GAS-LIQUID AND VAPOR-LIQUID FLOW IN POROUS MEDIA IN THE PRESENCE OF SURFACTANT (STEAMFOAMS, FOAM FLOODING, STABILITY)

The effective permeabilities of Berea Sandstones to vapor and liquid water in the presence of surfactant have been measured as a basic issue in the understanding of the foam plugging mechanism. Permeability to vapor was noticeable reduced while permeability to liquid increased with the addition of surfactant. Experiments conducted with nitrogen and brine yielded similar results for the liquid permeability but gas blockage was complete, indicating that very stable films or slugs of liquid at the pore throats were trapping the gaseous phase and that the surfactant solution moved along a continuous path of liquid. The increase in permeability to liquid was explained in terms of the redistribution of fluids arising from changes in the wettability of the rock as a result of surfactant adsorption onto the solid surface. A theoretical analysis of the consequences of capillarity, the Kelvin effect and heat exchange between core and surroundings on the measured permeabilities was also performed. Finally, a study of the effects of initial bubble size distribution on foam stability measurements used in the screening of surfactants as blocking agents led to the conclusion that any scientifically acceptable approach to characterize foam stability must involve measurement of the evolution of the bubble size distribution or perhaps fundamental studies of the gas transfer process between bubbles.