Energy Reports (Nov 2022)
Surfactant formulation for Green Enhanced Oil Recovery
Abstract
While the world continues to rely heavily on petroleum as a primary energy source, a great fraction of the oil-in-place remains inaccessible to traditional recovery means (thermal, gas, or chemical), posing significant environmental consequences and high treatment costs. Green enhanced oil recovery (GEOR) technologies, on the other hand, have generated interest in energy research as it involves the injection of specialized green fluids into reservoirs to improve sweep efficiency while also increasing residual oil production. Surfactant flooding, for example, has emerged as a viable green chemical EOR approach in which bioproducts produced by microbial metabolic processes are introduced into the reservoir to increase oil production These green surfactants (e.g., rhamnolipid, alkyl polyglycoside (APG), and lecithin) are now being studied for their possible uses in EOR processes as they have not been completely explored for their potential in chemical EOR. Therefore, in this study, a blend of rhamnolipid, APG, and lecithin are considered possible formulations to investigate the efficacy of these green surfactants in sandstone reservoirs based on phase behavior studies, interfacial tension measurement, and core-flooding experiments. It was found that all three blends (RB, RAB, and RL) performed well in the phase behavior study, resulting in stable middle phase microemulsions whereas only formulation RL had an ultralow IFT reduction between oil and brine. Consequently, this formulation (RL) performed the best of the three, with a tertiary recovery of 24% and a total recovery of approximately 70%. These results suggest that while other blends (RB and RAB) had good EOR potential, the third formulation (RL) is considered a more appropriate candidate for chemical EOR with a preference for biosurfactants (rhamnolipids) application. The outcomes of this study can aid in a better understanding of injection design methods and biosurfactant formulation selection, which is a critical attribute for green EOR technology.
