L. Anton et R. Hilfer, Trapping and mobilization of residual fluid during capillary desaturation in porous media, PHYS REV E, 59(6), 1999, pp. 6819-6823
We discuss the problem of trapping and mobilization of nonwetting fluids du
ring immiscible two-phase displacement processes in porous media. Capillary
desaturation curves give residual saturations as a function of capillary n
umber. Interpreting capillary numbers as the ratio of viscous to capillary
forces the breakpoint in experimental curves contradicts the theoretically
predicted force balance. We show that replotting the data against a novel m
acroscopic capillary number resolves the problem for discontinuous mode dis
placement.