AAPG/SEG/EAGE/SPE Middle East Region RDPETRO

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Selection of CO2-soluble surfactants for CO2 foam/emulsion in hot and salty carbonate reservoirs

Abstract

CO2 enhanced oil recovery (EOR) attracts more and more interests because of its high microscopic recovery efficiency. However, CO2 often early breaks through and segregates from oil zone due to the low viscosity and density in the field application. Therefore, foam/emulsion is proposed for controlling the mobility of CO2. Surfactants are common chemicals for stabilizing the foam/emulsion, and have been widely used in the fields. Among them, CO2-soluble surfactants are more competent, because the surfactants could be transferred in CO2 phase and generate the stable foam/emulsion wherever CO2 flows. However, the efficiency of the surfactants is often profoundly suppressed by high temperature and high salinity in carbonate reservoirs, which are common conditions in Abu Dhabi.

We present here the criteria and methods for selecting the surfactants regarding the CO2 foam/emulsion. And, various surfactants are evaluated and compared in laboratory scale. Novel alkyl-amine surfactants outperform the surfactants in literature, and can rapidly generate strong CO2 foam/emulsion at high temperature and high salinity. The results show that the novel alkyl-amine surfactants are promising for CO2 foam/emulsion assisted EOR in hot and salty carbonate reservoir.