Study on the Influence of Non-Darcy Effects on the Gas Well Productivity in Low-permeability Gas Reservoirs

Gas well productivity equation is derived in view of the permeable flow feature in low permeability gas reservoirs,based on high speed non-Darcy flow theory and by considering the factors of stress sensitivity,start-up pressure gradient,slippage effect and so on.Gas well productivity law in low permeability gas reservoirs is studied based on the equation derived.The results of the study show that the curves of formation pressure and permeability distribution in low permeability gas reservoirs take on funnel shape;the larger the start-up pressure gradient and the permeability deforming coefficient,the more rapidly the formation pressure declines;the larger the slippage factor and the more rapidly the formation pressure raises;gas reservoir permeability is mainly and interactively influenced by slippage effect and stress sensitivity,slippage effect increases gas well productivity,gas well productivity gradually increases with the increase in slippage factor and the stress damage caused by the pressure sensitivity adjacent to wellbore is mostly obvious.