Unconventional Reservoir Modeling with Complex Hydraulic-Natural Fracture Networks Using a Parallel Reservoir Simulator Coupled with Embedded Discrete Fracture Model

Abstract

Fracture diagnostic data for shale wells show that the fracture system after hydraulic fracturing is quite complex. Accurate and efficient simulation modeling of complex hydraulic and natural fracture networks is critical for evaluation of well performance and stimulation effectiveness in unconventional oil and gas reservoirs. The traditional method based on local grid refinement (LGR) has limitations in handling 3D hydraulic and natural fracture geometry. In addition, its computational efficiency is low, especially for dealing with a large number of hydraulic fractures and multiple horizontal wells. In this study, we develop a new workflow which, for the first time, utilizes embedded discrete fracture model (EDFM) method coupled with a parallel reservoir simulator (PRS) to simulate all types of 3D hydraulic and natural fractures. EDFM can easily avoid re-gridding matrix cells containing hydraulic and natural fractures. More realistic 3D fracture geometry from either fracture propagation simulation or user definition and geological model with corner point can be accurately honored. The input fractures can be smoothly embedded into the model grid through EDFM processing We validated the parallel reservoir simulator with EDFM by comparing the simulation results using dual porosity dual permeability (DPDP) model. After benchmarking, we applied this new workflow to simulate three synthetic field cases. The simulation results are also compared with a commercial reservoir simulator (CRS) with the EDFM method. Well performance for the real case with and without natural fractures can be efficiently simulated. The new EDFM workflow enables to model 3D hydraulic and natural fractures with any strike and dip angels efficiently and accurately in the parallel reservoir simulator. Modifications of fracture properties can be easily done. This new workflow enables a much faster and more robust fracture modeling process, which is highly effective for the fracture model calibration and development optimization in unconventional oil and gas reservoirs.