Gas condensate relative permeabilities in propped fracture porous media: Coupling versus inertia

Hydraulic fracturing is one of the most common well stimulation techniques for gas-condensate reservoirs. In recent years considerable effort has been directed towards understanding of flow around hydraulically fractured wells especially for tight gas reservoirs. However, there has been no report of a study of flow behaviour within propped fractured porous media for these low interfacial tension (IFT) systems. It is now a well established finding both experimentally and theoretically that the flow of gas-condensate fluid systems in porous media is affected by both coupling (the increase of relative permeability (k_r) as velocity increases and/or IFT decreases) and inertial (i.e., the reduction of k_r as velocity increases) effects. However, the interaction of capillary, viscous and inertial forces within highly conductive propped fractures is yet unknown. In this work, we report a series of steady state gas-condensate relative permeability values for a proppant filled and a sand packed fracture with permeability of 146 D and 15 D, respectively. These sets of kr data, which have been measured using our unique experimental facilities, covers IFT and velocity values ranging between 0.85 and 0.15 mNm^-1 and 250 to 3000 md^-1, respectively. The results indicate that inertia is quite dominant at all the tested conditions albeit to a greater extent at lower IFT and higher gas fractional flow rates. In the case of the fracture with the higher permeability, some kr values measured at the higher IFT are also reported, which are higher than the corresponding values at a lower IFT. We also compare the results with the corresponding predicted kr values by the generalized kr correlation, which we reported recently and expresses the combined effect of coupling and inertia with universal parameters. The unique contribution of inertial forces, as observed in the experiments and predicted by the correlation, is mainly attributed to the impact of the fracture properties and the fluid flowing in the fractures. Copyright 2008, Society of Petroleum Engineers.