Simulations in large tridimensional Discrete Fracture Networks (DFN): II. Flow simulations

We start this presentation by assuming that a model and a mesh of the DFNs have been computed *. We focus here on the numerical methods to solve efficiently single-phase flow problems. We will present the software NEF-Flow dedicated to solving single phase flow in large scale DFNs. NEF stands for Numerical Experiments involving Fractures. The software NEF-Flow is written in Matlab and implements the mixed-hybrid finite element method in an optimized way, using vectorization to decrease the computational time. It handles either matching or non-matching meshes at the intersection between fractures, sink/source terms and contrasts in transmissivities. A large set of benchmark test cases will be presented. Typically, we extended those proposed in [1, 2] to DFNs generated with the UFM framework [3, 4]. These DFNs are large scale DFNs where the fracture size distribution matches the observations and where fractures are organized so that large fractures inhibit the smaller ones, creating T-termination configurations. They may contain hundreds of thousands of fractures. Hydraulic properties will be computed efficiently on these networks. * See Laug et al. MASCOT 2018 abstract, Simulations in large tridimensional Discrete Fracture Networks (DFN): I. Geometric modeling and mesh generation.