Abstract Ionic liquids are recently considered as an alternation to surfactants for their application in enhanced oil recovery (EOR) because of their promising surface-active properties. In the present study, the ability of a series of synthesized ionic liquids (C8mimBF4, C10mimBF4 and C12mimBF4) to reduce interfacial tension (IFT) and change the wettability of oil-wet rock have been investigated. Results demonstrated that all three synthesized ionic liquids enhanced interfacial properties and rock-wetting characteristics. The ionic liquids were able to significantly reduce IFT and remained stable at high temperature and saline conditions. Addition of organic alkali also showed a synergistic effect on IFT reduction between crude oil and ionic liquid solution. FTIR and zeta potential measurements were conducted to establish the mechanism of wettability alteration of oil-wet rock. Emulsification tests confirmed the capability of the ionic liquids to emulsify the trapped oil, which is an important mechanism of chemical EOR. The loss of ionic liquids by adsorption on rock surface was studied, and the adsorption data were analyzed by Langmuir and Freundlich models. Microemulsion study showed Winsor type III behavior with ultra-low IFT, which is beneficial for EOR application. Sand pack flooding experiments were conducted to study the EOR efficiency using the synthesized ionic liquids and around 32.28% additional recovery was observed after the conventional water flooding with injection of ionic liquid, polymer and alkali slugs.

中文翻译：

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咪唑基离子液体作为新型表面活性剂提高采收率的机理研究

摘要 离子液体最近被认为是表面活性剂的替代品，因为它们具有良好的表面活性特性，可用于提高石油采收率 (EOR)。在本研究中，研究了一系列合成离子液体（C8mimBF4、C10mimBF4 和 C12mimBF4）降低界面张力（IFT）和改变油湿岩石润湿性的能力。结果表明，所有三种合成的离子液体都增强了界面性质和岩石润湿特性。离子液体能够显着降低 IFT 并在高温和盐水条件下保持稳定。有机碱的加入对原油和离子液体溶液之间的 IFT 降低也表现出协同作用。进行了FTIR和zeta电位测量，以建立油湿岩石润湿性改变的机制。乳化试验证实了离子液体乳化捕集油的能力，这是化学 EOR 的重要机制。研究了离子液体在岩石表面吸附的损失，并通过Langmuir和Freundlich模型分析了吸附数据。微乳液研究显示具有超低 IFT 的 Winsor III 型行为，有利于 EOR 应用。进行了填砂驱实验以研究使用合成离子液体的 EOR 效率，并且在注入离子液体、聚合物和碱段塞的常规水驱后观察到大约 32.28% 的额外采收率。乳化试验证实了离子液体乳化捕集油的能力，这是化学 EOR 的重要机制。研究了离子液体在岩石表面吸附的损失，并通过Langmuir和Freundlich模型分析了吸附数据。微乳液研究显示具有超低 IFT 的 Winsor III 型行为，有利于 EOR 应用。进行了填砂驱实验以研究使用合成离子液体的 EOR 效率，并且在注入离子液体、聚合物和碱段塞的常规水驱后观察到大约 32.28% 的额外采收率。乳化试验证实了离子液体乳化捕集油的能力，这是化学 EOR 的重要机制。研究了离子液体在岩石表面吸附的损失，并通过Langmuir和Freundlich模型分析了吸附数据。微乳液研究显示具有超低 IFT 的 Winsor III 型行为，有利于 EOR 应用。进行了填砂驱实验以研究使用合成离子液体的 EOR 效率，并且在注入离子液体、聚合物和碱段塞的常规水驱后观察到大约 32.28% 的额外采收率。吸附数据采用 Langmuir 和 Freundlich 模型分析。微乳液研究显示具有超低 IFT 的 Winsor III 型行为，有利于 EOR 应用。进行了填砂驱实验以研究使用合成离子液体的 EOR 效率，并且在注入离子液体、聚合物和碱段塞的常规水驱后观察到大约 32.28% 的额外采收率。吸附数据采用 Langmuir 和 Freundlich 模型分析。微乳液研究显示具有超低 IFT 的 Winsor III 型行为，有利于 EOR 应用。进行了填砂驱实验以研究使用合成离子液体的 EOR 效率，并且在注入离子液体、聚合物和碱段塞的常规水驱后观察到大约 32.28% 的额外采收率。