Rheology of foam in porous media at the "limiting capillary pressure

Recent research suggests that, for some "strong" foams, foam texture, which controls foam rheology, is in turn closely controlled by capillary pressure Pc. In particular, at steady state these foams flow under conditions in which Pc is nearly constant at the "limiting capillary pressure" Pc*, water saturation and water relative permeability are virtually invariant, and the pressure gradient Vp is proportional to water flow rate and independent of gas flow rate. This report examines some implications of these statements for cases of steady foam flow.