Different oil displacement experiments conducted on sandstone and carbonate samples show that low salinity water (LSW) injection can reduce the residual oil saturation (ROS). Recently, surfactant flooding (SF) in combination with low salinity water (known as low salinity surfactant (LSS) flooding) is proposed as a potentially promising hybrid enhanced oil recovery (EOR) process. A lower ROS is reported for a LSS process compared to that seen in SF or with LSW at the same capillary number. The capillary desaturation curve (CDC) is a well-known tool to study the effect of viscous and capillary forces on ROS for different EOR techniques. In this study, ROS data of various LSW, SF, and LSS flooding experiments at different capillary numbers are collected to develop a CDC to analyze the performance of the hybrid LSS method. This can help to analyze the effect of the hybrid method on an extra improvement in sweep efficiency and reduction in residual oil. A lower ROS is observed for LSS compared to LSW and SF in the same capillary number range. Our study shows different behaviors of the hybrid method at different ranges of capillary numbers. Three regions are identified based on the capillary number values. The difference in ROS is not significant in the first region (capillary number in the range of 10⁻⁷–10⁻⁵), which is not applicable in the presence of surfactant due to the low interfacial tension value. A significant reduction in ROS is observed in the second region (capillary number in the range of 10⁻⁵–10⁻²) for LSS compared to SF. This region is the most practical range for SF and LSS flooding. Hence, the application of LSS provides a noticeable benefit compared to normal EOR techniques. In the third region (capillary numbers greater than 10⁻²), where the surfactant flooding is a better performer, the difference in ROS is negligible.

在砂岩和碳酸盐样品上进行的不同驱油实验表明，注入低盐度水（LSW）可以减少残余油饱和度（ROS）。最近，表面活性剂驱油（SF）与低盐度水（称为低盐度表面活性剂（LSS）驱油）相结合被提议作为一种潜在有前途的混合增强采油（EOR）工艺。与在SF或具有相同毛细管数的LSW中观察到的相比，LSS过程的ROS更低。毛细管去饱和曲线（CDC）是研究不同EOR技术的黏性和毛细管力对ROS的影响的著名工具。在这项研究中，收集了在不同毛细管数下的各种LSW，SF和LSS驱替实验的ROS数据，以开发CDC来分析混合LSS方法的性能。这可以帮助分析混合方法对吹扫效率的进一步提高和残留油的减少的效果。在相同的毛细管数范围内，与LSW和SF相比，LSS的ROS较低。我们的研究显示了在毛细管数不同的范围内混合方法的不同行为。基于毛细管数值识别三个区域。ROS在第一个区域的差异不明显（毛细管数在10⁻⁷ –10 ^-5），由于界面张力值低，因此在表面活性剂存在下不适用。与SF相比，LSS在第二个区域观察到ROS显着降低（毛细管数在10 ^-5 –10 ^-2范围内）。该区域是SF和LSS洪水的最实用范围。因此，与普通的EOR技术相比，LSS的应用提供了明显的好处。在表面活性剂驱油性能更好的第三区域（毛细管数大于10 ^-2）中，ROS的差异可忽略不计。