Capillary Hyperdiffusion as a Test of Wettability

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Abstract
We study the time and space dependence of saturation in porous media consisting of mixtures of beads, in which immiscible fluid (oil and water) flows are driven. We use glass beads which are totally wetted by water and PMMA (polymethylmethacrylate) beads which are partially wetted by oil and water. In glass beads, saturation profiles exhibit capillary hyperdiffusion, whereas PMMA does not (sharp profiles). Mixtures of both kinds, i.e. fractional wettability, show evidence of hyperdiffusion even with a small amount of glass beads. This gives strong support to understanding transport properties in fractionally wet porous media in terms of connected and disconnected pockets.