Characteristics of gas flow and productivity of fractured wells in shale gas sediments

Based on the molecular kinetic theory, the gas seepage law was analyzed in shale gas sediments with nanopores. The motion equation and transport mathematical model of shale gas were established which were suitable for multi-scale media. The pressure distribution formula under radial flow was derived, and a new method to calculate the control area of shale gas wells was formed. The non-linear productivity equation of fractured wells was presented with three-region division. Some parameters, such as production pres-sure difference, fracture half-length, fracture conductivity and diffusion coefficient, which can influence the gas well production were analyzed according the numerical calculation of the Newton iteration method. It is shown that the gas well production increases with increasing diffusion coefficient, and the contribution of diffusion effect to production should not be ignored for shale gas reservoirs with nanopores. In a certain reservoir and production conditions the gas well production increases with the increase of fracture half-length, but the increase rate is slower. Thus there is an optimum combination of parameters for shale gas development.