三季铵盐表面活性剂界面性能及驱油效果评价

在化学驱中,降低油水界面张力是表面活性剂驱油最基本的机理。三季铵盐表面活性剂因其特殊结构表现出更好的界面性能。针对已合成的三季铵盐,探讨了各因素对界面性能的影响,结果表明,纯三季铵盐溶液与长庆油区模拟油界面张力可达10-2mN/m,比常规活性剂低1～2个数量级,具有较好的耐盐、耐高温性;与阴离子活性剂α-烯烃磺酸盐复配后,界面张力可达10-4mN/m,表现出较好的协同效应。驱替实验结果表明,纯三季铵盐可降低低渗透岩心注入压力10.6%,提高采收率8.35%;与α-烯烃磺酸盐复配后,降压率为17.4%,岩心采收率提高了11.1%,降压和驱油效果更佳,这也表明界面张力越低,提高低渗透岩心采收率效果越好。

Evaluation on interfacial properties and displacement effect of triquaternary ammonium salt

In the tertiary oil recovery,reducing the oil-water interfacial tension is the most basic mechanism of surfactant flooding.Tri-quaternary ammonium salt Gemini surfactant shows better interfacial activity because of its special structure.For the synthesized tri-quaternary ammonium salt,we test the influence of different factors on the interfacial properties.The results show that the interfacial tension between pure tri-quaternary ammonium salt solution and simulated oil of Changqing can decrease to 10-2mN/ m,which is 1-2 orders of magnitude lower than general surfactants;It has good abilities of tolerating salt and resisting high temperature;If mixed with anionic surfactant-a-olefin sulfonate,the interfacial tension can decrease to 10-4 mN/m,which shows good synergistic effect.The displacement experiments show that the pure tri-quaternary ammonium salt can reduce the injection pressure of low permeability core by 10.6% ,and enhance oil recovery by 8.35% ;when mixed with a-olefin sulfonate,the step-down rate is 17.4% ,and EOR is 11.1%.So,the mixture is favorable for oil displacement,and it also implies that the lower the interfa-cial tension,the better it can improve the recovery of low permeability core.