Adsorption of methyl ester sulfonate surfactant on Berea sandstone: Parametric optimization, kinetics, isotherm and thermodynamics studies

Abstract

Anionic surfactants are utilized as an enhanced oil recovery (EOR) additive in sandstone reservoirs due to their excellent surface-activity and self-assembly behaviour. Considering the toxicity of some of the conventional surfactants and the clamour for sustainability approach for oil and gas operations, this present study focuses on application of anionic bio-based surfactant (methyl ester sulfonate, MES) synthesized from used cooking oil in EOR. Studies on MES adsorption onto sandstone reservoir rock were conducted, and the influence of static conditions on adsorption rate using Taguchi experimental design approach was explored. Adsorption data were analyzed using various isotherm and kinetics models. The obtained findings from optimization studies showed that salinity had a significant effect on the process, followed by temperature and pH. The concentration of surfactant had the least effect on the static adsorption process. At an optimum initial MES concentration of 500 ppm, salinity of 3.0 wt%, pH of 4.0, and temperature of 30 °C, the maximum extent of MES adsorbed by the sandstone was 98.9±0.69%. Langmuir isotherm and pseudo-second-order kinetics models were found to fit well with the adsorption equilibrium and kinetics data, respectively. The obtained values of thermodynamic parameters confirmed that MES adsorption onto sandstone was feasible, spontaneous, and exothermic.