An Analysis for the Influences of Fracture Network System on Multi-Stage Fractured Horizontal Well Productivity in Shale Gas Reservoirs

This paper presents two representative models to analyze the flow dynamic of multi-scale porous medium in hydraulic fractured horizontal shale gas wells. In this work, considering the characteristic mechanisms (multi-scale porous space, desorption and diffusion), flow equations in shale are established. After that, two representative models (discrete fracture model and dual-porosity model) are tailored to our issues. Solved by the control-volume finite element method (CVFEM), influences of fracture network system on productivity in shale reservoirs are analyzed in detail. Based on the analysis, the effects can be summarized as follow: at the beginning of production, high conductivity fracture network means more free gas could be produced; at the later part of production, high conductive fracture network can form a large low pressure region, which can not only stimulate the desorption of adsorbed gas, but also reduce the flow resistance to the well. Finally, the sensitivities of characteristic parameters in shale are discussed.