Massively parallel numerical simulation technology for thermo-hydro-mechanical coupling using general embedded discrete fracture model

Coupled thermo-hydro-mechanical flows in complex fractured rock occur widely in unconventional and deep reservoir development scenarios. Coupled simulations of complex fracture networks will produce huge computational cost. Parallel computing technology is the effective method to achieve high-resolution simulations of complex discrete fractures. In this paper, massively parallel numerical simulation technology for thermo-hydro-mechanical coupling using general embedded discrete fracture model on unstructured grids is introduced. Firstly, a parallel solution of embedded discrete fracture model is achieved based on the domain decomposition method; and the way to decompose two independent matrix and fracture systems is introduced for unstructured grids. the existing embedded discrete fracture model by using two independent matrix and facture grid systems, and this approach significantly enhance the simulation ability of the EDFM for a complex 3D discrete fractures system. Secondly, for the thermo-hydro-mechanical coupling problem, the finite volume method is adopted to discretize compositional flow, heat transform and poro-mechanical equations uniformly, a parallel sequential implicit method is employed to solve the nonlinear coupling problem. Finally, this simulator is validated against two analytical model, and it is used for a multi-layer shale gas reservoir three-dimensional simulation and a deep high-temperature fractured reservoir simulation, and the parallel computational performance and scalability are analyzed at different parallel scales. The proposed methods can achieve high-resolution simulations of discrete fracture networks in practical engineering, and we obtain a great parallel performance and scalability at different scales, this simulator can be an efficient tool for the design and analysis of energy development in fractured rocks.