A CO2-modified Surfactant for Chemical Flooding and Reducing Carbon Emission

Abstract

Abstract A CO2-modified alkyl polyglycoside (C-APG) surfactant was synthesized from a commercial APG product under mild reaction conditions including a low temperature at 50 °C and a low pressure of 2.5 bar. With this reaction, CO2 was successfully incorporated into APG molecules for efficient reduction of carbon footprint. The performance of applying C-APG as chemical flooding for improved oil production application in carbonate reservoirs with heavy crude oil was investigated and compared with its precursor - APG surfactant. The synthesized C-APG was characterized by FTIR and the physicochemical properties of both APG and C-APG including compatibility, surface tension, interfacial tension (IFT) were evaluated. Both surfactants were compatible with the high-salinity water (HSW) and had a similar critical micelle concentration (CMC). However, C-APG exhibited a much pronounced effect in reducing IFT between oil and water. The IFT of C-APG was 10-fold lower than original APG surfactant, suggesting great potential in chemical flooding for oil displacement. Micromodel test showed that the produced heavy oil by injection of APG or C-APG solution was further enhanced after water flooding. C-APG shows higher effectiveness on oil displacement due to lower IFT and stronger emulsification. Core-flooding oil displacement test indicated that C-APG injection resulted in a lower differential pressure and a higher cumulative oil production comparing APG chemical flooding. The produced fluids from C-APG flooding and extended water flooding exhibited very strong emulsification comparing the fluids produced by APG flooding. The incomplete phase separation resulted in an underestimated oil displacement efficiency by C-APG flooding. This study shows a great potential of C-APG surfactant in terms of CO2 reduction and improving oil production.