Review on Potential Application of Saponin-Based Natural Surfactants for Green Chemical Enhanced Oil Recovery: Perspectives and Progresses

Synthetic chemical surfactants deployed in the petroleumindustryto improve oil recovery to meet growing global energy demand are describedto have detrimental environmental impacts and are expensive. In recenttimes, the exploration of saponin-rich plants as a substitute forenvironmentally threatening synthetic surfactants has garnered significantinterest from researchers. Saponin-based natural surfactants (SBNSs)are nontoxic, biodegradable, and possess desirable properties foruse in the oil and gas industry. This paper reviews the potentialapplication of saponin-based natural surfactants in enhanced oil recoveryprocesses that coincide with the interests of the United Nations'Sustainable Development Goal 7 for Affordable and Clean Energy. Wereviewed the mechanisms of saponin-based natural surfactants in enhancedoil recovery (EOR), surfactant adsorption, and the recent advancesin utilizing saponin-based natural surfactants for EOR purposes. Wealso provided a comprehensive analysis of the impact of salinity andtemperature on the performance of SBNSs. Moreover, the study alsopresented the economic feasibility and limitations of SBNSs for fieldenhanced oil recovery applications. We identified that a good numberof SBNSs can withstand harsh reservoir conditions, optimize interfacialtension by as high as 95.82% (although not to ultralow levels), andalter rock wettability from hydrophobicity to hydrophilicity, therebyreducing the contact angle by 3.64% to 87.5%. SBNSs also successfullyyielded a high incremental oil recovery factor of up to 36% in thepostsecondary recovery stage. The advent of techniques, such as alkaliincorporation and nanotechnology, support the achievement of ultralowinterfacial tension, mitigation of surfactant adsorption, and oilrecovery improvement. Future studies can adopt the recommendationsoutlined in this study to minimize uncertainty in the utilizationof SBNSs and enhance their design for "green" chemicalenhanced oil recovery applications.