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

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.

Automated summary

Developing numerical methods for fractured porous media is crucial in geoscience applications, as prior studies have shown that discrete fractures, cavities, and heterogeneity significantly impact the hydraulic properties of such media. This research presents a numerical investigation on fluid flow in heterogeneous porous media, taking into account the flux connection of fracture-cavity networks. A hybrid-dimensional modeling approach, combined with a dual fracture-pore model, is utilized, and the numerical scheme is derived from the Galerkin finite element method. The study focuses on the numerical treatment of flux interaction between multiple fractures. The model is verified through benchmark studies and grid convergence tests to demonstrate grid independence. Subsequently, a simulation is conducted on a fractured porous medium with different states of cavities, and the effects of impermeable and conductive fractures on fluid flow are studied. The study also compares the impacts of heterogeneity, boundary conditions, and conductivity of the fracture-cavity network on fluid flow. Furthermore, the pressure deviation induced by heterogeneity is analyzed based on different conductivities of fractures and cavities, revealing that pressure distribution is highly influenced by fracture conductivity and cavity state, and that the influence of heterogeneity on high-conductivity fractures is relatively smaller than that on low-conductivity fractures.