1 Introduction ................................................. 1
1.1 Introduction ............................................ 1
1.2 Oil and Natural Gas ..................................... 4
1.3 Coal Energy ............................................. 8
1.3.1 Coal Gasification ................................ 9
1.3.2 Coal Liquefaction ............................... 10
1.3.3 Coal Bed Methane ................................ 10
1.4 Geothermal Energy ...................................... 11
1.5 Nuclear Energy ......................................... 14
1.6 Nuclear Fusion ......................................... 16
1.7 Renewable Energy ....................................... 17
1.7.1 Hydropower ...................................... 17
1.7.2 Solar Energy .................................... 19
1.7.3 Bio-Energy ...................................... 21
1.7.4 Wind Energy ..................................... 22
1.7.5 Tidal Energy .................................... 24
1.7.6 Waves Energy .................................... 25
References .................................................. 27
2 World's Oil and Natural Gas Scenario ........................ 29
2.1 Introduction ........................................... 29
2.2 Oil Scenarios .......................................... 33
2.3 Natural Gas ............................................ 37
2.3.1 Natural Gas Scenario ............................. 39
2.4 Unconventional Oil ..................................... 41
2.4.1 Shale Oil ........................................ 43
2.5 Unconventional Gas ..................................... 43
2.5.1 Tight Sands ..................................... 44
2.5.2 Shale Gas ....................................... 44
2.5.3 Geopressured Zones .............................. 44
2.6 Hydrogen ............................................... 45
References .................................................. 46
3 Gas Hydrates ................................................ 49
3.1 Introduction ........................................... 49
3.2 What Are Gas Hydrates? ................................. 50
3.3 Crystal Structure ...................................... 52
3.4 Where Gas Hydrates Are Found? .......................... 54
3.5 Gas Hydrates Indicators ................................ 59
3.5.1 Geophysical Signatures .......................... 59
3.5.2 Geological Proxies .............................. 61
3.5.3 Geochemical Evidences ........................... 62
3.5.4 In-Situ Measurements ............................ 63
3.6 Possible Resource Estimates ............................ 66
References .................................................. 68
4 Stability Conditions ........................................ 73
4.1 Introduction ........................................... 73
4.2 Availability of Methane ................................ 74
4.3 Pressure-Temperature Conditions ........................ 75
4.3.1 Hydrostatic Pressure ............................ 76
4.3.2 Hydrothermal Gradients .......................... 76
4.3.3 Geothermal Gradients ............................ 77
4.4 Gas Hydrate Stability Zone ............................. 78
4.4.1 Salinity ........................................ 80
4.4.2 Gas Composition ................................. 81
4.4.3 Solubility of Methane ........................... 84
4.4.4 Geological Controls ............................. 85
4.5 Planetary Hydrates ..................................... 87
4.6 Climatic Impact ........................................ 87
4.7 Geological Hazards ..................................... 91
References .................................................. 93
5 Geological Indicators ....................................... 99
5.1 Introduction ........................................... 99
5.2 Geological Indicators ................................. 100
5.2.1 Distribution and Variability of BSR ............ 102
5.2.2 Sediment Deposition and Distribution ........... 112
5.2.3 Diapirism ...................................... 119
5.2.4 Fluid Migration Features ....................... 122
References ................................................. 125
6 Geophysical Indicators ..................................... 129
6.1 Introduction .......................................... 129
6.2 Geophysical Indicators ................................ 130
6.2.1 The Bottom Simulating Reflectors ............... 131
6.2.2 Enhanced Seismic Reflections Below BSR ......... 131
6.2.3 Seismic Chimney and Amplitude Blanking ......... 132
6.2.4 Hydrate Mounds ................................. 133
6.2.5 Instantaneous Seismic Attributes ............... 137
References ................................................. 139
7 Geophysical Surveys and Data Analysis ...................... 143
7.1 Introduction .......................................... 143
7.2 2D/3D Conventional Seismic Surveys .................... 145
7.3 4C Ocean Bottom Seismic Surveys ....................... 147
7.3.1 Patterns in Travel Time for Ocean Bottom
Seismometer Experiments ........................ 149
7.3.2 Example of 4C Seismic Experiment ............... 152
7.4 Vertical Seismic Profile Surveys ...................... 156
7.4.1 The Beginning Point: Zero Offset VSP ........... 157
7.4.2 Walk-Away VSP .................................. 159
7.4.3 Cross-Well Seismic Surveys (CSP) ............... 161
7.4.4 Some Remarks ................................... 164
7.5 Marine Controlled-Source Electromagnetic Methods
(CSEM) ................................................ 165
7.6 Seismic Data Analysis for Gas Hydrate
Characterization ...................................... 171
7.6.1 Patterns in Synthetic Seismograms for Gas
Hydrates ....................................... 174
7.6.2 Converted Wave Velocity Model for Gas Hydrate
Studies ........................................ 191
7.6.3 Processing of 4C OBS Data for Gas Hydrate
Studies ........................................ 197
7.7 Log Responses for Gas Hydrates ........................ 197
7.7.1 Electrical Resistivity Log Response ............ 198
7.7.2 Spontaneous Potential Log Response ............. 199
7.7.3 Caliper Log Response ........................... 200
7.7.4 Sonic Log Response ............................. 202
7.7.5 Neutron Log Response ........................... 203
7.7.6 Density Log Response ........................... 204
7.7.7 Some Remarks ................................... 204
References ................................................. 205
8 Identification to Quantification of Gas Hydrates ........... 211
8.1 Introduction .......................................... 211
8.2 Regional Mapping of Gas Hydrates ...................... 213
8.2.1 An Example from Kerala-Konkan (KK) Basin
Offshore India ................................. 214
8.2.2 Some Remarks ................................... 217
8.3 Amplitude Strength .................................... 221
8.3.1 Some Remarks ................................... 224
8.4 Amplitude vs. Offset Characteristics .................. 225
8.4.1 Calculation of Synthetic Seismogram and
Reflection Coefficient ......................... 226
8.4.2 Some Remarks ................................... 230
8.5 Seismic Attributes .................................... 231
8.5.1 Reflection Strength ............................ 232
8.5.2 Reflection Strength for Constant Thickness of
Hydrate Layer with Different Thickness of
Free Gas Layers ................................ 232
8.5.3 Reflection Strength for Constant Thickness of
Free Gas Layer with Different Thickness of
Gas Hydrate Layers ............................. 234
8.5.4 Example from Andaman Offshore Region, India .... 235
8.5.5 Example from Offshore Australia ................ 236
8.5.6 Instantaneous Frequency ........................ 238
8.5.7 Instantaneous Frequency for Constant
Thickness of Hydrate Layer with Different
Thickness of Free Gas Layers ................... 242
8.5.8 Instantaneous Frequency for Constant
Thickness of Free Gas Layer with Different
Thickness of Gas Hydrate Layers ................ 242
8.5.9 Example from Andaman Offshore Region, India .... 242
8.5.10 Example from Offshore Australia ................ 243
8.5.11 Some Remarks ................................... 245
8.6 Quantification Methods ................................ 245
8.6.1 Detection and Estimation of Gas Hydrates by
Rock Physics and Inversion ..................... 246
8.6.2 Estimating Volumetric Concentration of Gas
Hydrates by Modified Wood Equation ............. 249
8.6.3 Example from KG Basin India (NGHP
Expedition-01) ................................. 254
8.6.4 Integrating Geochemical and Geophysical
Methods for Gas Hydrates Characterization ...... 255
8.6.5 Waveform Inversion for Gas Hydrates ............ 257
References ................................................. 259
9 The Road Ahead ............................................. 265
9.1 Introduction .......................................... 266
9.2 Stability ............................................. 266
9.3 Bottom Simulating Reflector ........................... 268
9.4 Blanking .............................................. 270
9.5 Inferences from Velocities ............................ 271
9.6 AVO Modeling .......................................... 272
9.7 Seismic Data Acquisition .............................. 273
References ................................................. 274
Index ......................................................... 277
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