表面活性剂驱乳化作用对提高采收率的影响

Study of emulsification effect on oil recovery in surfactant flooding

表面活性剂驱是高温高盐油藏提高原油采收率的重要技术措施,但其乳化作用对提高采收率的影响并未受到足够重视。为了分析濮城油田高温高盐油藏表面活性剂驱乳化作用对提高采收率的影响,通过对表面活性剂降低油水界面张力的性能评价,优选出2种表面活性剂YD-G1和SHY-1,用高矿化度的濮城油田现场注入水配制质量分数为0.3%的溶液,将其放入120℃恒温箱30 d后,油水界面张力仍能达到10-3mN/m的超低数量级,表明2种表面活性剂均具有良好的耐温抗盐性能。将2种表面活性剂与濮城油田脱水脱气原油配制成乳状液,在同等质量分数下YD-G1乳状液的析水率低于SHY-1,且液滴的平均粒径也更小,表明YD-G1溶液比SHY-1溶液的乳化能力强。驱油实验结果表明,YD-G1溶液比SHY-1溶液的驱油效果更佳,表明乳化作用是提高采收率的关键因素之一。通过室内实验优化设计,确定YD-G1溶液的最佳注入量为0.5倍孔隙体积,最佳注入质量分数为0.3%。

For high-temperature and high-salinity reservoirs, the surfactant flooding is an important technical measure for enhancingoil recovery. But the study of emulsification effect on enhancing oil recovery was not given sufficient attention. To evaluate emulsifica-tion effect on oil recovery in Pucheng oilfield, two surfactants YD-G1 and SHY-1 are selected through the experiment of decreasing in-terfacial tension. The interfacial tensions between the two surfactants solution and Pucheng dehydrated and degassed crude oil canreach the ultra-low level of 10-3mN/m before and after two surfactants solution putting into constant temperature oven of 120 ℃ in 30days, which shows two surfactants have good thermal and salinity tolerance capability. Compared with the SHY-1 emulsion, the YD-G1 emulsion of same mass fraction has lower water separating proportion, smaller average diameter, which shows YD-G1 solution stron-ger emulsification capability. The two kinds of emulsion are prepared by using dehydrated and degassed crude oil from Pucheng oilfieldand the two surfactants. The YD-G1 solution which has stronger emulsifying ability has a better oil displacement effect than SHY-1,which illustrates that the emulsion is one of the key factors to enhance the recovery efficiency. The optimum injection concentration andvolume are 0.3wt% and 0.5 PV by optimization of laboratory experiments. In the preferred injection mode, the surfactant flooding canimprove the recovery factor of 13.5%.