EOR Design Gemini Surfactant Synthesis And Performance Testing

In this paper, cationic gemini surfactants with different symmetry were synthesized using imidazole and halogenated hydrocarbons as raw reactants. Characterizations were conducted by IR, EA, and MS. IR results indicate that all products have the similar structures. However, MS results show that the asymmetrical gemini surfactants are mixtures of symmetrical and asymmetrical products. Studies of surface tension have shown that the cmc and γcmc increase with the length of the lipophilic groups. In addition, the influence of increase spacers shows cmc decreases and γcmc increases. The results of oil/water interface tension measurements show that all the surfactants can efficiently reduce the oil/water interface tension to0.1mN m-1especially n-14,4-12-14, and4-14-16.Zwitterionic gemini surfactant with different hydrophobic tails (C-8, C-12and CA-12) were synthesized by using ethylene glycol, phosohorus trichloride, oxygen, et al. as reactants. They were structurally characterized by IR, EA, H NMR, and P NMR. Surface tension and oil/water interface tension were fully studied. The cmc of the synthesized surfactants evaluated by surface tension measurements ranges from2.17x10-4mol L-1to5.36x10-4mol L-1and the cmc surface tension values (ycmc) ranges from26.49mN m-1to29.06mN m-1, which show excellent efficiency at reducing the water surface tension among the comparison surfactants. And on the other hand, all the surfactants can efficiently reduce the oil/water interface tension.Then, several surfactants including C-12, CA-12, n-14, and4-14-16, have been selected and applied for the flooding experiments by the authentic sandstone microscopic model. The concentrations of these two series are0.075%and0.08%. The results show that all these surfactants can well improve the flooding efficiency by8.7%-29.2%after water flooding experiments.Finally, study of alkali/salt surfactant flooding mechanism is mainly talked about according to results of dynamic oil/water interface tension of solutions of alcoholethoxylatespropane sulfonic acid and alkali/salt. The mechanism indicates that reaction between alkali and acidic components in crude oil occurs at the interface. Then the acidic components will be effectively neutralized and produce new surface-active substances. Thus, the oil/water interface tension can be reduced efficiently. At the same time, the oil droplets are shapely changed to reduce resistance by the sandstone cracks and eventually displaced.