A fully coupled numerical model of thermo-hydro-mechanical processes and fracture contact mechanics in porous media

Stefansson, Ivar; Berre, Inga; Keilegavlen, Eirik

doi:10.1016/j.cma.2021.114122

Cited by 38 publications

(33 citation statements)

References 55 publications

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“…Excluding thermal effects, we use the same full set of model equations as Stefansson et al, (2020a).…”

Section: Modeling Of Fault Reactivation and Slip Accounting For Proce...mentioning

confidence: 99%

“…In this section, we utilize the advantages of physics-based modelling and discuss aspects affecting fault reactivation and slip illustrated by numerical examples. The test cases are set up using the open-source software PorePy (Keilegavlen et al, 2019) including the recent developments by (Stefansson et al, 2020a). The software as well as all details of the simulations, including run scripts, are available at GitHub (Stefansson, 2020c).…”

Section: Mechanisms Affecting Fault Reactivation and Slip Through Cou...mentioning

confidence: 99%

“…The increase in hydraulic aperture is typically proportional to slip up to a threshold value where production of gauge can explain the prevention of further permeability increase (Lee and Cho, 2002). Fault dilation interacts with the hydromechanical stresses on the fault, leading to a significant coupling (Stefansson et al, 2020a).…”

Section: Fault Reactivation Slip and Dilationmentioning

confidence: 99%

“…Based on conservation principles and constitutive relations, the conceptual principles 1 and 2 result in a coupled system of partial differential equations governing fault reactivation and deformation. Recently, numerical models based on discretization and fully-coupled solutions of the governing system of equations have been developed (Berge et al, 2020;Garipov and Hui, 2019;Garipov et al, 2018;Keilegavlen et al, 2019;Stefansson et al, 2020b), which also show appropriate grid convergence properties (Stefansson et al, 2020a). These models are based on conceptualizing the faults as two-dimensional surfaces in the three-dimensional domain.…”

Section: Modeling Of Fault Reactivation and Slip Accounting For Proce...mentioning

confidence: 99%

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Fault slip in hydraulic stimulation of geothermal reservoirs: Governing mechanisms and process-structure interaction

2020

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Hydraulic stimulation of geothermal reservoirs in low-permeability basement and crystalline igneous rock can enhance permeability by reactivation and shear dilation of existing fractures. The process is characterized by interaction between fluid flow, deformation, and the fractured structure of the formation. The flow is highly affected by the fracture network, which in turn is deformed because of hydromechanical stress changes caused by the fluid injection. This process-structure interaction is decisive for the outcome of hydraulic stimulation, and, in analysis of governing mechanisms, physics-based modeling has potential to complement field and experimental data. Here, we show how recently developed simulation technology is a valuable tool to understand governing mechanisms of hydromechanical coupled processes and the reactivation and deformation of faults. The methodology fully couples flow in faults and matrix with poroelastic matrix deformation and a contact mechanics model for the faults, including dilation because of slip. Key elements are high aspect ratios of faults and strong nonlinearities in highly coupled governing equations. Example simulations using our open-source software illustrate direct and indirect hydraulic fault reactivation and corresponding permeability enhancement. We investigate the effect of the fault and matrix permeability and the Biot coefficient. A higher matrix permeability leads to more leakage from a permeable fault and thus suppresses reactivation and slip of the fault compared to the case with a lower matrix permeability. If a fault is a barrier to flow, increase of pressure because of the fluid injection results in stabilization of the fault; the situation is opposite if the fault is highly permeable compared to the matrix. For the given setup, lowering the Biot coefficient results in more slip than the base case. While conceptually simple, the examples illustrate the strong hydromechanical couplings and the prospects of physics-based numerical models in investigating the dynamics.

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“…Excluding thermal effects, we use the same full set of model equations as Stefansson et al, (2020a).…”

Section: Modeling Of Fault Reactivation and Slip Accounting For Proce...mentioning

confidence: 99%

Section: Mechanisms Affecting Fault Reactivation and Slip Through Cou...mentioning

confidence: 99%

Section: Fault Reactivation Slip and Dilationmentioning

confidence: 99%

Section: Modeling Of Fault Reactivation and Slip Accounting For Proce...mentioning

confidence: 99%

See 2 more Smart Citations

Fault slip in hydraulic stimulation of geothermal reservoirs: Governing mechanisms and process-structure interaction

2020

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“…For more information on modeling of the relation between displacement and fracture aperture, see Stefansson et al. (2021).…”

Section: Example Model Problemsmentioning

confidence: 99%

Numerical Treatment of State‐Dependent Permeability in Multiphysics Problems

Stefansson

Keilegavlen

2023

Water Resources Research

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Constitutive laws relating fluid potentials and fluxes in a nonlinear manner are common in several porous media applications, including biological and reactive flows, poromechanics, and fracture deformation. Compared to the standard, linear Darcy’s law, such enhanced flux relations increase both the degree of nonlinearity, and, in the case of multiphysics simulations, coupling strength between processes. While incorporating the nonlinearities into simulation models is thus paramount for computational efficiency, correct linearization, as is needed for incorporation in Newton’s method, is challenging from a practical perspective. The standard approach is therefore to ignore nonlinearities in the permeability during linearization. For finite volume methods, which are popular in porous media applications, complete linearization is feasible only for the simplest flux discretization, namely the two‐point flux approximation. We introduce an approximated linearization scheme for finite volume methods that is exact for the two‐point scheme and can be applied to more advanced and accurate discretizations, exemplified herein by a multi‐point flux stencil. We test the new method for both nonlinear porous media flow and several multiphysics simulations. Our results show that the new linearization consistently outperforms the standard approach. Moreover our scheme achieves asymptotic second order convergence of the Newton iterations, in contrast to the linear convergence obtained with the standard approach.This article is protected by copyright. All rights reserved.

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Mixed-dimensional poromechanical models of fractured porous media

Boon

Nordbotten

2022

Acta Mech

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We combine classical continuum mechanics with the recently developed calculus for mixed-dimensional problems to obtain governing equations for flow in, and deformation of, fractured materials. We present models in both the context of finite and infinitesimal strain, and discuss nonlinear (and non-differentiable) constitutive laws such as friction models and contact mechanics in the fracture. Using the theory of well-posedness for evolutionary equations with maximal monotone operators, we show well-posedness of the model in the case of infinitesimal strain and under certain assumptions on the model parameters.

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A fully coupled numerical model of thermo-hydro-mechanical processes and fracture contact mechanics in porous media

Cited by 38 publications

References 55 publications

Fault slip in hydraulic stimulation of geothermal reservoirs: Governing mechanisms and process-structure interaction

Fault slip in hydraulic stimulation of geothermal reservoirs: Governing mechanisms and process-structure interaction

Numerical Treatment of State‐Dependent Permeability in Multiphysics Problems

Mixed-dimensional poromechanical models of fractured porous media

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