The Different Condensate Gas Recovery Using Gas Oil Permeability and Gas Condensate Permeability Curve

Abstract Till now, condensate reservoir engineers in China used substitute permeability curve, measured by unsteady-state method using model oil (kerosene etc.) and model gas (nitrogen etc.) system, to be basic input curve in numerical simulation and well testing. The typical interfacial tension of the model fluid system is about 30mN/m, which is much higher than true condensate system. The objectives of the work presented in this paper, were measuring relative permeability of condensate system and model fluid system, comparing their differences and resultant condensate gas recovery differences. The experiments employed true condensate system and formation core and were based on measurement of basic core and fluid properties, preliminary compositional simulation of fluid behavior. The measurements showed that the relative permeability curves to the gas condensate system are quite different to curves of model gas/oil system, and a relative permeability rate effect for both condensate oil and gas was observed, with the relative permeability of both phases increasing with an increase in flow rate. The CMG one-dimensional radial simulation results showed that the resultant condensate oil and gas recovery of condensate gas oil permeability curves are both largely different from those of model gas/oil permeability curves. The study highlights the need to use condensing fluids when measuring gas condensate relative permeability.