Switchable diamine surfactants for CO2 mobility control in enhanced oil recovery and sequestrationby Elhag, Amro S.; Chen, Yunshen; Reddy, Prathima P.; Noguera, Jose A.; Ou, Anne Marie; Hirasaki, George J.; Nguyen, Quoc P.; Biswal, Sibani L.; Johnston, Keith P.
The design of switchable amine surfactants for CO2 EOR in carbonate reservoirs at high temperatures is challenging because of the increase in the pH due to dissolution of calcium carbonate at acidic conditions. The increased pH hinders the protonation of the surfactant and its aqueous solubility. In this work, the addition of a second amine headgroup ensured that C16-18 N(EO) C3N(EO)(2) is soluble in 22% TDS brine at neutral pH conditions. Also, captive bubble tensiometry measurements confirmed the activity of the surfactant at the C-W interface by large reduction in the interfacial tension coupled with high adsorption. Also, the surfactant generated viscous foam that can stabilize the displacement front in CO2 EOR processes and decrease the mobility of CO2 for enhanced CO2 sequestration. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/3.0/).