Binary system of alkyl polyether carboxylate and quaternary ammonium with ultra-low interfacial tension at high temperature and a wide range of salinity

A novel formula of anionic surfactants with propoxy (PO) and ethoxy(EO) groups and cationic surfactants was developed and temperature and salt resistance performance of the formula has been studied with both model oil and crude oil. An obvious synergistic effect was evidenced by CMC values and interaction parameters of nonylphenol polyether carboxylate, hexadecyltrimethylammonium chloride and their mixtures. Effect of molar ratio of anionic surfactant and cationic surfactant, temperature, salinity, concentration and oil-water ratio on phase behavior and interfacial tension were investigated systematically. The results demonstrate that ultra-low interfacial tension and excellent phase behavior were obtained at temperature up to 120 °C and a wide range of salinity, which shows promising for enhanced oil recovery.