

0.80 

Resistivity 

0.90 (ohm-m) 
1.0 

1.2 
1.4 
1.6 
1.8 
2.0 

2.5 
3.0 

4.0 
5.0 
6.0 

8.0 
10 

15 
20 

30 

40 

50 

100 

200 



JPb 



F„ 



Back to Contents 



277 



Appendix A 



Water Saturation Grid for Resistivity Versus Porosity 



ForF„ 



500 



400 



300 



250 



200 



150 



Conductivity 
(mmho/m) 



100 



50 
40 
30 

20 
10 











Res 


stivity scale may be 


































mull 
in a 


ipliec 
night 


uy i 

r ran 


j Tor i 

ge 


se 















































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































2.5 



3.5 

4 

4.5 
5 



o Resistivity 
(ohm-m) 
9 

10 

12 
14 
16 

20 

25 
30 

40 
50 

100 

200 

500 

1,000 

2,000 



JPb 



278 



< ► 



Back to Contents 



Appendix B 



Logging Tool Response in Sedimentary Minerals 



Name 



Formula 



Plug 

(g/cm 3 ) 



^SNP 

(p.u.) 



»CNL 

(p.u.) 



9APS 1 

(p.u.) 



Ate 
(fis/ft) 



At, 
(US/ft) 



Pe 



8 

(farad/m) 



tp 
(ns/m) 



Gamma Ray 
(gAPI Units) 



(c.u.) 



Silicates 



Quartz 


Si0 2 


2.64 


-1 


-2 


-1 


56.0 


88.0 


1.8 


4.8 


4.65 


7.2 




4.3 


(i-cristobalite 


Si0 2 


2.15 


-2 


-3 








1.8 


3.9 








3.5 


Opal (3.5% H 2 0) 


Si0 2 (H 2 0)o.1209 


2.13 


4 


2 




58 




1.8 


3.7 








5.0 


Garnet' 


Fe 3 AI 2 (Si0 4 )3 


4.31 


3 


7 








11 


48 








45 


Hornblende* 


Ca 2 NaMg 2 Fe 2 
AISi B 22 (0,OH) 2 


3.20 


4 


8 




43.8 


81.5 


6.0 


19 








18 


Tourmaline 


NaMg 3 AI 6 B3Si 6 2 (OH|4 


3.02 


16 


22 








2.1 


6.5 








7450 


Zircon 


ZrSi0 4 


4.50 


-1 


-3 








69 


311 








6.9 



Carbonates 



Calcite 


CaC0 3 


2.71 











49.0 


88.4 


5.1 


13.8 


7.5 


9.1 




7.1 


Dolomite 


CaC0 3 MgC0 3 


2.85 


2 


1 


1 


44.0 


72 


3.1 


9.0 


6.8 


8.7 




4.7 


Ankerite 


Ca(Mg,Fe)(C0 3 ) 2 


2.86 





1 








9.3 


27 








22 


Siderite 


FeC0 3 


3.89 


5 


12 


3 


47 




15 


57 


6.8-7.5 


8.8-9.1 




52 



Oxidates 



Hematite 


Fe 2 3 


5.18 


4 


11 




42.9 


79.3 


21 


111 








101 


Magnetite 


Fe 3 4 


5.08 


3 


9 




73 




22 


113 








103 


Goethite 


FeO(OH) 


4.34 


50+ 


60+ 








19 


83 








85 


Limonite* 


FeO(OH)(H 2 OKos 


3.59 


50+ 


60+ 




56.9 


102.6 


13 


47 


9.9-10.9 


10.5-11.0 




71 


Gibbsite 


AI(OH) 3 


2.49 


50+ 


60+ 








1.1 










23 



Phosphates 



Hydroxyapatite 


Ca 5 (P0 4 ) 3 OH 


3.17 


5 


8 




42 




5.8 


18 








9.6 


Chlorapatite 


Ca 5 (P0 4 | 3 CI 


3.18 


-1 


-1 




42 




6.1 


19 








130 


Fluorapatite 


Ca 5 (P0 4 |3F 


3.21 


-1 


-2 




42 




5.8 


19 








8.5 


Carbonapatite 


(Ca 5 (P0 4 ) 3 )2C0 3 H 2 


3.13 


5 


8 








5.6 


17 








9.1 



Feldspars — Alkali* 



Orthoclase 


KAISbOa 


2.52 


-2 


-3 




69 




2.9 


7.2 


4.4-6.0 


7.0-8.2 


-220 


16 


Anorthoclase 


KAISbOa 


2.59 


-2 


-2 








2.9 


7.4 


4.4-6.0 


7.0-8.2 


-220 


16 


Microcline 


KAISi 3 B 


2.53 


-2 


-3 








2.9 


7.2 


4.4-6.0 


7.0-8.2 


-220 


16 



Feldspars — Plagioclase* 



Albite 


NaAISbOa 


2.59 


-1 


-2 


-2 


49 


85 


1.7 


4.4 


4.4-6.0 


7.0-8.2 




7.5 


Anorthite 


CaAI 2 Si 2 O a 


2.74 


-1 


-2 




45 




3.1 


8.6 


4.4-6.0 


7.0-8.2 




7.2 



Micas* 



Muscovite 


KAI 2 (SbAIO, }(OH| 2 


2.82 


12 


-20 


-13 


49 


149 


2.4 


6.7 


6.2-7.9 


8.3-9.4 


-270 


17 


Glauconite 


Ko.7(Mg,Fe 2 ,AD 
(Si 4 ,Aho)0 2 (OH) 


2.86 




-38 


-15 






4.8 


14 








21 


Biotite 


K(Mg,Fe) 3 (AISi 3 O, )(OH) 2 


-2.99 


-11 


-21 


-11 


50.8 


224 


6.3 


19 


4.8-6.0 


7.2-8.1 


-275 


30 


Phlogopite 


KMg 3 (AISi 3 Oio)(OH) 2 










50 


207 












33 



•APS* Accelerator Porosity Sonde porosity derived from near-to-array ratio (APLCI 
•Mean value, which may vary for individual samples 



For more information, see Reference 41. 



Back to Contents 



279 



Appendix B 



Logging Tool Response in Sedimentary Minerals 



Name 



Formula 



Plog 

(g/cm 3 ) 



9SNP 

(p.u.) 



OCNL 

(p.u.) 



9APS 1 

(p.u.) 



Ate 

(ps/ft) 



At, 
(US/ft) 



Pe 



8 

(farad/m) 



(ns/m) 



Gamma Ray 
(gAPI Units) 



(c.u.) 



Clays* 



Kaolinite 


AUSi 4 Oio(OH) 8 


2.41 


34 


-37 


-34 






1.8 


4.4 


-5.8 


-8.0 


80-130 


14 


Chlorite 


(Mg,Fe,AI) 6 (Si,AI) 4 
0,o(OH) a 


2.76 


37 


-52 


-35 






6.3 


17 


-5.8 


-8.0 


180-250 


25 


lllite 


Kl-1.5Al4(Si7-6.5,All-1.5) 

□2o(OH) 4 


2.52 


20 


-30 


-17 






3.5 


8.7 


-5.8 


-8.0 


250-300 


18 


Montmorillonite 


(Ca,Na) 7 (AI,Mg,Fe) 4 
(Si,AI) a 02o(OH)4(H 2 0)„ 


2.12 




-60 


-60 






2.0 


4.0 


-5.8 


-8.0 


150-200 


14 



Eva po rites 



Halite 


NaCI 


2.04 


-2 


-3 


21 


67.0 


120 


4.7 


9.5 


5.6-6.3 


7.9-8.4 




754 


Anhydrite 


CaS0 4 


2.98 


-1 


-2 


2 


50 




5.1 


15 


6.3 


8.4 




12 


Gypsum 


CaS0 4 (H 2 0) 2 


2.35 


50+ 


60+ 


60 


52 




4.0 


9.4 


4.1 


6.8 




19 


Trona 


Na 2 C03NaHCQ3H 2 


2.08 


24 


35 




65 




0.71 


1.5 








16 


Tachhydrite 


CaCI 2 (MgCI 2 | 2 (H 2 0), 2 


1.66 


50+ 


60+ 




92 




3.8 


6.4 








406 


Sylvite 


KCI 


1.86 


-2 


-3 








8.5 


16 


4.6-4.8 


7.2-7.3 


500+ 


565 


Carnalite 


KCIMgCl 2 (H 2 0| 6 


1.57 


41 


60+ 








4.1 


6.4 






-220 


369 


Langbeinite 


K 2 S0 4 (MgS0 4 ) 2 


2.82 


-1 


-2 








3.6 


10 






-290 


24 


Polyhalite 


K 2 S0 4 Mg 
S0 4 (CaS0 4 ) 2 (H 2 0) 2 


2.79 


14 


25 








4.3 


12 






-200 


24 


Kainite 


MgS0 4 KCI(H 2 0) 3 


2.12 


40 


60+ 








3.5 


7.4 






-245 


195 


Kieserite 


MgS0 4 (H 2 0) 


2.59 


38 


43 








1.8 


4.7 








14 


Epsomite 


MgS0 4 (H 2 0) 7 


1.71 


50+ 


60+ 








1.2 


2.0 








21 


Bischofite 


MgCI 2 (H 2 0} 6 


1.54 


50+ 


60+ 




100 




2.6 


4.0 








323 


B a rite 


BaS0 4 


4.09 


-1 


-2 








267 


1090 








6.8 


Celestite 


SrS0 4 


3.79 


-1 


-1 








55 


209 








7.9 



Sulfides 



Pyrite 


FeS 2 


4.99 


-2 


-3 




39.2 


62.1 


17 


85 








90 


Marcasite 


FeS 2 


4.87 


-2 


-3 








17 


83 








88 


Pyrrhotite 


Fe 7 S 8 


4.53 


-2 


-3 








21 


93 








94 


Sphalerite 


ZnS 


3.85 


-3 


-3 








36 


138 


7.8-8.1 


9.3-9.5 




25 


Chalcopyrite 


CuFeS 2 


4.07 


-2 


-3 








27 


109 








102 


Galena 


PbS 


6.39 


-3 


-3 








1,630 


10,400 








13 


Sulfur 


S 


2.02 


-2 


-3 




122 




5.4 


11 








20 



Coals 



Anthracite 


CHo.35bNd.OQ90o.022 


1.47 


37 


38 




105 




0.16 


0.23 








8.7 


Bituminous 


CH0.793N0.015O0.07B 


1.24 


50+ 


60+ 




120 




0.17 


0.21 








14 


Lignite 


CH0.BwN0.015O0.211 


1.19 


47 


52 




160 




0.20 


0.24 








13 



f APS* Accelerator Porosity Sonde porosity derived from near-to-array ratio (APLCI 
•Mean value, which may vary for individual samples 



For more information, see Reference 41. 



280 



Back to Contents 



Appendix C 



Acoustic Characteristics of Common Formations and Fluids 



Anhydrite 
Limestone 
Calcite 



50.0 
47.6 
49.7 



Nonporous Solids 


Material 


At 
(Us/ft) 




Sound Velocity 




Acoustic Impedance 




(ft/s) 




(m/s) 


(MRayl) 


Casing 


57.0 


17,500 




5,334 


41.60 


Dolomite 


43.5 


23,000 




7,010 


20.19 



20,000 


6,096 


18.17 


21,000 


6,400 


17.34 


20,100 


6,126 


16.60 



Quartz 
Gypsum 



52.9 
52.6 



18,900 
19,000 



5,760 
5,791 



15.21 
13.61 



Halite 



66.6 



15,000 



4,572 



9.33 



Kerosene 

Airat15psi,32°F[0°C] 

Air at 3,000 psi,212°F[100°C] 



Water-Saturated Porous Rock 


Material 


Porosity 
(%) 


At 
(ps/ft) 


Sound Velocity 




Acoustic Impedance 




(ft/s) 


(m/s) 


(MRayl) 


Dolomite 


5-20 


50.0-66.6 


20,000-15,000 


6,096^,572 


16.95-11.52 


Limestone 


5-20 


54.0-76.9 


18,500-13,000 


5,639-3,962 


14.83-9.43 


Sandstone 


5-20 


62.5-86.9 


16,000-11,500 


4,877-3,505 


12.58-8.20 


Sand 


20-35 


86.9-111.1 


11,500-9,000 


3,505-2,743 


8.20-6.0 


Shale 




58.8-143.0 


17,000-7,000 


5,181-2,133 


12.0-4.3 




Nonporous Solids 


Material 




At 
(ps/ft) 


Sound Velocity 




Acoustic Impedance 




(ft/s) 


(m/s) 


(MRayl) 


Water 




208 


4,800 


1,463 


1.46 


Water + 10% NaCI 




192.3 


5,200 


1,585 


1.66 


Water + 20% NaCI 




181.8 


5,500 


1,676 


1.84 


Seawater 




199 


5,020 


1,531 


1.57 



230 
920 
780 



4,340 


1,324 


1,088 


331 


1,280 


390 



1.07 

0.0004 

0.1 



Back to Contents 



281 



Appendix D 



Conversions 



Length 


\^ Multiply 
>v Number 

\ of 
to \^ 

Obtain by 


Centimeters 


Feet 


Inches 


Kilometers 


Nautical 
Miles 


Meters 


Mils 


Miles 


Millimeters 


Yards 


Centimeters 


1 


30.48 


2.540 


10= 


1.853x10= 


100 


2.540 x10- 3 


1.609x10= 


0.1 


91.44 


Feet 


3.281 x10 2 


1 


8.333 x10 2 


3281 


6080.27 


3.281 


8.333x10-= 


5280 


3.281 x10 3 


3 


Inches 


0.3937 


12 


1 


3.937x10' 


7.296x10" 


39.37 


0.001 


6.336x10" 


3.937 x10 2 


36 


Kilometers 


10-= 


3.048x10-" 


2.540x10-= 


1 


1.853 


0.001 


2.540x10-" 


1.609 


10-= 


9.144x10-" 


Nautical miles 




1.645x10-" 




0.5396 


1 


5.396x10" 




0.8684 




4.934x10" 


Meters 


0.01 


0.3048 


2.540 x10- 2 


1000 


1853 


1 




1609 


0.001 


0.9144 


Mils 


393.7 


1.2x 10" 


1000 


3.937x10' 




3.937x10" 


1 




39.37 


3.6x10" 


Miles 


6.214X 10 6 


1.894x10-" 


1.578X10 5 


0.6214 


1.1516 


6.214x10-" 




1 


6.214X10 7 


5.682x10-" 


Millimeters 


10 


304.8 


25.40 


10= 




1000 


2.540 x10- 2 




1 


914.4 


Yards 


1.094 x10 2 


0.3333 


2.778 x10 2 


1094 


2027 


1.094 


2.778x10 = 


1760 


1.094x10" 


1 



Area 


^^ Multiply 

^\ Number 

\ of 

to >^ 

Obtain (,y 


Acres 


Circular 
Mils 


Square 
Centimeters 


Square 
Feet 


Square 
Inches 


Square 
Kilometers 


Square 
Meters 


Square 
Miles 


Square 
Millimeters 


Square 
Yards 


Acres 


1 






2.296x10 = 




247.1 


2.471 x10-" 


640 




2.066x10" 


Circular mils 




1 


1.973x10= 


1.833x10" 


1.273x10" 




1.973x10" 




1973 




Square 
centimeters 




5.067X10 6 


1 


929.0 


6.452 


10'" 


10" 


2.590 x10 10 


0.01 


8361 


Square feet 


4.356x10" 




1.076X10 3 


1 


6.944x10-" 


1.076x10' 


10.76 


2.788x10' 


1.076x10 = 


9 


Square inches 


6,272,640 


7.854x10' 


0.1550 


144 


1 


1.550x10" 


1550 


4.015x10" 


1.550x10" 


1296 


Square 
kilometers 


4.047x10" 




10-'° 


9.290x10-" 


6.452 x10- ,D 


1 


10-" 


2.590 


10-' 2 


8.361 X10-' 


Square meters 


4047 




0.0001 


9.290X10- 2 


6.452x10-" 


10" 


1 


2.590x10" 


10-" 


0.8361 


Square miles 


1.562X10 3 




3.861 X10-" 


3.587x10" 




0.3861 


3.861 X10-' 


1 


3.861 x10-'" 


3.228x10-' 


Square 
millimeters 




5.067x10-" 


100 


9.290x10" 


645.2 


10 12 


10" 




1 


8.361 x10= 


Square yards 


4840 




1.196x10-" 


0.1111 


7.716x10-" 


1.196x10" 


1.196 


3.098x10" 


1.196x10" 


1 



282 



Back to Contents 



Appendix D 



Conversions 



Volume 


N. Multiply 
\ Number 

\ of 
to \a 

Obtain D y 


Bushels 

(Dry) 


Cubic 
Centimeters 


Cubic 
Feet 


Cubic 
Inches 


Cubic 
Meters 


Cubic 
Yards 


Gallons 
(Liquid) 


Liters 


Pints 
(Liquid) 


Quarts 
(Liquid) 


Bushels (dry) 


1 




0.8036 


4.651 x10- 4 


28.38 






2.838 x10- 2 






Cubic 
centimeters 


3.524 x10" 


1 


2.832X 10 4 


16.39 


10 E 


7.646x10= 


3785 


1000 


473.2 


946.4 


Cubic feet 


1.2445 


3.531 xirr 5 


1 


5.787x10-" 


35.31 


27 


0.1337 


3.531 x10 2 


1.671 x10 2 


3.342 x10 2 


Cubic inches 


2150.4 


6.102 xirr 2 


1728 


1 


6.102x10" 


46,656 


231 


61.02 


28.87 


57.75 


Cubic meters 


3.524 x1fr 2 


10^ 


2.832 x10 2 


1.639x10-= 


1 


0.7646 


3.785 X10 3 


0.001 


4.732x10-" 


9.464x10-" 


Cubic yards 




1.308x10 = 


3.704 x10- 2 


2.143x10 = 


1.308 


1 


4.951 x10 3 


1.308 x10 3 


6.189 x 10-" 


1.238 x10 3 


Gallons 
(liquid) 




2.642 x 10-" 


7.481 


4.329 xlO 3 


264.2 


202.0 


1 


0.2642 


0.125 


0.25 


Liters 


35.24 


0.001 


28.32 


1.639 x10 2 


1000 


764.6 


3.785 


1 


0.4732 


0.9464 


Pints (liquid) 




2.113 x 10 3 


59.84 


3.463 x10 2 


2113 


1616 


8 


2.113 


1 


2 


Quarts (liquid) 




1.057 x10- 3 


29.92 


1.732 x10- 2 


1057 


807.9 


4 


1.057 


0.5 


1 



Mass and Weight 


^v Multiply 
^\ Number 

\ of 
to \^ 

Obtain by 


Grains 


Grams 


Kilograms 


Milligrams 


Ounces' 


Pounds' 


Tons 
(Long) 


Tons 
(Metric) 


Tons 

(Short) 


Grains 


1 


15.43 


1.543x10" 


1.543 x10 2 


437.5 


7000 








Grams 


6.481 x10- 2 


1 


1000 


0.001 


28.35 


453.6 


1.016x10= 


10= 


9.072x10= 


Kilograms 


6.481 x10-= 


0.001 


1 


10-= 


2.835 x10- 2 


0.4536 


1016 


1000 


907.2 


Milligrams 


64.81 


1000 


10= 


1 


2.835x10" 


4.536x10= 


1.016x10 s 


10 9 


9.072x10" 


Ounces' 


2.286 x10- 3 


3.527 x10 2 


35.27 


3.527x10 = 


1 


16 


3.584x10" 


3.527x10" 


3.2x10" 


Pounds' 


1.429x10-" 


2.205 X10 3 


2.205 


2.205x10 = 


6.250 x10- 2 


1 


2240 


2205 


2000 


Tons (long) 




9.842x10-' 


9.842x10-" 


9.842 x10-'» 


2.790x10 = 


4.464x10-" 


1 


0.9842 


0.8929 


Tons (metric) 




io-= 


0.001 


10-= 


2.835x10-= 


4.536x10-" 


1.016 


1 


0.9072 


Tons (short) 




1.102x10-= 


1.102 x TO 3 


1.102 x 10 9 


3.125x10 = 


0.0005 


1.120 


1.102 


1 


'Avoirdupois pounds and ounces 



Back to Contents 



283 



Appendix D 



Conversions 



Pressure or Force per Unit Area 


\ Multiply 
\ Number 

\ of 
to \^ 

Obtain "^ by 


Atmospheres* 


Bayres or 
Dynes per 

Square 
Centimeter* 


Centimeters 

of Mercury 

at 0°C S 


Inches 

of Mercury 

at 0°C S 


Inches 

of Water 

at4°C 


Kilograms 

per 

Square 

Meter" 


Pounds 

per 

Square Foot 


Pounds 

per 
Square 
Inch** 


Tons (short) 

per 
Square Foot 


Pascals 


Atmospheres* 


1 


9.869x10-' 


1.316 x10- 2 


3.342 x10- 2 


2.458 x10- 3 


9.678x10-= 


4.725x10-* 


6.804 x10- 2 


0.9450 


9.869x10-= 


Bayres or dynes 
per square 
centimeter* 


1.013X 10 6 


1 


1.333x10* 


3.386x10* 


2.491 x10 3 


98.07 


478.8 


6.895x10* 


9.576x10= 


10 


Centimeters 
of mercury 
atO°C s 


76.00 


7.501 x10 5 


1 


2.540 


0.1868 


7.356 x10- 3 


3.591 x10 2 


5.171 


71.83 


7.501 X10-* 


Inches 
of mercury 
atO°C s 


29.92 


2.953x10-= 


0.3937 


1 


7.355 x10 2 


2.896 x10- 3 


1.414 x10- 2 


2.036 


28.28 


2.953x10-* 


Inches of 
water at 4°C 


406.8 


4.015x10-* 


5.354 


13.60 


1 


3.937 x10 2 


0.1922 


27.68 


384.5 


4.015 x10 3 


Kilograms 
per square 
meter'* 


1.033x10* 


1.020 x10- 2 


136.0 


345.3 


25.40 


1 


4.882 


703.1 


9765 


0.1020 


Pounds 
per square 
foot 


2117 


2.089 x10- 3 


27.85 


70.73 


5.204 


0.2048 


1 


144 


2000 


2.089 x10- 2 


Pounds per 
square inchM 


14.70 


1.450x10 = 


0.1934 


0.4912 


3.613 x10 2 


1.422 x10 3 


6.944 x10- 3 


1 


13.89 


1.450x10-* 


Tons (short) per 
square foot 


1.058 


1.044x10 = 


1.392 x10 2 


3.536 x10- 2 


2.601 X10 3 


1.024x10-* 


0.0005 


0.072 


1 


1.044x10 = 


Pascals 


1.013x10= 


io-' 


1.333 x10 3 


3.386 x10 3 


2.491 X10-* 


9.807 


47.88 


6.895 x10 3 


9.576x10* 


1 


* One atmosphere (standard) = 76 cm of mercury at 0°C 

* Bar 

s To convert height/; of a column of mercury at f°C to the equivalent height ht at 0°C, use h a = h[\ -[(m-l) f/1 +m!j} : where m = 0.0001 81 8 and /= 18.4 x 10 6 if the 
scale is engraved on brass; /=8.5 x TO 6 if on glass. This assumes the scale is correct at 0°C; for other cases (any liquid) see International Critical Tables,Vo\. 1,68. 

** 1 gram per square centimeter = 10 kilograms per square meter 

** psi = MPax 145.038 

psi/ft = 0.433 x g/cm 3 = Ibf/ft7l44 = lbf/gal/1 9.27 



Density or Mass per Unit Volume 


^^^^ Multiply 

^^^ Number 

\ of 

Obtain ^^ D y 


Grams per 

Cubic 
Centimeter 


Kilograms 

per 
Cubic Meter 


Pounds per 
Cubic Foot 


Pounds per 
Cubic Inch 


Pounds per 
Gallon 


Grams per cubic centimeter 


1 


0.001 


1.602 x10 2 


27.68 


0.1198 


Kilograms per cubic meter 


1000 


1 


16.02 


2.768x10" 


119.8 


Pounds per cubic foot 


62.43 


6.243 x10- 2 


1 


1728 


7.479 


Pounds per cubic inch 


3.613 x10 2 


3.613x10-= 


5.787x10* 


1 


4.329 X10 3 


Pounds per gallon 


8.347 


8.3 x10 3 


13.37x10 2 


231.0 


1 



Temperature 


°F 


1.8°C 


+ 32 


°C 


%{°F 


-32) 


°R 


°F + 459.69 


K 


°C + 


'73.16 



284 



Back to Contents 



Appendix E 



Symbols 



Traditional 


Standard 


Standard 


Symbol 


SPE 
and 
SPWLA f 


Computer 

Symbol 1 



Description 



Customary Unit or Relation 



L 
M 



L 
M 



LTH 

SAD 

MXP 



length, path length 

slope, sonic interval transit time versus 
density x 0.01, in M-N plot 

porosity (cementation) exponent 



ft, m, in. 

M = [(X f -X LOG )/(p b -p f )]x0.01 

Fr = KrAT 



Standard 

Reserve 

Symbol* 



a 


a 


ACT 


electrochemical activity 


equivalents/liter, moles/liter 




a 


Kr 


COER 


coefficient in F R -<t> relation 


Fr = K R /<T 




M R , a, C 


A 


A 


AWT 


atomic weight 


amu 






C 


C 


ECN 


conductivity (electrical logging) 


millimho per meter 


mmho/m) 


a 


C P 


E>cp 


CORCP 


sonic compaction correction factor 


< t ) SVcor = Bcp't'SV 




^cp 


D 


D 


DPH 


depth 


ft, m 




y,H 


d 


d 


DIA 


diameter 


in. 




D 


E 


E 


EMF 


electromotive force 


mV 




V 


F 


Fr 


FACHR 


formation resistivity factor 


Fr = K R /r 






G 


G 


GMF 


geometrical factor (multiplier) 






f G 


H 


Ih 


HYX 


hydrogen index 






in 


h 


h 


THK 


bed thickness, individual 


ft, m, in. 




d,e 


1 




-X 


index 






i 


FFI 


'ft 


FFX 


free fluid index 






ir-i 


SI 


'si 


SLX 


silt index 






'sit- isl> 'sit 




'♦ 


PRX 


porosity index 






i« 


SPI 


U2 


PRXSE 


secondary porosity index 






i 2 


J 


G P 


GMFP 


pseudogeometrical factor 






fsp 


K 


Kc 


COEC 


electrochemical SP coefficient 


E c = K c log(a w /a mf ) 




M c ,K ec 


k 


k 


PRM 


permeability, absolute (fluid flow) 


mD 




K 



s,t 



"BD 



N 


N 


SND 


slope, neutron porosity 
density, in M-N Plot 


versus 


N = ((fNf-<t ) N)/(P[ 


n 


n 


SXP 


saturation exponent 




S w n = pRR w /Rt 


P 


C 


CNC 


salinity 




g/g. ppm 


P 


P 


PRS 


pressure 




psi, kg/cm 2 , § atm 


Pc 


Pc 


PRSCP 


capillary pressure 




psi, kg/cm 2 , § atm 



>>ND 



c, n 



Pe 



photoelectric cross section 



P 
Pc Pc 



' SPE Letter and Computer Symbols Standard (1986). 

* Used only if conflict arises between standard symbols used in the same paper 

§ The unit of kilograms per square centimeter to be replaced in use by the SI metric unit of the pascal 

tr "DEL" in the operator field and "RAD" in the main-quantity field 

K Suggested computer symbol 



Back to Contents 



285 



Appendix E 



Symbols 



Traditional 


Standard 


Standard 


Symbol 


SPE 
and 
SPWLA f 


Computer 

Symbol 1 



Description 



Customary Unit or Relation 



BHT,T bh 
FT,T fm 



T 

Tbh 
T, 



TEM temperature 

TEMBH bottomhole temperature 

TEMF formation temperature 



3 F, °C, K 
3 F, °C, K 
3 F, °C, K 



Standard 

Reserve 

Symbol* 



Qv 






shaliness (CEC per mL water) 


meq/mL 






q 


f<|>shd 


FIMSHD 


dispersed-shale volume fraction of 
intermatrix porosity 






timfshd-l 


R 


R 


RES 


resistivity (electrical) 


ohm-m 




P.r 


r 


r 


RAD 


radial distance from hole axis 


in. 




R 


S 


S 


SAT 


saturation 


fraction or percent 
of pore volume 


p,s 



■>BH 



I 

t 

u 



TIM 
TAC 



time 

interval transit time 

volumetric cross section 



u.s, s, mm 



barns/cm 3 



t 

At 



v 
V 
V 



VAC 
VOL 

VLF 



velocity (acoustic) 
volume 
volume fraction 



ft/s, m/s 
cm 3 , ft 3 , etc. 



V, u 
v 



fv,F w 



Z 

a 

1 



Z ANM atomic number 

oc SP REDSP SP reduction factor 

Y SPG specific gravity (p/p m or p g /p air 



s, F s 



<t>2 



T dN 



POR porosity 



PORPR primary porosity 



PORSE secondary porosity 



fraction or percentage 
of bulk volume, p.u. 

fraction or percentage 
of bulk volume, p.u. 

fraction or percentage 
of bulk volume, p.u. 



XST neutron capture cross section 

XSTMAC macroscopic 

TIMDN thermal neutron decay time 



c.u., crrr 



LIS 



f,e 



fi-e. 



f*e 2 





4>ig 


PORIG 


intergranular porosity 


4>ig = (V b - 


-v gr )/v b 


Mg- E ig 


<t>z- <t>im 


<t>im 


PORIM 


intermatrix porosity 


<t>im = (Vb 


-v ma )/v b 


Mm' e im 


Ar 


Ar 


DELRAD" 


radial distance (increment) 


in. 




AR 


At 


1 


TAC 


sonic interval transit time 


U-S/ft 




At 


^Hex 




DELPORNX" 


excavation effect 


p.u. 






X 


^ani 


COEANI 


coefficient of anisotropy 






Mani 


P 


P 


DEN 


density 


g/cm 3 




D 



S 

t-dn 



' SPE Letter and Computer Symbols Standard{1986). 

* Used only if conflict arises between standard symbols used in the same paper 

§ The unit of kilograms per square centimeter is to be replaced in use by the SI metric unit of the pascal. 

Tt "DEL" in the operator field and "RAD" in the main-quantity field 

K Suggested computer symbol 



286 



Back to Contents 



Appendix F 



Subscripts 



Traditional 


Standard 


Standard 


Subscript 


SPE 
and 
SPWLA f 


Computer 
Subscript* 



Explanation 



Example 



g, gas 



gxo 



9 

gr 

gxo 



GR 
GXO 



gas 



gram 

gas in flushed zone 



J gxo 



Standard 

Reserve 

Subscript* 



a 


LOG 


L 


apparent from log reading 

(or use tool description subscript) 


R|_OG' 


Rll 


log 


a 


a 


A 


apparent (general) 


Ra 




ap 


abs 


cap 


C 


absorption, capture 


■^■cap 






anh 


anh 


AH 


anhydrite 








b 


b 


B 


bulk 


Pb 




B,t 


bh 


bh 


BH 


bottomhole 


Tbh 




w, BH 


clay 


cl 


CL 


clay 


V C | 




cla 


cor, c 


cor 


COR 


corrected 


tcor 






c 


c 


C 


electrochemical 


Ec 




ec 


cp 


cp 


CP 


compaction 


B cp 






D 


D 


D 


density log 






d 


dis 


shd 


SHD 


dispersed shale 


Mshd 






dol 


dol 


DL 


dolomite 


tdol 






e, eq 


eq 


EV 


equivalent 


"waqi 


"mfaq 


EV 


f, fluid 


f 


F 


fluid 


Pf 




fl 


fm 


f 


F 


formation (rock) 


T f 




fm 



GXO 



gyp 


gyp 


GY 


gypsum 


Pgyp 




h 


h 


H 


hole 


d h 


H 


h 


h 


H 


hydrocarbon 


Ph 


H 


hr 


hr 


HR 


residual hydrocarbon 


Shr 




i 


i 


1 


invaded zone (inner boundary) 


di 


1 


ig 


ig 


IG 


intergranular (incl. disp. and str. shale) 


*i£l 




im, z 


im 


IM 


intermatrix (incl. disp. shale) 


<t>im 




int 


int 


1 


intrinsic (as opposed to log value) 


E int 




irr 


i 


IR 


irreducible 


Syvi 


ir, i 


J 


J 


J 


liquid junction 


E i 


( 


k 


k 


K 


electro kinetic 


E k 


ek 


1 




L 


log 


*Pi 


log 


lam 


f 


LAM 


lamination, laminated 


V sn f 


L 


lim 


lim 


LM 


limiting value 


<t>lim 




liq 


L 


L 


liquid 


PL 


(' 



SPE Letter and Computer Symbols Standard (1986). 

Used only if conflict arises between standard symbols used in the same paper 



< ► 



Back to Contents 



287 



Appendix F 



Subscripts 



Traditional 


Standard 


Standard 


Subscript 


SPE 
and 
SPWLA f 


Computer 
Subscript* 



Explanation 



Example 



Standard 

Reserve 

Subscript* 



log 


LOG 


L 


log values 


t|_0G 


log 


Is 


Is 


LS 


limestone 


tls 


1st 


m 


m 


M 


mud 


Rm 




max 


max 


MX 


maximum 


9 max 




ma 


ma 


MA 


matrix 


Mna 




mc 


mc 


MC 


mudcake 


"mc 




mf 


mf 


MF 


mud filtrate 


R mf 




mfa 


mfa 


MFA 


mud filtrate, apparent 


Rmfa 




min 


min 


MN 


minimum value 






ni 






noninvaded zone 


R ni 













oil (except with resistivity) 


So 


N 


or 


or 


OR 


residual oil 


^or 




o,0 (zero) 


O(zero) 


ZR 


100-percent water saturated 


Fo 


zr 


P 






propagation 


tpw 




PSP 


pSP 


PSP 


pseudostatic SP 


Epsp 




pri 


1 (one) 


PR 


primary 


♦ l 


p,pri 


r 


r 


R 


relative 


Kro< ^rw 


R 


r 


r 


R 


residual 


^or> ^hr 


R 


s 


s 


S 


adjacent (surrounding) formation 


R s 




sd 


sd 


SD 


sand 




sa 


ss 


ss 


SS 


sandstone 




sst 


sec 


2 


SE 


secondary 


<t>2 


s, sec 


sh 


sh 


SH 


shale 


Vsh 


sha 


silt 


si 


SL 


silt 


1.1 


sit 


SP 


SP 


SP 


spontaneous potential 


Esp 


sp 


SSP 


SSP 


SSP 


static spontaneous potential 


Essp 




str 


sh st 


SHST 


structural shale 


Mihst 


s 


t, ni 


t 


T 


true (as opposed to apparent) 


Rt 


tr 


T 


t 


T 


total 


c, 


T 


w 


w 


W 


water, formation water 


^w 


W 


wa 


wa 


WA 


formation water, apparent 


"wa 


Wap 


wf 


wf 


WF 


well flowing conditions 


Pwf 


f 


ws 


ws 


WS 


well static conditions 


Pws 


s 


xo 


xo 


XO 


flushed zone 


R xo 




z, im 


im 


IM 


intermatrix 


*lm 





SPE Letter and Computer Symbols Standardises). 

Used only if conflict arises between standard symbols used in the same paper 



288 



Back to Contents 



Appendix F 



Subscripts 



Traditional 


Standard 


Standard 


Subscript 


SPE 
and 
SPWLA 1 


Computer 

Subscript 1 ' 



Explanation 



Example 



Standard 

Reserve 

Subscript* 



(zero) 


O(zero) 


ZR 


100 percent water saturated 


Ro 


zr 


AD 




RAD 


from CDR attenuation deep 


Rad 




D 


D 


D 


from density log 


4>D 


d 




GG 


GG 


from gamma-gamma log 


<t>GG 


gg 


IL 


I 


I 


from induction log 


Ri 


i 


ILD 


ID 


ID 


from deep induction log 


R|D 


id 


ILM 


IM 


IM 


from medium induction log 


R|M 


im 


LL 


LL(alsoLL3, 
LL8, etc.) 


LL 


from laterolog 

(also LL3, LL7, LL8, LLD, LLS) 


Rll 


('(' 


N 


N 


N 


from normal resistivity log 


Rn 


n 


N 


N 


N 


from neutron log 


<t>N 


n 


PS 




RPS 


from CDR phase-shift shallow 


Rps 




16", 16"N 






from 16-in. normal Log 


Rl6" 




1"x 1" 






from 1 -in. by 1-in. microinverse (Ml) 


Ri"xi" 




2" 






from 2-in. micronormal (MN) 


R 2 . 





SPE Letter and Computer Symbols Standard (1986). 

Used only if conflict arises between standard symbols used in the same paper 



Back to Contents 



289 



Appendix G 



Unit Abbreviations 



These unit abbreviations, which are based on those adopted by the 
Society of Petroleum Engineers (SPE), are appropriate for most publi- 
cations. However, an accepted industry standard may be used instead. 
For instance, in the drilling field, ppg may be more common than 
lbm/gal when referring to pounds per gallon 

In some instances, two abbreviations are given: customary and 
metric. When using the International System of Units (SI), or metric, 
abbreviations, use the one designated for metric (e.g., m 3 /h instead of 
mVhr). The use of SI prefix symbols and prefix names with customaiy 
unit abbreviations and names, although common, is not preferred 
(e.g., 1,000 lbf instead of klbf). 

Unit abbreviations are followed by a period only when the abbrevia- 
tion forms a word (for example, in. for inch). 

acre Spell out 

acre-foot acre-ft 

ampere A 

ampere-hour A-hr 

angstrom unit (10~ 8 cm) A 

atmosphere atm 

atomic mass unit amu 

barrel bbl 

barrels of fluid per day BFPD 

barrels of liquid per day BLPD 

barrels of oil per day BOPD 

barrels of water per day BWPD 

barrels per day B/D 

barrels per minute bbl/min 

billion cubic feet (billion = 10 9 ) Bcf 

billion cubic feet per day Bcf/D 

billion standard cubic feet per day Use Bcf7D instead of Bscf/D 

(see "standard cubic foot") 

bits per inch bpi 

bits per second bps 

brake horsepower bhp 

British thermal unit Btu 

capture unit c.u. 

centimeter cm 

centipoise cp 

centistoke cSt 

coulomb C 

counts per second cps 

cubic centimeter cm 3 

cubic foot ft 3 

cubic feet per barrel ft 3 /bbl 

cubic feet per day ft 3 /D 

cubic feet per minute ft 3 /min 

cubic feet per pound ft/Vlbm 

cubic feet per second ft 3 /s 

cubic inch in. 3 

cubic meter m 3 

cubic millimeter mm 3 

cubic yard yd 3 

290 

a ► Back 



curie Ci 

dalton Da 

darcy, darcies D 

day (customary) D 

day (metric) d 

dead-weight ton DWT 

decibel dB 

degree (American Petroleum Institute) "API 

degree Celsius °C 

degree Fahrenheit °F 

degree Kelvin See "kelvin" 

degree Rankine °R 

dots per inch dpi 

electromotive force emf 

electron volt eV 

farad F 

feet per minute ft/min 

feet per second ft/s 

foot ft 

foot-pound ft-lbf 

gallon gal 

gallons per day gal/D 

gallons per minute gal/min 

gigabyte Gbyte 

gigahertz GHz 

gigapascal GPa 

gigawatt GW 

gram g 

hertz Hz 

horsepower hp 

horsepower-hour hp-hr 

hour (customary) hr 

hour (metric) h 

hydraulic horsepower hhp 

inch in. 

inches per second in./s 

joule J 

kelvin K 

kilobyte kB 

kilogram kg 

kilogram-meter kg-m 

kilohertz kHz 

kilojoule kJ 

kilometer km 

kilopascal kPa 

kilopound (force) (1,000 lbf) klbf 

kilovolt kV 

kilowatt kW 

kilowatt-hour kW-hr 

kips per square inch ksi 



to Contents 



Appendix G 



Unit Abbreviations 



lines per inch lpi 

lines per minute 1pm 

lines per second lps 

liter L 

megabyte MB 

megagram (metric ton) Mg 

megahertz MHz 

megajoule MJ 

meter m 

metric ton (tonne) t or Mg 

mho per meter U/m 

microsecond us 

mile Spell out 

miles per hour mph 

milliamperes mA 

millicurie mCi 

millidarcy, millidarcies mD 

milliequivalent meq 

milligram mg 

milliliter mL 

millimeter mm 

millimho mmho 

million cubic feet (million = 10 6 ) MMcf 

million cubic feet per day MMcf/D 

million electron volts MeV 

million standard cubic feet per day Use MMcf/D instead of MMscf/D 

(see "standard cubic foot") 

milliPascal mPa 

millisecond ms 

millisiemens mS 

millivolt mV 

mils per year mil/yr 

minute min 

mole mol 

nanosecond ns 

newton N 

ohm ohm 

ohm-centimeter ohm-cm 

ohm-meter ohm-m 

ounce oz 

parts per million ppm 

pascal Pa 

picofarad pF 

pint pt 

porosity unit p.u. 

pound (force) lbf 

pound (mass) lbm 

pound per cubic foot lbm/ft 3 

pound per gallon lbm/gal 



pounds of proppant added ppa 

pounds per square inch psi 

pounds per square inch absolute psia 

pounds per square inch gauge psig 

pounds per thousand barrels (salt content) ptb 

quart qt 

reservoir barrel res bbl 

reservoir barrel per day RB/D 

revolutions per minute rpm 

saturation unit s.u. 

second s 

shots per foot spf 

specific gravity sg 

square sq 

square centimeter cm 2 

square foot ft 2 

square inch in. 2 

square meter m 2 

square mile sq mile 

square millimeter mm 2 

standard std 

standard cubic feet per day Use ft 3 /D instead of scf/D 

(see "standard cubic foot") 

standard cubic foot Use ft 3 or cf as specified on this list. 

Do not use set unless the standard 

conditions at which the measurement 

was made are specified. 

The straight volumetric conversion factor 

is 1 ft 3 = 0.02831685 m 3 

stock-tank barrel STB 

stock-tank barrels per day STB/D 

stoke St 

teragram Tg 

thousand cubic feet Mcf 

thousand cubic feet per day Mcf/D 

thousand pounds per square inch kpsi 

thousand standard cubic feet per day Use Mcf/D instead of Mscf/D 

(see "standard cubic foot") 

tonne (metric ton) t 

trillion cubic feet (trillion = 10 12 ) Tcf 

trillion cubic feet per day Tcf/D 

volt V 

volume percent vol% 

volume per volume vol/vol 

watt W 

weight percent wt% 

yard yd 

year (customary) yr 

year (metric) a 



Back to Contents 



291 



Appendix H 



References 



1. Overton HL and Lipson LB: "A Correlation of the Electrical 
Properties of Drilling Fluids with Solids Content," Transactions, 
AIME (1958) 213. 

2. Desai KP and Moore EJ: "Equivalent NaCl Concentrations from 
Ionic Concentrations," The Log Analyst (May-June 1969). 

3. Gondouin M, Tixier MP, and Simard GL: "An Experimental Study 
on the Influence of the Chemical Composition of Electrolytes on 
the SP Curve," JPT (February 1957). 

4. Segesman FF: "New SP Correction Charts," Geophysics 
(December 1962) 27, No. 6, PI. 

5. Alger RP, Locke S, Nagel WA, and Sherman H: "The Dual Spacing 
Neutron Log-CNL," paper SPE 3565, presented at the 46th SPE 
Annual Meeting, New Orleans, Louisiana, USA (1971). 

6. Segesman FF and Liu OYH: "The Excavation Effect," 
Transactions of the SPWLA 12th Annual Logging Symposium 
(1971). 

7. Burke JA, Campbell RL Jr, and Schmidt AW: "The Litho-Porosity 
Crossplot," Transactions of the SPWLA 10th Annual Logging 
Symposium (1969), paper Y. 

8. Clavier C and Rust DH: "MID-PLOT: A New Lithology 
Technique," The Log Analyst (November-December 1976). 

9. Tixier MP, Alger RP, Biggs WP, and Carpenter BN: "Dual 
Induction-Laterolog: A New Tool for Resistivity Analysis," paper 
713, presented at the 38th SPE Annual Meeting, New Orleans, 
Louisiana, USA (1963). 

10. Wahl JS, Nelligan WB, Frentrop AH, Johnstone CW, and 
Schwartz RJ: "The Thermal Neutron Decay Time Log," SPE J 
(December 1970). 

11. Clavier C, Hoyle WR, and Meunier D: "Quantitative 
Interpretation of Thermal Neutron Decay Time Logs, Part I and 
II," JPT (June 1971). 

12. Poupon A, Loy ME, and Tixier MP: "A Contribution to Electrical 
Log Interpretation in Shaly Sands," JPT (June 1954). 

13. Tixier MP, Alger RP, and Tanguy DR: "New Developments in 
Induction and Sonic Logging," paper 1300G, presented at the 
34th SPE Annual Meeting, Dallas, Texas, USA (1959). 

14. Rodermund CG, Alger RP, and Tittman J: "Logging Empty 
Holes," OGJ (June 1961). 

15. Tixier MP: "Evaluation of Permeability from Electric Log 
Resistivity Gradients," OGJ (June 1949). 

16. Morris RL and Biggs WP: "Using Log-Derived Values of Water 
Saturation and Porosity," Transactions of the SPWLA 8th 
Annual Logging Symposium (1967). 

17. Timur A: "An Investigation of Permeability, Porosity, and 
Residual Water Saturation Relationships for Sandstone 
Reservoirs," The Log Analyst (July-August 1968). 



18. Wyllie MRJ, Gregory AR, and Gardner GHF: "Elastic Wave 
Velocities in Heterogeneous and Porous Media," Geophysics 
(January 1956) 21, No. 1. 

19. Tixier MP, Alger RP, and Doh CA: "Sonic Logging," JPT (May 
1959) 11, No. 5. 

20. Raymer LL, Hunt ER, and Gardner JS: "An Improved Sonic 
Transit Time-to-Porosity Transform," Transactions of the 
SPWLA 21st Annual Logging Symposium (1980). 

21. Coates GR and Dumanoir JR: "A New Approach to Improved 
Log-Derived Permeability," The Log Analyst (January-February 
1974). 

22. Raymer LL: "Elevation and Hydrocarbon Density Correction for 
Log-Derived Permeability Relationships," The Log Analyst 
(May-June 1981). 

23. Westaway P, Hertzog R, and Plasic RE: "The Gamma 
Spectrometer Tool, Inelastic and Capture Gamma Ray 
Spectroscopy for Reservoir Analysis," paper SPE 9461, 
presented at the 55th SPE Annual Technical Conference 
and Exhibition, Dallas, Texas, USA (1980). 

24. Quirein JA, Gardner JS, and Watson JT: "Combined Natural 
Gamma Ray Spectral/Litho-Density Measurements Applied to 
Complex Lithologies," paper SPE 11143, presented at the 57th 
SPE Annual Technical Conference and Exhibition, New Orleans, 
Louisiana, USA (1982). 

25. Harton RP, Hazen GA, Rau RN, and Best DL: "Electromagnetic 
Propagation Logging: Advances in Technique and 
Interpretation," paper SPE 9267, presented at the 55th SPE 
Annual Technical Conference and Exhibition, Dallas, Texas, 
USA (1980). 

26. Serra 0, Baldwin JL, and Quirein JA: "Theory and Practical 
Application of Natural Gamma Ray Spectrometry," Transactions 
of the SPWLA 21st Annual Logging Symposium (1980). 

27. Gardner JS and Dumanoir JL: "Litho-Density Log 
Interpretation," Transactions of the SPWLA 21st Annual 
Logging Symposium (1980). 

28. Edmondson H and Raymer LL: "Radioactivity Logging 
Parameters for Common Minerals," Transactions of the SPWLA 
20th Annual Logging Symposium (1979). 

29. Barber TD: "Real-Time Environmental Corrections for the 
Phasor Dual Induction Tool," Transactions of the SPWLA 26th 
Annual Logging Symposium (1985). 

30. Roscoe BA and Grau J: "Response of the Carbon-Oxygen 
Measurement for an Inelastic Gamma Ray Spectroscopy Tool," 
paper SPE 14460, presented at the 60th SPE Annual Technical 
Conference and Exhibition, Las Vegas, Nevada, USA (1985). 



292 



Back to Contents 



Appendix H 



References 



31. Freedman R and Grove G: "Interpretation of EPT-G Logs in the 
Presence of Mudcakes," paper presented at the 63rd SPE 
Annual Technical Conference and Exhibition, Houston, Texas, 
USA (1988). 

32. Gilchrist WA Jr, Galford JE, Flaum C, Soran PD, and Gardner JS: 
"Improved Environmental Corrections for Compensated 
Neutron Logs," paper SPE 15540, presented at the 61st SPE 
Annual Technical Conference and Exhibition, New Orleans, 
Louisiana, USA (1986). 

33. Tabanou JR, Glowinski R, and Rouault GF: "SP Deconvolution 
and Quantitative Interpretation in Shaly Sands," Transactions 
of the SPWLA 28th Annual Logging Symposium (1987). 

34. Kienitz C, Flaum C, Olesen J-R, and Barber T: "Accurate Logging 
in Large Boreholes," Transactions of the SPWLA 27th Annual 
Logging Symposium (1986). 

35. Galford JE, Flaum C, Gilchrist WA Jr, and Duckett SW: 
"Enhanced Resolution Processing of Compensated Neutron 
Logs, paper SPE 15541, presented at the 61st SPE Annual 
Technical Conference and Exhibition, New Orleans, Louisiana, 
USA (1986). 

36. Lowe TA and Dunlap HF: "Estimation of Mud Filtrate Resistivity 
in Fresh Water Drilling Muds," The Log Analyst (March-April 
1986). 

37. Clark B, Luling MG, Jundt J, Ross M, and Best D: "A Dual Depth 
Resistivity for FEWD," Transactions of the SPWLA 29th Annual 
Logging Symposium (1988). 

38. Ellis DV, Flaum C, Galford JE, and Scott HD: "The Effect of 
Formation Absorption on the Thermal Neutron Porosity 
Measurement," paper presented at the 62nd SPE Annual 
Technical Conference and Exhibition, Dallas, Texas, USA (1987). 

39. Watfa M and Nurmi R: "Calculation of Saturation, Secondaiy 
Porosity and Producibility in Complex Middle East Carbonate 
Reservoirs," Transactions of the SPWLA 28th Annual Logging 
Symposium (1987). 



40. Brie A, Johnson DL, and Nurmi RD: "Effect of Spherical Pores 
on Sonic and Resistivity Measurements," Transactions of the 
SPWLA 26th Annual Logging Symposium (1985). 

41. Serra 0: Element Mineral Rock Catalog, Schlumberger (1990). 

42. Grove GP and Minerbo GN: "An Adaptive Borehole Correction 
Scheme for Array Induction Tools," Transactions of the SPWLA 
32nd Annual Logging Symposium, Midland, Texas, USA, June 
16-19, 1991, paper F. 

43. Barber T and Rosthal R: "Using a Multiarray Induction Tool to 
Achieve Logs with Minimum Environmental Effects," paper SPE 
22725, presented at SPE Annual Technical Conference and 
Exhibition, Dallas, Texas, USA, October 6-9, 1991. 

44. Moran JH: "Induction Method and Apparatus for Investigating 
Earth Formations Utilizing Two Quadrature Phase Components of 
a Detected Signal," US Patent No. 3,147,429 (September 1, 1964). 

45. Barber TD: "Phasor Processing of Induction Logs Including 
Shoulder and Skin Effect Correction," US Patent No. 4,513,376 
(September 11, 1984). 

46. Barber T et al.: "Interpretation of Multiarray Induction Logs 
in Invaded Formations at High Relative Dip Angles," The Log 
Analyst 40, no. 3 (May-June 1990): 202-217. 

47. Anderson BI and Barber TD: Induction Logging, Sugar Land, 
Texas, USA: Schlumberger Wireline & Testing, 1995 (SMP-7056). 

48. Gerritsma CJ, Oosting PH, and Trappeniers NJ: "Proton Spin- 
Lattice Relaxation and Self Diffusion in Methanes, II "Physica 
51 (1971), 381-394. 

49. Wyllie MRJ and Rose WD: "Some Theoretical Considerations 
Related to the Quantitative Evaluation of the Physical 
Characteristics of Reservoir Rock from Electrical Log Data," 
JPT2 (1950), 189. 



Back to Contents 



293 



-4 ► 



Back to Contents 



< ► Contents 



fJllTUDJ! 




The Schlumberger "chartbook" was initially developed to 
correct raw measurements to account for environmental 
effects and to interpret the corrected measurements. 



Although software may be more effective in deriving results, 
especially in complex well situations, the chartbook still 
serves two primary functions, for training and sensitivity 
analysis. 

Entering the chartbook will take you to the y,,,,,,.,.^ 
where you can access any chart by clicking its entrj 

You can also browse the PDF normally. 

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Contents 







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introduction 



Contents