Nonionic–anionic surfactants are expected to be applied in chemical flooding due to their important properties such as ultralow IFT values, good salt tolerance, and no chromatographic separation in porous media. In this study, a new type of nonionic–anionic–hydrophobic group structure surfactant N, N-dihydroxyethylalkylamide carboxylate (EAMC) was synthesized. The synergistic effects between petroleum sulfonate (KPS) and EAMC in reducing interfacial tension (IFT) and emulsification properties were studied. The influences of salt, alkali and Ca2+ on the IFTs of surfactant solutions were also investigated. One-dimensional core flooding experiments were used to characterize the enhanced oil recovery capability of the KPS and EAMC mixed system. The experimental results show that both EAMC and KPS have high interfacial activity and can reduce IFTs to about 0.01 mN/m order of magnitude against decane at optimized concentrations. The area occupied by the hydrophilic group of EAMC on the interface is smaller than that of its own hydrophobic group. The interfacial film formed by EAMC alone is relatively loose. The IFTs of KPS containing different structure petroleum sulfonates is affected by the difference in the adsorption rate of petroleum sulfonates on the interface, which shows that both the dynamic and equilibrium interfacial tensions can have the lowest values. However, the IFTs of the EAMC solutions against crude oil can be reduced to ultralow values because the mixed tight adsorption film is formed by EAMC and crude oil fraction molecules with synergistic effect. On the other hand, the KPS molecule has a hydrophobic part with large size and no synergism with crude oil fractions can be observed in the solutions containing only KPS. The combination of EAMC and KPS shows synergistic effect, namely ultralow IFT values, good emulsification properties, high alkali tolerance, and good salt and Ca2+ tolerance during a wide percentage range of EAMC. The best formula of EAMC and KPS system can be applied for EOR after polymer flooding. The studies in this paper are helpful for the design and application of a chemical flooding formula with nonionic–anionic–hydrophobic group structure surfactants.

中文翻译：

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石油磺酸盐与非离子-阴离子表面活性剂提高采收率的协同作用研究

非离子-阴离子表面活性剂由于其超低的 IFT 值、良好的耐盐性和在多孔介质中无色谱分离等重要特性，有望应用于化学驱。本研究合成了一种新型非离子-阴离子-疏水基团结构的表面活性剂N,N-二羟乙基烷基酰胺羧酸盐（EAMC）。研究了石油磺酸盐（KPS）和EAMC在降低界面张力（IFT）和乳化性能方面的协同作用。还研究了盐、碱和Ca2+对表面活性剂溶液IFTs的影响。采用一维岩心驱实验表征 KPS 和 EAMC 混合体系提高采收率的能力。实验结果表明，EAMC 和 KPS 都具有较高的界面活性，并且在优化浓度下，可以将 IFT 降低到对癸烷的约 0.01 mN/m 数量级。EAMC的亲水基团在界面上所占的面积小于其自身疏水基团的面积。EAMC单独形成的界面膜比较松散。含有不同结构石油磺酸盐的KPS的IFTs受石油磺酸盐在界面上吸附率的差异影响，表明动态和平衡界面张力都可以具有最低值。然而，EAMC 溶液对原油的 IFT 可以降低到超低值，因为 EAMC 和原油馏分分子形成了混合紧密吸附膜，具有协同作用。另一方面，KPS 分子具有大尺寸的疏水部分，在仅含有 KPS 的溶液中未观察到与原油馏分的协同作用。EAMC与KPS的组合显示出协同效应，即在EAMC的较宽百分比范围内具有超低IFT值、良好的乳化性能、高耐碱性以及良好的盐和Ca2+耐受性。EAMC和KPS体系的最佳配方可用于聚合物驱后的EOR。本文的研究有助于非离子-阴离子-疏水基团结构表面活性剂化学驱配方的设计和应用。在 EAMC 的较宽百分比范围内具有良好的乳化性能、高耐碱性和良好的耐盐性和耐 Ca2+ 性。EAMC和KPS体系的最佳配方可用于聚合物驱后的EOR。本文的研究有助于非离子-阴离子-疏水基团结构表面活性剂化学驱配方的设计和应用。在 EAMC 的较宽百分比范围内具有良好的乳化性能、高耐碱性和良好的耐盐性和耐 Ca2+ 性。EAMC和KPS体系的最佳配方可用于聚合物驱后的EOR。本文的研究有助于非离子-阴离子-疏水基团结构表面活性剂化学驱配方的设计和应用。