New Frontiers in Oil and Gas Exploration (eBook)

Preface 5
Contents 7
Chapter 1: Understanding Asphaltene Aggregation and Precipitation Through Theoretical and Computational Studies 9
1.1 Introduction 10
1.2 Experiment Studies 11
1.3 Theoretical Studies 15
1.3.1 Theoretical Modeling of Asphaltene Aggregation 15
1.3.2 Theoretical Modeling of Asphaltene Precipitation 16
1.3.2.1 Models Based on Colloidal Theory 17
1.3.2.2 Models Based on Solubility Theory 18
Models Based on Regular Solution Theory 19
Models Based on Equation of State Methods 24
1.4 Computational Studies 27
1.4.1 Studies Using QM Approach 33
1.4.2 Studies Using MM and MD Approaches 35
1.4.2.1 Studies Using MM Approach 35
1.4.2.2 Studies Using MD Approach 36
1.4.3 Studies Using Mesoscopic Simulation Techniques 42
1.5 Summary and Future Perspectives 43
References 43
Chapter 2: Advancement in Numerical Simulations of Gas Hydrate Dissociation in Porous Media 56
2.1 Introduction 57
2.2 Background 58
2.2.1 Introduction to Gas Hydrates 58
2.2.2 Existing Research on Gas Hydrates 59
2.2.3 Numerical Simulations of Gas Hydrates 61
2.3 Basic Mechanisms in Hydrate Disassociation: Governing Equation System 64
2.3.1 Basic Mechanisms Involved in Gas Hydrate Dissociation 64
2.3.2 A Unified Mathematical Framework for Different Mechanisms 66
2.3.3 Classification of Existing Methods 69
2.3.4 Comparison and Integration 71
2.3.4.1 Classifications Based on Criteria 1, 2, and 3 71
2.3.4.2 Classifications Based on Criteria 4 76
2.4 Materials Properties for Gas Hydrate Modeling: Auxiliary Relationships 78
2.4.1 Material Properties Related to Heat Transfer 79
2.4.1.1 Heat Capacity 80
2.4.1.2 Thermal Conductivity 81
2.4.1.3 Thermal Diffusivity 83
2.4.2 Material Properties Related to Mass Transfer 83
2.4.2.1 Absolute Permeability and Permeability Considering Hydrate Saturation 84
2.4.2.2 Relative Permeability 85
2.4.2.3 Capillary Pressure-Saturation Relationship 86
2.4.2.4 Diffusion Coefficients 87
2.4.2.5 Hydraulic Diffusivity 88
2.4.2.6 Mass Transfer Between Phases 88
2.4.3 Material Properties Related to Chemical Reactions 89
2.4.3.1 Thermodynamic State 89
2.4.3.2 Equilibrium: Phase Diagram 90
2.4.3.3 Kinetic: Dissociation Kinetics 92
2.4.4 Material Parameters for Momentum Balance 94
2.4.4.1 Solid: Geomechanical Properties, Solid-Fluid Coupling, Constitutive Relations 94
2.4.4.2 Liquid: Darcy´s Law, Viscosity 96
2.4.4.3 Solid-Liquid Interaction: Stress Formulation 97
2.5 Discussions 98
2.5.1 Validation of the Performance of Existing Models 99
2.5.1.1 Validations by Experiments 99
2.5.1.2 Mutual Validation Between Models 100
2.5.1.3 Applications 100
2.5.2 Suggestion on Practice Production by Model Simulations 101
2.5.2.1 Recovery Schemes 101
2.5.2.2 Critical Factors in Recovery 102
2.5.2.3 Governing Mechanisms for Hydrate Dissociation 104
2.5.3 Research Trends and Future Needs 105
2.5.3.1 Physical Fields 105
2.5.3.2 Phases and Components 105
2.5.3.3 Equilibrium Versus Kinetic Models 105
2.5.3.4 Environmental Effects 106
2.6 Conclusion 107
References 108
Chapter 3: Discrete Element Modeling of the Role of In Situ Stress on the Interactions Between Hydraulic and Natural Fractures 119
3.1 Introduction 119
3.2 Discrete Element Method 120
3.3 Representing Discrete Fracture 121
3.4 Hydromechanical Coupling 122
3.5 PKN Model Simulation 123
3.6 Hydraulic (HF) and Natural (NF) Fracture Interaction 128
3.7 Parametric Study: Reference Model 129
3.7.1 Anisotropic Stress Field 131
3.7.2 Effect of Different Orientation of the NF 134
3.7.3 Effect of Different Orientation of a Dilatant NF Combined with Higher Anisotropic Stress Field 138
3.8 Conclusions 139
References 140
Chapter 4: Rock Physics Modeling in Conventional Reservoirs 143
4.1 Review of Geophysical Concepts 143
4.2 Empirical Relations 145
4.3 Solid Phase 148
4.4 Fluid Phase 151
4.5 Dry Rock Properties 153
4.5.1 Granular Media Models 155
4.5.2 Inclusion Models 156
4.6 Saturated Rock Properties 159
4.7 Example 161
4.8 Other Rock Physics Models 162
4.9 Rock Physics Inversion 164
References 168
Chapter 5: Geomechanics and Elastic Anisotropy of Shale Formations 170
5.1 Introduction 170
5.2 Theory of Anisotropy 172
5.2.1 Elastic Anisotropy 172
5.2.2 Classification of Anisotropic Media 172
5.2.3 VTI Medium 173
5.2.4 Shale Anisotropy 174
5.2.5 Case Study 175
5.3 Fundamentals of Geomechanical Modeling for Wellbore Instability 179
5.3.1 Chemically Induced Instability 179
5.3.2 Mechanically Induced Instability 179
5.3.3 Factors Influencing Wellbore Stability 179
5.3.4 In Situ Stress Field 180
5.3.5 Wellbore Pressure 181
5.3.6 Fractures and Damages in the Formation 181
5.3.7 Thermal Effect 182
5.3.8 Fluid Flow into the Wellbore 182
5.3.9 Chemical Effects (in Shales) 182
5.3.10 Numerical Modeling of Wellbore Stability 183
5.3.10.1 Elastic Models 183
5.3.10.2 Elastoplastic and Poro-elastoplastic Models 184
5.3.10.3 Stress Distribution Around the Wellbore 184
5.3.10.4 Mohr-Coulomb Failure Criterion 187
The Minimum Wellbore Pressure 187
The Maximum Wellbore Pressure 188
Elastoplastic Stress Analysis 188
5.3.10.5 Wellbore Stability in Laminated (VTI) Formations 191
Anisotropic Strength Model 191
5.4 Anisotropic Geomechanical Modeling Case Study-Bakken Formation 193
5.4.1 Anisotropy in Geomechanical Modeling 193
5.4.1.1 Vertical Stress 194
5.4.1.2 Pore Pressure 195
5.4.1.3 Horizontal Stress 195
5.4.1.4 Anisotropic Elastic Parameters 196
5.4.1.5 Stress Profile 197
5.4.1.6 Maximum Horizontal Principal Stress (Second Approach) 199
5.4.1.7 Maximum Principal Horizontal Stress Orientation 200
5.4.2 3D Numerical Modeling 201
5.4.2.1 Vertical Well (0 Deviation Angle) 201
5.4.2.2 Inclined Well (45 Attack Angle) (Figs.5.26, 5.27, 5.28, and 5.29) 205
5.5 Summary and Recommendations 209
References 210
Chapter 6: Nano-Scale Characterization of Organic-Rich Shale via Indentation Methods 213
6.1 Introduction 214
6.2 Multi-scale Thought Model for Shale 214
6.3 Experimental Procedure 216
6.3.1 Materials 216
6.3.2 Grinding and Polishing 216
6.3.3 Roughness Characterization 220
6.4 Mechanical Properties 221
6.4.1 Elastic Properties 221
6.4.2 Indentation Equipment 222
6.4.3 Indentation Experiment 223
6.4.4 Statistical Nano-Indentation 225
6.4.5 Elastic Mechanical Homogenization 232
6.5 Conclusion and Future Perspectives 234
References 235
7: On the Production Analysis of a Multi-Fractured Horizontal Well 238
7.1 Introduction 239
7.2 Mathematical Formulation 241
7.3 Auxiliary Problem (Unit Step Pressure Decline) 242
7.3.1 Single Fracture 244
7.3.2 Infinite Fracture Array () 244
7.3.3 Finite Fracture Array Problem 246
7.3.3.1 Production Rate 247
7.3.3.2 Cumulative Production 248
7.3.4 Uniform Leak-in Approximation 248
7.4 Transient Pressure Decline: Constant Rate of Production from Fractured Well 252
7.4.1 Single Fracture 253
7.4.2 Infinite Fracture Array 253
7.4.3 Finite Fracture Array 254
7.4.3.1 Pressure Evolution 254
7.4.3.2 Cumulative Produced Volume 254
7.4.4 Uniform Leak-in Approximation 254
7.5 Summary 257
References 258
8: Interfacial Engineering for Oil and Gas Applications: Role of Modeling and Simulation 259
8.1 Introduction 259
8.2 Enhanced Oil Recovery 261
8.2.1 Surfactants and Additives 261
8.2.2 Supercritical CO2 263
8.2.3 Produced Water Demulsification and Treatment 263
8.3 Flow Assurance 266
8.3.1 Hydrate Formation Mechanisms 266
8.3.2 Kinetic Inhibitor Design 267
8.4 Carbon Capture and Separation 268
8.4.1 Adsorbents 268
8.4.2 Membranes 269
8.5 CO2 Conversion and Utilization 271
8.6 Conclusion and Outlook 272
References 273
Chapter 9: Petroleum Geomechanics: A Computational Perspective 286
9.1 Introduction 286
9.2 Subsidence 287
9.3 Borehole Stability 300
9.3.1 Case 1: Impact of the FEM Schemes (SGS/GSGS and Galerkin FEM) 309
9.3.2 Case 2: Impact of Thermal and Solute Convection in Lower Permeability Formations 310
9.3.3 Case 3: Impact of Thermal and Solute Convection in Higher Permeability Formations 312
9.3.4 Case 4: Impact of the Membrane Efficiency 314
9.4 Hydraulic Fracturing 316
9.4.1 Case 1: Fully Coupled XFEM Solution 323
9.4.2 Case 2: Impact of Injection Rate 325
9.4.3 Case 3: Impact of Injection Temperature 326
9.4.4 Case 4: Impact of Aquifer Stiffness 327
9.4.5 Case 5: Impact of Aquifer Permeability 328
9.4.6 Case 6: Impact of the Stabilized FEM Scheme 329
9.4.7 Case 7: Impact of the FEM Mesh Size 330
9.5 Conclusions 330
References 331
Chapter 10: Insights on the REV of Source Shale from Nano- and Micromechanics 335
10.1 Introduction 336
10.2 Sample Preparation for Nano- and Micro-Scale Shale Characterization 338
10.3 Test Methods 340
10.3.1 Compositional Analysis 340
10.3.2 Nanoindentation 340
10.3.3 Micro-Cantilever Beams 341
10.4 Nano- and Micro-Measurements 343
10.4.1 Compositional Analysis 343
10.4.2 Nanoindentation 345
10.4.3 Micro-Cantilever Beams loading 346
10.5 Micro-Measurement Cantilever-Beam Overview 357
10.5.1 Macro-Measurements of Kerogen-Rich Shale Following ASTM and ISRM Methods 359
10.5.1.1 Brazilian Tensile Test 359
10.5.2 Three-Point Chevron Notch Semicircular Bending Shale Sample (CNSCB) 360
10.5.2.1 Anisotropic Tensile Strength 361
10.6 Summary and Future Direction (Macro-Scale) 363
References 365
11: Experimental and Numerical Investigation of Mechanical Interactions of Proppant and Hydraulic Fractures 367
11.1 Introduction 367
11.2 Experimental Investigation 370
11.3 Theoretical Study and Numerical Modeling 374
11.4 Discussion 380
11.5 Concluding Remarks 382
References 383
Chapter 12: Integrated Experimental and Computational Characterization of Shale at Multiple Length Scales 389
12.1 Introduction 389
12.2 Experimental Studies 391
12.2.1 Overview of Experimental Studies for the Mechanical Characterization of Shale 391
12.2.1.1 Field Scale 391
12.2.1.2 Macroscopic Scale 392
12.2.1.3 Mesoscopic Scale 395
12.2.1.4 Microscopic and Nanometer Scales 396
12.2.2 Experimental Characterization of Marcellus Shale at the Macroscopic Scale 398
12.2.2.1 Sample Preparation 399
12.2.2.2 Ultrasonic Pulse Velocity 400
12.2.2.3 Brazilian Tensile Tests 402
12.2.2.4 Uniaxial Compression Tests 405
12.2.2.5 Three-Point-Bending Tests 407
12.2.3 Discussion 408
12.3 Computational Studies 409
12.3.1 Overview of Modeling Techniques for the Mechanical Characterization of Shale 409
12.3.1.1 Macroscopic Scale 410
12.3.1.2 Mesoscopic Scale 413
12.3.1.3 Microscopic and Nanometer Scales 415
12.3.1.4 Multiscale Algorithm 416
12.3.2 A Micromechanical Discrete Approach 417
12.3.2.1 Geometrical Characterization of Shale Internal Structure 418
12.3.2.2 Constitutive Equations 419
Elastic Behavior 419
Fracturing Behavior 421
Frictional Behavior 422
12.3.2.3 Preliminary Results 422
12.3.3 Discussion 424
References 425
13: Recent Advances in Global Fracture Mechanics of Growth of Large Hydraulic Crack Systems in Gas or Oil Shale: A Review 435
13.1 Introduction 435
13.2 Brief Overview of Fracking Technology 436
13.3 Estimation of Hydraulic Crack Spacing from Gas Flow History Observed at Wellhead 438
13.3.1 Diffusion of Gas from Shale into Hydraulic Cracks 438
13.3.2 Total Volume and Surface Area of Hydraulic Crack System 440
13.3.3 Flow of Gas from the Hydraulic Crack System to the Wellhead 440
13.3.4 Long-Term Gas Flow as the Main Indicator of Crack Spacing 442
13.4 Evolution of a System of Parallel Hydraulic Cracks 443
13.4.1 Hydrothermal Analogy 443
13.4.2 Review of Stability of Parallel Crack Systems 444
13.5 Evolution of Two Orthogonal Systems of Hydraulic Cracks 446
13.5.1 Cracked Finite Elements for Crack Band Model 447
13.5.2 Secondary Lateral Crack Initiation and the Necessity to Include Diffusion 447
13.5.3 Water Flow Through Hydraulic Cracks and Pores 449
13.5.4 Combined Diffusion Through Shale Pores and Flow Along the Cracks 449
13.5.5 Crack Opening Corresponding to Smeared Damage Strain in Crack Band Model 451
13.5.6 Pore Pressure Effect on Stresses in the Shale 451
13.5.7 Numerical Prediction of Evolutions of Hydraulic Crack System 452
13.6 Closing Comments 454
References 457
Chapter 14: Fundamentals of the Hydromechanical Behavior of Multiphase Granular Materials 461
14.1 Introduction 461
14.1.1 Fundamental Definition in Terms of Volumes and Weights 462
14.1.2 Definition of Suction 464
14.1.3 Soil Water Retention Curve (SWRC) 465
14.1.3.1 Enhanced Models to Describe the WRC Based on Microstructural Features 467
14.1.4 Stress Variable in Unsaturated Conditions 472
14.1.5 Small Strain Stiffness 474
14.1.6 Stiffness at Moderate (Larger) Strain: Compressibility 476
14.1.6.1 Modelling the Compressibility Behavior 477
14.1.7 Strength of Unsaturated Soils 478
References 483
Chapter 15: Beyond Hydrocarbon Extraction: Enhanced Geothermal Systems 487
15.1 Introduction to Sedimentary Enhanced Geothermal Systems (SEGS) 488
15.2 Description of a Modeled SEGS Reservoir 489
15.2.1 Flow Equations 491
15.2.2 Heat Transfer Equations 492
15.3 Interpretation of Simulation Results 493
15.3.1 Effect of Reservoir Permeability on Thermal Breakthrough Time and Reservoir Thermal Performance 497
15.3.2 Effect of Boundaries on Reservoir Thermal Performance 498
15.4 Issues of Long-Term Heat Extraction 499
15.5 In Situ Stresses and Their Re-distribution in EGS 501
15.6 Concluding Remarks 504
References 505
16: Some Economic Issues in the Exploration for Oil and Gas 507
16.1 Introduction 507
16.2 Modeling Exploration 508
16.3 Some Empirical Evidence 510
16.3.1 Trends in the Probability of a Dry Hole 510
16.3.2 Trends in Price and Drilling 511
16.4 Developments in the Gulf of Mexico 512
16.5 Discussion 516
References 517
ERRATUM TO 519
Index 520