Preparation and Performance Evaluation of Ultra-Low Interfacial Tension Foam Agent

In accordance with the characteristics of crude oil in the Bohai X oilfield block, the surfactant CM was synthesized through laboratory experiments, leading to the development of the ultra-low interfacial tension foam agent CM-EH. The experimental study revealed that the optimal synthesis conditions for CM were a reaction temperature of 75 °C, a molar ratio of fatty alcohol polyoxyethylene ether to halo sulfonate of 1:1.2, and a reaction time of 6 h. The ultra-low interfacial tension foam agent CM-EH demonstrated an ability to effectively reduce oil-water interfacial tension to 10–4 mN/m. Furthermore, it exhibited relatively stable foaming performance, strong resistance to temperature and salinity, and a high resistance factor, all of which contribute to enhanced oil displacement efficiency. The oil displacement efficiency of the ultra-low interfacial tension foam agent CM-EH at a concentration of 0.5% increased by 18 percentage points compared to water flooding, indicating its potential for effective enhanced oil recovery in the Bohai X oilfield.