Preface ...................................................... xiii
Acknowledgments .............................................. xvii
Part I The basics .............................................. 1
1 Forward modeling of seismic reflections for rock
characterization ............................................. 3
1.1 Introduction ............................................ 3
1.2 Quantifying elastic properties of earth by forward
modeling: a primer ...................................... 4
1.3 Quantifying rock properties by forward modeling:
a primer ................................................ 9
1.4 Rock physics transforms: a primer ....................... 9
1.5 Synthetic seismic catalogues ........................... 10
2 Rock physics models and transforms .......................... 13
2.1 Rock physics transforms ................................ 13
2.2 Elastic constants ...................................... 13
2.3 Solid phase ............................................ 14
2.4 Fluid phase ............................................ 16
2.5 Fluid substitution ..................................... 18
2.6 The Raymer-Hunt-Gardner transform ...................... 22
2.7 Other 5-wave velocity predictors ....................... 24
2.8 Contact-cement model ................................... 26
2.9 Soft-sand model ........................................ 28
2.10 Stiff-s'and model ...................................... 29
2.11 Constant-cement model .................................. 30
2.12 Inclusion models ....................................... 31
2.13 Summary of the models .................................. 34
2.14 Properties of the pore fluid phases .................... 35
2.15 A note on effective and total porosity and fluid
substitution ........................................... 35
2.16 Example of applying rock physics models to simulate
seismic amplitude ...................................... 41
3 Rock physics diagnostics .................................... 43
3.1 Quantitative diagnostics ............................... 43
3.2 Qualitative diagnostics: staring at the data ........... 47
3.3 Word of caution when using well data ................... 49
Part II Synthetic seismic amplitude ........................... 51
4 Modeling at an interface: quick-look approach ............... 53
4.1 Reflection modeling at an interface: the concept ....... 53
4.2 Normal reflectivity and reflectivity at an angle ....... 53
4.3 Forward modeling using elastic constants ............... 56
4.4 Forward modeling directly from rock properties ......... 60
5 Pseudo-wells: principles and examples ....................... 68
5.1 Sandwich (three-layer) model ........................... 68
5.2 Geologically consistent inputs ......................... 72
5.3 Depth and compaction ................................... 83
6 Pseudo-wells: statistics-based generation ................... 90
6.1 Introduction ........................................... 90
6.2 Monte Carlo simulation ................................. 91
6.3 Monte Carlo simulation with spatial correlation ........ 92
6.4 Monte Carlo simulation within facies ................... 97
6.5 Stochastic simulation of related variables ............. 98
6.6 Examples and sensitivity analysis ..................... 100
6.7 Pseudo-logs of facies ................................. 102
6.8 Spatial simulation of rock properties and
reflections ........................................... 106
Part III From well data and geology to earth models and
reflections ................................................... 113
7 Clastic sequences: diagnostics and Vs prediction ........... 115
7.1 Unconsolidated gas sand ............................... 115
7.2 Consolidated cemented gas sand ........................ 125
8 Log shapes at the well scale and seismic reflections in
clastic sequences .......................................... 132
8.1 Examples of shapes encountered in clastic sequences ... 132
8.2 Typical shapes and pseudo-wells in clastic sequences .. 137
9 Synthetic modeling in carbonates ........................... 153
9.1 Background and models ................................. 153
9.2 Laboratory and well data .............................. 157
9.3 Pseudo-wells and reflections .......................... 159
10 Time lapse (4D) reservoir monitoring ....................... 165
10.1 Background ............................................ 165
10.2 Fluid substitution on velocity-pressure data .......... 169
10.3 Synthetic seismic gathers ............................. 172
10.4 Conclusion ............................................ 175
Part IV Frontier exploration ................................. 177
11 Rock-physics-based workflow in oil and gas exploration ..... 179
11.1 Introduction .......................................... 179
11.2 Rock physics modeling for amplitude calibration ....... 180
11.3 Log and seismic quality control and conditioning ...... 181
11.4 Velocity in exploration seismology .................... 182
11.5 Time-to-depth calibration ............................. 183
11.6 Rock typing ........................................... 185
11.7 Seismic forward modeling .............................. 185
11.8 Rock property upscaling ............................... 186
11.9 Depth trends, rock physics diagnostics, and model
formulation ........................................... 187
11.10 Using trends at prospect location .................... 194
12 DHI validation and prospect risking ........................ 197
12.1 Introduction .......................................... 197
12.2 Feasibility studies ................................... 197
12.3 Recognition of seismic anomalies ...................... 198
12.4 DHI validation and prospect risking ................... 199
Part V Advanced rock physics: diagenetic trends, self-
similarity, permeability, Poisson's ratio in gas sand,
seismic wave attenuation, gas hydrates ........................ 205
13 Rock physics case studies .................................. 207
13.1 Universality of diagenetic trends ..................... 207
13.2 Self-similarity in rock physics ....................... 212
13.3 Elastic properties of rock and its permeability ....... 218
13.4 Stratigraphy-constrained rock physics modeling ........ 220
14 Poisson's ratio and seismic reflections .................... 225
14.1 The high Poisson's ratio issue in gas sand ............ 225
14.2 Physics-based explanations ............................ 229
14.3 But how much does it really matter? ................... 237
15 Seismic wave attenuation ................................... 239
15.1 Background and definitions ............................ 239
15.2 Attenuation and modulus (velocity) dispersion ......... 241
15.3 Q data ................................................ 243
15.4 Modulus dispersion and attenuation at partial
saturation ............................................ 244
15.5 Modulus dispersion and attenuation in wet rock ........ 252
15.6 Examples .............................................. 254
15.7 Effect of attenuation on seismic traces ............... 255
15.8 Approximate theory of S-wave attenuation .............. 256
16 Gas hydrates ............................................... 262
16.1 Background ............................................ 262
16.2 Rock physics models for sediment with gas hydrate ..... 264
16.3 Attenuation in sediment with gas hydrate .............. 269
16.4 Pseudo-wells and synthetic seismic in gas hydrates .... 273
Part VI Rock physics operations directly applied to seismic
amplitude and impedance ....................................... 275
17 Fluid substitution on seismic amplitude .................... 277
17.1 Background ............................................ 277
17.2 Primer: model-based reflection between two half-
spaces ................................................ 278
17.3 Model-based effect of thickness ....................... 279
17.4 Applying a model-based approach to a case study ....... 285
17.5 Lessons and conclusions ............................... 289
17.6 Practical application ................................. 291
18 Rock physics and seismically derived impedance ............. 292
Part VII Evolving methods .................................... 297
19 Computational rock physics ................................. 299
19.1 Third source of controlled experimental data .......... 299
19.2 Scale of experiment and trends ........................ 301
19.3 More examples ......................................... 304
19.4 Multiphase flow ....................................... 305
19.5 Conclusion ............................................ 307
Appendix: Direct hydrocarbon indicator checklist .............. 308
References .................................................... 312
Index ......................................................... 323
Color plates appear between pages 126 and 127.
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