The use of discrete fracture networks for modelling coupled geomechanical and hydrological behaviour of fractured rocks

Lei, Qinghua; Latham, John; Tsang, Chin‐Fu

doi:10.1016/j.compgeo.2016.12.024

Cited by 400 publications

(182 citation statements)

References 256 publications

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“…Rock fracture network controls the main paths of fluid flow and contaminant migration in deep underground, and the estimation of permeability of fractured rock masses has been extensively studied during the past several decades in many geoengineering and geosciences such as CO 2 sequestration, enhanced oil recovery, and geothermal energy development [1][2][3][4][5][6][7][8][9]. The fluid flow in rock fractures and/or fracture networks is commonly assumed to obey the cubic law, in which the flow rate is linearly proportional to the pressure drop [10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

A Review of Critical Conditions for the Onset of Nonlinear Fluid Flow in Rock Fractures

Jiang

2017

Geofluids

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Selecting appropriate governing equations for fluid flow in fractured rock masses is of special importance for estimating the permeability of rock fracture networks. When the flow velocity is small, the flow is in the linear regime and obeys the cubic law, whereas when the flow velocity is large, the flow is in the nonlinear regime and should be simulated by solving the complex NavierStokes equations. The critical conditions such as critical Reynolds number and critical hydraulic gradient are commonly defined in the previous works to quantify the onset of nonlinear fluid flow. This study reviews the simplifications of governing equations from the Navier-Stokes equations, Stokes equation, and Reynold equation to the cubic law and reviews the evolutions of critical Reynolds number and critical hydraulic gradient for fluid flow in rock fractures and fracture networks, considering the influences of shear displacement, normal stress and/or confining pressure, fracture surface roughness, aperture, and number of intersections. This review provides a reference for the engineers and hydrogeologists especially the beginners to thoroughly understand the nonlinear flow regimes/mechanisms within complex fractured rock masses.

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Section: Introductionmentioning

confidence: 99%

A Review of Critical Conditions for the Onset of Nonlinear Fluid Flow in Rock Fractures

Jiang

2017

Geofluids

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“…These naturally occurring discontinuities often comprise complex networks and dominate hydromechanical processes in the subsurface (Zimmerman and Main 2004;Lei et al 2017). The understanding of the nontrivial effects of natural fractures on the bulk properties of highly disordered geological media is important for many engineering applications including groundwater management, petroleum recovery, geothermal production and radioactive waste disposal (Rutqvist and Stephansson 2003).…”

Section: Introductionmentioning

confidence: 99%

Polyaxial stress-dependent permeability of a three-dimensional fractured rock layer

et al. 2017

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A study about the influence of polyaxial (true-triaxial) stresses on the permeability of a three-dimensional (3D) fractured rock layer is presented. The 3D fracture system is constructed by extruding a two-dimensional (2D) outcrop pattern of a limestone bed that exhibits a ladder structure consisting of a Bthrough-going^joint set abutted by later-stage short fractures. Geomechanical behaviour of the 3D fractured rock in response to in-situ stresses is modelled by the finite-discrete element method, which can capture the deformation of matrix blocks, variation of stress fields, reactivation of pre-existing rough fractures and propagation of new cracks. A series of numerical simulations is designed to load the fractured rock using various polyaxial in-situ stresses and the stress-dependent flow properties are further calculated. The fractured layer tends to exhibit stronger flow localisation and higher equivalent permeability as the far-field stress ratio is increased and the stress field is rotated such that fractures are preferentially oriented for shearing. The shear dilation of pre-existing fractures has dominant effects on flow localisation in the system, while the propagation of new fractures has minor impacts. The role of the overburden stress suggests that the conventional 2D analysis that neglects the effect of the out-of-plane stress (perpendicular to the bedding interface) may provide indicative approximations but not fully capture the polyaxial stress-dependent fracture network behaviour. The results of this study have important implications for understanding the heterogeneous flow of geological fluids (e.g. groundwater, petroleum) in subsurface and upscaling permeability for largescale assessments.

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“…In the framework of the fracture process analysis of rocks, continuum‐based methods include the finite element method (FEM), the finite difference method (FDM), the boundary element method (BEM), the scaled‐boundary finite element method (SBFEM), the extended finite element method (XFEM), meshless methods, methods based on peridynamics and phase‐field methods, while discontinuum‐based methods include the distinct element method (DEM), the lattice model (LM) method, and molecular dynamics (MD). More detailed information on recent advances in the computational fracture mechanics of rocks can be found in recently published review articles . To realistically simulate the fracture process of rock, numerical techniques must be capable of capturing crack onset, arbitrary crack growth, the correct crack length within a given time interval and the propagating directions.…”

Section: Introductionmentioning

confidence: 99%

Development of a GPGPU‐parallelized hybrid finite‐discrete element method for modeling rock fracture

Fukuda

Mohammadnejad

Liu

et al. 2019

Num Anal Meth Geomechanics

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Summary The hybrid finite‐discrete element method (FDEM) is widely used for engineering applications, which, however, is computationally expensive and needs further development, especially when rock fracture process is modeled. This study aims to further develop a sequential hybrid FDEM code formerly proposed by the authors and parallelize it using compute unified device architecture (CUDA) C/C++ on the basis of a general‐purpose graphics processing unit (GPGPU) for rock engineering applications. Because the contact detection algorithm in the sequential code is not suitable for GPGPU parallelization, a different contact detection algorithm is implemented in the GPGPU‐parallelized hybrid FDEM. Moreover, a number of new features are implemented in the hybrid FDEM code, including the local damping technique for efficient geostatic stress analysis, contact damping, contact friction, and the absorbing boundary. Then, a number of simulations with both quasi‐static and dynamic loading conditions are conducted using the GPGPU‐parallelized hybrid FDEM, and the obtained results are compared both quantitatively and qualitatively with those from either theoretical analysis or the literature to calibrate the implementations. Finally, the speed‐up performance of the hybrid FDEM is discussed in terms of its performance on various GPGPU accelerators and a comparison with the sequential code, which reveals that the GPGPU‐parallelized hybrid FDEM can run more than 128 times faster than the sequential code if it is run on appropriate GPGPU accelerators, such as the Quadro GP100. It is concluded that the GPGPU‐parallelized hybrid FDEM developed in this study is a valuable and powerful numerical tool for rock engineering applications.

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The use of discrete fracture networks for modelling coupled geomechanical and hydrological behaviour of fractured rocks

Cited by 400 publications

References 256 publications

A Review of Critical Conditions for the Onset of Nonlinear Fluid Flow in Rock Fractures

A Review of Critical Conditions for the Onset of Nonlinear Fluid Flow in Rock Fractures

Polyaxial stress-dependent permeability of a three-dimensional fractured rock layer

Development of a GPGPU‐parallelized hybrid finite‐discrete element method for modeling rock fracture

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