Synthesis of temperature-resistant and salttolerant surfactant SDB-7 and its performance evaluation for Tahe Oilfield flooding (China)

In order to improve the enhanced oil recovery of high-temperature and high-salt oilfields, a novel temperature-resistant and salt-tolerant surfactant(denoted as SDB-7) was synthesized and evaluated for the Tahe Oilfield(Xinjiang, China), which is representative of high-temperature and high-salt oilfields. It has a central reservoir temperature of 140 °C and salinity of 22.6×104 mg/L. The temperature-resistant and salt-tolerant performance, interfacial activity, oil displacement efficiency, aging properties, and adsorption properties of the synthesized surfactant were evaluated for Tahe Oilfield flooding. The results showed that the SDB-7 was temperature-resistant and salt-tolerant capacity of 140 °C and 22.6×104 mg/L, respectively, oil displacement efficiency under static condition of 84%, and adsorption loss of 0.4 mg/g(less than 1 mg/g-oil sand). In the heat aging experiment(under the temperature of 140 °C for 60 days), the oil-water interfacial tension and oil displacement efficiency of SDB-7 were almost unchanged. The oil displacement experiments showed that, under the temperature of 140 °C and the salinity of 22.6×104 mg/L, the surfactant SDB-7 can enhance oil recovery by 14.5% after water flooding,suggesting that SDB-7 has a promising application in high temperature and high salinity(HT/HS) reservoir.