Hybrid Analytical and Numerical Approach for Modeling Fluid Flow in Simplified Three-Dimensional Fracture Networks

Abstract

Modeling fluid flow in three-dimensional fracture networks is required in a wide variety of applications related to fractured rocks. Numerical approaches developed for this purpose rely on either simplified representations of the physics of the considered problem using mesh-free methods at the fracture scale or complex meshing of the studied systems resulting in considerable computational costs. Here, we derive an alternative approach that does not rely on a full meshing of the fracture network yet maintains an accurate representation of the modeled physical processes. This is done by considering simplified fracture networks in which the fractures are represented as rectangles that are divided into rectangular subfractures such that the fracture intersections are defined on the borders of these subfractures. Two-dimensional analytical solutions for the Darcy-scale flow problem are utilized at the subfracture scale and coupled at the fracture-network scale through discretization nodes located on the subfracture borders. We investigate the impact of parameters related to the location and number of the discretization nodes on the results obtained, and we compare our results with those calculated using reference solutions, which are an analytical solution for simple configurations and a standard finite-element modeling approach for complex configurations. This work represents a first step towards the development of 3D hybrid analytical and numerical approaches where the impact of the surrounding matrix will be eventually considered.

Numerical Simulation of Cracking Behavior of Precracked Rock under Mechanical-Hydraulic Loading

“…Many scholars have used the numerical simulation method (RFPA, PFC, and FLAC3D) to study the fracture mechanism of the fissured rock mass, which helps to understand the stress state and provides a powerful criterion for the initiation and propagation of cracks [10][11][12][13][14][15][16][17][18][19][20].…”

“…Numerical models are not only useful for analyzing and interpreting the crack types observed in physical experiments but also useful tools for observing the dynamic images of the stress field and seepage field evolution in the process of fracture propagation [17,18]. However, many studies have only focused on the analysis of preset single crack growth, which cannot completely simulate the whole process of crack initiation, development, and interpenetration under different strength parameters and hydraulic coupling environment [19,20]. Therefore, some more complex conditions of the actual work need to be further considered to simulate the cracking behavior and propagation mechanism of precracked rock, such as different strength parameters and hydraulic coupling.…”