Study On Multi-scale Nonlinear Coupled Flow Model Of Shale Gas

As the concept of environmental protection has gradually won support among the people,natural gas,a clean energy,has become more and more popular.Vigorously developing shale gas technology has become one of the mainstream directions of natural gas development.Low permeability or ultra-low permeability is the main factor restricting shale gas exploitation.Based on shale pore characteristics: matrix pores and fractures coexist;nanopores to millimeter fractures coexist,the main work are as follows:(1)the equivalent Darcy permeability model in matrix pore is derived.The model can be applied to the flow process of continuous flow,transition flow and Knudsen flow;(2)based on the Poiseuille equation,the equivalent Darcy permeability model of natural fractures is derived;(3)based on Hertz contact theory and power law,and considering the effect of compaction and embedding of proppant,the equivalent Darcy permeability model of artificial fracture is established;(4)based on the law of mass conservation,the non-linear coupled flow model of shale gas is derived;(5)matrix bidisperse model,matrix-natural fracture simulation model and matrix-natural fracture-artificial fracture simulation model are established,and simulation APPs which can run independently are developed to facilitate the use of non-simulation professionals.The results show that the permeability of nanopore and micropore differs by several orders of magnitude,and the flow of nanopore is extremely difficult.In the case,the natural fractures are compacted by the effective stress of the formation,and the permeability is reduced about 6%;when the proppant in the artificial fractures are embedded in the fracture wall,the permeability of the artificial fracture is significantly reduced,and the drop is up to 90%?...