Effect of temperature and salinity on interfacial behavior of alkyl ether carboxylate surfactants

Abstract

This work investigates the interfacial behavior of alkyl ether carboxylate (AEC) surfactants in examples of sodium laureth-11 carboxylate and sodium trideceth-7 carboxylate. AECs have two hydrophilic groups and demonstrate both anionic and nonionic properties, displaying stability under harsh reservoir conditions during surfactant flooding. The interfacial tension measurements were conducted with a spinning drop tensiometer; n-decane, and oil were used as the hydrocarbon phase. The influence of surfactant concentration, temperature (25 °C and 70 °C), and various ions (Na+, Ca2+, Mg2+, Cl−, SO4 −, and HCO3 −) were evaluated. It was found that the temperature increase has no significant effect on critical micelle concentration (CMC) for both surfactants but influences interfacial tension values in pre-CMC and post-CMC regions. According to data obtained, the temperature rise has a stronger impact on a surfactant with a longer oxyethylene chain sodium laureth-11 carboxylate. In contrast, brine salinity has a more substantial effect on sodium trideceth-7 carboxylate interfacial behavior.