Unstructured Grid Generation in Porous Domains for Flow Simulations with Discrete-Fracture Network Model

Abstract

In this paper, an unstructured grid generation algorithm is presented to produce two-and three-dimensional grids in porous media with networks of discrete fractures. The proposed grid generation algorithm considers underground contours map data to adapt unstructured grids to geological geometries. This allows construction of more realistic geometrical models. Sample two-and three-dimensional unstructured grids have been generated in complex porous media with seven intersecting fractures. Two-dimensional grids were generated within 0.17-2.37 s of CPU time. Generation of three-dimensional grids including grid quality improvement measures took 109 s of CPU time. This final grid contains 763 fracture cells and 49,403 matrix cells. Angle distribution histograms of the three-dimensional grids show no skewed and flat angles within fracture and matrix cells. Two-and three-dimensional computational unstructured grids have been generated for geometries similar to published fractured porous media test cases. Incompressible and immiscible water-oil flow simulations were then obtained using these computational grids. Simulations gave identical results with published data which confirms the computational feature of the proposed unstructured grid generation algorithm.

Numerical investigation of vortex formation in water intake system of a pumping station during low and high tides

“…Simulation results are highly dependent on grid generation accuracy [33]. A grid study is carried out to minimize the grid size effect on simulation results.…”

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

“…The complex configuration of multiple fractures leads to a challenge of grid generation (Hyman et al, 2015). There are many research works of mesh generation focusing on the DFM-based methods, typically the efficient and fast algorithms to generate finite element meshes (Berrone et al, 2013;Hyman et al, 2014;Bahrainian et al, 2015). In this way, an efficient treatment is that the discrete fractures are considered as the relative low-dimensional objects placed on the interfaces of matrix cells.…”

Modeling and Simulation of Shale Fracture Attitude

“…As shown in Figure 1, the types of models are roughly divided into discrete fracture models, continuous models, and hybrid models of discrete fracture models and continuous fracture models. The fracture geometry in discrete fracture models is the same as the fracture geometry in the real formation, such as the model of Bahrainian et al 9 The continuous model regards the fracture as the same continuous medium as the matrix, such as the models of Li et al 10 and Liu et al 11 In the hybrid model, some large-scale fractures are regarded as discrete fractures, and some small-scale fractures are regarded as continuous media, such as the model of Brenner et al 12 and Zhao et al 13 The continuous (double porosity or triple porosity) model is an ideal fracture model, which has certain limitations for modeling complex fractures. For example, it is difficult to describe the fracture attitude.…”