Study on Cardanolbetaine Surfactants for Ultralow Interfacial Tension in a Low Range of Surfactant Concentration and Wide Range of Temperature Applied in Compound Flooding

Surfactant flooding aims at lowering the interfacial tensions between the oil and water phases to improve the displacement efficiency during oil recovery. However, ionic surfactants will lose their property in high temperature and high salt reservoirs. This investigation considers the cardanolbetaine surfactants as candidates for enhanced oil recovery (EOR) application in high temperature and high salt reservoirs. According to the experimental results, these surfactants can be effective in lowering interfacial tension (IFT) at dilute concentration, without requiring an alkaline or co-surfactants. In addition, these surfactants exhibit a low IFT at high salinity, high temperature and high concentration of divalent condition, the best surfactant concentration is 0.3 g L−1. The temperature resistance results show that it also has an excellent interfacial property at a wide range temperature from 35.0°C to 85.0°C, and remains its ultralow IFT (≤ 10−3 mN m−1) during 60 days at 85.0°C. The optimal concentration of salt tolerance is 50 g L−1 to 100 g L−1 of NaCl, 100 mg L−1 to 300 mg L−1 of Ca2+ respectively.