In shale gas reservoirs with natural fractures

the artificial fractures and natural fractures communicate with each other after fracturing. The traditional dual media model can not accurately reflect the impact of natural fractures on well production. In order to investigate the influence on shale gas well productivity caused by gas transport in nanometer-size pores

the mathematical model of multi-stage fractured horizontal well in shale gas reservoir is built

which considers the influence of the complex flow mechanism such as the viscous flow

Knudsen diffusion

surface diffusion

adsorption layerand gas desorption. Discrete fracture model（DFM） is used to simplify the fracture and finite element method is applied to solve the model. The numerical simulation results of Pingqiao shale gas reservoir indicate that the free gas in fracture system mainly contributes to shale gas production in the early stage

and the average recovery of adsorbed gas is only 10.1 %. The existence of unmodified reservoir makes the influence of bedrock permeability on cumulative production greater. The density and connectivity of fracture networks have dominant effects on gas production and its decline trend.