Higher-order simulation of two-phase compositional flow in 3D with non-planar fractures

Abstract

Non-planar fractures are often created in hydraulic fracturing. These irregular shape fractures may reduce the penetration into the formation; they may also improve the reservoir reach. Accurate flow simulation of two-phase compositional flows in domains with complex non-planar fractures is beyond the capabilities of current numerical models. In this work we present a higher-order numerical model for compositional two-phase flow in a domain with non-planar fractures. Fully unstructured gridding in 3D is a natural choice for description of geometry with irregular fracture shapes. We apply the concept of fracture cross-flow equilibrium (FCFE) in simulations of porous media flows with non-planar fractures. FCFE allows accurate flow and composition calculations at low CPU cost. Our implementation is in the context of the hybridized form of the mass conservative mixed finite element (MFE) and the higher-order discontinuous Galerkin (DG) method. In this work we introduce a simple and effective approach for design of non-planar fractures through the mesh interface that connects computer-aided-design (CAD) software to the mesh generator. In our algorithm we can simulate all ranges of fracture permeability accurately as opposed to other approaches where low permeability fractures affect the accuracy.