PORE-SCALE DIFFERENCE BETWEEN MISCIBLE AND IMMISCIBLE VISCOUS FINGERING IN POROUS-MEDIA

The purpose of this work is to better understand the pore-scale phenomena of displacement. Immiscible viscous fingering in a two-dimensional network model, with negligible effects of the interfacial tension, has been studied by Chen and Wilkinson. Although qualitative agreement was found between simulations and experiments for the immiscible case, some fundamental difference was found for the miscible case. The cause of difference and other relevant experimental observations will be discussed. Experimental data indicate that in both miscible and immiscible displacement experiments for matched viscosity cases, the displacement front is stable at high flow rates in all samples. Miscible displacement experiments for the matched viscosity case show that the displacement in each pore is rather uniform whereas for the unfavorable viscosity ratio case the water fingers even in each pore. This work is pertinent to oil recovery.