Coupled Thermo-Hydro-Mechanical Processes in Fractured Rock Masses: Discrete Element Modeling and Engineering Applications

✍ Scribed by Fengshou Zhang, Branko Damjanac, Jason Furtney

• Publisher: Springer
• Year: 2023
• Tongue: English
• Leaves: 316
• Category: Library

✦ Synopsis

The subject of thermo-hydro-mechanical coupled processes in fractured rock masses has close relevance to energy-related deep earth engineering activities, such as enhanced geothermal systems, geological disposal of radioactive waste, sequestration of CO2, long-term disposal of waste water and recovery of hydrocarbons from unconventional reservoirs. Despite great efforts by engineers and researchers, comprehensive understanding of the thermo-hydro-mechanical coupled processes in fractured rock mass remains a great challenge. The discrete element method (DEM), originally developed by Dr. Peter Cundall, has become widely used for the modeling of a rock mass, including its deformation, damage, fracturing and stability. DEM modeling of the coupled thermo-hydro-mechanical processes in fractured rock masses can provide some unique insights, to say the least, for better understanding of those complex issues.

The authors of this book have participated in various projects involving DEM modeling of coupled thermo-hydro-mechanical processes during treatment of a rock mass by fluid injection and/or extraction and have provided consulting services to some of the largest oil-and-gas companies in the world. The breadth and depth of our engineering expertise are reflected by its successful applications in the major unconventional plays in the world, including Permian, Marcellus, Bakken, Eagle Ford, Horn River, Chicontepec, Sichuan, Ordos and many more. The unique combination of the state-of-the-art numerical modeling techniques with state-of-the-practice engineering applications makes the presented material relevant and valuable for engineering practice. We believe that it is beneficial to share the advances on this subject and promote some further development.

✦ Table of Contents

Foreword
Preface
Contents
Nomenclature
1 Introduction to the Discrete Element Method (DEM)
1.1 Introduction
1.2 Basics of DEM
1.2.1 Definition
1.2.2 Numerical Formulation
1.2.3 Block Interaction
1.3 Bonded-Particle Model (BPM)
1.3.1 Approximation of Brittle Mechanical Behavior
1.3.2 Contact Models Used in BPM
1.4 Lattice
1.4.1 Description
1.4.2 Lattice Types and Upscaling
1.5 Fluid Mechanics Concepts in DEM Implementations of Hydro-Mechanical Coupling
1.5.1 Flow in Porous Media
1.5.2 Flow in Rock Fractures
1.5.3 Hydro-Mechanical Coupling
1.5.4 Additional Topics
1.5.5 Further Reading in Fluid Mechanics
References
2 Discrete Element Modeling of Hydraulic Fracturing
2.1 Introduction
2.2 Pore Network Model
2.3 Fracture Interactions with a Hybrid Discrete-Continuum Method
2.3.1 Hybrid Discrete-Continuum Method
2.3.2 Model Calibration for a Hydraulic Fracture in Intact Rock
2.3.3 Orthogonal Crossing
2.3.4 Non-orthogonal Crossing
2.3.5 Fracturing Complexity
2.4 DEM Modeling of Supercritical Carbon Dioxide Fracturing
2.4.1 New Algorithm for the Toughness-Dominated Regime
2.4.2 Numerical Model Setup
2.4.3 Hydraulic Fracturing in Intact Rock Sample
2.4.4 Hydraulic Fracturing in Fractured Rock Sample
2.5 DEM Modeling of Fluid Injection into Dense Granular Media
2.5.1 Background and Experimental Motivation
2.5.2 Model Setup
2.5.3 Effect of the Injection Rate
2.5.4 Dimensionless Time Scaling
2.5.5 Energy Partition
2.6 Conclusions
References
3 DEM Coupled with Computational Fluid Dynamics (CFD)
3.1 Introduction
3.2 Numerical Framework of CFD-DEM
3.2.1 Fluid-Prticle Interaction
3.2.2 Calculation Cycle
3.2.3 Porosity Calculation
3.2.4 Numerical Stability and Linear Relaxation
3.3 Applications
3.4 Extended Methods of CFD-DEM
3.5 Conclusions
References
4 DEM Coupled with Dynamic Fluid Mesh (DFM)
4.1 Introduction
4.2 Numerical Algorithm of Dynamic Fluid Mesh (DFM) in DEM
4.2.1 Workflow of DEM-DFM Coupling
4.2.2 Fluid Mesh Generation in DEM
4.2.3 Solve Permeability and Fluid Velocity
4.2.4 Hydro-Mechanical Forces on the Particles
4.3 Modeling of Suffusion in Gap-Graded Soils
4.3.1 Model Setup
4.3.2 Numerical Results of Baseline Test
4.4 Parametric Studies
4.4.1 Effect of Pressure Difference
4.4.2 Effect of Confining Stress
4.4.3 Effect of Particle Size Ratio
4.5 Conclusions
References
5 DEM Coupled with Lattice-Boltzmann Method (LBM)
5.1 Introduction
5.2 Formulation of DEM/LBM Coupling
5.3 Modeling of Particle-Fluid Interaction
5.4 Pore-Scale Fluid Flow Through Idealized Porous Media
5.4.1 Flow Through a Square Periodic Array of Cylinders (2D)
5.4.2 Flow Through a Cubic Array of Spheres (3D)
5.4.3 Comments of Pore-Scale Fluid Flow Through Porous Media
5.5 Modeling of Multi-phase Fluid in Porous Rocks
5.5.1 Model Setup
5.5.2 Simulation Results of Multi-phase Fluid in Porous Rocks
5.5.3 Implications of Multi-phase Fluid in Porous Rocks
5.6 Conclusions
References
6 Hydraulic Stimulation of Naturally Fractured Reservoirs
6.1 Introduction
6.2 Fracture Network Engineering (FNE)
6.3 DEM Model of Fracture Flow
6.3.1 Representation of Fractures and DFN Using DEM
6.3.2 Fluid Flow in a Joint
6.4 Condition for Fracture Propagation
6.5 Verification Test: PKN Fracture
6.6 Example Application
6.7 Conclusions
References
7 Models of Stimulation and Production from Enhanced Geothermal Systems
7.1 Introduction
7.2 Verification of Hydro-thermal Model: Cold Water Injection into a Single Fracture
7.3 Numerical Modeling of EGS
7.3.1 Representation of DFN
7.3.2 In-Situ Stresses and Slip Condition
7.3.3 Model Setup
7.3.4 Stimulation and Production Indices
7.4 Results
7.4.1 Effect of Well Positioning
7.4.2 Effect of Pre-existing Fracture Spacing
7.5 Effect of Dilation Angle of Pre-existing Fractures
7.5.1 Effect of Fracture Size Distribution
7.5.2 Effect of Injection Rate During Production
7.6 Conclusions
References
8 Hydraulic Fracturing Induced Fault Reactivation
8.1 Introduction
8.2 Engineering Background
8.2.1 Basic Information
8.2.2 Evidence of Fault Reactivation
8.3 Microseismic Analysis of Field Data
8.4 Evaluation of 3D Geomechanical Modeling
8.4.1 Numerical Scheme
8.4.2 Model Setup
8.4.3 Simulation Results of Baseline Case
8.5 Parametric Studies
8.5.1 Effect of Injection Rate/Volume
8.5.2 Effect of Injection Fluid Viscosity
8.5.3 Effect of Mesh Size
8.6 Discussion
8.6.1 Energy Budget
8.6.2 Seismic Mitigation
8.7 Conclusions
References
9 3D Lattice Modeling of Hydraulic Fracturing in Naturally Fractured Reservoirs
9.1 Introduction
9.2 Synthetic Rock Mass (SRM) Approach
9.3 Fluid Flow in Lattice Models
9.3.1 Geometry
9.3.2 Formulation of Flow
9.3.3 Hydro-mechanical Coupling
9.3.4 Optimization of Explicit Integration Scheme
9.3.5 Lattice Model of Stimulation of Fractured Reservoir from Two Wells
9.4 Conclusions
References
10 Heat Advection and Forced Convection in a Lattice Code
10.1 Introduction
10.2 Thermal Formulation
10.2.1 Convection Heat Transfer Coefficient
10.2.2 Heat Advection and Forced Convection in the Fluid
10.2.3 Heat Conduction in the Rock and Forced Convection from the Fracture
10.3 Numerical Implementation
10.3.1 Heat Advection-Convection in XSite
10.3.2 Stable Time Step for the Advection Process
10.3.3 Heat Conduction-Convection in the Rock
10.3.4 Coupled Scheme
10.4 Example Application
10.5 Conclusions
References
11 Near Wellbore HF Propagation for Different Perforation Models
11.1 Introduction
11.2 Numerical Model Setup
11.3 Numerical Modeling Results
11.3.1 Spiral Perforation Model
11.3.2 Oriented Perforation Model
11.3.3 Tristim Perforation Model
11.4 Discussion
11.4.1 Characteristics of Different Perforation Models
11.4.2 Qualification of Toughness Dominated Regime
11.4.3 Comparison with Experimental Results
11.5 Conclusions
References
12 Design of Extreme Limited Entry Perforation
12.1 Introduction
12.2 3D Numerical Model of XLE Completion
12.2.1 Engineering Background of XLE Completion in Changqing Oilfield
12.2.2 Numerical Model of XLE Completion
12.2.3 Simulation Results and Validation of Numerical Model
12.3 Parametric Analyses
12.3.1 Injection Rate
12.3.2 Cluster Spacing
12.3.3 Cluster Number
12.3.4 Stress Difference Between Clusters
12.4 Discussion
12.5 Conclusions
References