Gas Migration (eBook)

Front Cover 1
Gas Migration: Events Preceding Earthquakes 4
Copyright Page 5
Contents 8
Foreword 14
Preface 16
Part I: Tectonics and Gas Migration 20
Chapter 1. Tectonics and Earthquakes 22
Introduction 22
Geologic Setting for Earthquakes 23
Summary 35
Chapter 2. Gas Migration at Plate Boundaries 36
Seeps 36
California Offshore Seeps 46
Relationship of Faults to Seeps 58
Chapter 3. Surface Soil—Gas Surveys 61
Introduction 61
Migration of Methane and Other Hydrocarbons 63
Helium and Hydrogen Gas Migration 73
Carbon-Dioxide Migration 80
Radon Gas Migration 87
Chapter 4. Southern California—Faults and Petroleum Reservoirs 93
Activity along the San Andreas Fault System 93
Southern California Faults 104
Los Angeles Basin Petroleum Deposits 106
Part II: Events Preceding Earthquakes 116
Chapter 5. Earthquake Precursors 118
Chapter 6. Occurrence and Consequences of Quakes 121
Introduction 121
Earthquakes in General 127
Chapter 7. Causes of Earthquakes 132
Introduction 132
Simple Models for Earthquakes 139
Chapter 8. Magnitude and Intensity of Earthquakes 152
Introduction 152
The Nature of Waves 152
Characteristics of Earthquake 154
Chapter 9. Forecasting Large Earthquakes 163
Introduction 163
Types of Forecasts 163
Chapter 10. Ancient Fortellers 176
Cosmic Events 176
Chapter 11. Messages from the Earth Crust 182
Introduction 182
Physical Models of Rupture 182
Tilt and Strain Observations 192
Discrete Structure of the Crust 195
Chapter 12. Fluids Talk 207
Hydrodynamic Anomalies 207
Chemistry of Groundwater 211
Chapter 13. Whispering Gases 213
Introduction 213
Radon Gas Concentration as a Precursor 214
Carbon Dioxide Gas Migration as a Precursor 218
Changes in Concentrations of Light Gases 221
Variations in Concentrations of Gases (Soil Air and Groundwater) Near Faults and Fractured Zones 223
Changes in the Performance of Oil Fields 224
Hydrocarbon Seepage in the Marine Environment 225
Primary Causes of Geochemical Anomalies 227
Chapter 14. Progress in Developing a Forecasting System, Preferential Precursors and Monitoring Network 228
Decision Making in Earthquake Prediction 228
Selection of Short-term Precursors 231
Development of a Monitoring Network 232
Identifying Distinct Patterns 233
Conclusions 237
Part III: Principles of Gas Migration 240
Chapter 15. Gas Migration 242
Introduction 242
Sources of Migrating Gases 243
Chapter 16. Typical Composition of Natural Gases 257
Introduction 257
Density of Natural Gases 259
Chapter 17. Mechanisms of Gas Migration 267
Introduction 267
Types of Gas Migration 267
Intergranular Flow: Gas Globules Larger than Pore Throat Diameters 275
Chapter 18. Paths of Gas Migration 283
Introduction 283
Pressure Determination 286
Chapter 19. Hazards Resulting from Migrating Gas 298
Introduction 298
Case Studies of Gas Migration 298
Chapter 20. Hazards of Gas Storage Fields 309
Introduction 309
Case Histories of Gas Migration Problems 221
Recommendations for Gas Storage 320
Part IV: Interrelationships Among Subsidence, Gas Migration, and Seismic Activity 326
Chapter 21. Interrelationships Among Subsidence, Gas Migration, and Seismic Activity 328
Introduction 328
Subsidence Due to Fluid Withdrawal 328
Compaction 331
Subsidence Bowl 331
Chapter 22. Subsidence Mechanics 333
Introduction 333
Changes in the Aquifer 337
Chapter 23. Fracturing Due to Subsidence 339
Rates of Subsidence 339
Stress and Strain Distribution in Subsiding Formations 340
Surface Fractures Caused by Subsidence 343
Chapter 24 .Water Aquifer Subsidence 346
Chapter 25. Technologically Induced Earthquakes 352
Chapter 26. Gas Migration in Seismically-Active Areas 354
Chapter 27. Joint Forecasting of Subsidence, Gas Migration, and Seismic Activity 356
Chapter 28 .Conclusions 359
References 361
Author Index 388
Subject Index 394
About the Authors 407