Three-dimensional representation of discrete fracture matrix model for fractured reservoirs

Accurate modeling of fractures is a matter of growing scientific interest. Several existing methods for 3D fractures modeling are available only for oversimplified geometries, e.g. rectangle. The identification of intersections of complex polygonal fractures with dip angles has not been clearly resolved, which results in inaccurate grid transmissibility calculation between fracture cells. This study aims at obtaining an efficient modeling strategy for 3D fractures with arbitrary spatial distributions and field-scale fracture modeling application. The dimensionality reduction method based on coordinate transformation is employed to identify the intersections of arbitrary shaped polygon fractures with any dip angles. Meanwhile, fine grid cells are generated in the vicinity of fractures to adapt high-pressure gradients, which is favorable to the simulation accuracy. For another, the local refinement allows transitions of cell sizes from the near-fracture region to far-fracture region, reducing grid number and further computational cost. The model validation is given in a tailored case where Cartesian grids are used to model vertical fractures with a local grid refinement by the industry-reference simulator ECLIPSE-E100 and a good match is achieved by our model. Three complex examples with different fracture densities are computed to demonstrate the robustness and stability of the simulator. The influence of 3D fracture parameters on the oil production, including the height, dip angle, area and shape, is analyzed.