Study on properties of low interfacial tension foam flooding system as betaine

In view of the reservoir conditions of Dagang Oilfield, a low-interface-tension foam flooding system with favorable foaming and interface tension properties was obtained. A series of alkyl acylamide hydroxypropyl sulfobetaines were synthesized and the tetradecyl acylamide hydroxypropyl sulfobetaine was screened as primary agent by measuring the interfacial tension and foam properties. The low interfacial tension foam flooding system was prepared by the combination of tetradecyl acylamide hydroxypropyl sulfobetaine and sodium dodecyl sulphate (SDS). For crude oil and formation water from Dagang Oilfield, the oil-water interfacial tension could be reduced to 10–2 mN/m and the initial foam volume could be 5 times of the initial solution volume, which could meet the requirement of low interfacial tension foam flooding system for interfacial tension and foaming volume. Using the crude oil from Dagang Oilfield as the simulating oil, the results of oil flooding test showed that oil displacement efficiency of low interfacial tension foam flooding system was 12.6% which was significantly higher than those of low-interfacial tension flooding system and foam flooding system.