Effect of Pressure-Dependent Permeability inTight Gas Reservoirs,Transient Radial Flow

摘要

It may be common for tight gas reservoirs (k <0. 1 md). Tohave pressure-dependent permeability. But it is not commonto have this data available when analyzing well test orperformance data. Consequently, engineers may not be awareof pressure-dependent permeability or may ignore thiscomplication because the data are not available. This projectattempts to evaluate the error made in ignoring pressure-dependent permeability when, in fact, it should be included inanalysis.If pressure-dependent permeability data are available, itcan be integrated into a modified real gas pseudo pressure, m(p), which would be expected to 'linearize ' the differentialequation and provide correct values for permeability and skinfactor. But if the customary real gas pseudo pressure, m(p)isused, then erroneous values for permeability and skin factorwill be calculated.This work was done by simulating pressure-dependentpermeability using an exponential form for permeability vs. Pressure drop. This is a convenient permeability model whichjust requires one parameter, γ.