A novel and adaptive mesh method for arbitrary discrete fracture networks DFN simulations

The computation mesh is one of the important challenges for the simulation of the discrete fracture networks (DFN). In this work, an efficient mesh method is introduced to tackle this problem. First, convert the map with complexity fracture network into a numerical image comprised Npix-x × Npix-y pixels. Then, calculate the distance of pixel j (j = 1, ⋯, Npix-x × Npix-y) to all pixels on the ith fracture grid and select the shortest one as the effective distance of pixel j to the ith fracture grid. Next, calculate the effective distance of pixel j to all the fracture grids in the domain and assign the pixel j to the fracture grid with the shortest effective distance. Finally, the volume of coarse matrix block assigned to ith fracture grid is the summation of the volume of all pixels associated with the ith fracture grid. Each coarse matrix block is locally associated with a fracture grid, and it is equivalently discretized to logarithmically refined grid blocks. The orthogonal fractures model is used in our house reservoir simulator (EDFN) to benchmark with CMG, this method provides very consistent results and its accuracy is validated. The results show that this method is appropriate to be applied in reservoirs with different geometry and arbitrary complex fracture networks.