A family of alkyl sulfate gemini surfactants. 2. Water-oil interfacial tension reduction.

A family of sulfate gemini surfactants that has great potential for various industrial applications was previously prepared and characterized in our lab. The unique and versatile structure of these surfactants has endowed them with properties that are attractive for enhanced oil recovery (EOR). A detailed experimental study was carried out and is presented here on the water-oil interfacial properties of these novel molecules. This series of seven sulfate gemini surfactants of different hydrophobic tail and spacer group lengths shows systematic trends in interfacial tension (IFT) reduction with changing solution conditions. These molecules exhibit extraordinary aqueous stability even in high salinity and hard brines. Ultra-low interfacial tension values were measured with low surfactant concentrations. The results from this study showed the potential of utilizing these surfactants at low concentrations and in harsh reservoir environments.