Synthesis and properties evaluation of novel Gemini surfactant with temperature tolerance and salt resistance for heavy oil

In order to construct an emulsification and viscosity reduction system of temperature tolerance and salt resis-tance surfactants, a series of surfactants E4An (E4A6, E4A10, E4A15) with different oxyethylene groups were synthesized and studied. The structures of the optimal product were characterized by infrared (IR) and nuclear magnetic resonance (1H NMR). According to the requirement of surfactant used for heavy oil, the physico-chemical properties including cloud point (Tc), surface tension, oil/water interfacial tension (IFT), emulsifica-tion effect, heat stability and salt resistance were fully described. Experimental results showed that the surfactant E4A10 had better surface activity (gamma cmc = 28.79 mN/m). The HLB value of E4A10 was 13, and the Tc was 71 degrees C. In addition, the surfactants E4An demonstrated good temperature tolerance and salt resistance at high salinity (8246 mg/L) and high temperature (300 degrees C, 24 h), where viscosity reduction ratio for heavy oil of Bohai oilfield still reached 98.0 % and the particle size of the emulsion droplets for E4A10 was only 13.25 mu m. The IFT of E4A10 had no obvious fluctuation before and after aging, and exhibited better interfacial activity (0.65 mN/m).