Ultra-low interfacial tension in high salinity reservoir driven by synergistic interaction of zwitterionic and anionic surfactants

Abstract

The present work investigates the use of synergistic interactions between zwitterionic and anionic surfactants to obtain ultra-low interfacial tension (IFT) in a high salinity reservoir. Zwitterionic surfactant N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate was found to be compatible with simulated high salinity water, reducing crude oil/water interfacial tension to a magnitude of 10 -2 mN·m -1 in a surfactant concentration range of 0.07%-0.39% (mass fraction), whereas ultra-low IFT was obtained by adding anionic surfactant sodium dodecyl sulfate. Furthermore, the effects of total surfactant concentration, metal ion concentration, and molar ratio on the dynamic interfacial tension of zwitterionic/anionic surfactant mixtures were studied. Results showed that 10 -5 mN·m -1 magnitude ultra-low IFT was obtained over a wide range of surfactant concentrations from as low as 0.04% and up to 0.37% in high salinity water. The synergistic mechanism of ultra-low IFT formed in zwitterionic/anionic surfactant systems was further analyzed. © Editorial office of Acta Physico-Chimica Sinica.