Well Logging - Data Acquisition and Applications

707 Pages·2004·76.4 MB·English

by  Serra

Well Logging
Data Acquisition and Applications
Oberto SERRA
Doctorate degree in geology
Engineer from ENSPM (IFP)
From 1968 to 1978, former manager of the Well logging Department
in the Exploration Division of the ELF-Aquitaine group
Former chief geologist of Schlumberger Technical Services
Scientific advisor of the Serralog Company
and
Lorenzo SERRA
Master degree in Physics
Former Schlumberger field engineer
Executive manager of Serralog Company
Serralog Q 2004
Bibliographic reference of this book:
SERRA, 0. & L. (2004) -Well Logging - Data Acquisition and Applications
ISBN : 978295156125
Editions Serralog - 25 rue des Chaumieres - 14370 Mery Corbon - France
0 Serralog 2004
Serralog 0 2004 i
Foreword
As the previous books of Oberto SERRAg ot a very good reception by reviewers (G.B. Asquith from AAPG, H.M.
Johnson from Tulane University, A.V. Messineo from SPWLA, M. Verdier from IFP), we have been encouraged to work
on a complete revision and updating.
This book, a companion of the "Well Logging and Geology" book published last year, deals with the acquisition and
applications of logging data. Its goals are to explain the physical principles of the different measurements realized either
during the drilling itself (logging while drilling or LWD), or thanks to tools lowered into the borehole at the end of a cable
(wireline logging or WL). But, even old tools, as they are often used in synthetis works on a filed or a basin, are des-
cribed.
Thousands of technical papers and several books have been written describing the various logging methods, the
physical principles of the tools, their applications and interpretation. This abundant literature is overwhelming in content
and frequently unavailable to the average well log user (geologist, petrophysicist, reservoir engineer).
This book tries to synthesize the necessary knowledge needed to understand how the measurements are acquired,
and to give to the reader an idea of their applications. It is abundantly illustrated to make its reading more attractive.
We have tried to explain the physical principles of the different measurements realized in a wellbore using terms that
can be understood by non mathematicians or physicists, even, if sometimes, we have reproduced formula which can
be esoteric for certain readers. In any case, if the reader wants to go back to the original papers or books, he will find
at the end of each chapter numerous references which have helped us to produce this document.
We hope that this book will be read not only by petrophysicists, geologists and reservoir engineers, but also by
managers. Indeed, too often, oil company managers want to reduce costs on logging acquisition as much as possible.
The objective in itself is reasonable because reducing costs is always a good thing in itself and, in the bottom line, com-
panies want to make profit. But, managers have to realize that a reduction of 25% of the logging cost will save only
2.5% of the well cost assuming the logging cost would represent statistically only 10% of the well cost! As a conse-
quence, reduction of logging data, (most of the time natural gamma ray spectrometry and dipmeter or image data) will
not allow the precise and accurate 3-D description of the reservoir. In addition, the error on volume estimation will be
certainly much higher than the error on porosity measurement! Finally, the short term economy realized on logging can
prove to be disastrous on a long term. An incomplete and imprecise knowledge of the local geology may result in much
higher expenses due to wrong location of production and injection wells! Do not consider the logs as a commodity but
as a very valuable and necessary source of subsurface information. And even if the logging measurements are affec-
ted by errors, remember, as pointed out by Philippe Theys (Petrophysics, vol. 44, no 1, p.14, 2003), that "when you eva-
luate the magnitude of the errors that affect logging measurements, you find that the ones induced by the limitations of
physics or technology are smaller than the human errors". You would not rely on a diagnostic made by a doctor who
would only examine your throat, take your temperature and measure your blood pressure! Why would you trust a reser-
voir evaluation based on a reduced logging set?
Consequently, do not reduce too much the logging data set! Do not restrict their use for only evaluation of reservoir
porosity, permeability and water saturation as too often practised. Interpret as well the surrounding beds to better
determine the precise depositional environment. Use the log data to better reconstruct the geological setting of the
energy resources. At the same time, exploit completely the logging information. Do not leave the logs "sleeping" in their
drawers or files! Analyze and interpret them in depth! Squeeze the lemon!
Oberto and Lorenzo SERRA
ii Serralog Q 2004
TABLE OF CONTENTS
Foreword i Logging truck and offshore units 59
Acknowledgements ii Cable 60
Chapter 1 Tool transport 61
Review of fundamental notions 1 Conductor of electrical signals 61
Introduction 1 Depth measurement 61
Definitions 1 The bridle 62
Sources of informations 1 The “fish” 62
Outcrops 1 The logging tools 62
Information provided by subsurface data 1 The sonde 62
Information provided bysurface seismics 2 The cartridge 63
Information provided by drilling 3 The telemetry system 63
Goals of logging measurements 10 Recording equipment 63
Geologist’s goals 10 Photographic recorder 63
Petrophysicist‘s goals 12 Magnetic tape recorder 64
Geophysicist‘s goals 12 Electronic camera 64
Reservoir and production engineer’s goals 12 Tool combinations 64
Rock properties 12 Memorization 64
Rock physical properties 12 Logging While Drilling Equipments 64
Rock chemical properties 13 The sondes 65
Rock geological attributes 13 Sampling rate 66
Rock petrophysical properties 14 Data transmission 66
Porosity 14 Cable transmission 66
Resistivity and conductivity 16 Mud pulse lelemetry 66
Formation factor 17 Data storage 68
Resistivity and water salinity 20 Advanteges of MWD/LWD measurements 68
Resistivity and temperature 21 Borehole influences on measurements 69
Water saturation 22 Borehole effects 69
Permeability 24 Drilling mud 69
Effective and relative permabilities 24 Invasion 69
Relationship between’ permeability and porosity 25 Fluid mobility 71
Relationship between permeability and saturation 26 Casing and cement 72
Capillarity 26 Temperature effect 72
Interfacial tensions 27 Pressure effect 73
Factors affecting the petrophysical properties 28 The effect of tool geometry 74
The resistivity of clays 28 Tool diameter 74
Clay distribution 32 Tool components 74
Laminated shales 32 Spacing - gap 74
Dispersed clays 33 Geometrical factor 74
Structural shales 34 Radial geometrical factor 75
Total shale relationship 34 Integrated geometrical factor 75
Determination of the rock properties from well logging data 36 Depth of investigation 75
Determination of rock composition 36 Vertical resolution 76
Matrix 37 Relation between depth of investigation and vertical resolution 79
Shale, silt and claystone 37 Measure point 79
Fluids 39 Tool position - Eccentralization 79
Rock texture and structure 39 Logging speed 80
Determination of petrophysical parameters 42 Tool rotation 81
Determination of formation-water resistivity 42 Sampling rate 81
Determination of a and rn 43 Hostile environments 82
Determination of n 45 Tool calibrations 82
Porosity determination 45 Surface system alignment 82
Water-saturation determination 46 Repeatability 84
Permeability determination 50 Logging data formats 84
Well Logging applications 50 Floppy disk format 85
Relationship between geological attributes and well logging parameters Tape formats 88
50 LIS format 88
References and Bibliography 52 DLlS format 88
Data transmission 88
Chapter 2 References and Bibliography 88
General processes used for recording physical parameters 57
Introduction 57 Chapter 3
Measurement classification 57 Generalities on electrical measurements 91
Natural phenomena 58 Introduction - Review of general notions 91
Physical ‘parameters measured by inducing responses from the for- Ohm’s law 91
mation 58 Maxwell’s equations 91
Other operations 58 Propagation of an electromagnetic wave 93
Wireline logging equipment 59 Some other rock properties 93
Frequences used in electrical measurements 94
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I1 Well Logging Data Acquisition and Applications
References and Bibliography 94 Bed thickness 123
Dip determination 123
Chapter 4 References and Bibliography 123
Resistivity measurements 95
Introduction 95 Chapter 5
Review of fundamental notions 96 Conductivity measurements 125
Measuring principle 96 Introduction 125
Non-focusing long-spacing tools 96 Measurement principle 125
The normal configuration 96 The geometrical factor 126
Lateral and inverse configurations 97 Measuring point - radius of investigation - vertical resolution 127
The current path 97 Radial characteristics 127
Measuring point (depth zero) 97 Vertical characteristics 128
The normal 97 Focusing 129
The lateral and inverse 97 Deconvolution 130
Radius of investigation 98 Integrated geometrical factors 130
The normal 98 Skin effect 131
Lateral and inverse 98 The induction tools 132
Environmental corrections 98 Old induction wireline tools 132
The shape of the apparent resistivity curves 98 The 6FF40 induction-electrical survey (IES) 132
The normal 99 The 6FF28 IES 132
The lateral and inverse 99 The DIL-LL8 system 132
Non-focusings hort-spacing tools 100 The Induction-SFL (ISF) 132
Principle 100 The DIL-SFL system 132
Environmental effects 100 The Phasor*lnduction tool 133
Tool response 101 The modern induction tools 134
Porous permeable formations 101 The AIT' Array Induction Imager 134
Shaly formations 101 The High-Definition Induction Log (HDILSM) 135
Tight formations 101 The High Resolution Induction (HRITM) 136
Focusing long-spacing tools 101 The induction LWD tools 136
General principle 101 Environmental factors affecting the measurements 137
Old laterologs 102 Borehole effect and tool standoff 138
Laterolog-3. LL3 102 Bed thickness and adjacent beds 138
Laterolog-7. LL7 102 Invasion 139
Laterolog-8. LL8 103 The annulus 139
The dual laterolog-DLL 103 Dip 139
Modern laterologs 106 Geological factors affecting the conductivity 140
The Azimuthal Resistivity Imager (ARI') 106 Applications 140
The High-resolution Azimuthal Laterolog (HALS) 108 Induction or Laterolog? 140
The High Resolution Laterolog Array (HRLA) 109 References and Bibliography 140
The High-Definition Lateral Log (HDLLTM) 109
Spherically Focused Log (SFL) 110 Chapter 6
The Ultra-Long-Spacing Electrical Log (ULSEL) 111 Electromagnetic wave propagation and attenuation measurements
Resistivity measurement behind casing 112 143
Introduction 112 Introduction 143
Principle 112 Theory of the measurement 143
The TCRTM (Through Casing Resistivity tool) 112 Definitions 143
The CHFR (Cased Hole Formation Resistivity) tool 113 Polarization 144
Logging While Drilling Resistivity Measurements 115 Measurement principle 145
Focusing short-spacing micro-resistivity tools 118 The sondes 146
The microlaterolog-MLL 118 The high frequency sondes 147
The proximity log (PL) 119 Computation of transit time and attenuation 148
The microSFL (MSFL) 119 Sampling rate 149
Thin-Bed Resistivity Tool (TBRTTM) 120 Log quality control 149
Factors influencing the resistivity measurements 120 Depth of investigation 149
Environmental effects 120 Vertical resolution 150
Geological factors influencing resistivity 120 The medium frequency sondes 150
Rock composition 120 Environmental factors influencing the responses 151
Rock texture 120 Hole-size and shape 151
Dips 120 Fluid 151
Fractures 121 Dispersion 151
Sedimentary structure, facies. .. 121 Mud-cake 152
Temperature 121 Temperature 152
Pressure-compaction 121 Interpretation 152
Ptrophysicalf actors affecting the resistivity 121 Energy losses 152
Applications 121 Interpretation in losless formations - Method too 153
Petrophysical applications 122 Interpretation in lossy formations - Method CTA 153
Water saturation determination 122 Interpretation of medium frequency measurement 154
Porosity evaluation 122 Geological parameters affecting the measurement 154
Water resistivity 122 Mineralogical composition 154
Geological applications 122 Texture 155
Correlation between wells 122 Structure 156
Compaction - Fracturing 122 Fluids 156
Sedimentology, lithology 122 Applications 156
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Petrophysical applications 156 Hole diameter 186
Porosity evaluation 156 Depth of invasion 186
Hydrocarbon detection 157 Bed thickness 186
Water saturation evaluation 157 Formation resistivities 186
Thin bed detection 158 Tight formations 187
Continuous computation of the m exponent 158 Shale base-line shifts, and drift 187
Geological applications 160 Irregular invasion profile 188
Determination of the mineral composition 160 High resistivity effects 189
Evaluation of the shale content 160 SP anomalies - Noise 189
Textural information 160 Bimetallism 189
Facies 160 Crosstalk 189
References and Bibliography 161 Magnetism 189
Influence of geological parameters on the SP 189
Chapter 7 Composition of the rock 189
Magnetic susceptibility and total magnetic field measurements Major minerals 190
163 Shales 190
Introduction 163 The fluids 190
Review of fundamental geological notions 164 Rock texture 190
Magnetism 164 Temperature 191
Diamuagnetism 164 Pressure 191
Paramagnetism 165 Facies, sequence and depositional environment 191
Ferromagnetism 165 Applications 191
The Earth’s magnetic field 165 References and Bibliography 192
Origin of the Earth’s magnetic field 165
Components of the magnetic field 166 Chapter 9
Secular variations 166 Generalities on nuclear measurements 195
Polarity inversions 167 Introduction 195
Rock magnetization 167 Review of fundamental notions 195
Behavior of magnetic materials 167 Radiation interactions 197
Different modes of paleofield acquisition 168 Gamma ray interactcions 197
Thermal Remanent Magnetism (TRM) 168 Pair production 197
Isothermal Remanent Magnetism (IRM) 168 Compton scattering 198
Depositional Remanent Magnetism (DRM) 168 Photoelectric effect 199
Chemical Remanent Magnetism (CRM) 169 Gamma ray detectrors 199
Viscous Remanent Magnetism (VRM) 169 Geiger-Mueller counter 199
Components of magnetization 169 Ionization chamber 199
Natural magnetic minerals 169 Scintillation counter 200
Measurement principle 170 Scintillation detector quality 201
Measurement of the magnetic field 170 Semiconductor detectors 202
Magnetometers 170 Recording capability 203
lnductometers 170 Statistical variations 203
Measurement of the magnetic susceptibility 170 Poisson distribution 203
The GHMT sonde 171 Gaussian distribution 203
The SUMT sonde 171 Dead-time effect 204
The NMRT sonde 172 Logging speed effect 205
Data interpretation 173 Bed thickness 206
Method of the Coefficient C 174 Measuring point 207
Environmental influences 175 Measurement uncertainty 207
Mud polution 175 References and Bibliography 207
Casing proximity 175
Applications 176 Chapter 10
Datation 176 Generalities on natural radioactivity 209
Determination of the sedimentary rate 176 Definition 209
Lithology evaluation 176 Review of basic concepts 209
Borehole image 177 a - radiation 209
References and Bibliography 177 p - radiation, p+ or p- 210
y - radiation 210
Chapter 8 Radioactive decay 21 1
Spontaneous Potential measurement 179 Radioactive equilibrium 212
Introduction 179 The units of radioactivity 212
Measurement principle 179 The origin of natural radioactivity in rocks 214
Origin of the spontaneous potential 179 Minerals and rocks containing radioactive elements 214
The origin of the electrokinetic potential 180 Potassium-bearing minerals and rocks 214
Electrokinetic potential through the mud-cake 180 Uranium-bearing minerals and rocks 215
Electrokinetic potential through the shales 180 Solubility of uranium 216
Electrokinetic potential through permeable formations 181 Transport mechanisms 216
The origin of the electrochemical potential 183 Thorium-bearing minerals and rocks 218
Liquid junction or diffusion potential : EJ 183 Summary 219
Membrane potential : EM 184 References and Bibliography 219
The electrochemical potential : E , 184
Chapter 11
Ionic activity, concentration, and resistivity 184
Total Natural Radioactivity measurement 221
The static SP 185
Introduction 221
Amplitude and shape of the SP curve 186
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Measurement principle 22 1 Measurement of the photoelectric index 258
Response of the tool 221 Principle of measurement 258
Tools 223 Definition of the photoelectric absorption index 259
Units 223 Photoelectric index of a composite mterial 259
Measuring point 223 Sources of gamma rays 260
Depth of investigation 224 Detectors 260
Vertical resolution 224 Calibrations. Units 260
Factors affecting the gamma ray response 225 Tools 261
Statistical variations 225 Wireline tools 26 1
Logging speed 225 Logging while drilling tools 266
Hole condition effects 225 Sampling rate 267
Hole fluid 225 Depth of investigation 268
Tubing, casing, etc. 226 Vertical resolution 268
Cement 226 Measure point 268
Bed thickness 226 Fundamental factors affecting the measurements 268
Calibrations 227 Statistical variations 268
Applications 228 Borehole 268
Lithology determination 228 Nominal diameter of the hole 268
Sedimentology 228 Nature of the drilling fluid 269
Well-to-well correlations 228 Nature of the borehole wall 269
Detection of unconformities or transgressions 228 Presence of mud-cake 270
Tectonic applications 228 Presence of casing 270
Estimation of shale fraction of reservoir rocks 229 Invasion 270
Depth control of sampling, perforating and testing equipment 229 Effect of deviation 271
The evaluation of injection profile 230 Effect of the tool rotation in the case of a measurement while
References and Bibliography 230 drilling 271
Geological factors influencing measurements 272
Chapter 12 Clays 272
Spectrometry of natural radioactivity 231 Water 273
Introduction 231 Hydrocarbons 273
Measurement principle 232 Interpretation of the density measurement 274
Logging tools 232 Interpretation of the photoelectric index 274
Detectors 233 Geological factors affecting the measurements 275
Calibration 236 Rock composition 275
Depth of investigation 238 Rock texture 275
Vertical resolution 238 Bed thickness 276
Environmental and other effects on the measurement 238 Temperature 277
Time constant (vertical smoothing), logging speed, dead time 238 Pressure 277
The borehole 238 Depositional environment. Sequential evolution 277
Tool position 238 Applications 277
Casing 238 Geophysical applications 277
Bed thickness 239 Petrophysicala pplications 278
Fundamental geological factors influencing the measurements 239 Geological applications 278
Computation of Th, U and K content 240 Lithology determination 278
Filtering 240 Mineralogical composition of the formation 278
Applications - Interpretation 240 Study of diagenesis and compaction 278
Lithology 240 Sedimentological studies: determination of the depositional
Evaporitic environment 240 environment 280
Sand-sahle series 24 1 Detection of fractures 280
Carbonate series 246 Dip measurement 280
Well-to-well correlations 247 References and Bibliography 281
Detection of unconformities 247
Fracture and stylolite detection 248 Chapter 14
Hydrocarbon potential 248 Generalities on neutron physics 283
Igneous rock recognition 248 Introduction 283
Sedimentology 249 Definition 283
Diagenesis 250 Classification 283
Estimation of the uranium potential 250 Types of interaction 283
An approach to the cation exchange capacity 250 Interactions with fast neutrons 284
Radioactive scaling 250 Nuclear reactions 285
References and Bibliography 250 Radioactivation 285
Elastic scattering 286
Chapter 13 The slowing-down phase 286
Density and photoelectric index measurements 253 Diffusion phase 288
Introduction 253 Absorption phase 289
Physical principles of measurements 253 Thermal-neutron capture 289
Pair production 253 Delayed thermal activation 290
Compton scattering 254 Summary 290
Photoelectric effect 254 Cross-sections 290
Measurements realized in wells 256 Neutron sources 292
Density measurement 256 Chemical sources 292
Principle of measurement 256 Interaction of a particles with target element (Be) 292
Equation of attenuation 256 Californium source 293
Relationship between the electronic density and the bulk density 257 Particle accelerators 293
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Neutron detectors 293 Reservoir analysis by spectrometry 329
Neutron-based measurements 294 Measured spectra 329
References and Bibliography 294 Measuring techniques -The window method 330
The carbon/oxygen tool 331
Chapter 15 Interpretation 331
Neutron porosity measurements 297 Overlay technique 332
Introduction 297 Environmental effects 332
Measurement principle 297 Fluid salinity 332
Spatial distribution of neutrons and capture gamma rays 298 Hydrocarbon density 332
Different types of neutron tools 30 1 Shaliness 332
The neutron-epithermal neutron tools 30 1 Coal 333
The neutron-thermal neutron tools 302 The “Weighted least-squares’’ (WLS) method - The Gamma
The neutron-gamma tools 302 Spectrometer Tool (GST) 333
Calibration and units 303 GST measurement system 333
Neutron tools 303 WLS spectral analysis 334
Historical tools 303 Reprocessing of data 334
GNT (Gamma-ray/Neutron Tool) 303 Interpretation 335
SNP (Sidewall Neutron Porosity tool) 304 Hydrocarbon saturations from the C and 0 yields 335
CNT (Compensated Neutron Tool) 304 The yield ratios as qualitative indicators 337
Modern Wireline tools 305 Summary of environmental effects 337
Logging While Drilling neutron tools 307 High Resolution Spectroscopy (HRS) 339
Tool characteristics 308 Geochemical Logging Tool (GLT) 339
Depth of investigation 308 Recent tools 342
Vertical resolution 310 Elemental Capture Spectroscopy (ECS*) 342
Measuring point 310 Reservoir Saturation Tool (RST’) 343
Factors influencing the measurement 310 Interpretation 344
Element composition of the rocks 310 Reservoir Performance Monitor (RPM) 345
Hydrogen 310 Multiparameter Spectroscopy Instrument (MSI) 345
Presence of neutron absorbers 31 1 Pulsed Spectral Gamma (PSGTMt)o ol 346
Mineral composition of the rocks 31 1 Reservoir Monitor Tool (RMTTM) 346
Solid fraction (matrix of log analysts) other than shale 31 1 Applications 346
Clays, shales, or micas, etc 312 Geological applications 346
Porosity 312 Detailed mineralogy 346
Fluid salinity 312 Source-rock evaluation 349
Hydrocarbons 31 2 Coal evaluation 349
Environmental effects 314 Grain size 350
Time-constant, logging speed, dead-time, bed thickness 314 Petrophysical applications 350
Borehole effects 314 Quantitative evaluation of reservoirs 350
Mud-type 314 Saturation computation 351
Hole diameter 314 Permeability evaluation 351
Tool positioning 314 Shaliness 352
Mud-cake 315 Cation Exchange Capacity (CEC) evaluation 352
Cased hole 31 5 Computation of the density of the solid fraction 352
Summary 31 5 References and Bibliography 354
Invasion 316
Interpretation 316 Chapter 17
Early neutron tools (API logging units) 316 Thermal neutron die-away measurements 357
Modern tools 31 7 Introduction 357
The neutron response equation 31 7 Physical principle of measurement 357
Geological factors affecting the hydrogen index 31 7 Neutron capture 357
Lithology and pore-fluids 31 7 The exponential decay 357
Rock texture 31 7 Neutron diffusion 359
Temperature 317 Measuring the neutron population 359
Pressure 317 Measurement of capture cross-section 360
Depositional environment, sequential evolution 31 7 Old tools 360
Applications 317 Neutron Lifetime Log (NLL) 360
References and Bibliography 319 Schlumberger tools 360
TDT-K 36 1
Chapter 16 TDT-M 361
Spectrometry of induced gamma rays 32 1 Modern tools 362
Introduction 32 1 Dual-Burst* TDT* 362
Induced gamma ray techniques 323 Thermal Multigate Decay-Lithology (TMD-LTM) 364
Fast neutron interactions 323 PDK-100 364
Inelastic scattering 323 Other data on the tools 364
Nuclear reactions 324 Recording speed 364
Radioactivation 325 Spacing 364
Thermal-neutron capture 326 Vertical resolution 364
Delayed thermal activation 327 Depth of investigation 364
Old wireline tools 327 Units 364
Principle of chlorine log 327 Measure point 365
Measurement characteristics 327 Calib rations 365
Interpretation 328 Factors influencing the 2 measurement 365
The shale compensated chlorine log (SCCL) 328 The solid fraction or matrix (Zma) 365
Applications 329
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VI Well Logging Data Acquisition and Applications
Porosity - Fluids 366 Textural information 395
Formation water (z) , 366 References and Bibliography 396
Hydrocarbons (zhY) 367 Chapter 19
Shales 368 Generalities on acoustic measurements 399
Acidization 368 Introduction 399
Envionmental effects 368 Acoustic sources - Transducers 399
Borehole signal 368 Monopole source 399
Diffusion 368 Dipole source 400
Borehole configuration 369 Quadrupole sources 401
Fluids 369 Acoustic signals 401
Casing 369 Period 401
Hole-size 369 Frequency 401
Tool eccentralization 369 Wavelength 401
Invasion 369 Acoustic waves 401
Time constant, logging speed, bed thickness and Bulk or body waves 401
vertical resolution 369 Compressional or longitudinal waves 401
Geological factors affecting the S measurement 369 Transverse or shear waves 402
Composition of the rock 369 Surface waves 402
Rock texture 369 Waveform 403
Temperature 370 Acoustic propagation in the borehole 403
Pressure 370 Acoustic Receivers 404
Porosity 370 Elastic properties of rocks 404
Applications 370 Sound wave velocities 405
Petrophysics 370 Sound wave propagation - Reflection and refraction 405
Saturation evaluation 370 Acoustic impedance 406
Response equations 371 Reflection coefficient 406
Time lapse - Reservoir monitoring 372 Wave interference - Dispersion 406
Gas indication from the count-rates 374 Acoustic parameters 408
Residual oil saturation 374 References and Bibliography 408
Formation fluid 374
Old wells 374 Chapter 20
Porosity evaluation 374 Sonic transit time measurement 409
Geology 374 Brief historical review 409
References and Bibliography 374 Measurement principle 409
The BoreHole Compensated (BHC) sonde 412
Chapter 18 Modern wireline sondes 412
Nuclear magnetic resonance measurements 377 The Long Spacing Sonic (LSS*) tool 413
Introduction 377 Array-Sonic* Service (ASS) 414
Relaxation mechanisms 380 Low Frequency Dipole Tool (LFDTTM) 415
Grain surface relaxation 380 Multipole Acoustic Logging Service 416
Relaxation by molecular diffusion in magnetic field gradients 380 Multipole Array AcoustilogSM (MAC) 416
Bulk fluid relaxation 380 Cross-Multipole Array Acoustilog (XMACSM) 416
Relaxation processes summary 381 Logging While Drilling Sondes 416
The sondes 381 Waveform processing of wireline data 417
History 381 Digital First Motion Detection (DFMD) processing 417
NMT-C tool 38 1 Slowness-Time-Coherence processing 417
Description 381 Dipole waveform processing 418
Method of measurement 382 Borehole compensation 419
Signal processing 382 Factors affecting the measurements 419
Modern tools 383 Lithology influence 419
CMR* (Combinable Magnetic Resonance) tools 383 Porosity and fluids 419
MRlL tools 387 Temperature and pressure 419
MRIL-WD 388 Texture 42 1
Geological factors influencing the NMR measurement 389 Environmental effects on acoustic measurements 422
Mineral composition - Shale 389 Transit time stretching 422
Fluids 389 Cycle skipping 422
Bound water 389 Kicks to smaller At 422
Oil 389 The borehole 423
Gas 389 Hole size 423
Free water 389 The drilling mud 423
Texture 389 Invasion 423
Temperature 389 Radial cracking effects 424
Applications 390 Travel time integration 424
Petrophysics 390 Interpretation 425
Porosity determination 390 Sonic Rescaling 427
Pore size determination and distribution 391 Applications 429
Permeability estimation 392 Geological applications 429
Determination of hydrocarbon characteristics 393 Lithology determination 429
Well producibility 393 Compaction study 430
Irreducible water saturation determination 393 Maximum depth of burial 431
Predicting reservoir flow 394 Maturation of the organic matter 431
Residual oil saturation 394 Fracture detection 431
Geology 395 Petrophysical applications 431
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Geophysical applications 432 Intrusions 476
Determination of rock elastic parameters 433 Geometrical representation of structures 476
References and Bibliography 434 Stereonet projection 476
Principle 476
Chapter 21 Planes and lines on a stereonet 477
Sonic amplitude and attenuation measurements 437 Structures on stereonet 478
Introduction 437 Cross-section 479
Theoretical causes of attenuation 437 Block diagram 479
Loss of energy through heat flow 437 Texture 479
Solid-to-solid friction 437 Textural components 479
Solid-to-fluid friction 437
Fluid-to-fluid friction 437 Chapter 24
Redistribution of energy 437 “Dip” and image acquisition, interpretation and applications 483
Transfers along the media limits 437 Introduction 483
Transfers across media boundaries 438 Principle of the well logging method 483
Dispersion 438 GPlT General Purpose lnclinometry Tool 485
Causes of attenuation in the borehole 438 lnclinometry 485
Open hole 438 Depth or speed variation 486
Attenuation in the mud 438 Borehole geometry 486
Attenuation by transmission of energy 439 Depth of investigation (electrical diameter) 486
Attenuation in the rock 439 Wireline “dipmeter” tools 487
Cased hole 440 Short history 487
Measurement of attenuation 440 Dual dipmeter 488
Cement Bond Log 440 HDT High resolution Dipmeter Tool 490
Attenuation index 443 The six arms tools 491
Expression of the law of attenuation in open hole 444 OBDT* Oil-Base Dipmeter Tool 49 1
Variable Density Log (VDL) 444 Wireline imaging tools 492
Detection of fractures 446 Micro-resistivity images 492
Effects on body waves 447 Formation Microscanner tool (FMS) 493
Arrival time 448 FMI* (Formation Microlmager) tool 493
Attenuation of body waves 448 The EM1 (Electrical Micro Imaging) tool 495
Normalized Differential Energies (NDE) 448 The Oil-Base Mud Imager (OBMI’) 495
Amplitude spike analysis 448 EARTH ImagerTM 498
Crisscross patterns 448 Wireline macro-resistivity images 498
Effects on Stoneley waves 449 ARI” Azimuthal Resistivity Imager 499
Stoneley reflections 449 PLATFORM EXPRESS* integrated wireline logging tool 499
References and Bibliography 450 Wireline acoustic image tools 500
BoreHole Televiewer (BHTV) 500
Chapter 22 Acoustic TeleScanner* tool 502
Well seismic techniques 453 UBI* Ultrasonic Borehole Imager 502
Introduction 453 The STAR Imager tool 503
Measurement principle 453
Circumferential Borehole Imaging Log (CBILTM) 504
Zero-offset VSP 454
The CAST-V tool 504
Offset VSP 454
Magnetic susceptibility sonde 504
Walkaway VSP 455
Downhole Video Services 504
Walk-above VSP 455
Logging While Drilling imaging tools 505
Salt-Proximity VSP 455
RAB* Resistivity-At-the-Bit tool 505
Drill-noise VSP or seismic-while-drilling 456
The ADN tool 506
Shear-wave VSP 456
Multiwell VISION system 507
Tools 456
Comparison of the three imaging techniques 507
Data recording 457
Processing of the raw dipmeter and image data 508
Data processing 458
Introduction 508
Signal-based method 458
Corrections of raw data 509
Model-based method 459
Speed and depth corrections 509
Wave equation method 459
Direct application of measured z-axis acceleration 509
Array Seismic Imager (ASI*) 459
Speed buttons 509
Combinable Seismic Imager (CSI*) 459
Image-based depth correction 51 0
Applications 459
Current intensity correction 51 1
References and Bibliography 462 Gain and offset equalization - dead button correction 51 1
Scaling (resistivity calibration) 51 1
Chapter 23
Electrical effects which control dipmeter and image-too response s at
Generalities on rock texture and structure determination 465
each level 51 2
Introduction - Review of geological principles 465
High-resolution Component 51 2
Stratigraphy, structure and texture 465
Low-resolution component 512
Stratum, bed and lamina 465
Choosing a calibration reference 512
Surface and plane 466
Calibration procedure for the FMllFMS images 513
Structure classification and description 466
SYNRES 513
Primary sedimentary structures 467
Normalization 513
Secondary sedimentary structures 471
Conversion of current intensity to images 513
Disconformities 471
Static normalization 514
Structures generated by stress action 471
Dynamic normalization 514
Folds 472
Processing for electrical image generation at wellsite 515
Faults 473
Dip computation from dipmeter data 515
Fractures 475
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