Performance and Salinity Tolerance of Palm Oil-Derived Anionic Biosurfactant and Synthetic Surfactant for Waxy Oil Recovery in Sandstone Reservoirs

Currently, biosurfactants are receiving increased interest as a substitute for surfactants synthesized from petroleum products due to their biodegradability. Palm oil derivatives are one of the interesting candidates for biosurfactants because of the superior properties of the hydrocarbon structure in the range of C16–C18. This paper aims to measure the properties of palm oil-derived anionic biosurfactants compared to the sodium dodecylbenzene sulfonate (SDBS) surfactant from petroleum sources, in terms of adsorption, interfacial tension (IFT), and oil recovery in order to observe their performance with different surfactant molecules and cation concentrations. The adsorption behavior was illustrated in the form of an isotherm model while the adsorption parameters were fitted and determined by regression methods, as well as IFT and oil recovery measurements were accomplished by tensiometer and coreflooding, respectively. The results from this study revealed that palm oil-derived surfactants, i.e., methyl ester sulfonate (MES) and alkyl sulfate, show good performance in both adsorption and oil recovery performance compared to SDBS, with the highest oil recovery from alkyl sulfate injection because of its lowest adsorption and highest solubility. The oil recovery effectiveness of surfactants could be improved by mixing them with brine due to the synergistic effect of the salt and surfactant mixture, resulting in further reduction of IFT in saline solutions. However, when the total salinities of SDBS and carboxylate surfactant solutions were increased, they behaved like a nonideal solution with surface bridging between adjacent ionic molecules, which resulted in the reduction of surfactant molecule activity for oil recovery among these low-soluble surfactant solutions. Additionally, the surfactant material cost analysis was compared between surfactants and it showed that all of these palm oil-derived biosurfactants could be competitive with the cost of SDBS, with the range of surfactant costs per produced oil being between 6–27 USD/bbl oil.