Dynamic prediction model for the low-permeability gas reservoir taking the real gas into account

In view of the production characteristics of the gas reservoirs,based on the steady seepage theory and the high speed non-Darcy,considering the real gas PVT parameters with pressure changes combining the material balance equation,creating a new pseudoressure form,with the influence of the start-up pressure gradient,slippage effect and stress sensitivity taken into account,a dynamic prediction model was established for the low-permeability gas reservoirs,and the productivity characteristic was discussed by analyzing and calculating examples.The result indicates that based on the high speed non-Darcy,the lower flow resistance caused by the slippage effect will load to the increasing of the stable production period and the decreasing rapidly of the formation pressure,while the higher flow resistance caused by the start-up pressure gradient and stress sensitivity load to the decreasing of the stable production period and the decreasing slowly of the formation pressure.The bigger the start-up pressure gradient and deformation coefficient of permeability are,the more decreasing extent of the stable production period,and the slower the reduction of the formation pressure would be,while the more slippage effect,the more decreasing extent of the stable production period and the faster reduction of the formation pressure would be.