Experimental study and field demonstration of air-foam flooding for heavy oil EOR

Foam flooding is an effective oil displacement technique to improve fluid sweep efficiency and increase oil recovery. The objective of this study is to investigate the application of air-foam for heavy oil recovery under heterogeneous reservoir conditions. The paper first investigated the air-foam flow behavior in porous media and identified the effects of different factors such as gas-liquid ratio, injection rate, and crude oil saturation on air-foam resistance. Then, dual-tube sand-packs were used to evaluate the performance of air-foam for heavy oil recovery from heterogeneous reservoir conditions. The results indicated that the air-foam could divert the fluid from the high-permeability zone to the low-permeability zone, decrease the water cut and improve the oil recovery. Further studies revealed that there existed an optimal reservoir permeability contrast ratio in air-foam flooding for heavy oil recovery. The air foam performance for oil recovery would be reduced beyond or below this permeability contrast ratio. Finally, field tests on air-foam for heavy oil recover demonstrated that air foam flooding could increase heavy oil production rate and decrease the production water cut.