Dynamic Interfacial Tension Behavior of Alkyl Amino Sulfonate in Crude Oil-Brine System

Abstract

Abstract The compatibility of surfactants, a series of alkyl amino sulfonate containing various the length of alkyl chain (dodecyl, tetradecyl, hexadecyl and octadecyl, developed in our laboratory), with formation water matching the Xinjiang Oil Field reservoir water and the dynamic interfacial tensions (DIT) behaviors between the crude oil and the formation water for a number of alkaline flooding systems were measured. These surfactants are found to be well compatible with formation water up to 0.10 g L−1 surfactant concentration, especially Dodec-AS and Tetradec-AS show a good compatibility with formation water over the full range of surfactant concentration investigated (0.01–0.20 g L−1). All surfactants exhibit the dynamic interfacial tension behavior, and can reach and maintain low interfacial tension at very low concentration. The time for reaching the equilibrium DIT (DITeq) is longer for surfactant with stronger lipophilicity, e.g. octadecyl-AS. It is interestingly found that the ratio value between DITeq and the tension at crude oil/reservoir water interface in the absence of surfactant is in the range of 10−4–10−3 mN m−1, accordingly based on which and the previous results, four surfactants individually or with other additives together may become potent candidates for enhanced oil recovery. Fortunately, the alkyl amino sulfonate combinational systems without alkali designed by our group can reduce the interfacial tension even to 10−4 mN m−1 at very low surfactant concentration. These surfactants or their systems have characteristic of “Green”, in addition to the excellent salt-tolerance and the less expensive cost for enhanced oil recovery, and therefore they are good oil-displacing reagents for enhanced oil recovery.