Prediction of interfacial areas during imbibition in simple porous media

The interfacial area between wetting (W-) and non-wetting (NW-) phases is one of the crucial parameters in several flow and transport processes in porous media. This paper gives predictions of such areas during imbibition (displacement of NW-phase by W) in simple porous media. The total interfacial area includes contributions from thin films of W-phase around soil particles, from trapped volumes of NW-phase, and from the meniscus between bulk NW- and W-phases. Imbibition was simulated with simple but physically representative pore-scale calculations in a geometrically predetermined random sphere packing. This approach allows the prediction of interfacial areas for different initial conditions (arising from different drainage endpoints, for example) and the investigation of the influence of phenomena such as “snap-off” of NW-phase due to coalescence of pendular rings. We find that the trend of interfacial area as a function of saturation is not sensitive to these considerations. These predictions were compared to different experimental data and were consistent with most of them. The predictions are also consistent with the conditions imposed by thermodynamics.