Photographic observations of unusual flow phenomena in porous media at interfacial tensions below 0.1 mN m −1

Abstract

Two-phase flow within porous media at low interfacial tension and high capillary number (>10 −3) behaves very differently from flow at high interfacial tension and low capillary number. Qualitative features have been observed experimentally using 2,6-lutidine-water mixtures in a transparent model porous medium. Three photographic observations are presented; the first illustrates a “pore-to-pore hopping” mechanism of wetting phase movement, the second shows pore-to-pore transfer of wetting phase in a different pore geometry, and the third reveals a gravity induced instability.