Evidence of capillary hyperdiffusion in two-phase fluid flows

Abstract

By means of an acoustic technique we record the saturation time and space dependence in a porous medium consisting of sandstone into which immiscible flows are driven. When a totally wetting fluid (here water) injection is performed (imbibition), in a prewet sample (i.e. a medium at irreducible water saturation), the capillary diffusion presents symptoms of hyperdiffusion, which means that the saturation profile extends more widely than in classical diffusion