Novel surfactants alcohol polyoxypropylene polyoxyethylene ether carboxylates (APPEC) were successfully synthesised by carboxymethylation reaction of alcohol polyoxypropylene polyoxyethylene ether (APPE) to meet alkali-surfactant-polymer (ASP) flooding needs. The structure of APPEC was characterised by Fourier transform infrared (FTIR) spectrometry. The reaction conditions of APPEC including reaction ratio of raw materials, temperature and reaction time were optimised. Interfacial tension and ASP core flooding experiments were also carried out to evaluate the enhanced oil recovery (EOR) performance of the APPEC surfactants. The interfacial tension between Xinjiang crude oil and synthetic water could be decreased to ultra-low level in a short time with 0.4 wt% APPEC at 28.7°C. Two core flooding experiments proved that ASP flooding system could improve the oil recovery by 21.5% or 22.3%. Therefore, the APPEC surfactant formulas could improve oil displacement efficiency under Xinjiang reservoir condition.
Keywords: enhanced oil recovery, chemical flooding, surfactant, alcohol ether carboxylate