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Novel Alkyl-Amine Surfactants for CO2 Emulsion Assisted Enhanced Oil Recovery

Cui, Leyu, Dubos, Fabienne, Bourrel, Maurice
Energy & fuels 2018 v.32 no.8 pp. 8220-8229
anaerobic conditions, carbon dioxide, emulsifying, emulsions, fluorine, foams, fuels, oils, pH, porous media, salinity, silicon, sodium chloride, solubility, surfactants, temperature, thermal stability
Novel CO₂-soluble surfactants are designed for generating stable CO₂ emulsion/foam at high temperature (110 °C) and high salinity (220 g/L NaCl). The novel surfactants only consist of alkyl chains and amine heads without any fluorine, silicon, or poly alkyl-oxide groups and outperform the surfactants in literature regarding the solubility, thermal stability, and emulsifying ability in harsh conditions. 0.2 wt % of the novel surfactants are soluble in 220 g/L NaCl brine at pH ≤ 8 from 20 to 120 °C and are soluble in CO₂ at high temperature (110 °C) and relatively low pressure (91 bar). The surfactants are thermally stable at 110 °C and pH = 4 under anaerobic conditions. Strong CO₂ emulsion can be readily generated in bulk and in porous media at 25–110 °C and 150 bar. Unlike the common surfactants in literature, the performance of the novel surfactants can be profoundly enhanced by salinity and temperature. The strategy for designing these novel molecules and tuning the surfactant formulation for emulsion-assisted CO₂ enhanced oil recovery (EOR) is discussed as well.