Enhanced CO2 foam based on amide and amine surfactants and synergistically coupled with sodium dodecyl sulfate at high temperature and high pressure.

CO 2 foam can be used for mobility control and blocking gas breakthrough channels during CO 2 injection for enhanced oil recovery, and specially designed and formulated foam agents are needed to enhance the stability of the foams especially under reservoir conditions. In this study, the performance of CO 2 foams with various surfactants has been investigated, including amide based surfactants (e.g. coconut monoethanol amide (CMEA), lauryl diethanol amide (LDEA)), amine based surfactants (cocoacyl propyl dimethylamine (UC 11 AMPM)), sodium dodecyl sulfate (SDS) and its mixtures with the amides and amines. A visualized high pressure and high temperature foam meter and a sand-pack flooding setup were used to assess the foam's performance, along with the surface tension measurement of the surfactant solutions in the presence of CO 2. The influence of temperature, the surface tension of the aqueous solution, and SDS on CO 2 foam performance of amide and amine based surfactant were investigated. The experimental results indicate that the amide or amine based surfactant alone all show poor foam performance, while their CO 2 foam stability and their mobility control capability can be greatly enhanced at high temperature up to 100 °C with the salinity of 50000 mg/L. After adding SDS to CMEA, LDEA, or UC 11 AMPM, an excellent synergistic effect can be formed among the molecules, which can reduce the surface tensions of individual surfactant solution and enhance the stability of CO 2 foams. • The CO 2 foam performance of amine and amide based surfactants were tested at HTHP conditions. • Stable CO 2 foams can be generated by amine surfactant with SDS at temperature up to 130 °C. • The synergistic effect of amine based surfactant with SDS has been demonstrated for CO 2 foams at high temperature. [ABSTRACT FROM AUTHOR]