Professional Level Rock Physics for Seismic Amplitude Interpretation

Professional Level Rock Physics for Seismic Amplitude Interpretation......Page 1
1. Introduction......Page 3
2. Fundamentals......Page 8
2.1 Seismic Basics......Page 10
2.2 Approach to Seismic Modelling......Page 13
Aspects of Seismic Amplitude Interpretation......Page 14
2.3 Elastic Parameters......Page 17
2.4 Modelling Seismic Reflectivity......Page 20
2.5. Types of Seismic Models......Page 25
2.6. Relating Seismic Data to Models......Page 26
3. Rock Properties and AVO......Page 32
3.1 AVO Response Description......Page 34
Practical Polarity Conventions  and AVO Classes......Page 36
3.2 Rock Property Controls on AVO......Page 40
4. Rock Physics, AVO and Seismic Interpretation......Page 52
4.1. Seismic Interpretation and AVO......Page 54
4.2 Trend Curves and the Stratigraphic Context of AVO Models......Page 57
4.3 Some Examples......Page 58
5. Characteristics of Seismic Wavelets......Page 66
5.1 Seismic Data - Bandwidth and Phase......Page 68
5.2 Zero Phase and Minimum Phase......Page 69
5.4 Idealized Wavelets......Page 70
5.5. Wavelet Phase and Processing......Page 71
5.7 Enhancing Frequency Content......Page 72
6. Resolution......Page 74
6.1 The Problem of Interference......Page 76
6.2 Temporal Resolution......Page 77
6.4 Vertical Resolution and Depth......Page 79
6.5 The Effect of Wavelet Shape and Filter Slopes on Resolution......Page 80
6.6 Thickness Prediction from Seismic......Page 81
6.7 Net Pay Prediction in Isolated Thin Beds......Page 82
6.8 Lateral Resolution......Page 83
6.9 Resolution - Sections vs. Maps......Page 84
7. Well Ties......Page 86
7.1 The Well Tie Process......Page 88
7.2 A Quantitative Approach to Well Ties......Page 91
7.3 The Need for Precision in Well Ties - two examples......Page 95
7.4 Practical Issues......Page 96
8. Deriving Inputs forSeismic Models......Page 104
8.1 Introduction......Page 106
8.2 Gassmanns' Equation......Page 108
8.3 Gassmann with Log Data - a General Workflow......Page 110
8.4 Practical Gassmann Scenarios......Page 139
8.6 A Discussion of Rock Models......Page 148
8.7 Log Editing......Page 154
9. Detailed SeismicModelling......Page 162
9.1 Discussion......Page 164
10. Seismic TraceInversion......Page 170
10.2 Seismic Data and Bandlimited Impedance......Page 172
Polarity Conventions......Page 176
10.3. Towards Absolute Impedance from Seismic......Page 181
10.4 Broadband Inversion......Page 183
10.5 Interpretation Issues......Page 192
11. AVO Analysis......Page 194
11.1 Introduction......Page 196
11.2 Conventional Intercept-Gradient AVO Analysis......Page 197
11.3 Seismic Processing Issues......Page 216
11.4 Other Reflectivity Techniques......Page 223
11.5 Elastic Inversion......Page 228
12. Rock Physics and Probability......Page 244
12.1 Introduction......Page 246
12.2 A Workflow......Page 247
13. Rock Physics and Time Lapse Seismic......Page 258
13.1 Introduction......Page 260
13.2 Which Reservoirs are Candidates for Time-lapse?......Page 261
13.3 Two Important Rock Physics Issues......Page 265
14. Anisotropy......Page 272
14.1 Types of Anisotropy - What is Anisotropy?......Page 274
14.3 VTI in Real Rocks......Page 276
14.4 Effect of VTI on Seismic Imaging......Page 278
14.5 Effect of VTI on Seismic Amplitude......Page 281
14.6 Another Complication - Attenuation......Page 282
14.8 Azimuthal Anisotropy and the Phenomonen of Shear Wave Splitting......Page 283
14.9 P Wave Exploitation of Azimuthal Anisotropy (AVZ, AVOA, AVAZ, AVO)......Page 285
15. Issues in Applying Rock Physics in Prospect Evaluation......Page 288
15.2 Amplitude (DHI) Interpretation......Page 290
15.3 Amplitudes in the Risking Context......Page 293
15.4 Comments on DHI Risking......Page 299
15.5 A Risking Dilemma - Geology vs. Geophysics......Page 304
16. Exercises......Page 306
16.1 Quick-look workflow (Well H)......Page 308
16.2 Log Conditioning and Modelling Workflow (Well R)......Page 312
16.3 Forward modelling using the Xu_White Model......Page 317
16.4 20 AVA modelling - lithology and fluid......Page 318
16.5 Elastic inversion interpretation exercise......Page 321
16.6a Facies discrimination using two variables - using fuzzy logic with a test data set......Page 323
16.6b Acoustic facies discrimination using fuzzy logic......Page 325
16.6c Effect of low gas saturations on elastic attributes......Page 327
16.7 Time-Lapse Exercise......Page 328
16.8 Anisotropy (VTI) exercise......Page 330
17. Exercises - Answers......Page 332
16.1 Quick-look workflow (Well H)......Page 334
16.2 Log conditioning and modelling workflow......Page 336
16.3 Forward modelling using Xu-White......Page 337
16.4 20 AVA modelling - lithology and fluid......Page 338
16.5 Elastic inversion interpretation exercise......Page 339
16.6a Facies discrimination with two variables - using fuzzy logic with a test data set......Page 340
16.6b Acoustic facies discrimination using fuzzy logic......Page 341
16.6c Effect of low gas saturation on elastic attributes......Page 342
16.7 Time-lapse exercise......Page 343
16.8 Anistotropy (VTI) exercise......Page 344
18. References......Page 346
Section 2......Page 347
Section 3......Page 348
Section 5......Page 349
Section 7......Page 350
Section 8......Page 351
Section 10......Page 356
Section 11......Page 357
Section 12......Page 360
Section 13......Page 362
Section 14......Page 363
Section 15......Page 365