Contents
1 Development Characteristics of Tight Oil and Gas Reservoirs 1
1.1 Reservoir Characteristics of Tight Oil and Gas Reservoirs 1
1.1.1 The Macroscopic Heterogeneity of Tight Reservoirs 1
1.1.2 The Microscopic Heterogeneity and Characteristics
of Pore-Fracture Media at Different Scales 5
1.2 Development Mode and Characteristics of Tight Oil and Gas Reservoirs 13
1.2.1 Development Mode with Horizontal Wells 15
1.2.2 Stimulation Mode of Hydraulic Fracturing 17
1.2.3 Flow Behavior Between Horizontal Wells and Reservoirs 18
1.2.4 Production Mode 19
1.3 Problems and Requirements for the Numerical Simulation Process in Unconventional Tight Reservoirs. 25
1.3.1 Problems and Requirements for the Geo-Modeling Technologies of Unconventional Tight Oil and Gas Reservoirs 25
1.3.2 Problems and Requirements in Numerical Simulation Theory of Unconventional Tight Reservoirs 29
1.3.3 Problems and Requirements in Numerical Simulation Technologies of Unconventional Tight Oil and Gas Reservoirs 31
References 32
2 Flow and Recovery Mechanisms in Tight Oil and Gas Reservoirs 35
2.1 Classification and Characteristics of Multiple Media at Different Scales in Tight Reservoirs 35
2.1.1 Definition and Classification of Multiple Media at Different Scales 35
2.1.2 Classification Method of Multiple Media. 41
2.2 Flow Regimes and Flow Mechanisms 42
2.2.1 Definition of Flow Regime 42
2.2.2 Classification of Flow Regimes and Flow Mechanisms 42
2.3 Mechanisms of Displacement Processes 49
2.3.1 Conventional Displacement Mechanisms of Tight Oil and Gas Reservoirs 49
2.3.2 Special Mechanisms of Tight Oil Reservoirs 52
2.3.3 Special Displacement Mechanisms of Tight Gas Reservoirs 53
2.4 Oil-Producing Capacity for the Porous Media at Different Scales 55
2.4.1 Oil-Producing Capacity of Reservoir Matrix 55
2.4.2 Oil-Drainage Area of Reservoir Matrix 59
2.5 Coupled Recovery Mechanisms of Pore-Fracture Media at Different Scales 60
2.5.1 Coupled Flow Behavior Between Multiple Media 61
2.5.2 Coupled Recovery Mechanisms in Different Production Stages 63
References 69
3 Mathematical Model of Multiphase Flow in Multiple Media at Different Scales 71
3.1 Mathematical Model of Multiphase Flow in Multiple Media for Tight Oil Reservoirs 71
3.1.1 Mathematical Model of Multiphase Flow in Continuous Single Media 71
3.1.2 Mathematical Model of Multiphase Flow in Continuous Dual Media 74
3.1.3 Mathematical Model of Multiphase Flow in Continuous Multiple Media 75
3.1.4 Mathematical Model of Multiphase Flow in Discontinuous Multiple Media 79
3.2 Mathematical Model of Multiphase Flow in Multiple Media for Tight Gas Reservoirs 86
3.2.1 Mathematical Model of Multiphase Flow in Continuous Single Media 86
3.2.2 Mathematical Model of Multiphase Flow in Continuous Dual Media 86
3.2.3 Mathematical Model of Multiphase Flow in Continuous Multiple Media 87
3.2.4 Mathematical Model of Multiphase Flow in Discontinuous Multiple Media 89
References 94
4 Discretization Methods on Unstructured Grids and Mathematical Models of Multiphase Flow in Multiple Media at Different Scales 97
4.1 Grid Partitioning and Grid Generation Technology for Numerical Simulation 97
4.1.1 Structured Grid Technology 100
4.1.2 Unstructured Grid Technology 105
4.1.3 Hybrid Grid Technology 114
4.2 Grid Connectivity Characterization Technology for Numerical Simulation 117
4.2.1 Grid Ordering Technology for Numerical Simulation 118
4.2.2 Grid Neighbor Characterization Technology for Numerical Simulation 123
4.2.3 Grid Connectivity Characterization Technology for Numerical Simulation 125
4.3 The Discretization Technology of the Mathematical Model for Multiphase Flow in Multiple Media at Different Scales 132
4.3.1 The Spatial Discretization Method of the Mathematical Model for Multiphase Flow in Multiple Media at Different Scales 132
4.3.2 Finite Volume Discretization Method of the Mathematical Model for Multiphase Flow in Discontinuous Multiple Media at Different Scales 133
References 148
7 Coupled Multiphase Flow-Geomechanics Simulation for Multiple Media with Different-Size Pores and Natural/Hydraulic Fractures in Fracturing-Injection-Production Process 229
7.1 Coupled Flow-Geomechanics Deformation Mechanism of Multiple Media with Different Scales Pores and Fractures 229
7.1.1 The Principle of Effective Stress in Multiple Media with Different Scales Pores and Fractures 229
7.1.2 Mechanisms of Matrix Pore Expansion�� Hydraulic/Natural Fracture Propagation During Pore Pressure Increasing 234
7.1.3 Mechanisms of Matrix Pore Compression�� Hydraulic/Natural Fractures Closure Deformation During Pore Pressure Decreasing 238
7.1.4 Characteristics Analysis of Dynamic Change of Multiple Media with Different Scales Pores and Fractures 241
7.2 Coupled Flow-Geomechanics Dynamic Simulation for Multiple Media with Different Sca