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 | موضوع: كتاب Mechanics of Hydraulic Fracturing - Experiment, Model, and Monitoring الأحد 12 مارس 2023, 10:32 pm | |
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أخواني في الله أحضرت لكم كتاب Mechanics of Hydraulic Fracturing - Experiment, Model, and Monitoring Edited by Xi Zhang China University of Geosciences Wuhan, China Bisheng Wu Tsinghua University Beijing, China Diansen Yang Wuhan University Wuhan, China Andrew Bunger University of Pittsburgh Pittsburgh, PA, USA
 و المحتوى كما يلي :
Contents List of Contributors xiii Foreword xv Preface xvii 1 Hydraulic Fracture Geometry from Mineback Mapping 1 R. G. Jeffrey 1.1 Introduction 1 1.2 Summary of Mapped Fracture Geometries 1 1.2.1 Fractures in Coal 1 1.2.1.1 DHM-7 Fracture 2 1.2.1.2 DDH 190 Fracture 2 1.2.2 Fractures in Hard Rock 5 1.2.2.1 Northparkes E48 Mapped Fractures 5 1.2.3 Other Mapped Fractures 7 1.3 Comparison of Mapped Fracture Geometries 7 1.3.1 Dimensionless Parameters 7 1.4 Fracture Geometry Summary 8 1.5 Conclusions 9 References 9 2 Measurements of the Evolution of the Fluid Lag in Laboratory Hydraulic Fracture Experiments in Rocks 11 Dong Liu and Brice Lecampion 2.1 Introduction 11 2.2 Materials and Methods 12 2.2.1 Materials and Experimental Set-up 12 2.2.2 Methods 12 2.2.3 Experimental Design 13 2.3 Results 14 2.3.1 MARB-005 – A HF Growth with a Fluid Lag 14 2.3.2 MARB-007 – A HF Growth during and after the Injection 15 2.3.3 GABB-002 – A Point-Load Like HF Growth 16 2.4 Discussions and Conclusions 18 2.4.1 Resolution of the Fluid Front Location 18 2.4.2 Quasi-Brittle Effects 18 2.4.3 Hydraulic Fracture Surfaces 19 2.4.4 Conclusions 21 Data Availability 21 Appendix A Determination of the Time of Fracture Initiation 21 References 22 v3 Mapping Hydraulic Fracture Growth Using Tiltmeter Monitoring Technique 25 Z. R. Chen and R. G. Jeffrey 3.1 Introduction 25 3.2 Forward Problem Formulation 26 3.2.1 Forward Model Definition 26 3.2.2 Forward Model 27 3.2.2.1 Point Source Dislocation Singularity Model 28 3.2.2.2 A General Distributed Dislocation Model 29 3.3 Bayesian Inversion Method 30 3.4 Field Applications 31 3.4.1 Inversion Results Using the Point Source Forward Model 31 3.4.2 Inversion Results Using the General Planar Forward Model 31 3.5 Conclusions 34 Acknowledgments 34 References 34 4 Experimental Observations of Hydraulic Fracturing 37 Guangqing Zhang and Dawei Zhou 4.1 Introduction 37 4.2 Experimental Setup on Laboratory-Scale 37 4.3 Laboratory Investigation of Fluid-Driven Fractures in Various Applications 38 4.3.1 Hydraulic Fracturing in Oil and Gas Reservoirs 38 4.3.1.1 Basic Issues of Breakdown Pressure and Fracture Geometry 38 4.3.1.2 Multiple Hydraulic Fracture Growth 39 4.3.1.3 Interactions Between Hydraulic Fractures and Natural Fractures 40 4.3.1.4 Fracture Propagation Through the Layered Formation 41 4.3.1.5 Nonlinear Fracturing in the Deep Reservoir 42 4.3.1.6 Cyclic Fracturing 43 4.3.2 Environmental Fracturing in a Shallow Formation 44 4.3.3 Hydraulic Stimulation in EGS 44 4.4 Conclusions and Future Work 45 References 46 5 First Field Trail and Experimental Studies on scCO2 Fracturing 51 Haiyan Zhu, Lei Tao, Shouceng Tian, and Haizhu Wang 5.1 Introduction 51 5.2 Review on scCO2 Fracturing 52 5.2.1 Shale and scCO2 Interaction 52 5.2.1.1 Microscale Physical Changes 52 5.2.1.2 Microscale Chemical Changes 52 5.2.1.3 Macroscale Mechanical Changes 53 5.2.1.4 Conclusions on the Experiments on Shale and scCO2 Interaction 54 5.2.2 Experiments and Numerical Simulations on scCO2 Fracturing 54 5.2.2.1 Experiments on scCO2 Fracturing 54 5.2.2.2 Numerical Simulations on scCO2 Fracturing 57 5.3 A Field Trail on scCO2 Fracturing of Continental Shale in Yanchang Oil Field 57 5.3.1 scCO2 Fracturing Technology 57 5.3.2 scCO2 Fracturing Field Test 58 5.3.2.1 Reservoir Properties of Test Wells 58 5.3.2.2 Fracturing Process and Operation Parameters 58 5.3.3 Field Test Results and Analysis 59 5.3.3.1 Microseismic Monitoring and Inversion of Fracture Geometry 59 vi Contents5.3.3.2 Production Data 60 5.4 Challenges in scCO2 Fracturing 60 5.4.1 scCO2 Fracturing Mechanism Is Still Not Clear 60 5.4.2 Challenges in Proppants Carrying 60 5.4.3 Challenge on the Predicting and Monitoring CO2 Phase 61 5.4.4 Lack of Specialized Equipment for scCO2 Fracturing 61 5.5 Conclusions 61 Acknowledgments 61 References 61 6 An Unstructured Moving Element Mesh for Hydraulic Fracture Modeling 65 John Napier and Emmanuel Detournay 6.1 Introduction 65 6.2 Discrete Model of a Planar Hydraulic Fracture 65 6.2.1 Unstructured Mesh 66 6.2.2 Discrete Elasticity Equation 66 6.2.3 Discretized Lubrication Equations for Channel Elements 67 6.2.4 Tip Elements 67 6.3 Time-Marching Algorithm 67 6.3.1 Iteration Loops 68 6.3.2 Local Front Update 68 6.3.3 Generation of a New Ring of Tip Elements 68 6.3.4 Crack Surface Remeshing 69 6.3.5 General Solution Algorithm Logic 69 6.4 Numerical Simulations: Stress Barriers 70 6.4.1 Description of Experiment 70 6.4.2 Numerical Simulations (no Remeshing) 70 6.4.3 Comparison with Experimental Results and Other Simulations 71 6.4.4 Illustration and Assessment of the Element Re-Meshing Strategy 71 6.5 Conclusions 73 Acknowledgments 73 References 73 7 Study of Hydraulic Fracture Interference with a Lattice Model 75 C. Detournay, B. Damjanac, M. Torres, and Y. Han 7.1 Introduction 75 7.2 XSite Code Overview 75 7.3 Numerical Studies of Fracture Interference 75 7.3.1 Interaction of a Hydraulic Fracture with a Natural Fracture 76 7.3.2 Interaction of Two Hydraulic Fractures 76 7.3.2.1 Numerical Study 76 7.3.2.2 Interpretation of Results 78 7.3.3 Interaction of Hydraulic Fractures in Injection of Multiple Clusters 79 7.3.4 Interaction of Hydraulic Fractures in Fractured Medium 81 7.3.5 Interaction of Hydraulic Fractures in Zipper-Stage Injection 83 7.4 Afterword 83 References 85 8 The Tipping Point: How Tip Asymptotics Can Enhance Numerical Modeling of Hydraulic Fracture Evolution 87 A. Peirce 8.1 Introduction 87 8.2 Mathematical Model 87 Contents vii8.2.1 Assumptions 87 8.2.2 Governing Equation 88 8.2.2.1 Elasticity 88 8.2.2.2 Fluid Transport 88 8.2.2.3 Boundary and Propagation Conditions 88 8.2.2.4 Tip Asymptotics, Vertex Solutions, and Generalized Asymptotes 89 8.3 Discretization, Coupled Equations, and the Multiscale ILSA Scheme to Locate the Free Boundary 91 8.3.1 Discretization 91 8.3.1.1 Displacement Discontinuity Formulation for Planar Fractures 91 8.3.2 Locating the Free Boundary Using the Implicit Level Set Algorithm (ILSA) 92 8.4 Numerical Results 95 8.4.1 Symmetric Stress Barrier: m-Vertex Solution vs Experiment and the Effect of Toughness 95 8.4.2 A Stress Drop: Distinct Propagation Regimes Along the Periphery 95 8.5 Conclusions 95 8.6 Acknowledgment 97 References 97 9 Plasticity: A Mechanism for Hydraulic Fracture Height Containment 99 Panos Papanastasiou 9.1 Introduction 99 9.2 The Dependence of the Effective Fracture Toughness on Propagation Direction 100 9.3 Effective Fracture Toughness vs. Closure Stress 101 9.4 A New Brittleness Index Defines Fracture Containment 102 9.5 Conclusions 103 Acknowledgments 104 References 104 10 Turbulent Flow Effects on Propagation of Radial Hydraulic Fracture in Permeable Rock 107 E.A. Kanin, D.I. Garagash, and A.A. Osiptsov 10.1 Introduction 107 10.2 Model Formulation 108 10.2.1 Problem Definition 108 10.2.2 Governing Equations 109 10.2.2.1 Crack Elasticity 109 10.2.2.2 Fluid Flow 109 10.2.2.3 Fracture Propagation 110 10.2.2.4 Boundary Conditions 110 10.2.2.5 Global Fluid Volume Balance 110 10.3 Solution Approach 111 10.4 Solution Examples for Typical Field Applications 112 10.5 Limiting Propagation Regimes 115 10.6 Normalization of the Governing Equations 118 10.7 Problem Parameter Space Analyses 119 10.7.1 Zero Leak-Off Case (Impermeable Rock) 120 10.7.2 Nonzero Leak-Off Case (Permeable Rock) 121 10.8 Conclusions 122 Acknowledgments 124 References 125 11 Analysis of a Constant Height Hydraulic Fracture 127 E.V. Dontsov 11.1 Introduction 127 viii Contents11.2 Governing Equations 128 11.3 Tip Region 129 11.4 Vertex Solutions 132 11.4.1 Storage Viscosity 132 11.4.2 Leak-off Viscosity 133 11.4.3 Storage Toughness 133 11.4.4 Leak-off Toughness 133 11.5 Full Solution 134 11.6 Application Examples 136 11.7 Summary 137 References 137 12 Discrete Element Modeling of Hydraulic Fracturing 141 Mengli Li and Fengshou Zhang 12.1 Introduction 141 12.2 Discrete Element Modeling of Hydraulic Fracturing 142 12.3 Hydraulic Fracture Interacting with Natural Fractures 142 12.3.1 Hybrid Discrete-Continuum Method 143 12.3.2 Model Calibration for a Hydraulic Fracture in Intact Rock 144 12.3.3 Orthogonal Crossing 145 12.3.3.1 Effects of Stress Ratio and Friction of Natural Fractures 145 12.3.3.2 Effect of Strength (Toughness) Contrast 147 12.3.3.3 Effect of Stiffness (Modulus) Contrast 149 12.3.4 Non-Orthogonal Crossing 150 12.3.5 Fracturing Complexity 151 12.4 DEM Modeling of Supercritical Carbon Dioxide Fracturing 153 12.4.1 New Algorithm for the Toughness-Dominated Regime 153 12.4.2 Numerical Model Setup 154 12.4.2.1 Model Description 154 12.4.2.2 Model Verification 156 12.4.3 Hydraulic Fracturing in Intact Rock Sample 157 12.4.4 Hydraulic Fracturing in Fractured Rock Sample 161 12.5 DEM Modeling of Fluid Injection into Dense Granular Media 163 12.5.1 Background and Experimental Motivation 163 12.5.2 Model Setup 165 12.5.3 Effect of the Injection Rate 166 12.5.4 Dimensionless Time Scaling 168 12.5.5 Energy Partition 170 12.6 Discussion 171 12.7 Conclusions 171 References 172 13 Interaction of a Hydraulic Fracture with Natural Fractures of Lesser Height and Weak Bedding Interfaces as a Possible Mechanism for Fracture Swarms 177 Xiaowei Weng and Olga Kresse 13.1 Introduction 177 13.2 Possible Mechanisms for Fracture Bifurcation 179 13.3 Interaction of Closely Spaced Parallel Fractures 182 13.3.1 Fracture Tip Extension in Overlapped Region 182 13.3.2 Instability of Closely Spaced Parallel Hydraulic Fractures – Shared Inlet 183 13.3.3 Instability of Closely Spaced Parallel Hydraulic Fractures – Separate Inlets 184 13.4 Possible Mechanisms for Creating Fracture Swarms 185 Contents ix13.5 Conclusions 188 References 189 14 Hydraulic Fracturing Mechanisms Leading to Self-Organization Within Dyke Swarms 193 Andrew. P. Bunger, D. Gunaydin, S. T. Thiele, and A. R. Cruden 14.1 Introduction 193 14.2 Swarm Morphology and Fundamental Drivers 193 14.3 Dyke Swarm Model and Energetics 194 14.4 Alignment 196 14.5 Avoidance 197 14.6 Stress Shadow 197 14.7 Stress Plugs 199 14.8 Attraction 199 14.9 Emergent Spacing 200 14.10 Simulating Dyke Swarm Assembly 201 14.11 Conclusions 202 Acknowledgments 203 References 203 15 Numerical Simulation of Thermal Fracturing During Heat Extraction from a Closed-Loop Circulation Enhanced Geothermal System 207 Z. Lei, Bisheng Wu, and Z. Chen 15.1 Introduction 207 15.2 Mathematical Formulation 208 15.2.1 Problem Description 208 15.2.2 Governing Equations of Coupled Thermoelastic Model 209 15.2.2.1 Fluid Flow 209 15.2.2.2 Rock Deformation 209 15.2.2.3 Fracture Initiation and Propagation 210 15.2.2.4 Thermal Transport Through Fluid Flow 211 15.2.2.5 Heat Transfer in Rock Matrix 211 15.2.3 Boundary and Initial Conditions 211 15.3 Solution Methodology and Computational Procedures 211 15.3.1 Coupled Fluid-Fracture Solver 211 15.3.1.1 Weak Form and FEM Discretization 211 15.3.1.2 Extended Finite Element Approximation 212 15.3.2 Coupled Fluid-Thermal Solver 213 15.3.3 Solution Strategy 213 15.4 Numerical Results 214 15.4.1 Fluid Flow and Production Temperature 214 15.4.2 Temperature Distribution in Rock Formation 216 15.4.3 Fracture Propagation 216 15.4.3.1 Single Fracture Case 216 15.4.3.2 Double Fracture Case 220 15.5 Conclusions 221 References 221 16 Multiple Hydraulic Fractures Growth from a Highly Deviated Well: A XFEM Study 225 Yun Zhou and Diansen Yang 16.1 Introduction 225 16.2 Problem Formulation 227 16.2.1 Governing Equations 228 x Contents16.2.1.1 Solid Deformation 228 16.2.1.2 Fluid Flow in Matrix 229 16.2.1.3 Fluid Flow in Fractures 229 16.2.1.4 Flow Rate Division to Multiple Fractures 229 16.2.1.5 Fracture Propagation 229 16.2.2 Weak Forms 230 16.3 Numerical Method 230 16.3.1 XFEM Approximation of u(x, t) and p(x, t) 230 16.3.2 Spatial and Time Discretization 231 16.3.3 Solution Strategy 231 16.3.3.1 Solution of HM-Coupled Equations 231 16.3.3.2 Solution of Flow Rate Division 231 16.4 Numerical Results 232 16.4.1 Verification of the Model 232 16.4.2 Multi-Cluster Hydraulic Fracturing in High-Angle Well 233 16.4.2.1 Model Set-up 234 16.4.2.2 Operational Parameters 235 16.4.2.3 Deviation Angle 236 16.4.2.4 Fracture Spacing 239 16.4.2.5 Fracture Placement 240 16.4.2.6 Fracture Number 241 16.5 Discussion 245 16.6 Conclusions 245 Appendix 16.A Dimensionless Toughness κ 245 Appendix 16.B Dimensionless Parameter Gm 246 Appendix 16.C Dimensionless Variability Coefficient Cv 246 References 246 17 Hydraulic Fracturing-Induced Slip on a Permeable Fault 251 Xi. Zhang, R. G. Jeffrey, and J. Yang 17.1 Introduction 251 17.2 Model Setup 252 17.3 Summary of Modeling Results 254 17.3.1 Fully Closed Fractures 254 17.3.1.1 Constant Fault Permeability 254 17.3.1.2 Enhanced Fault Permeability 254 17.3.1.3 Fault Permeability Reduction 255 17.3.2 Partially Opened Fracture 256 17.3.2.1 Planar Fault 256 17.3.2.2 Nonplanar Fault 256 17.4 Radiated Energy 256 17.5 Conclusions and Future Work 258 Acknowledgment 259 References 259 Index 263 Index Note: Page numbers in italics refer to figures; page numbers in bold refer to tables. a ABAQUS 208–209, 212–213, 221 acoustic emission (AE) 38–39, 45 acoustic imaging system 12 AE, see acoustic emission alignment, dyke swarms 196–197 ANSYS 207 attraction, dyke swarms 199–200 avoidance, dyke swarms 197 b Bayesian inversion method, tiltmeter 30–31 bedding interfaces, fracture swarms 182 BEM, see boundary element method bifurcation, fracture swarms 179–182, 180 boundaries, geothermal 211 boundary conditions 88–89 constant height fracture 129–131 HW, HAW 228 radial hydraulic fracture 110 seismic events 253–254 boundary element method 73, 185, 208, 254 breakdown pressure 38, 38–39 brittleness index 102–103, 103 c carbon dioxide fracturing, DEM modeling 153–163 Carrara marble 12, 12, 13 channel elements, unstructured mesh 66, 66–67 China University of Petroleum at Beijing 38 closed fractures 254–256 closure stress 101–102 coal 1 coalbed methane 1 coalescent fluid 89 coal fractures 1–5, 2 complex fracture model, Kresse 177–178, 178 COMSOL Multiphysics 207 constant height 127–139, 128 boundary condition 129–131 leak-off, dimensionless 136 leak-off toughness 133–134 leak-off viscosity 133 linear elastic fracture mechanics (LEFM) 127 parametric space 130, 135 PKN fracture 128–130, 130, 134–136 plane strain 127 storage toughness 133 storage viscosity 132 tip region 129–131, 130 transitions 131 vertex solutions 132–134, 136 containment, fracture 102–103 CO2 phase, scCO2 fracturing 61 coupled fluid-thermal solver 213–214, 214 crack elasticity equation 109 crack surface remeshing 69 crystalline rock 1 cyclic fracturing 43, 43 d DDH 190 fractures 2–5, 4, 5, 8 DDM, see displacement discontinuity method degrees of freedom 213, 226, 230 DEM 141–175 carbon dioxide fracturing, DEM modeling 153–163 discrete/continuum modeling 143, 143–144 discrete element modeling 142 energy components 170–171, 170–171 Fast Lagrangian Analysis of Continua (FLAC) 143 fluid injection, DEM modeling 163–171 fluid viscosity 164 fractured rock 161–163, 162, 163, 172 friction 145–147 glycerin solutions 164 granular media 141, 163–171 injection rate 166, 166–168, 167–168, 172 material inhomogeneity 172 natural fracture intersections 151–153, 152–153, 172 natural fractures 142–153, 144, 144, 147, 155, 171 non-orthogonal crossing 150–151, 151 numerical model 154–157, 155–156, 157, 160 offset crossing 148 orthogonal crossing 145–146, 146, 148, 172 orthogonal natural fractures 145–146, 146–147 particle flow code (PFC) 143–144, 144, 144 Contents List of Contributors xiii Foreword xv Preface xvii 1 Hydraulic Fracture Geometry from Mineback Mapping 1 R. G. Jeffrey 1.1 Introduction 1 1.2 Summary of Mapped Fracture Geometries 1 1.2.1 Fractures in Coal 1 1.2.1.1 DHM-7 Fracture 2 1.2.1.2 DDH 190 Fracture 2 1.2.2 Fractures in Hard Rock 5 1.2.2.1 Northparkes E48 Mapped Fractures 5 1.2.3 Other Mapped Fractures 7 1.3 Comparison of Mapped Fracture Geometries 7 1.3.1 Dimensionless Parameters 7 1.4 Fracture Geometry Summary 8 1.5 Conclusions 9 References 9 2 Measurements of the Evolution of the Fluid Lag in Laboratory Hydraulic Fracture Experiments in Rocks 11 Dong Liu and Brice Lecampion 2.1 Introduction 11 2.2 Materials and Methods 12 2.2.1 Materials and Experimental Set-up 12 2.2.2 Methods 12 2.2.3 Experimental Design 13 2.3 Results 14 2.3.1 MARB-005 – A HF Growth with a Fluid Lag 14 2.3.2 MARB-007 – A HF Growth during and after the Injection 15 2.3.3 GABB-002 – A Point-Load Like HF Growth 16 2.4 Discussions and Conclusions 18 2.4.1 Resolution of the Fluid Front Location 18 2.4.2 Quasi-Brittle Effects 18 2.4.3 Hydraulic Fracture Surfaces 19 2.4.4 Conclusions 21 Data Availability 21 Appendix A Determination of the Time of Fracture Initiation 21 References 22 v3 Mapping Hydraulic Fracture Growth Using Tiltmeter Monitoring Technique 25 Z. R. Chen and R. G. Jeffrey 3.1 Introduction 25 3.2 Forward Problem Formulation 26 3.2.1 Forward Model Definition 26 3.2.2 Forward Model 27 3.2.2.1 Point Source Dislocation Singularity Model 28 3.2.2.2 A General Distributed Dislocation Model 29 3.3 Bayesian Inversion Method 30 3.4 Field Applications 31 3.4.1 Inversion Results Using the Point Source Forward Model 31 3.4.2 Inversion Results Using the General Planar Forward Model 31 3.5 Conclusions 34 Acknowledgments 34 References 34 4 Experimental Observations of Hydraulic Fracturing 37 Guangqing Zhang and Dawei Zhou 4.1 Introduction 37 4.2 Experimental Setup on Laboratory-Scale 37 4.3 Laboratory Investigation of Fluid-Driven Fractures in Various Applications 38 4.3.1 Hydraulic Fracturing in Oil and Gas Reservoirs 38 4.3.1.1 Basic Issues of Breakdown Pressure and Fracture Geometry 38 4.3.1.2 Multiple Hydraulic Fracture Growth 39 4.3.1.3 Interactions Between Hydraulic Fractures and Natural Fractures 40 4.3.1.4 Fracture Propagation Through the Layered Formation 41 4.3.1.5 Nonlinear Fracturing in the Deep Reservoir 42 4.3.1.6 Cyclic Fracturing 43 4.3.2 Environmental Fracturing in a Shallow Formation 44 4.3.3 Hydraulic Stimulation in EGS 44 4.4 Conclusions and Future Work 45 References 46 5 First Field Trail and Experimental Studies on scCO2 Fracturing 51 Haiyan Zhu, Lei Tao, Shouceng Tian, and Haizhu Wang 5.1 Introduction 51 5.2 Review on scCO2 Fracturing 52 5.2.1 Shale and scCO2 Interaction 52 5.2.1.1 Microscale Physical Changes 52 5.2.1.2 Microscale Chemical Changes 52 5.2.1.3 Macroscale Mechanical Changes 53 5.2.1.4 Conclusions on the Experiments on Shale and scCO2 Interaction 54 5.2.2 Experiments and Numerical Simulations on scCO2 Fracturing 54 5.2.2.1 Experiments on scCO2 Fracturing 54 5.2.2.2 Numerical Simulations on scCO2 Fracturing 57 5.3 A Field Trail on scCO2 Fracturing of Continental Shale in Yanchang Oil Field 57 5.3.1 scCO2 Fracturing Technology 57 5.3.2 scCO2 Fracturing Field Test 58 5.3.2.1 Reservoir Properties of Test Wells 58 5.3.2.2 Fracturing Process and Operation Parameters 58 5.3.3 Field Test Results and Analysis 59 5.3.3.1 Microseismic Monitoring and Inversion of Fracture Geometry 59 vi Contents5.3.3.2 Production Data 60 5.4 Challenges in scCO2 Fracturing 60 5.4.1 scCO2 Fracturing Mechanism Is Still Not Clear 60 5.4.2 Challenges in Proppants Carrying 60 5.4.3 Challenge on the Predicting and Monitoring CO2 Phase 61 5.4.4 Lack of Specialized Equipment for scCO2 Fracturing 61 5.5 Conclusions 61 Acknowledgments 61 References 61 6 An Unstructured Moving Element Mesh for Hydraulic Fracture Modeling 65 John Napier and Emmanuel Detournay 6.1 Introduction 65 6.2 Discrete Model of a Planar Hydraulic Fracture 65 6.2.1 Unstructured Mesh 66 6.2.2 Discrete Elasticity Equation 66 6.2.3 Discretized Lubrication Equations for Channel Elements 67 6.2.4 Tip Elements 67 6.3 Time-Marching Algorithm 67 6.3.1 Iteration Loops 68 6.3.2 Local Front Update 68 6.3.3 Generation of a New Ring of Tip Elements 68 6.3.4 Crack Surface Remeshing 69 6.3.5 General Solution Algorithm Logic 69 6.4 Numerical Simulations: Stress Barriers 70 6.4.1 Description of Experiment 70 6.4.2 Numerical Simulations (no Remeshing) 70 6.4.3 Comparison with Experimental Results and Other Simulations 71 6.4.4 Illustration and Assessment of the Element Re-Meshing Strategy 71 6.5 Conclusions 73 Acknowledgments 73 References 73 7 Study of Hydraulic Fracture Interference with a Lattice Model 75 C. Detournay, B. Damjanac, M. Torres, and Y. Han 7.1 Introduction 75 7.2 XSite Code Overview 75 7.3 Numerical Studies of Fracture Interference 75 7.3.1 Interaction of a Hydraulic Fracture with a Natural Fracture 76 7.3.2 Interaction of Two Hydraulic Fractures 76 7.3.2.1 Numerical Study 76 7.3.2.2 Interpretation of Results 78 7.3.3 Interaction of Hydraulic Fractures in Injection of Multiple Clusters 79 7.3.4 Interaction of Hydraulic Fractures in Fractured Medium 81 7.3.5 Interaction of Hydraulic Fractures in Zipper-Stage Injection 83 7.4 Afterword 83 References 85 8 The Tipping Point: How Tip Asymptotics Can Enhance Numerical Modeling of Hydraulic Fracture Evolution 87 A. Peirce 8.1 Introduction 87 8.2 Mathematical Model 87 Contents vii8.2.1 Assumptions 87 8.2.2 Governing Equation 88 8.2.2.1 Elasticity 88 8.2.2.2 Fluid Transport 88 8.2.2.3 Boundary and Propagation Conditions 88 8.2.2.4 Tip Asymptotics, Vertex Solutions, and Generalized Asymptotes 89 8.3 Discretization, Coupled Equations, and the Multiscale ILSA Scheme to Locate the Free Boundary 91 8.3.1 Discretization 91 8.3.1.1 Displacement Discontinuity Formulation for Planar Fractures 91 8.3.2 Locating the Free Boundary Using the Implicit Level Set Algorithm (ILSA) 92 8.4 Numerical Results 95 8.4.1 Symmetric Stress Barrier: m-Vertex Solution vs Experiment and the Effect of Toughness 95 8.4.2 A Stress Drop: Distinct Propagation Regimes Along the Periphery 95 8.5 Conclusions 95 8.6 Acknowledgment 97 References 97 9 Plasticity: A Mechanism for Hydraulic Fracture Height Containment 99 Panos Papanastasiou 9.1 Introduction 99 9.2 The Dependence of the Effective Fracture Toughness on Propagation Direction 100 9.3 Effective Fracture Toughness vs. Closure Stress 101 9.4 A New Brittleness Index Defines Fracture Containment 102 9.5 Conclusions 103 Acknowledgments 104 References 104 10 Turbulent Flow Effects on Propagation of Radial Hydraulic Fracture in Permeable Rock 107 E.A. Kanin, D.I. Garagash, and A.A. Osiptsov 10.1 Introduction 107 10.2 Model Formulation 108 10.2.1 Problem Definition 108 10.2.2 Governing Equations 109 10.2.2.1 Crack Elasticity 109 10.2.2.2 Fluid Flow 109 10.2.2.3 Fracture Propagation 110 10.2.2.4 Boundary Conditions 110 10.2.2.5 Global Fluid Volume Balance 110 10.3 Solution Approach 111 10.4 Solution Examples for Typical Field Applications 112 10.5 Limiting Propagation Regimes 115 10.6 Normalization of the Governing Equations 118 10.7 Problem Parameter Space Analyses 119 10.7.1 Zero Leak-Off Case (Impermeable Rock) 120 10.7.2 Nonzero Leak-Off Case (Permeable Rock) 121 10.8 Conclusions 122 Acknowledgments 124 References 125 11 Analysis of a Constant Height Hydraulic Fracture 127 E.V. Dontsov 11.1 Introduction 127 viii Contents11.2 Governing Equations 128 11.3 Tip Region 129 11.4 Vertex Solutions 132 11.4.1 Storage Viscosity 132 11.4.2 Leak-off Viscosity 133 11.4.3 Storage Toughness 133 11.4.4 Leak-off Toughness 133 11.5 Full Solution 134 11.6 Application Examples 136 11.7 Summary 137 References 137 12 Discrete Element Modeling of Hydraulic Fracturing 141 Mengli Li and Fengshou Zhang 12.1 Introduction 141 12.2 Discrete Element Modeling of Hydraulic Fracturing 142 12.3 Hydraulic Fracture Interacting with Natural Fractures 142 12.3.1 Hybrid Discrete-Continuum Method 143 12.3.2 Model Calibration for a Hydraulic Fracture in Intact Rock 144 12.3.3 Orthogonal Crossing 145 12.3.3.1 Effects of Stress Ratio and Friction of Natural Fractures 145 12.3.3.2 Effect of Strength (Toughness) Contrast 147 12.3.3.3 Effect of Stiffness (Modulus) Contrast 149 12.3.4 Non-Orthogonal Crossing 150 12.3.5 Fracturing Complexity 151 12.4 DEM Modeling of Supercritical Carbon Dioxide Fracturing 153 12.4.1 New Algorithm for the Toughness-Dominated Regime 153 12.4.2 Numerical Model Setup 154 12.4.2.1 Model Description 154 12.4.2.2 Model Verification 156 12.4.3 Hydraulic Fracturing in Intact Rock Sample 157 12.4.4 Hydraulic Fracturing in Fractured Rock Sample 161 12.5 DEM Modeling of Fluid Injection into Dense Granular Media 163 12.5.1 Background and Experimental Motivation 163 12.5.2 Model Setup 165 12.5.3 Effect of the Injection Rate 166 12.5.4 Dimensionless Time Scaling 168 12.5.5 Energy Partition 170 12.6 Discussion 171 12.7 Conclusions 171 References 172 13 Interaction of a Hydraulic Fracture with Natural Fractures of Lesser Height and Weak Bedding Interfaces as a Possible Mechanism for Fracture Swarms 177 Xiaowei Weng and Olga Kresse 13.1 Introduction 177 13.2 Possible Mechanisms for Fracture Bifurcation 179 13.3 Interaction of Closely Spaced Parallel Fractures 182 13.3.1 Fracture Tip Extension in Overlapped Region 182 13.3.2 Instability of Closely Spaced Parallel Hydraulic Fractures – Shared Inlet 183 13.3.3 Instability of Closely Spaced Parallel Hydraulic Fractures – Separate Inlets 184 13.4 Possible Mechanisms for Creating Fracture Swarms 185 Contents ix13.5 Conclusions 188 References 189 14 Hydraulic Fracturing Mechanisms Leading to Self-Organization Within Dyke Swarms 193 Andrew. P. Bunger, D. Gunaydin, S. T. Thiele, and A. R. Cruden 14.1 Introduction 193 14.2 Swarm Morphology and Fundamental Drivers 193 14.3 Dyke Swarm Model and Energetics 194 14.4 Alignment 196 14.5 Avoidance 197 14.6 Stress Shadow 197 14.7 Stress Plugs 199 14.8 Attraction 199 14.9 Emergent Spacing 200 14.10 Simulating Dyke Swarm Assembly 201 14.11 Conclusions 202 Acknowledgments 203 References 203 15 Numerical Simulation of Thermal Fracturing During Heat Extraction from a Closed-Loop Circulation Enhanced Geothermal System 207 Z. Lei, Bisheng Wu, and Z. Chen 15.1 Introduction 207 15.2 Mathematical Formulation 208 15.2.1 Problem Description 208 15.2.2 Governing Equations of Coupled Thermoelastic Model 209 15.2.2.1 Fluid Flow 209 15.2.2.2 Rock Deformation 209 15.2.2.3 Fracture Initiation and Propagation 210 15.2.2.4 Thermal Transport Through Fluid Flow 211 15.2.2.5 Heat Transfer in Rock Matrix 211 15.2.3 Boundary and Initial Conditions 211 15.3 Solution Methodology and Computational Procedures 211 15.3.1 Coupled Fluid-Fracture Solver 211 15.3.1.1 Weak Form and FEM Discretization 211 15.3.1.2 Extended Finite Element Approximation 212 15.3.2 Coupled Fluid-Thermal Solver 213 15.3.3 Solution Strategy 213 15.4 Numerical Results 214 15.4.1 Fluid Flow and Production Temperature 214 15.4.2 Temperature Distribution in Rock Formation 216 15.4.3 Fracture Propagation 216 15.4.3.1 Single Fracture Case 216 15.4.3.2 Double Fracture Case 220 15.5 Conclusions 221 References 221 16 Multiple Hydraulic Fractures Growth from a Highly Deviated Well: A XFEM Study 225 Yun Zhou and Diansen Yang 16.1 Introduction 225 16.2 Problem Formulation 227 16.2.1 Governing Equations 228 x Contents16.2.1.1 Solid Deformation 228 16.2.1.2 Fluid Flow in Matrix 229 16.2.1.3 Fluid Flow in Fractures 229 16.2.1.4 Flow Rate Division to Multiple Fractures 229 16.2.1.5 Fracture Propagation 229 16.2.2 Weak Forms 230 16.3 Numerical Method 230 16.3.1 XFEM Approximation of u(x, t) and p(x, t) 230 16.3.2 Spatial and Time Discretization 231 16.3.3 Solution Strategy 231 16.3.3.1 Solution of HM-Coupled Equations 231 16.3.3.2 Solution of Flow Rate Division 231 16.4 Numerical Results 232 16.4.1 Verification of the Model 232 16.4.2 Multi-Cluster Hydraulic Fracturing in High-Angle Well 233 16.4.2.1 Model Set-up 234 16.4.2.2 Operational Parameters 235 16.4.2.3 Deviation Angle 236 16.4.2.4 Fracture Spacing 239 16.4.2.5 Fracture Placement 240 16.4.2.6 Fracture Number 241 16.5 Discussion 245 16.6 Conclusions 245 Appendix 16.A Dimensionless Toughness κ 245 Appendix 16.B Dimensionless Parameter Gm 246 Appendix 16.C Dimensionless Variability Coefficient Cv 246 References 246 17 Hydraulic Fracturing-Induced Slip on a Permeable Fault 251 Xi. Zhang, R. G. Jeffrey, and J. Yang 17.1 Introduction 251 17.2 Model Setup 252 17.3 Summary of Modeling Results 254 17.3.1 Fully Closed Fractures 254 17.3.1.1 Constant Fault Permeability 254 17.3.1.2 Enhanced Fault Permeability 254 17.3.1.3 Fault Permeability Reduction 255 17.3.2 Partially Opened Fracture 256 17.3.2.1 Planar Fault 256 17.3.2.2 Nonplanar Fault 256 17.4 Radiated Energy 256 17.5 Conclusions and Future Work 258 Acknowledgment 259 References 259 Index 263
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