Study On Steady - State Productivity Of Gas - Water And Horizontal Wells In Tight Sandstone Gas Reservoir

As one of the main forces of domestic natural gas production, tight sandstone gas resource will hopefully act as a’leader’of the development of unconventional gas resources in a quite long period of time. While due to the special characteristics of gas reservoir and percolation mechanism in tight sandstone gas reservoirs, in contrast with conventional gas reservoirs, the tight sandstone gas reservoirs had smaller reserves and bigger production decline rate, which would eventually make the development of tight sandstone gas reservoirs difficult and required high technicals. So the research on tight sandstone gas reservoirs’ characteristics, percolation mechanism and gas wells’productivity with different well types would be of great importance.In this paper, the author based on sufficient investigation and research on the productivity of conventional horizontal wells, gas-water wells and fractured horizontal wells, combined with the basic characteristics of tight sandstone gas reservoir, water production mechanism and percolation mechanism, considered the effect of stress sensitivity in gas reservoir and hydraulic fractures, gas slippage effect and high speed non-Darcy flow in near-wellbore area on productivity, defined single phase generalized pressure and gas-water two phase generalized stress in gas reservoir and hydraulic fractures, used the conformal mapping method and superposition principle of potential to build the productivity models of horizontal wells and fractured horizontal wells under the conditiom of single-phase and two-phase flow. Meanwhile, the anisotropic coefficient and skin factor had been applied to modify the productivity models. Also the variable mass flow in horizontal wellbore had been taken into accout, which led to a new productivity model coupling seepage in gas reservoir, seepage in hydraulic fractures and wellbore conduit flow. Finally instance data had been used to verify the accuracy of productivity models. Simultaneously, the author analyzed the factors that influenced the productivity of horizontal wells and fractured horizontal wells under gas-water two phase, got the impact extent of every factor on productivity.The research in this paper enriches and perfects the productivity analysis theory system under different well types in tight sandstone gas reservoir, research results can be used to optimize the construction parameters and determine the reasonable working rule of gas well, meanwhile, they will have the high value and broad application prospects, eventually lying the theoretical foundation for deeper stuty on tight sandstone gas reservoir.