Production performance simulation of a horizontal well in a shale gas reservoir considering the propagation of hydraulic fractures

Abstract

In recent years, shale gas has become an important energy source due to its abundant reserves. Due to their extremely tight initial properties, shale gas reservoirs require the use of the multi-stage fractured horizontal well (MFHW) technique to break the shale rock, activate closed natural fractures, and form a complex fracture network. In this study, to solve the issue of how to describe the fracture network's geometry and to predict the production performance accurately, a model that couples the fracture propagation with the fracturing fluid and proppant flow in a horizontal wellbore and hydraulic fractures is established. The displacement discontinuity method (DDM) and finite volume method are used to iteratively obtain numerical simulations of the fracture propagation. The accuracy of the fracture propagation model is verified through comparison with analytical and numerical models. Then, the coupled continuous media and discrete fracture network model considering multiscale flow mechanisms in shale is developed, which is solved numerically using the control volume finite element method (CVFEM) and unstructured tri-prism grids. Finally, the numerical simulation models are successfully applied to synthetic and field cases, sensitivity analysis is conducted to evaluate the influences of the proppant injection, stress anisotropy and distribution of the natural fractures on the fracture propagation and production performance of the MFHW in a shale gas reservoir.