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 A X ^1^ \ v > s> > \ \ \ s s V \ N > N > 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 > 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 ** y „.-- - 4 y ^ *■ ^ ..... '" ***'" / x * .... ..-• * ? .-** ,»** 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* u- f .y e*" _, 150°F }• y •' .' .^ ' _ — o s * y J S ' ' ■ ■'Mill Jt +Z' en £ /* .?* S -" ,^125°F 60 / r t' *■ ■* .^ <L S* ' ' x' J V /- rf' X' »■ Jf /? 7 ' •' ' _ .»r< _ , . , i 7 ^ „^ ^ - t ns/m jf tl 7 + ^ . "•_. -""" I UU r ' ----2-^ jt 1 ^t- /. ' «, .. £- en t & t ^< r =.^ 50 iWy 1 - - 7 A '?■ xf 75°F Jttf/j ■' •* ^ iLt-f^ji ^ i£ -- — 20°C >m ty ' ' ^ * *"* ..— •" II\f\ i ' ' j ' * *<£ -^ -^ '"" II if W /' f / ** *■ „. '"^ il\f\m ' i 4* ^ ^ *"* ft 1 fft r f '' . " • *" 40 'f/wW/ S ■' '" N i ff // / S ft"* '^ Ilta/jf/ J r* j*^ III ff/// J y / iff/// / jf *r ffflMut/ / f.S S^ m&V A xi*^ mar^^y^^ 1 ^ M/F^y^^^ immt ^^ 30 ~"9 ~*m *M 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 > ^ . \ k ^ ^ 1 c 1 C > s. 3 L 3 A \ V t 3 L \ ^ 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 . 0.2 ~ 0.4 : o.6 1 1 . 2 \ 4 : 6 i 10 . 20 ! 40 : 60 I 100 2 3 == EE3^S^= -■ R mf /R w 4 5 il : ~~r|*tVS^ EEEEEEEEEEEEEEEE E EE I_ 4 3J E^ S 6 == E_6 8 10 8 ll|l|l L io ^ fl J A j ^ V V \ w s^ ^ H ^ !s ^ r \\ \ V k c- i 1 ■ <fc V '^ ^ .CH " 20 i il I ". "k^r ^.CK T 40 A ,- . \ Vr % ^ V£>\ ■M Formation : temperature ee " ^ .= " &<£&&\t°3i . \\o'\ffo (\(T' w- 30 ---m^Yi' Prrc %" jm 40 1 \Wx\i InT z- 5U 1 l_Lj_l L-L-L- +50 ( © 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 \ ] \ \ \ V _75°C A V- \\ \ T7 \ \ \ \ s V 50°C \ 1 \ 25 c U \ \ Saturation VX- ^ v/N r ^t ^ v. «» .^ N • , -- ^ ^^ <N\ V X "--.^ ^ **" 2SO°r Si ^ ' — ■ i y c m >, • s ^^ » , 20o°n ^ V \ s * ^ *J i L S V N *»- *» " ISq^p - s > •v N ^ ^7/J, s > '^{ L °°n /I s v ^ ?s °c \ <5 > s^ (9 X. . \ u C ■ % PL ■ i i i i i i i . i i >i o.oc © 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 $ [ ' \ v \ ± ± \ _L \ . A V J a > . u 12 i r t t r _ . \ T- \ T V _ M | _1J A I L _L_ J .__x i___ \ \ .% , Natural -£■ j + ¥ 1 T X — ^ v a - - v 9 _ _f_ ' 1 A - ■ A- . A - . & _ £ . _ \ _ \ ... r 4 1 \ i 'i __. _3__ __ ^_. 3 L _- _^__ ._> . Mud weight (Ihrn/qql) 18 16 I I f L V- ' X V- X~ X \~ R.rito 14 4 4 4X1 \ \ X \ Bante 1^ j 1 A T X i v \ 10 r i ~v V I A \ X \ \ 8 t ± ± ± i . ± Jl. ^ J _ . )0 "I \ V X ^T S ^ N S> «^. ^^ "^^^ Borehole temperature \ \ \ \. V S. S S^ s s^^ S ^^ ^^ v CF) A S___X— -V— XI' »< N <v N\ "^^^ v>, -> a \ i 4 i "J T "s"^ 50 \ — h l- ^C" -=5 ^ -is : - ^^ ^ S^b, - ^ : • n Pressure I : / • / •'/ j~'' / ••*? /~ .v"" (1,000 xpsi) tl 1 ■' t -'7 yf /.. - 2 Z ■■■'' y -/ P t^ /-•■' 4 -•■' 7 .••> 2 Z - '' y .•••'"' / Water-hasp mud I- / ■* / 1 -•' / 1 ••' 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 V V \ v f \ \ 4 4 4 4^444 \ \ 1.0 _ 1 ± ± _ ± \ \ \ \_ \ l 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. i 1 1 j < / J J J 1 ' ' ' ' / , 8 in. 1 I j 1 1 , 1 i 1 / i / / j f / J / t / 7 / / / / / y y / / / / / f / y / y • / / / / / / ' f / y y y / / r 10 in. I 1 i i i i 1 / / i 1 j J / J / / J / / / V / / / / / / / / / / y / v s y • s y / / / y / y y y y y y • / / / / z / s y y y X y y y y / / / y y y y y / z / , 4 3 12 in. 2 1 i i i_ i 1 j 1 y ' / J ) / / / / / / / / / y y y / / / / / y y y y y y- y y y y y y S y y y y y y y y y y y yy y ** y y y* y y y y y y y ** y y y^ y y s y y y -* y y y y'L ^y y 7 Standoff g (in.) 5 18 in. 4 3 2 1 • 10 9 8 7 6 24 in. 5 4 3 2 1 ^ 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 I ) I 1 , 1 1 • J / J f t 1 j ' 1 J I 1 / / / / / / / / / / f / / / f / y / y / y / / / r / ' r / y y y / < ! 75 250 mm 25 1 / J / 1 / 4 / 1 1 / / / I / / / J / J / / / / y / / / 7 / / / t / s y y y / y / / / / / / y y y y S y y / s / / 7 / s y y y y y y s y / / ' y y y y / / f 100 75 300 mm 50 25 1 1 1 J / 1 I 1 y 1 / / / / / / / / / / / / / y y s y y / / y y y y y y y y y y y S y y y ^y y s s s y y ** ** ^ y y S> y y s y y y •*■" ** *• y y s y / y y **■ s' y y y 2T / 175 Standoff q 5Q (mm) 125 450 mm 10 ° 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 / / ' / / / / / / / / / / • / t / / / > / / / / / / / / / / f / / / / / / *- f" y -- 0- y -"■ -- y «• **• s ^- <-" > ,'' *"' +*' *>*' © 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 ' ' - !' 1 i „ " ' / / -'"J- i / / t j. i / r 30 20 Fresh water i ' / / / / / / ' 1 / .? / J / -/ - 1 r / / / / / / 250,000- ppm water 10 4- ■s /. / — ', S / / 'U. -> ± *i— 70 60 Limestone formation g n Formation! (c.u.) 40 30 Freshwater ^ - ' " , ^' I J / / f 4 , —■ / 250,000-ppm water 10 ±~ ^— —r 70 60 Dolomite formation eg Formation! (c.u.) 40 30 Freshwater 1 j i j ' „ ' , f j ' / / -' "j. / / / 1 r / / 1 i i J — J- ^ - fir / ** *■— 3 **z. Formation salinity 100 (1,000 x ppm) 250 \ V V \ L V \ \ \ \ 5 v. ' \ V > v V \ s S \ v \ \ \ \ \ s V s V, \ A^ \ \ \ V \ \ v s \ ( © Schlumberger i i i ||m ) 10 20 30 1 ' ' 1 1 1 40 50 < ► 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 70 60 50 40 Sandstone formation Mineral! (c.u.) 30 20 10 i 7 r I ' , 1 ' , , f ' , r I J / j I 1 _J r / t / I / / / / 1 / / 1 / y / . J I ] / J r / I 1 1 1 / / / _f / 2 ^ / / / f / Fresh water 70 60 50 40 Limestone formation Mineral! (c.u.) 30 20 10 1 / / / \ / / \ / 1 / h r f 1 1 f / 7 / , 1 I I J 1 I / / f- — y / / *■ — — ■*■ —** ^ - ~? 7"— * — 70 60 50 40 Dolomite formation Mineral! (c.u.) 30 20 10 "T "I 1 t ' 7 j f . J .j ± 7 7 , r / j ' f_ I I 1 [ , Y J r 1 4 / t / J / / / / / s /- 4- Fresh water ( © 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 Sandstone formation Fluid Zlc.u.) 160 140 120 100 80 Fresh water 60 250,000-ppm water ^g 20 160 Limestone formation Fluid Zlc.u.) Fresh water 250,000-ppm water »g 20 160 Dolomite formation Fluid Zlc.u.) Freshwater 250,000-ppm water 4Q 10 20 30 40 50 I 4 4 T 140 _ . 1 . 1 . A -t- - - - - - 1 t r 1 120 .._.... -t - r — ± ..i ...... 1 4 —t 4—4 A 10° t -i t I -i- t t 1 - 4 7 I i - so _ . _ . I 3 . 7 . . t f_ t_ T_ 60 j J 1 1 J 1 J j J 4 t t J I J J t t 40 _ .1.-7 1.1.. f _ 7 . 7_ 7 . .7 - h ■ ? - / 7 7/ / / 7 20 -= 7 7 7 ^ = 7 3 7 V *£ = I f 4 T 4 T 140 _ _±_ . _ . I . _± - - I . _±_ j -T t i -t t i 120 j. ....... t. _.f _j _ ...t . . d ... J I i ^ i ^ 4 100 - - 1 -7 -f J - -H- --J - J - - 1 1 i / i j 7 h 80 J 1 I j L L -1 1 1 j f t J j j l t 60 _ . f . z . _7_ /_ _7 . 7 . . Z-. 7 / iiiJifftt 40 _ 7 . / / _7 . . f _ . / / . / 7 . f -? / 7 7 / / / 7 20 =f 7 7 7 ^ a z a z ^ 7 = Formation salinity (1,000 xppm) 250 ^^^^ © Schlumberger 10 20 30 n -1 40 ~1 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 -- Casing weight (Ibm/ftl 13.5.. 15.1.. 17.. 20.. 26.. 20 -■ 29.. -■ 47.. 0.3 40.. 0.4 4'/2 5'/2 7 OD(in.) 0.5 1 Cement thickness (in.) 2 v s s V s ^ ^. *v ~> ^ S s v. s, *v ^ ■^. ». ^ 8% in. s s s " •^ s - >v V ■v ^ ■ ■- \ s s s V ■v S \ S. s S \ s s s S S I s v \ N s -1.0 \ \ \ \ 3 -\ \ > ^_ \ \ ■u J4 ii i. \ y y 1 I \ \ \ \ \ i l i L i L 1 I \ \ \ \ \ 1 +0.3 \ \ ■1 6 I in. " \ \ \ V +0.5 Borehole, casing, and cement correction =-1.0 + 0.3 + 0.5 Metric Neutron log porosity index L (p.u.) 10() Diameter of borehole 200 before running casing (mm) 300 Casing weight (kg/m) Casing thickness (mm) 4CI0 14 r \ 5 17 L 2 1.C- 20 23 25.5.. 30.0. 34.5.. 30 39 43. 60. 70. 114 140 178 245 ODImm) Cement thickness (mm) 7 9 11 13 25 50 75 10 10 20 30 j_I_i 20 30 j_I_i 40 40 50 X s -^ s s "S s s "s V V ^ *% ~s *•» -» ^ -*. ^ ■^. S V s N V V V "V V ^. >v •**. ^ ••i -222 mn l S S S s r- "N ^ V s. V >* V s V S V s s s \, >« v V S, \ \ s \ \ s s S s s \ S s 1- s N s s \ \ \ V \ \ \ \ \ -7.7 r r t- L- (- 1 t- _ y y \ y r \ \ \ \ \ \ ' ' 1 \ L L L 1 i i \ \ \ \ \ -^ S \ s -41 mm s - s s 50 jJ Calcite (limestone) Quartz sandstone Dolomite 10 _I_L 10 Neutron porosity equivalence 20 30 j_I_i 20 I l_L 30 40 ■ I i 10 L-Ll 20 jJ_i 30 40 jJ_i 50 jJ 50 _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) Actual borehole size (in.) 14 12 10 1 1 1C i 1 1 20 i 30 1 40 1 \ SO 1 1 / — , - r / i 1 if 7 -lie— = *5= IL if ij it -+- i 1 1 1 1 1 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 (mm) (g/cm 3 3====='F===^-===3F====i7===^7==== J 7==^F== = ^E==3=== || LM 1 f#_ U U U LU. 'J ■ ! 400 350 300 250 200 *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 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) / / -X-\\±--\ '±nv: 10,000 69 l>snnn in? :\ ' : \x 20,000 138 X ^A 5 5 i TlsS Wf\ IT'S- 4V N / ^* jr SiTSNatHjI ^ y s\ / v/N^J\wffl~T „ ** " y „ * X*"\, ■•* ~^sl» ^ -' j. S y* ^. *^j r*\r - I I I -f-p -p ^ - <S** ** ii --"" T~] "Xt 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_ L r r 1 T F I T x_ 1 T T 1 1 1 . 1 . 250 200 Mud 150 nnnn" mty i 100 (1,000 xppm) 50 T j • T f f r f f r r _ 250 200 Formation 150 Mnnn initV , 100 (1,000 xppm) 50 \ — , 1 \ 1 1 \ \ \ : l \ 1 \ i . \ \ 1 i \ , , r \ ] ] ! i \ 1 \ ( *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 / Borehole (m.) io \ f 9 . . R / , 1 260 _ \ \ \ \ 210 _ V \ \ loci 160 _ L \ In 1 y 110 _ 60 t 70 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 \ 200 \ i \ \ 1 \ i \ Formation 150 . \ \ \ r 1 I \ I salinity 100 ; L \ \ (1,000 xppm) „ ; \ \ 50 I \ \ \ I 1 \ \ \ 3 \ \ > 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 1 1 I I ]_ t 1 1^ t I \ \ t I i \ \ i \ 1 \ \ I i \ J \ ^r \ j 11 10 9 R 1 ! / \ \ N, \ \ I / \ \\ \ \ \ / 1 ' \\ r V \ \ / 1 I \l \ \ \ \ / 1 \\ \ V / i 1 V t / \ \ / / 1 j \ \ \\ \ / / 1 / \ \ V A / / 1/ > \\ / Mud salinity ppm 50,000 ppm 100,000 ppm 150,000 ppm 200,000 ppm / V V i \tt 1 \ i 1 1 i' 1 ) | 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 » '.V 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 / * 'S N ^ // / K 1 * ^ S" " 4 *^Si 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 i i i 1 1 1 r i i i 1 1 I 1 / / / i i / • • s • <•* • -•■ ? ?l , 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 i / i i i : i / / ; / / 1 / f / i i / / „. '£ :.'-- s / .» - / *• * / V ,-**■ 1 © 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 / '- «• " '■ -m ^ ■ //' ■* - * ■*» r> *V - X ■V "* ^ .. • ' " 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 / - - -- "*■* -. "S 1 t ' 1° '■ *» N. N. '/ V X X ' ■ X -.. I '-■-. 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. / / ; i * i i i i / / i i i V k 1 >.; S=" -. 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 ?n 12i 14 i 16 i 1. 1. 1 1 1 1 1 I I I I 1 1 1 1 1 1 1 5 i n y I / t' 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 I ; / f 1 1 1 1 1 I ( 1 1 ' 1 / r / 1 / / / k'> £ * s *::' ii ' ' ™ y / 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 ' / i i i \ Jl] II 1 i / \' \j > if i 1 ! L *' < "m H ' - — — — -■■■—- 10 6 I j —1 I I i n. / ' i / r / I I I I I 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 'S 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 i / 1 > / / / 1 1 1 i 1 i /s s s ^ s ' _ / ■:llu - V 1 ' '-A '/ 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 I 1 1 / 1 / ' / / / 1 1 1 1 1 1 ,' 1 / / / 1 1 / *' s ' t •= ^•**'/>\ : : — : z ==: :i:= ^ : := = 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 1 1 1 1 / / / / / 1 1 1 1 <*> • • / .- - - ' fj.r 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 / J f / / 1 1 t 1 .,;<. ■* -•"T^ - — " s • * ; v£ JJf r::: z ==z: .= =:.:= = =: =: __ — r::: -■—-■- -■-■—- :::::: ' ' f t 10' 10 2 10 3 RLA3/R m Standoff = 0.5 in. 10 4 10 5 10 6 1 1 / ; / ; / / / / : / 1 1 i 1 1 1 i I 1 l / / 1 1 <* / - / . -' ^ - / / •4* «r ;;; ; . 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 ; 4 / 1 J 1 f< » * zz _ - / / ■ ' ■.■• Jj >* ■'■■' 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 / / i i 1 / i i i _ — - .' • *• ' .. — — — — -__ ^ 3 -z ~ 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 / / / 1 1 1 1 1 1 1 ;*?*■ • '- s / s * 1 •— ■ ■ ,- -, "7 _ ■ ■■ -- - - ~ ai£24 imiii ■ ■-■ ■■ ■ i- 10 6 1 ' 1 ' / 1 / r / 1 f 1 1 / / / r ' .< 1 / / / T " \ 1 1 <*-■;[ ■■'}:J^- ^ ** . .-' / • • •^0 w* ft^t : : " uini 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-' _ - • - '<, ^ =='== «H s= ::= = — — S=S= ■:.= J ' 11 11! '. v, ! ' -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 / '' 1 .' i r w -■- i = i"iS ■m - *T » ■« *?!*.--~-~:~i"~Y:';Y?: " -■.";" ..- ,T ■,— ■- 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 / / / / / .. *>'' ^f ±? 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 < ► Back to Contents 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 < ► Back to Contents 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. < ► Back to Contents 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 Back to Contents 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 < ► Back to Contents 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 < ► Back to Contents 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 < ► Back to Contents 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. < ► Back to Contents 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 < ► Back to Contents 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. < ► Back to Contents 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 < ► Back to Contents 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. < ► Back to Contents 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 < ► Back to Contents 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. < ► Back to Contents 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 < ► Back to Contents 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. < ► Back to Contents 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 < ► Back to Contents 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 < ► Back to Contents 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. < ► Back to Contents 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 77 77/ ^7— ' "••:••:••:••■ / / / VTT7TJJ /A'///// / / / //// V/////7 '////// ////// ///// //// °Dielectric assumption £ r = 5 + 108.5R-°- 35 *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° 10' 10 2 R„, (ohm-m) 10 3 3.0 Resistivity spacing 16 in. 22 in / 2.5 28 in. 34 in. 40 in. / /, R,/R ps 2.0 e, = 2e r 1.5 °Dielect e r = 5+1 ric a 08.5 SSL R-° m 35 at n 1.0 0.5 e 2 = 0.5e r 10 4 3.5 3.0 2.5 R,/R ad 2.0 1.5 1.0 0.5 10- *Markof Schlumberger © Schlumberger Resistivity spacing 16 in. 22 in 28 in. 34 in. 40 in. j. e 2 = 0. 5e r D Dielect e r = 5 + 'ic a 108.! ;su >R- mf 135 )ti 1 — — -m M « * 95 '^ ^ ^ 1 ?t , = 2e r HI 10° 10' 10 2 R art (ohm-m) 10 3 10 4 < ► 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 0.45 0.50 0.55 0.60 1 0.65 0.70 0.75 i 0.80 0.85 1 0.90 0.95 1.0 I 1 0.80 '' 1 0.85 1 i '| i ' i 0.90 r 1 ' 1 0.95 I I 1.0 © Schlumberger (S mA /S wR ) 4 168 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 10 2 HLLD/R X0 10 1 10° 10- 1 8 15 18 >o 2 2 24 28 3? ?f n . - ^ 1 000 y 41 i ^ * y i / / / X y' y y ?~T 7- ' y x y y y ' i / / I , / / s R,/R„ X 500 y s y y / 50 I l ' j 1 i i / / / / /• y y y y y y y\ y y An V- , / / 200 ^ *» ' y y ?"• y y y y — y- ' 1 ' Jy . y/ / 80 l'l ' 1 U nn y X s * ' y \^ y\' ^y — ¥^T t y yf f 1 nn j'l ' t ' >-M- i ' 50 ' s * s '' V i i/ ' / ~~7~ . s ''Is) / & i'i ii/// • / * •• y * y/ & d, (in. / '* 's y X y "> /y ' / * s 7S4J " u/ / , ' > * \ y i'i^; -— '-/ ' A ' ",!/' 1 ' / ,^<< 7 > ■y I 1 ! 1 , , ' V/N /V ftis"//,, . <" y s> \}aittt^C -W \U"'.""% yyy Kjl/////Sy/y j^7 \ h 05 i ',' '. ,0.2 \ 1 © Schlumberger 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 10 1 10° 10- 1 3 15 18 20 22 24 28 32 -9fi 7 s 1, 1 / y •a / • / y i ^^- / / x y y y- y S V45— V ; : 1 / R t /R„ / 5C s y y y y y y y * 1 50 1,1 ' / 1.1 ' ' / / * ' •* ' y y y y y* ■ •r y *• j 7{ so I ' ' ' \ 1 1 / r 1 -. : — •* / / 2( • »• / / • •• ~y~~- y y — y y— y y \ y y y y- y/ an ■ ' ' ' ■ ' 100 — 7* s -* *""«^- y 1 1 / / / J y/ f ■ nn ll / / * / y 'y\y " / y ■1-1/ / / , / ' • / y y) fy l l 1 l // / 5 ] ' / / x y s y \y . /'y r / / ' , • ' ■ s ''J' y d, (in. I 1 1 1 1 1 / 's '• / y y St * tfy III" 1 f ~ 7 ~~/ 4-tt/ / / > / ' • y^ ~~^K s- 1 ,l/' ' 7 // ' v^ • y '/ , V- v' TT^-Ll/^/ / ,' 7 X " ,i;,;////^ K ' <f f .!///// /yS y ^1 J 0.5 i, V V 1 / ( 0.2 1 © Schlumberger 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 Back to Contents 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 9 8 7 6 5 n r ing'''bni A 3 2 1 rVR m = 50 d h = 8.5 in. 1 R IA 1.8 18 2.0 1 / R/R 1.0 _^ -^"•^ !T20 16 ^" *' / ^•^ 1.4 * A • > * * 7^3.0 > s a*t //^ * > ****7^ * ^f ^11 15^ *£-' r *< - X > // Uyf *?Y — — -- *^' * / y <■» y * / dj jf / "7/ s£ * 24 1 i/ /r Jsy S j 4* / /•/ •*" / 100 1' \ /a '4 s* / / 4 / s ' / * O^ en yu i / / 1/ J> <'': iO R,/Rx / 1 s' Jt^ f. / ^-^ s' ?n 11/ is * s *? Jj" '*/* / ' ' ^ j' s7/ . /' /y Z' 15 \6 1 f / f /^f~~ -^£Xr 1.2 // Jl /'/J* /'/'/ -^10 M /il /' f' \\i 'f/U SI 12 i, T/' 5 i Jr't *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 10 9 8 7 6 5 4 3 2 d h = 8.5 in. di 14- _1.4_ -1.5 H t /H bd 1 ? 15 13 —y V £_ / r ^ 1 1 • * X" ,/■>■ 16 s * Z ^^ >^ i 12^, * x • ^ ' ^ «*■ -* *^ ,// <£. —jt ** n ^^ ^' 18 / Sj, • S * *■ ^» '7 • ** ^ ^ 100 n / s f *' 'f >^ 70 i ** / / s ~~f s ^ ' Jt ^r x " 50 11 / i / //• * *S 1 ^ /i <y 30 / 1 "7^7 ^^^ ^& II 1 ' i J S' • JV 1/ I / - *«' t/ / *' ?n S J Y \*f » / 'i ^ t^. > / • • x ^ 15 if / i / f _£. 'A'S'A'' i/7 ' f ii ^**t /' f 10 F VR» T > /r f^ ~y ' sj rs " * A ' * 1 JT i /JL S '/^* *^77 T^ n; > 1's UI I \> J % ?/ 3 l JiJk f 2 1 1 1 1 2 3 4 5 "bJ"bm *Markof Schlumberger © 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 d h = 8.5 in. 9 c .0 40 10 28 , -24 9 R t /h bit _ y • ^-34- 2 J X / / • H 1.E /• ^ "K' 40 7 00 ■>- 7-' ^ s • ' •; S / j R V •' ^ ■f /^ / • • > bU c , / s^ *• / y ^ V V i /***' 100 5 20 ^^ s s ,' /a ^^ ^^ s * *~50 4 t JuS yS- *"*V / y y 30 ^ /S / V /^ /^m*" y» > s s j/s /^ 20 3 18 / •"V ^ , •v 15 i)f / • / <*■ -■v^X / ■ / x„, in fi^/A J? */ / ^4/ • 1.4 7 * '/jvf?^^ *^r / S^t /s • ^_ 7 ? z\rf^^ * i R // // /, rl^A S * 5 ^\, t % ii />S / i 3 J/C w s JS 1 wr£ 7> 1 *Markof Schlumberger © 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 rWr>bd _ b 4 3 2 1 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 * • * • * ^ 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 VLjfrY/ <0.65 5r \ 0.3 ^o.t ^o'29- 55 l <* " y ■ ^ — — — 48 -" 44 40 Xi Ilw// / j ^Kl'/l I / / U 2 ° dilin.P 32 ' mill/ 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 ' ' /V///M f 2 WM 48,7 S." / '/ // //\i / i^m / '1 7^/56 0? '/ l',i< vfBi / / A /.!/ / / '/ / \ 44 // IA"l) mm VI flMMMIi 1 A / n //v/) ]B Jm/) / \ / /I If) fl/lJ ' l/i/lllu 1 / V i/i'i* Ufli / / ** v / ^.f* ' /• / . ' n/iu 1 / ii/jy pij i "nfi/ j / P^Mf/'lff /'/ v\N l'ii Mi II \ /i iihtfj ifl h II •// ulfln\ilff 'wW'Wfi /'IB / r / a n Ii/fI/ 1 1 / fv'fJnflfi/l s 7 i '/MIN s 1 / u /// {/ 1 // y 1 Z-0.1 /,'' 1/ ' / f / 1 1 [II / / 16-in.R p ,/ / *T 1 ■"* / 0.3'/////// /{' / A/ 1 1 £ 7/40-in. R ad /R t =1 40-m. R ad / X / /A / // / IS/ 1 /'/ / / 1/ /// iyf 1/ if * 1 1 / s 1 1 / ' ///////' ' ' S , s ' 1 1 / / / 1/ * / '//408, jf / \ 7 / i * s^l / / / /ftl'/// / i 40/'' JS1 1 / // ///// / i / / /%$Wf / / i / d, (in. x.o.3 /,///,?/ 1 / > / Ao / P A />(4y ' !/ /'//jy i/ •, y/tff i/ / 1 /Jy' r /- ' 1/ 4r / A / ' /> / • / ' 0.15 / / y /./ / / / / * / i / / / / ' /f / / / / / / , o = 0.1 ohn i-m —■ / i 7 24 / 0.01 ^~—7"& ^?7 32 J>1% i 0. ]1 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. < ► Back to Contents 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. < ► Back to Contents 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. < ► Back to Contents 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 -V V \ 1 G J \ } II ji_J 05^ c/J J _L Lg to T 1 T + T + ) I 1 ■+ T .3 -T J - n ■ ■ .a ) ) 2- o ■ " M 1 » * -S T v ^ t t l en ' ' ,_ i 4- ) A t ' :?„ 1 CO ■ rn T 1 " CNl 1 § ■ ■" _J *- 5- A O CO CJ ?A o o T S ) h ■ ■ T_G> 1 *~ ■ ' ■ i )h ■ - ■ ■ • - ■ o . ■ ■■ ■ «— T I 1 + 1 r VH 1 r-i ^H oj^T .^j ±=^ ^- X .c L < .■III 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 ) ■ ■ \ ■ ■ •V <MI 1 ♦i ' T CO CO , ■ v \ :§ v 3 + .1 ■ 1 + " ■ 4 • S n ? 1 1 ^ ) > CU 5; tco 4- 1 " 1 C/l r ) A t ■ • ■ % 2 =) ■ O - ol r~ \ CO £ - ■— "„ 4 -J CO 3 ) \ ■ ■ o "" Q - ^h . ■ *-? " 4S . . ■ ' 1 c , * - - 4 J 1 h 1 ■ ■ • ■ ■ ■ -- -O ■ ■ ?.7 ■ E? f EZ tz ■■ . . - - ^K "■ J. X T it + o AH Sl^t =3 -oj >CJ -C 1_ 1= V < I ■ Lc ■3 .■ill *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. < ► Back to Contents 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 ) _ . . . ,oiio nr,n 10 20 30 4q Apparent total porosity, cp ta (%) -resn waier (u ppmi, p f = i.u g/cm°, u f = u.jao 5alt>A/atDr /9nnnnn nnml n. - 1 11 n/rm3 II. - 1 ^R ' ^,7 . 7 // r^T * / // // <? ' /, ''■■/.' '/ '/ // / /,'/ s, \v0 ' / / V // ■'j / s> ' y , V / , '/■', g s\ xx V '/ ■y* * /. y ' S/ y. / / V '//, ' ', ' M / / Ss /a '// '// C'^ YVv\\uW '/ *'/ 'J // /> ' . > £ ^ tf'/s A, ■ /M "& S^ 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. < ► Back to Contents continued on next page 199 Lithology — Wireline, LWD Density Tool Lithology Identification — Open Hole Schlumberger Lith-6 (former CP-21) T> A ' ' 2.3 :: Sa t ., k 2.4 1 _. \ o X ^" 1 £ k- =S V ^, ^ ~S~ i < - j ?.R r 2.6 K-feldspar j\ O: 'ire — _^ i n In/rm 11 V "~ >V -^._ 40 -i-»- PmaaW UM / \ S \ ?f^— 60 " — >1v"- 80 27 = 5? -5s^ \ ^ > *yt.... >, ^ \ S \ ~~tx Calcite s, v j^ ?^-S ^c— — ^\/_l *J ' '•jS^ V -S^S * \j 1 .y'x ""** — ^UkJy'i i i\ 1 L/f "W 5 ' - \J "' \. > v -XLt 0, \ >tj > ^' V 2.8 _l8>, X-F^Sr £S- "}> V-I- V »<v -+*• V \ s ^ ^ ^ &r^ <s$?4- S r ^ X^ v^° 5^~ -V^ * 7 ^°V J?<Si * »\« S 1 t ly ~LJ n i ■+ j 9 uoiomite ^^ ^k .... f. Anhydrite L^ 3.0 ■ i- r» llhte ^u 1- 3.1 2 4 6 8 Apparent matrix volumetri © Schlumberger 10 12 14 16 : photoelectric factor, U maa 200 < ► Back to Contents 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. < ► Back to Contents 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 » / P ■ , = 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 t ^ •* 1 1 Secondar\ porosity r */- • 1 1 v ma = 5943 m/s j • J» = 1 9,500 ft/s lim 3StO ne) • • Q *•- •* uartz sandstone = 5486 m/s M >W » XT 4 = 18,000 ft/s Dolomite ^ r r 324 1 j • AnhydritG / / / V ' r" Sulfur Af proxim ate shale region 0. 3 0.4 0.5 0.6 0.7 N 8 202 < ► Back to Contents 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. < ► Back to Contents 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 1(1 t t <$' 4 S 1 1 Secondary porosity i */- y nq 1 1 v ma = 5943 m/s -• = 19,500 ft/s Pair i; m . JStO ne) r 4 s Quartz sandstone v m „ = 5486 m/s 08 • <Xr a 123.4 = 18,000 ft/s o '' 07 1 Anhydrite / / / V ■ f~ Sulfur or Ap proximE te shale region OF 0.3 0.4 0.5 0.6 0.7 0.8 *Markof Schlumberger © Schlumberger 204 < ► Back to Contents 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. < ► Back to Contents 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 ^ \ l - , \ \ ', 120 110 100 90 Interval grj transit time, t (us/ft) 70 60 50 40 30 \ \ \ \ \ \ * V \ \ \ \ v \ L S \ \ V \ \ > \ \ \ \ S > \ 40 V v \ "" \ \ \ \ \ V \ \ V W \ V 3C V r ^pparenl rossplol \ \ \ \ \ * *J L y v \ \ 0^ ?n\ \ V v \ \ \ \ V \ 1 ^ . vl\ V V^N V V \ \ N v \ \ ^ If " \ v \ V ^ ^ \ \ \ ^ V rf \ \ \ \ \ . s \ \ \ \ ^ # . \ \ S s V v \ \ s \ 1 s •^ \ ^ > \ V f 1 n * V \ \ \ >, v> ^ \ yX 1 y v \ \\ \ \ V \\\ S s s ?n V i V s s JV X s V xkv X \ """■ N V s s s \ '?n \ \ s,' v s \ V *i .n V V JnnS \ \ v$j^ 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 20 ^ \ \ \ 325 300 275 250 Interval 225 transit time, t (u,s/m) 200 175 150 125 100 \ \ \ \ v \ \ V i \ > \ V \ ' i \ \ s V \ \ \ \ ;•, V \ \ i \ Apparent v s 3 n V orosity, > ^F \ ■ \ y \ ,* V o< s* 20 y 1 k \ \ \ \ <>' \ > s ^ 10 k s^v \ \ -? v V *\ V \ <* > »\ V tf ' 1 n k * ^> > \ V 9n N ► \ \ ^ \ ' 3n \ V * s V "/ n v^ k\ vj£3^ 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 ^ rf^ **" & 3 Quartz I. ) Calcite c _) D Dk IT it a ! ) - f\r h ,d rit e ( ^ J *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. /riui* in 1 IUI >"y/ 2.1 <. Salt q. ;np) w (C U 2.2 2.3 2.4 2.5 rj? ^ v\ J K rmaa C-F !» (g/cm 3 ) 2 6 Quarl z ' ) 2.7 ;alcit i ( ') —S 2.8 r ) [ )olomiT8 ^*- 1 2.9 i \nr yd rite ( ~) 3.0 J 3.1 100 120 140 160 180 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 Porosity, <Mp.u.) 20 10 Timp avprarjp Fiplri nhspruatinn f 40 30 Porosity, <p (p-u.) 20 10 / / / / / f -< r 4* * ' 7 / 1 1 / ' -^ *- / /£■ W f t^ / / x / / sf / "/" / i.; _ / / / / ' / / / y / / / / / t i.: i / ^ / / ' / / > / / /, / / i.' / / / / ' ^ \, / > / / / / / / # ,<? / / / 1.! • ' / A\ & f / / / / / $ •fS>) / 4 / / / / i r ° V, / / / / / s ^ /° <$ / / / ' / / / / r ! / / / / / / / ' J cp / / / / / / / / / r / i / / / / / / / / / / / / / i / / 1 i / / / / / / I / / / ' i * / / / Uft/s / / / ' , / / / x s / / / / / i f \ S^ 1 ' / ' , '. '. '. '. / / <$?] / " -S6 V S© / 1 **\ ♦\< /, ■*?"* / f. $ y '/ / 7 '/ 1 , / 1 / / / i 1/ 1 / > / / /; 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 Timfi averarjp Field observation / 40 30 Porosity, (|>(p.u.) 20 10 / / / / / . / 1'' / f ,, V *<r / / * 1.1 / / -V /^ / f / / ^ , / i / 1.2 / s7 / / ' / / / /' ' / / / / /' 1.2 '' / _©. y^ ' . / / c/ 5 / // ' / 1.4 / / -^ <&/ / / / / / * 21^ U / <■ / 1.E /_ * *?,*> ' r *v- / / ' / / / v<v; / / / / 1 fi / *tf > / / / / * / <" v / ' / / / / / S cp / / / / / / / N L / / / ' / ' , ' / / / , / / / 1 ' / / ' / / / / /#/ / / / / / / 1 fa ' / ' / / / / / / 4 $>■■' / / // '/ / &// / / / / / . / cl / '4 wJrs / /, 'V / / V ma>"" j) \ / // ' / / . ' / / \ •J- rS / /( #> V // V // / A& >y / <v ?'- / A ^ <: /cWl V / / *\ l<§> &§ //' //rV V / <oV ' '/<£> /<£ // / U- / / / / '/ / / // 1. / / i f 1C © Schlumberger 150 200 250 300 350 400 Interval transit time. At (|is/m) Purpose This chart is used similarly to Chart Por-1 with metric units. < ► Back to Contents 213 Porosity — Wireline, LWD Density Tool Porosity Determination — Open Hole Schlumberger Por-3 (former Por-5) P,(g/cm 3 ) 1.0 0.9 0.8 1.1/ - - / // 1.2 / 40 Z - / / s\ 7> /' o 30 Porosity, <Mp.u.) 20 10 nC p / , 4 ^ ^ \ *y * v y Ul /& >/I7 W ^ yf *, AVLV A *V l vAssj? f Z/&7& / <5 *';-/<$ / /<5^7T// / / /"* «? ~~ - '/ 7 i/^ / r / t / / y / / / / / / Pma-Pb • / ( ) = — / / f Hma Hf / ./ / / / / ' / / ► / / f 4 / * / * / / 4 / / i ' , / / ' / / / / / / / f / / • / / *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 apih FPLC RNP y \y s / / / / s / s / / / / / f / f y / ,' f / f /' t /' * / f AS <* *s / <k c* / -vV & t / 4 $ / a 49 / < >>■ ■ ^'. / / $> •* • c a / s> / '^ 4 / / s / ' / f / '/ ' 1. V '/ / y\jtf 'jpr *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 Formation salinity . / ppm / / NPHI / / * / / / / / / * / / &* ' * &/ r> / j?r, nf> / / & <2-~S s * *v *S ',*. <^ sS* *& & & & y<\ <3yr *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 20 10 / / * / y / • / / ? • / / / 4 ?/ 4$ f / / s f/ ,••'< t / / / / / / / / / / / / / i / / / / -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 4 / / / * / / / / ' & / »< • ^ / \ <& X $> xv- ■S>° 4 s <sV \>- . .,<^yr-^ s z$^ ^ <F/ V f • ' s s / s s s ' ' * s f / / s S * t *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 5 s / s ' ' / S * / # • .< *\ ^ & • A' <£ =J-° 4 / i>*> \y 4*— «a N v / ' s \<t A<S» <j u n\0 V . ' W- • * / / s s / / ' ' * ' / / • x- /• • / ' *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 ." s / y' s ' *• s s * s s / • & y x^s^r c& / i4 j* &/ . • S • ^ X n\° V* S>° s ' / • / » • ' • / • / • • / / ' / / / *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 • X s s s s s * s • •* • V s ' s +• s s / *■ «P a S • _ * / • ^ s ( b* ofS< s / ^ • ' ' , ' V s / * • 4 4 • • / ' / / s ' s ' s * / y s / s 4 * s * ' t> 4 s * ■■' * / s / s • * *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 .' s / f / s s s s / 4' & s ' i- V s 4 J» * s $> s , & -&< • V / ^ <^> /■ • s • s / y / s / s ' • / • -* / • / * s / y / / s * * y / s z. * *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 Bulk density, p„(g/cm 3 ) 2 - 5 2.6 2.7 2.8 2.9 3.0 & 45 40 35 30 25 20 Density 15 porosity, 0D (P.U.) (p ma = 2.71 g/cm 3 , 10 p, = 1.0 g/cm 3 ) 5 -5 -10 -15 WP * c >J 'u fi £> (. > J >all * A k rfp X J f, >l. °o t ,. ?a '' fe / "?> *3> S 'i .** / c, 'O, \ <» oCS c^ t M k 9. s k 'V <f f rf i / V ^ &* *• ^ rfrl I* T\ oR> rK\ y A* vy />' J* 4" n {■• S> s 1? ' o> N<» > a v> •\> /*.« tf ^ . i \> •fr Q \ v i < i <rs <S Ar h ,H rit *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 35 30 25 20 Density porosity, <t>D (P-U.) 15 ( Pma = 2.71 g/cm 3 , p f = 1.19 g/cm 3 ) 10 5 5 -10 -15 ifc < < ^Sulfur & > Salt & ", * **. V >« Ik- n*> S •y W f> *4 c o r M 3 O^l "<9 r r .' o, 1 o c ^ ^ ,< \ nCN / <~ '*>"•> / y ',<#> - Sp' S r $ n 'v $> <o? *V" ^ y> tf <s A* v>- . \ <*<?■ S o ' V o,V ir> <; \0> ,< ;» ~\ \ , J r p .< ^s ^\ <<& <-, ' \0 W ,< a < ^ > v \ <^ \ ^> *o 5, ( 5 Anhydrite *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 APin FPin h b.V * i ^ N 4 c °1V S> fc °+/k dp ^ ' ^ o*"»at. °0^[ <¥ £ s "r* '/) N n * rf> /,«• - \ •** & Ts •5 k ,o i^ < & $L S*.Q -<?< 'JS? K&* P.N d? 50- rvj. «s» <$> v v n? %- YJZ JF \> /" \V> j \n£ ; '1 Jr„x ■fc" 3 p<*i \ v ) \? x„ ' \ J /** ^ \c * <p ^ < (\ r.Ol r,^ i 4 < -tf» * "V v- <o -V £ $> <s> *6 fri <•- o> > j / / ' A 6 / ' V 6, / \ *Markof Schlumberger © Schlumberger 10 20 30 40 Corrected APS apparent limestone neutron porosity, <t> APS ,, or (p.u.) Purpose This chart is used to determine the lithology and porosity from the Litho-Density bulk density and APS Accelerator Porosity Sonde porosity log curves (APLC or FPLC). This chart applies to boreholes filled with freshwater drilling fluid; Chart Por-14 is used for saltwater fluids. Description Enter either the APLC or FPLC porosity on the x-axis and the bulk density on the y-axis. Use the blue matrix curves for APLC porosity values and the red curves for FPLC porosity values. Anhydrite plots on separate curves. The gas correction direction is indicated for for- mations containing gas. Move parallel to the blue correction line if the APLC porosity is used or to the red correction line if the FPLC porosity is used. Example Given: Find: Answer: APLC porosity = 8 p.u. and bulk density = 2.2 g/cm 3 . Approximate quartz sandstone porosity. Enter at 8 p.u. on the x-axis and 2.2 g/cm 3 on the y-axis to find the intersection point is in the gas-in-formation correction region. Because the APLC porosity value was used, move parallel to the blue gas correction line until the blue quartz sandstone curve is intersected at approx- imately 19 p.u. Back to Contents 227 Porosity — Wireline APS* and Litho-Density* Tools (saltwater formation) Porosity and Lithology — Open Hole Schlumberger Por-14 (former CP-1h) 1.9 Liquid-Filled Borehole (p, = 1.190 g/cm 3 and C, = 250,000 ppm) 2.0 2.1 2.2 2.3 2.4 Bulk density, p b (g/cm 3 ) 25 2.6 2.7 2.8 2.9 3.0 APLC . FPLC 1< IJPSP K-" fcj§ \ /) t n> -* *% 9»~ %/» •p rfc /*r I *Cf ■v. " rfp *- y \ >, "T^i" s 4> c ^ k ■«v\ / A **' ~T „7 <^ O o^- <„ >f 'S J 'H J V ^-<N *%t ' % «$>* 'S'Vl c^ 4> ^^ V ^ ^ o' 1 r i-. V^ v - \'j N" J> ^ <* ^ ) T° v'-xe -<» V ,r,* v JZ* <N ^ ?°: V 1 v. ^ nCS V 5 ! .•^ y ^ \- ^ Cs $ ^ -< <5 y. V i > , / ', ■x» / y $ / ' «V ** *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 D Salt *■ W / .(N • / •. •A *> , *> \^ 9. 0^ "£ ^ / * / / <$ * / * fr J ;Si >,<*> v U° *- „<^ .Q \ nK> <$\ >&" «0 * \ o D- *W •|V> •^e x <r '.w %■> ' v>° <*<?> \* ' ^ c\ lr^ \^ '(, V ^ •Ks *, *o, Oo <b •V ^ <i ?> _ *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 W r V> li > i- s / s i «A- vs>: «<y V", & s r^ \ s <\ p / /V / *p »*" -Is ' •A ^ 4a W ■>> I '4 ■y c / $ > -■$ V\N <? '. K <1 T° Hi ' Vj" \ V J '»<?. *> "y Kc^ x <QP V \^> h <o <; > 0, <5 <^ <5> _ *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, p b (g/cm 3 ) 2.5 2.6 2.7 2.8 2.9 3.0 ^ ^ n^ 4>- c\ & .;<$ & '5^ R 4> n<^ n j '1 >W <&•" % ^ ^ J??? /^ <*> i^ *,*y *!$ <^> /^ s? ;■> t \\N L_ '.<& ^> »» •? X" V *■<<? v a <* v" < j' \r «K\ t? ^ O <* ^ \° <5 <i * o _ *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 Bulk density, p b (g/cm 3 ) 2.5 2.6 2.7 2.8 2.9 3.0 N-> KV ) * i Sal n<- n< !. ■\ t> n<N rrf» _ 2. 3 r *> -NO> 4 f J "^ «b' l'> 6° ' / *Ps ■ft sO^ V v> «<? f» V- \\* / <-. .$* V \C * ^ i 'I o, y «$• > ^ <0 J y> ^ N c\ »j A h\ _ *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, Pb (g/cm3) 2A 2.5 2.6 2.7 2.8 2.9 3.0 »•> *i &. ^ f L rbaiL o; tf> oft ■> I '5 n<* 'P p. '3 W 'j>° V * '&' nsi , }•■• * '•> <s« ■^ ■v 1 S.f* \> K i^ \ l J « ^ ';*» \ \<& < i \ ^ <^ V < ^> ^ < ■> < Q Anhydrite 3 _ *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 / e 1 II11H HV/HTHIJH Field observation / / / 1 1 .' / / / / -^ t **> ^' fa / / / / r mo "V 1 o / £>J 1 'b ^ ''^ t ' / <* "D ^ / <*> >.«y ** >l ) '*' fa / / /. ^ ? 17 / / s/ / /* -.1 ^ /> ■? J 1 A r\y / ' qo i •b\ 1i V <i° 'V\ j 1 <n 1 / £V i c> 'S\ / / / ' ( / / / /*f. 1 / *■ <V 1 / <n 1 / ni^ K 'v\ / r \. / / •y RO f / S> V *? 5 / O^ / ■> ' X / 1 / 5 4 > f ,y> / l 5\ s/ *> / <\ 'V X // t / '„« /, ? • ^ / fr * / / ,/ :? ®.s /k« > / <: >° / >• N. 70 V 4\ s/ <\ <p // * / < 0* / > y . ' "*s> V A // / V : ► /7 * <r > ■*» / y '*', •fc > V V RO 5 / > // >$• $> y nV /> -/ v> > .^ ' • ? > > ' \ / 5 V 7" \ <. * / V ' > "> <* > r *> > v^ *o V ^o ^ ,v> \ /' ' V ' 1 ** o / \ / y •> >> ^ f C^ ■7 / 40 10 20 30 40 Corrected CNL* apparent limestone neutron porosity, 4> CNLcor (p.u.) *Markof Schlumberger © Schlumberger < ► Back to Contents 235 Porosity — Wireline Sonic and Thermal Neutron Crossplot Porosity and Lithology — Open Hole, Freshwater Invaded Schlumberger Por-21 (metric, former CP-2cm) t, = 620 u.s/m and C f = ppm Sonic transit time. At (u.s/m) sro Ti i 1 - Field observation •) / / 1 / 1 y 1 »^ 340 / .. 1 / *» / / ■V f § / £> / 3?n "^ '.<? V ?/ V ^ i / * 7& '1 / / ■J 'J 1 > son ■.<*/ <$ i / & /£ *, i v/ <? O' «<?, / / <&> / / < $ ^ V / > / i ?Rn / / ^ ^. / „ 1 > A i > / '#s 1 1 ' r - ^ / / / £ & N t* ^' ' 9Rn X- ' ? J l \ N ' / / / r < \ ^ <^ «V, / < J / \ /c ^? <V ' V /X y 1 / ««. N r ■?/in r «$ J' -i s> v / /,<* ./ <S y f ■-» -/ ' > & :> -j N< -> ■7 >' ' "%■ >' '\ «V -/ ??n V y / ' (. ) *fci> N / & / > V s r V ' > <o v/ •?> \ '/ -^ N/ * ?nn ?/ y t // £■ V v/ *\ p N >' r> M $ ■■ ^ Si N / *. 1RD <o \ y • 9 / > ' V • £ ) \ $ V ^ ) '> ^ V > ^ ) \ ; a v Ififl *. ' ; ■/ > ' j / o > s. -• c S <i i /in *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 < ► Back to Contents 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) T Field observation 3y vit c J 6 1.9 ?0 § vo *>, Salt Sultu r T I 7.1 *~ "* *-% riS> On ^ 2.2 v?» £ y^ c <?< r 4 / sjr . ?3 / CV 'yjr x / ¥ ^/^ W •f>' 4 o Gypsum •$ s /. 24 / / / > ' / ) / ?F > j ^ ^ $> s ~fe A v s ■$ // * ?fi *V H •* 'i ? > .c» ^ ctf ^ •i <5 > / 27 c ^OV A $> •§> •s y < <v c ^ ?R / O Polyhahte / .a / C5 ^ li <; ?9 > Ar ih\ dr te 30 l 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 $> Hi- *>. f O Salt O ( Sulfur ronj ** LI I -- 72'. ^§3 w \ »$ ^ Q *' <o *° / ^r] / *% / J ^A y/ * r ysfo/ /% n n ypsum ^, A $<& 4 ' JP y ' / / i f / / w ^."N •*>, .4 */ <$> <£ &7JEZ 'V* '/t\/ <o* i <i <*//.< #;< •>/ -$> '& A # i <5 & , 'IV Po lyhc lite 1 A .& $ f 4 ^=>" o Anhydrite 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 < ► Back to Contents 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 / / 20 ?F *3b / Pornsitv 40 ^ / \ '■m \ / 30 s "30 i0 S / \ / A t ' 2b 80 ?n s 2b t 4U 100 2C ilJ ' Ko ?r Hi 100 K„ s 1 '} r u fuf ]0 ' 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 < ► Back to Contents 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/' /T 1 n /P "^ 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 < ► Back to Contents 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 < ► Back to Contents 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 ^s ^ ^— ^ — V. sS s s s V. N \ ^^ v -F„ 1 ¥ p 1 ■ ^X ■^ v. m F H - — - s *.s \ / o m V ■^ / \/ ^^ '* ^< "V Vuqs oi \^ ■N i nhmiral nr,r ne ^ ^^2.b J>2_,2_5 )2.15 7 Fractures 1 ^ s?5 - -fe- ::! \ *< *S, ^s^ ^^S s-2 2 ^ s v ^s, \ 1.0 \ S~ 2u \ l"B - a2 X ^ V \ 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). < ► Back to Contents 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%. < ► Back to Contents 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 < ► Back to Contents 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. < ► Back to Contents 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 $>' / 50 40 30 20 10 8 6 5 4 3 R xc, „ R, 1 0.8 0.6 0.5 0.4 0.3 0.2 0.1 0.08 75 100 . Temperature 150 (°F) 200 ; 300 : © Schlumberger 80 70 60 4>' y \y y \ ' \ y 1 R.n fc PSP = -Mog-^-2 K c log ^ ™t 50 S>' \ \ Sxo = V^w 40 30 25 20 15 10 4 & / - C ■-,■*■* A;:$I#- C^Z TSJt !?V £y ic^ Zv?\°.^ B sty M c\\ci y t iS> *^ 1 i ,»\« > / t> 1.( I 0.9 0.8 0.7 6 tff / 'vj. S xo °w _ °xol°wa' . 25 50 T 7r . Temperature ! 100 ( ° c) 150 $ •> / <^ , 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 40 50 60 V*\ n ' ////// / / / / / / / / / / / / s* \\\ \ 1 1 i /;////////x/^<y>'^ \Vri \ l \lili//////////X////^/^^ 20 10 c -20 -40 -60 -80 -100 -120 -140 Ep SP orE SS p(mV) 252 < ► Back to Contents 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%. < ► Back to Contents 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 V i" / / ■ 1 oc v if ) 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. Enterthe chartboo © 2009 Schlumberger. All rights reserved. *Mark of Schlumberger Other company, product, and service names are he properties of their respective owners. Contents ^ V \ introduction Contents