Contents
Chapter 1 Introduction 1
1.1 Introduction 1
1.2 Deflection of fracturing fracture network disturbed by discontinuity in
rock 2
1.3 Deflection of fracturing fracture network disturbed by multiple fractures
in rock 7
1.4 Propagation and deflection of fracturing fracture network in supercritical
CO2 fracturing 11
1.5 Research contents of the book 14
References 15
Chapter 2 Dynamic intersection and deflection behaviours of hydraulic
fractures meeting granules and natural fractures in tight reservoir rock based on statistical modelling and fractal characterization 18
2.1 Introduction 18
2.2 Statistical modelling for tight heterogeneous reservoir rock 22
2.2.1 Statistical uniform and Weibull distribution of heterogeneous reservoir rock 22
2.2.2 Establishment process of statistical models with granules and natural fractures 24
2.3 Governing partial differential equations and numerical discretization of
hydrofracturing in fractured porous media 26
2.3.1 Governing equation of solid deformation 26
2.3.2 Governing equations of fluid flow in fractured porous media 27
2.3.3 Fracture criterion 27
2.3.4 Numerical discretization based on the combined finite element-discrete
element-finite volume method 29
2.4 Fractal characterization method for fracture network morphology 30
2.5 Global procedure for statistical modelling, fracture propagation, and
fractal characterization 31
2.6 Results and discussions 32
2.6.1 Propagation behaviours and fractal characterization of fracturing fracture network in homogeneous tight reservoirs 32
2.6.2 Intersection and deflection behaviours of hydraulic fractures meeting granules 34
2.6.3 Intersection and deflection behaviours of hydraulic fractures meeting natural
fractures 38
2.7 Conclusions 43
References 45
Chapter 3 Deflection behaviours and fractal morphology of hydraulic
fractures meeting beddings and granules with variable geometrical configurations and geomechanical properties 50
3.1 Introduction 50
3.2 Governing partial differential equations and numerical discretization 52
3.2.1 Governing equation of solid deformation 52
3.2.2 Governing equations of fluid flow in fractured porous media 52
3.2.3 Numerical discretization 53
3.3 Fractal morphology of fracturing fracture network based on fractal characterization method 53
3.4 Global procedure for deflection behaviours and fractal morphology of hydraulic fractures meeting beddings and granules 54
3.5 Numerical models and cases of heterogeneous reservoirs 55
3.5.1 Beddings with variable geometrical configurations and geomechanical properties 55
3.5.2 Granules with variable geometrical configurations and geomechanical properties 57
3.6 Results and discussion 58
3.6.1 Beddings with variable geometrical configurations 58
3.6.2 Beddings with variable geomechanical properties 62
3.6.3 Granules with variable geometrical configurations 66
3.6.4 Granules with variable geomechanical properties 69
3.7 Conclusions 72
References 73
Chapter 4 Dynamic propagation of tensile and shear fractures induced by impact load in rock based on dual bilinear cohesive zone model 77
4.1 Introduction 77
4.2 Governing partial differential equations for rock fracture induced by impact load 79
4.3 Fracture criteria based on dual bilinear cohesive zone model 80
4.4 Numerical discretization of finite elements 81
4.5 Detection and separation of discrete elements 81
4.6 Global algorithm and procedure 83
4.7 Results and discussion 83
4.7.1 Verification of tensile and shear fractures induced by impact load in rock disc 83
4.7.2 Dynamic propagation of fractures in rock disc 86
4.7.3 Dynamic propagation of fractures in rock stratum 90
4.8 Conclusions 95
References 96
Chapter 5 Center-and edge-type intersections of hydraulic fracture network under varying crossed natural fractures and fluid injection rate + +100
5.1 Introduction 100
5.2 Combined finite element-discrete element method and model considering hydro-mechanical coupling 102
5.2.1 Governing partial differential equations 102
5.2.2 Discrete fracture network model 103
5.3 Numerical models of fractured reservoir embedded discrete fracture networks 104
5.3.1 Geometrical models 104
5.3.2 Cases study for typical pre-existing crossed natural fractures 105
5.4 Results and discussion 110
5.4.1 Sensitivity factors of pre-existing natural fractures 110
5.4.2 Quantitative length of fracture networks 114
5.4.3 Gas production in fractured reservoirs 117
5.5 Conclusions 120
References 122
Chapter 6 Wells connection and long hydraulic fracture induced by multi-well hydrofracturing utilizing cross-perforation clusters 125
6.1 Introduction 125
6.2 Governing equations of multi-well hydrofracturing considering thermal-hydraulic-mechanical coupling 127
6.3 Numerical models of multi-well hydrofracturing utilizing crossperforation clusters 128
6.4 Results and analysis 130
6.4.1 Hydraulic fracture propagation of parallel and cross perforation clusters in
multi-wells 130
6.4.2 Connected long hydraulic fractures in multi-well hydrofracturing with different well spacings 134
6.4.3 Connected long hydraulic fractures in multi-well hydrofracturing with different well initiation sequences 137
6.4.4 Multi-well hydrofracturing induced microseismic events 140
6.5 Conclusions 146
References 147
Chapter 7 Deflection of fracture networks and gas production in multi-well hydrofracturing utilizing parallel and crossed perforation clusters 149
7.1 Introduction 149
7.2 Combined finite element-discrete element method and model considering thermo-hydro-mechanical coupling 151
7.2.1 Governing partial differential equations 151
7.2.2 Numerical models of multi-well hydrofracturing 153
7.3 Deflection of fracture networks in multi-well hydrofracturing utilizing parallel and crossed perforation clusters 156
7.3.1 Fracture deflection in multi-well hydrofracturing utilizing parallel perforation clusters 156
7.3.2 Fracture deflection in multi-well hydrofracturing utilizing crossed perforation clusters 158
7.4 Gas production in multi-well hydrofracturing utilizing parallel and crossed perforation clusters 162
7.4.1 Gas production in multi-well hydrofracturing utilizing parallel perforation clusters 162
7.4.2 Gas production in multi-well hydrofracturing utilizing crossed perforation clusters 165
7.5 Conclusions 169
References 170
Chapter 8 Supercritical-CO2-driven intersections of multi-well fracturing fracture network and induced microseismic events in naturally fractured reservoir 172
8.1 Introduction 172
8.2 Geomechanical equations of supercritical CO2 fracturing and
microseismic analysis considering thermal-hydro-mechanical coupling 176
8.2.1 Geomechanical equations considering thermal-hydro- mechanical coupling 176
8.2.2 Microseismicity analysis by the evaluation of moment tensors 177
8.2.3 Discrete fracture network model 179
8.3 Numerical models of supercritical CO2 fracturing in fractured reservoir 180
8.3.1 Geometrical and finite element models 180
8.3.2 Cases study for typical fracturing fluids: Slick water and supercritical CO2.183
8.4 Results and discussion 184
8.4.1 Intersections and connections of fracturing fracture networks 184
8.4.2 Quantitative variation of fracture networks, fluid rate, and pore pressure 190
8.4.3 Microseismic damage and contact-slip events 194
8.5 Conclusions 200
References 201
Chapter 9 Summary and prospect 206
9.1 Summary 206
9.2 Prospect 211
Abstract 212
編后記 213