The experimental testing of the impact of interfacial coupling on two-phase flow in porous media

Traditional Darcian transport equations to describe two-phase flow through porous media ignore the influence of interfacial coupling between the two flowing phases. Because of this neglect, a significant amount of error may be introduced into two-phase flow properties such as relative permeability and capillary pressure, as indicated in some recent studies.; Several researchers have attempted to gain a better understanding of the probable impacts of interfacial coupling during two-phase flow through porous media. However, none of them has been able to provide a satisfactory explanation of its physical origin. Moreover, none of these attempts has provided a convenient method to estimate quantitatively the effects of interfacial coupling on two-phase flow through porous media.; In this study, a partition concept has been introduced into Kaladjian's transport equations to construct modified transport equations that enable a better understanding of the role of interfacial coupling in two-phase flow through natural porous media. Using these equations, it is demonstrated that, in natural porous media, the physical origin of interfacial coupling is the capillarity of the porous medium (capillary coupling), and not interfacial momentum transfer (viscous coupling), as is usually assumed. Moreover, it is suggested that the magnitude of capillary coupling in a porous medium-fluids system is directly related to the porosity of the porous medium.; Furthermore, to test the new theory experimentally, a relatively new experimental apparatus to conduct steady sate and unsteady-state two-phase flow experiments was constructed. Using this experimental set-up, several two-phase flow experiments were conducted successfully, where two different porous media and two different viscosity fluids were used.; Experimental testing of the new theory has shown that the pressure profiles predicted using the new transport equations are consistent with those determined experimentally. Moreover, it appears that the capillarity of the porous medium is the physical origin of interfacial coupling. Finally, the amount of interfacial coupling that takes place, which depends on porosity, appears to be consistent with the new theory.