超低界面张力型与乳化型复合体系驱替稠油特征对比

Comparative Study between Ultra-low Interfacial Tension and Emulsification Oriented Compound Systems on Recovering Heavy Oil

为了明确超低界面张力(IFT)和乳化机理对稠油复合驱提高采收率的影响,研究了两种分别以超低IFT和良好乳化性为导向的复合体系的IFT、乳化性能、泡沫性能和驱油性能。结果表明,超低IFT型复合体系可将油水IFT降至2.6×10^(-4)mN/m,但其形成乳状液的稳定性、体系起泡性和泡沫稳定性均较乳化型复合体系差,而后者仅可将油水IFT降至0.25 m N/m。尽管超低IFT型与乳化型复合体系性能相差较大,复合驱过程中,由于体系扩大波及体积能力相对较弱,两种体系提高采收率增幅相差较小。超低IFT型泡沫驱采收率增幅可达38.3%,显著高于乳化型泡沫驱的28.9%。在泡沫辅助下,超低IFT洗油机理比乳化降黏机理更为关键。超低IFT型泡沫驱驱替稠油的采收率增幅大于大段塞复合驱,前者0.3 PV化学剂用量下的增幅达38.3%,后者0.5 PV化学剂用量下的增幅仅为30.7%。超低IFT型泡沫驱是目前提高稠油采收率较好的方式,单一复合体系驱替稠油存在化学药剂的潜在浪费。图7表1参15。

In order to clarify the relative importance of ultra-low interfacial tension(IFT)and emulsification mechanisms for recovering heavy oil by compound flooding,the IFT,emulsification,foam and oil displacement performances of two compound systems guided by ultra-low IFT and good emulsification were studied.The results showed that,for the ultra-low IFT system,the oil-water IFT could be reduced to 2.6×10-4 mN/m,but it performed poorer in foaming and stabilizing emulsion and foam than the emulsified compound system,while the oil-water IFT of the later was only 0.25 mN/m.Although the properties of those two systems differed greatly,the increased oil recovery by ultra-low IFT system was similar to that of emulsion system during the simple compound flooding,which might be caused by the poor sweep volume during flooding.However,that increased by ultra-low IFT foam was 38.3%,which was much higher than that of 28.9%by emulsion foam flooding.This indicated that the mechanism of oil washing by ultra-low IFT was more critical than that of viscosity reduction by oil-in-water emulsification during foam flooding.Ultra-low IFT foam flooding(water alternative gas injection)could improve heavy oil recovery more than increasing the slug of compound system.The recovery could be increased to 38.3%by 0.3 PV the former strategy,while 30.7%by 0.5 PV the latter.Ultra-low IFT foam flooding was the better way to improve heavy oil recovery at the present,and the displacement of heavy oil by single compound system might be a waste of chemical agents.