A systematic study of fracture parameters effect on fracture network permeability based on discrete-fracture model employing Finite Element Analyses

Due to the discontinuity of porous media, naturally fractured reservoirs are different from traditional reservoirs. Accurate description of seepage law and quantitative study of the influence of fracture parameters on flow capabilities have always been a complicated and challenging task. In this paper, the influence of various fracture parameters (i.e. fracture orientation, fracture length, fracture aperture, intersection relationship and their comprehensive influence) on permeability is studied quantitatively and systematically based on the discrete fracture model (DFM) and Finite Element Analyses. A series of fracture models are established to get a comprehensive understanding of the inherent rules and the permeability of each model is calculated. For further insight of the fracture seepage law, the article also conducts research on pressure distribution, streamline distribution and velocity field distribution. Results show that fractures parallel to mainstream line have bigger contribution to seepage process, the sensitivity interval of fracture aperture, in this paper, is 0.1mm-0.01 mm, and longer fracture will generate higher permeability while super long fracture approaching the injector and the producer should be avoided. For the discrete fracture network, if the intersecting cracks cannot serve as part of the mainstream channels, this intersection is almost meaningless. The sensitivity analysis can provide a guidance for modeling DFM as well as probing into the complex flow characteristics in naturally fractured reservoirs and other complex fractured reservoirs.