Synthesis of didodecylmethyl hydroxyl sulfobetaine and its evaluation for alkali-free flooding

In this paper, didodecylmethyl hydroxyl sulfobetaine was synthesized by reaction of didodecylmethyl amine with sodium 2-hydroxy-3-chloro propanesulfate. The interfacial tensions between Dagang crude oil and solution of the surfactants, solution of surfactant-polymer mixtures were measured. The effects of surfactant concentration and aging time on the interfacial tension were investigated. It is found that the synthesized betaine surfactant could reduce the interfacial tension to ultra-low without alkali, alcohol and the other additives in the absence of or presence of polymer. The surfactant-polymer system could lower the interfacial tension to ultra-low, even was aged for more than 2 weeks. The sand-pack flooding tests indicated that, with 0.2 wt% of the betaine and with 1,500 mg/L of polymer, 16.89 % of an additional OOIP (original oil in place) was recovered from a sand pack. This result suggested that the didodecylmethyl hydroxyl sulfobetaine might be a good surfactant candidate for enhanced oil recovery.