Modelling of pressure transient behaviour for fractured gas wells under stress-sensitive and slippage effects

A semi-analytical model considering effects of slippage and pressure sensitivity was presented to investigate pressure transient behaviour for fractured gas wells. The numerical convolution method was employed to solve gas nonlinear flow problems. Calculative results showed that in radial flow period the pressure derivative curve showed 0.5 constant under no slippage and no pressure sensitive effects, showed 0.3 constant with slippage effects under no pressure sensitivity, and upturned with pressure sensitivity under no slippage effects. The results also showed that a bigger pressure-sensitive coefficient gamma(D) would cause bigger pressure depletion in late time. The existence of the slippage will cause smaller pressure depletion because it makes the permeability become bigger. So the slippage effect is positive and helps production. Effects of parameters on pore pressure behaviour were also discussed in detail. It is necessary to coordinate these parameters so as to reduce the pressure depletion.