The effect of velocity and interfacial tension on relative permeability of gas condensate fluids in the wellbore region

Abstract

High-pressure core flood experiments using gas condensate fluids in long sandstone cores were conducted to determine the effect of flow rate and interfacial tension on relative permeability. The data are applicable to near wellbore flow in gas condensate reservoirs, because viscous forces increased over capillary forces during the tests. A relative permeability rate effect for both gas and condensate phases was observed when using steady-state and unsteady-state testing methods. The tests were repeated at increasing flow rates which showed that the relative permeability of both phases increased with the increase in flow rate. Increasing the value of interfacial tension between the phases reduced the relative permeability of the gas phase more than the condensate phase; but the relative permeability of both phases continued to increase at higher flow rates. The influence of core end-effects was shown to be negligible at the low IFT conditions used in the tests. The Reynolds number indicated that flow was within the laminar regime at all test conditions. The observed rate effect was contrary to that of the conventional non-Darcy flow where the effective permeability decreases with increasing flow rates. Relative permeability tests conducted with conventional gas oil fluids at similar test conditions did not exhibit any significant rate effects. This study is applicable to the vicinity of producing wells, where the rate effect on gas relative permeability can significantly affect well productivity.