NUMERICAL SIMULATION OF MULTI-FRACTURED HORIZONTAL WELL IN SHALE GAS RESERVOIR CONSIDERING MULTIPLE GAS TRANSPORT MECHANISMS

Shale is a typical micro-nano-scale porous media, in which free gas and absorbed gas coexist, so traditional Darcy's law is unable to describe gas transport mechanisms of micro-nano-scale accurately. Based on double porosity model and discrete fracture model, the fractured horizontal well numerical model has been built in shale gas reservoir. Viscous flow, Knudsen di usion and surface di usion have been considered in shale matrix, while viscous flow and Knudsen di usion are considered in the natural fracture. The finite element method is applied to solve the model. The results show that the smaller intrinsic matrix permeability, the greater the e ect of surface di usion and Knudsen di usion. The properties of hydraulic fractures including fracture number, aperture, half-length and spacing, mainly a ect the early production. With the augment of those parameter values, the production rate and cumulative gas of multi-fractured horizontal well increase. Then the development of induced fractures and natural fractures has a significant e ect on the shale gas production and the production will be low when the natural fractures surrounding the horizontal well are closed or not developed.