The enhanced oil recovery (EOR) results of foam flooding depend largely on the stability of foam flow within reservoirs in the presence of crude oil. Experimental studies indicated that oil would impact the foam stability greatly. This paper discussed the effect of oil on the stability of polymer enhanced foams. Two commercial polymers including hydrolysed polyacrylamide (HPAM) and modified polyacrylamide (MPAM) were employed. Mechanism on interaction between foam and oil for experimental foam systems was also studied quantitatively based on several physical-chemical parameters including spreading coefficient, entering coefficient, bridging coefficient and lamella number. The foam stability could be remarkably improved with both HPAM and MPAM. The effect of oil on the stability of polymer enhanced foams could not be fully understood by related coefficient theories. The increase in viscoelasticity of foam films would play a key role in the stability improvement for polymer enhanced foams.
Keywords: foam, stability, polymer, surfactant, foam flooding, enhanced oil recovery, EOR, oil