Novel microemulsion formation by the hydrophilic- lipophilic deviation concept using carboxylate extended surfactants for Eor application

Abstract

The Winsor type III (middle phase) microemulsion formation is widely used for enhanced oil recovery (EOR) application. A novel carboxylate surfactant has been an attractive surfactant for the oil recovery due to high chemical stability in harsh reservoir conditions (i.e., high brine concentration and high temperature). This study aims to formulate the middle phase microemulsion in order to obtain the minimum IFT and high solubilization capacity with binary anionic surfactant system using sodium dioctyl sulfosuccinate (AOT) and carboxylate extended surfactants with varying the polyethylene oxide number (EO = 2, 4 and 6) at three mixing molar ratios of 5:5, 7:3 and 9:1 in heptane, octane, decane, dodecane and hexadecane. The results showed that the decrease in the carboxylate extended surfactant fraction in the mixture significantly decreased the optimal salinity (S*). The S* increased with the increasing number of EO groups. The Hydrophilic-Lipophilic Deviation (HLD) equation was used to estimate the optimal condition, where the determined K and Cc values of the carboxylate extended surfactant were conducted and compared. In addition, the batch adsorption of the carboxylate extended surfactant onto quartz sand surface showed less adsorption capacity compared with other surfactants. The increasing of EO groups decreased the surfactant adsorption. Therefore, the carbox-ylate based extended surfactants could be an appropriate system for preventing the surfactant losses by the adsorption and economic viability of surfactant flooding in EOR application.