An Enhanced Discrete Fracture Network model for multiphase flow in fractured reservoirs

摘要

We present an Enhanced Discrete Fracture Network (EDFN) model for multiphase flow simulation in fractured reservoirs. EDFN can efficiently represent complex fractured porous media and accurately simulate fluid exchange between matrix and fracture. By using EDFN the fracture network is discretized with minimum number of grids based on the fracture intersecting points and fracture extremities. The matrix is also optimally decomposed into coarse blocks with different geometries using a rapid image processing algorithm. Each coarse matrix block is designed to be associated with one fracture grid and then discretized logarithmically to handle 1D flow between matrix and fracture. EDFN can greatly optimize the discretization for fractured porous media to conform interconnected fractures of arbitrary orientations. Via unstructured format, EDFN is successfully linked with an in-house unstructured compositional simulator. We validate the accuracy of EDFN through a number of multiphase flow simulations in fractured porous media with/without considering capillary pressure. Its efficiency is demonstrated to be superior by using a much less grid blocks comparing with other approaches. Ultimately EDFN is applied to predict hydrocarbon production in a shale oil reservoir and it enables to capture multi-scale fluid transfer in such complex system.