Improving performances of double-chain single-head surfactants for SP flooding by combining with conventional anionic surfactants

The binary surfactant mixtures of 1,3-dialkyl (diC₈-diC₁₂) glyceryl ether ethoxylates with didodecylmethylhydroxylpropyl sulfobetaine (diC₁₂HSB) are good formulations for surfactant–polymer flooding of Daqing crude oil, China, but suffer from low aqueous solubility. By combining with α-olefin sulfonates (AOS) at small molar fractions, the aqueous solubility of the formulations can be significantly improved due to the formation of charged mixed micelles. The ternary formulations can reduce Daqing crude oil/connate water interfacial tension to ultralow at a wide range of total surfactant concentration (0.625?～?10?mM), have good resistance to adsorption by sandstone, and can keep sandstone surface water-wet.