Homogenization Schemes for Hydro-Mechanical Constitutive Modeling of Fractured Media

In recent years, significant advances in computing power and numerical algorithms have given researchers the ability to model geologic systems at unprecedented levels of detail. Simulations with millions or even billions of grid cells are increasingly common in academic and industrial settings. At the same time, computing power alone is insufficient to capture the pervasive heterogeneities intrinsic to geologic materials. Efficient strategies are necessary for capturing sub-grid-scale processes and their impacts on macroscopic behavior. In this work, we focus on the particular problem of coupled hydro-mechanical simulations of fractured media. We describe a homogenization strategy for computing both the mechanical and fluid flow constitutive behavior of fractured rock. Important features such as strength and permeability anisotropy arise naturally from the small-scale description of the phase and fracture distribution. We show how the resulting material models may be readily incorporated into continuum or discrete-fracture-network simulations of reservoir systems, providing an efficient way of capturing both large- and small-scale processes. Prepared by LLNL under Contract DE-AC52-07NA27344.