Effects of rhamnolipid bio-surfactant and sodium dodecylbenzene sulfonate (SDBS) surfactant on enhanced oil recovery from carbonate reservoirs

Bio-surfactant solutions have been point out as a promissory component to replace fossil-derived surfactants to improving the displacement efficiency in enhanced oil recovery (EOR) methods. This study compares the performance of rhamnolipid as a bio-surfactant and sodium dodecylbenzene sulfonate (SDBS) as a synthetic surfactant in EOR from carbonate reservoirs. The effects of their use were evaluated by considering the effect of different levels of salinity and the results of various well-established experimental tests such as of fluid-phase behaviour, wettability alteration, interfacial tension (IFT) reduction, and core flooding. The rhamnolipid bio-surfactant has been recognized as a better surface agent used to change the wettability of calcite to a strong water-wet system in comparison to sodium dodecylbenzene sulfonate. The results confirmed that when the salinity of low-saline brine was increased to 0.6 M, with a concentration of 0.5 wt. % of rhamnolipid, the wettability of the rock surfaces changed to become more water-wet. Also, values of IFT between model oil and low-saline brine were measured as 1.1 ± 0.3 and 2.8 ± 0.4 (mN/m) when using the rhamnolipid and SDBS respectively as modifiers within the aqueous solutions. Finally, the outcomes of core flooding experiments revealed that the rhamnolipid surfactant could minimize flow problems arising from the formation of emulsions, leading to 14.98% higher ultimate oil recovery compared to SDBS.