Evaluation on inflow performance relationship of gas wells in pressure-sensitive reservoir using generalized pseudo pressure

To precisely describe the permeability characteristics of real gas in pressure-sensitive reservoir,the generalized pseudo pressure function is introduced to characterize the gas flow in pressure-sensitive reservoir.Thus the gas seepage-diffusion equation has the same expression with the diffusion equation of the slightly compressible liquid flow with single direction.While evaluating the generalized pseudo pressure function,corresponding models can first be used to calculate the gas velocity,the deviation factors and the formation permeability under constant temperature and various pressures.Secondly,the step-size pressure is calculated according to the trapezoidal rule.Numerical integration is applied to evaluate the generalized pseudo pressure fit to a constant temperature and any pressure and regress the coefficients to the gas seepage-diffusion equation.The expression for the relation between the pseudo pressure and the pressure of real gas is obtained and then applied to analyze the inflow performance relationship of gas wells.Results show that the expression of the gas seepage-diffusion equation can be simplified by introducing generalized pseudo pressure coefficients to describe the permeability characteristics of real gas in pressure-sensitive reservoir.Then a method to calculate the pseudo pressure for real gas is proposed,which makes the calculation of more rapid and accurate.It lays a solid foundation for analyzing gas-well inflow performance relationship and is very important in improving stimulated precision of pressure-sensitive reservoir.