Hybrid-dimensional modeling for fluid flow in heterogeneous porous media using dual fracture-pore model with flux interaction of fracture–cavity network

Abstract

Developing numerical method of fractured porous media is of paramount importance in geoscience applications. Previous studies have revealed that the discrete fractures and cavities as well as the heterogeneity have considerable influences on hydraulic property of porous media. This work presents a numerical investigation on fluid flow in heterogeneous porous media with the consideration of flux connection of fracture–cavity network. A hybrid-dimensional modeling approach combined with the dual fracture-pore model is presented. Then, the numerical scheme is derived from Galerkin finite element method. Especially, the numerical treatment on flux interaction of multiple fractures is elaborated. Next, this model is verified by a benchmark study, and grid convergence test is performed to show the grid independence. Later, a fractured porous medium is simulated with different states of cavity. The effects of impermeable and conductive fractures on fluid flow are studied. In contrast to the homogeneous situation, we consider the effects of heterogeneity. Meanwhile, a comparison study is conducted to investigate the impacts of heterogeneity, boundary conditions and conductivity of the fracture–cavity network on fluid flow. Furthermore, pressure deviation induced by heterogeneity is analyzed with different conductivities of fractures and cavities. It appears that pressure distribution is highly related to fractures conductivity and the state of cavities, where the influence of heterogeneity on the high-conductivity fractures is relatively smaller than the low-conductivity.