致密油藏纳米微乳液性能评价与驱油机理分析

Performance Evaluation and Oil Displacement Mechanism Analysis of Nano-microemulsion Using in Tight Oil Reservoir

赵雅洁 侯吉瑞 屈鸣 肖立晓 刘彦伯

ZHAO Yajie，HOU Jirui，QU Ming，XIAO Lixiao，LIU Yanbo

自发渗吸为致密油藏提高采收率的主要方式，但常规驱油所用的表面活性剂易被岩石吸附，吸附损失较大，在苛刻油藏中不能满足强化采油的使用要求，提高自发渗吸采收率效果不明显。以环辛烷、脂肪醇聚氧乙烯醚类乳化剂、乙二醇、三乙醇胺为原料，制得以有机相为内相、表面活性剂为壳膜的纳米微乳液。通过界面张力及润湿反转实验揭示了其驱油机理，通过自发渗吸实验验证了提高采收率效果。结果表明，0.3%的纳米微乳液体系粒径尺寸约为10 nm，油水界面张力为3.56 mN/m，可将油湿石英片表面的润湿性（130.6°）反转为水湿表面（11.7°），具有良好的润湿反转能力。岩心在该乳液中的最终自发渗吸采收率为43.2%，约为水的2.4 倍，自发渗吸提高采收率效果显著。

Spontaneous imbibition is the main way to improve oil recovery in tight reservoir. But the surfactant used in conventional oil flooding is easy to be adsorbed by rock and the adsorption loss is large. It cannot meet the requirement of enhanced oil recovery in harsh reservoir，and the effect of improving spontaneous imbibition recovery is not obvious. Using cyclooctane，fatty alcohol polyoxyethylene ether emulsifier，ethylene glycol and triethanolamine as raw materials，the nano-microemulsion with organic phase as inner phase and surfactant as shell film was prepared. The oil displacement mechanism was revealed by interfacial tension and wettability inversion experiments，and the effect of enhanced oil recovery was verified by spontaneous imbibition experiment. The results showed that the particle size of 0.3% nano-microemulsion system was about 10 nm，and the oil-water interfacial tension was 3.56 mN/m. The nano-microemulsion could reverse the wettability of quartz surface from oil-wet（130.6°）to water-wet （11.7°），showing good wettability reversal. The ultimate spontaneous imbibition recovery of core in the emulsion was 43.2%，that was about 2.4 times bigger than that of water. The spontaneous imbibition improved the recovery significantly.

10.19346/j.cnki.1000-4092.2022.02.025