PERFORMANCE ANALYSIS OF MULTI-FRACTURED HORIZONTAL WELLS WITH COMPLEX FRACTURE NETWORKS IN SHALE GAS RESERVOIRS

摘要

Shale gas reservoirs are composed of multiscale porous media and complex secondary fractures around hydraulic fractures, and it is necessary to consider the effects of multiscale transport mechanisms and distribution of complex fracture networks. In this paper, a fractal multiple porosity media (FMPM) model with a detailed description of complex fracture networks was presented. In the proposed model, the fractal diffusion equation (FDE) was combined with a triple-media model to describe complex fracture networks in the inner reservoir between two adjacent hydraulic fractures, and a conventional dual-porosity model was used to describe the gas flow in the outer reservoir beyond the tips of hydraulic fractures. Parameters of fracture networks were analyzed, and the results showed that the larger the fractal dimension is, or the smaller the conductivity index of fracture networks is, the higher the production rate will be in the early-time flow period. The production rate difference between the inner reservoir and the outer reservoir slowly decreased as the development time was extended. The resulting curve calculated by the presented model was closer to the actual production than that of conventional models in the early period, which means that it could indicate the complexity of fracture networks around hydraulic fractures.