Hydraulic Fracture Simulation of Two-Phase Flow: Discrete Fracture Modelling/Mixed Finite Element Approach

Abstract

Abstract Hydraulic fracturing is a technique commonly used to mitigate formation damage and improve well productivity. This stimulation technique is frequently used to improve oil and gas recoveries from tight reservoirs by virtue of squeezing fracturing fluid under high pressure exceeding formation fracture and propagation pressures. However, the prediction of the production performance of hydraulically-fractured wells, an essential step during hydraulic fracture design, uses analytical solutions that cannot reproduce the complexities associated with flow from the near-wellbore area into the well with both matrix and fracture flow contributions. A sophisticated numerical model, which is based on Computational Fluid Dynamics (CFD), has been used to simulate the fluid flow near the wellbore with the presence of an induced fracture perpendicular to the well trajectory at the pay zone. We used the DFM (Discrete Fracture Model) where the hydraulic fracture is explicitly represented in the model. In this modeling proposal, the fracture is presented as an interface through the rock matrix domain with nonlocal transmission conditions. This allows for communication between flow through the fracture and flow into the matrix systems. Therefore, it will not be necessary to use mesh refinement around the fracture. This is considered a big advantage over most currently used modeling techniques. It is emphasized in this modeling scheme that the fracture is discretized as a 1-D entity to account for fracture aperture by an integral form of the flow equations. Following this, the discrete fracture model is implemented using the MFEM (Mixed Finite Element Method). A case study is presented to support the field application of this unique modeling approach.