Carbon dioxide (CO₂) flooding is one of the most globally used EOR processes to enhance oil recovery. However, the low gas viscosity and density result in gas channeling and gravity override which lead to poor sweep efficiency. Foam application for mobility control is a promising technology to increase the gas viscosity, lower the mobility and improve the sweep efficiency in the reservoir. Foam is generated in the reservoir by co-injection of surfactant solutions and gas. Although there are many surfactants that can be used for such purpose, their performance with supercritical CO₂ (ScCO₂) is weak causing poor or loss of mobility control. This experimental study evaluates a newly developed surfactant (CNF) that was introduced for ScCO₂ mobility control in comparison with a common foaming agent, anionic alpha olefin sulfonate (AOS) surfactant. Experimental work was divided into three stages: foam static tests, interfacial tension measurements, and foam dynamic tests. Both surfactants were investigated at different conditions. In general, results show that both surfactants are good foaming agents to reduce the mobility of ScCO₂ with better performance of CNF surfactant. Shaking tests in the presence of crude oil show that the foam life for CNF extends to more than 24 h but less than that for AOS. Moreover, CNF features lower critical micelle concentration (CMC), higher adsorption, and smaller area/molecule at the liquid–air interface. Furthermore, entering, spreading, and bridging coefficients indicate that CNF surfactant produces very stable foam with light crude oil in both deionized and saline water, whereas AOS was stable only in deionized water. At all conditions for mobility reduction evaluation, CNF exhibits stronger flow resistance, higher foam viscosity, and higher mobility reduction factor than that of AOS surfactant. In addition, CNF and ScCO₂ simultaneous injection produced 8.83% higher oil recovery than that of the baseline experiment and 7.87% higher than that of AOS. Pressure drop profiles for foam flooding using CNF was slightly higher than that of AOS indicating that CNF is better in terms of foam–oil tolerance which resulted in higher oil recovery.

中文翻译：

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用新开发的阴离子表面活性剂稳定的气/水泡沫，用于气体迁移率控制应用

二氧化碳（CO ₂）驱油是全球使用最广泛的提高采收率的EOR工艺之一。然而，低的气体粘度和密度导致气体通道和重力超驰，这导致差的吹扫效率。应用泡沫控制迁移率是增加气体粘度，降低迁移率和提高储层扫除效率的有前途的技术。通过共同注入表面活性剂溶液和气体在储层中产生泡沫。尽管有许多表面活性剂可用于此目的，但它们与超临界CO ₂（ScCO ₂）的性能较弱，导致迁移率控制差或丧失。这项实验研究评估了针对ScCO ₂引入的新开发的表面活性剂（CNF）与常见的发泡剂阴离子α烯烃磺酸盐（AOS）表面活性剂相比，它具有更好的流动性控制。实验工作分为三个阶段：泡沫静态测试，界面张力测量和泡沫动态测试。在不同条件下研究了两种表面活性剂。通常，结果表明两种表面活性剂都是良好的发泡剂，可降低ScCO ₂的迁移率具有更好的CNF表面活性剂性能。在原油存在下的振动试验表明，CNF的泡沫寿命可以延长到24小时以上，但比AOS的要短。此外，CNF具有较低的临界胶束浓度（CMC），较高的吸附力以及液-气界面处的面积/分子较小的特征。此外，进入，扩散和桥联系数表明，CNF表面活性剂在去离子水和盐水中均与轻质原油一起产生非常稳定的泡沫，而AOS仅在去离子水中稳定。在所有用于迁移率降低评估的条件下，与AOS表面活性剂相比，CNF表现出更强的流动阻力，更高的泡沫粘度和更高的迁移率降低因子。此外，CNF和ScCO ₂同时注入比基础实验提高了8.83％的采油率，比AOS提高了7.87％。使用CNF进行泡沫驱油的压降曲线略高于AOS，这表明CNF的泡沫耐油性更好，从而提高了采油率。