红河油田长8超低渗透油藏化学驱的适应性

Adaptability of Chemical Flooding Agents in Chang 8 Ultra-low Permeability Reservoirs of Honghe Oilfield

刘岳龙 刘毅恒 叶双祥 邓学峰 强 星 魏开鹏 张 浩 杨 洋

LIU Yuelong LIU Yiheng YE Shuangxiang DENG Xuefeng QIANG Xing WEI Kaipeng ZHANG Hao YANG Yang

红河油田长8超低渗透油藏注水压力高、驱油效率低，需开展化学驱提高原油采收率，但驱油剂油藏适应性不明。针对以上问题，对比研究了表面活性剂、纳米乳液、活性二氧化硅纳米流体（简称活性纳米流体）3类驱油剂的界面活性、降压增注及驱油性能，结合界面-渗流阻力-驱油效率相关性分析明确了不同类驱油剂在长8超低渗透油藏的适应性。研究结果表明，单相渗流条件下，注入质量分数为 0.3%表面活性剂 AMS、质量分数为0.5%纳米乳液 LIE、质量分数为0.3%活性纳米流体ASN后，降压率分别为 15.1%，5.8%和9.1%。AMS降压率最高，主要原因在于表面活性剂可将中性润湿岩石表面调整为弱亲油状态，有助于削弱水膜作用。两相渗流条件下，表面活性剂AMS无法抑制原油与水形成油包水型乳状液，无法实现降压，而纳米乳液 LIE 和活性纳米流体ASN在降低油水界面张力的同时可抑制油包水乳液的生成，可实现驱替压力的有效降低，其中纳米乳液降低油水界面张力性能优于活性纳米流体，降压率最高，为38.6%。天然岩心驱替表面活性剂、纳米乳液、活性纳米流体分别可提高原油采收率 26.67 百分点、23.51 百分点和 16.35 百分点，表面活性剂提高采收率幅度最高，但考虑其无法在两相渗流条件下实现降压，与长8超低渗透油藏适应性最好的化学驱体系为纳米乳液。

The Chang 8 ultra-low permeability reservoirs of Honghe Oilfield suffer from high water flooding pressure and low oil-displacement efficiency. Chemical flooding could be a method to enhance the oil recovery in Chang 8 ultra-low permeability reservoirs. However，the adaptability of flooding agents in reservoirs is not clear. Therefore，the interfacial activity，pressure reducing and oil displacement ability of three types flooding agents，including surfactant，nano emulsion，and a silica nanofluid， were comparatively studied and their adaptability in Chang 8 ultra-low permeability reservoirs was analyzed. The results showed that the pressure-reducing rates of the 0.3% surfactant AMS，0.5% nano emulsion LIE，and 0.3% the silica nanofluid were 15.1%， 5.8% and 9.1%，respectively，under single-phase seepage conditions. The surfactant exhibited the highest pressure-reducing rate， which resulted from its superior wettability alteration ability. The wettability of rock changed from intermediate-wet to weak oil-wet under the effect of the surfactant. In contrast，the surfactant could not achieve pressure-reducing under two-phase seepage conditions because the surfactant could not inhibit the formation of oil-in-water emulsions. Meanwhile，the nano emulsion LIE and the silica nanofluid ASN exhibited favorable pressure-reducing performance due to their interfacial tension reducing ability and oil-in-water emulsion inhibition ability. The nano emulsion exhibited the highest pressure-reducing rate，being of 38.6%，because the interfacial tension reducing ability of the nano emulsion was better than that of the silica nanofluid. In nature core flooding experiments，the surfactant，the nano emulsion，and the silica nanofluid achieved enhanced oil recovery of 26.67 percentage point， 23.51 percentage point and 16.35 percentage point，respectively. The surfactant exhibited the best enhanced oil recovery ability. However，considering that the surfactant could not achieve pressure-reducing effect under two-phase seepage conditions，the nano emulsion was the best alternative for chemical flooding in Chang 8 ultra-low permeability reservoirs.

10.19346/j.cnki.1000-4092.2024.04.010