Structural aspects, mechanisms and emerging prospects of Gemini surfactant-based alternative Enhanced Oil Recovery technology: A review

The design and development of chemical routes with fascinating physicochemical attributes comprise a major field of research in enhanced oil recovery (EOR). 'Dimerization' depicts a novel way to control structural assemblies and physicochemical properties, to achieve marked improvements in the chemical EOR process, and strategize oil recovery performance. There are immense possibilities for the diversification of gemini surfactant structure, which essentially consists of two identical or distinct amphiphilic units linked with a spacer group. Gemini surfactant molecules possess significantly lower critical micelle concentration (CMC) as compared to their monomeric counterparts, owing to their ability to selfaggregate at low dosages. Gemini surfactants exhibit a uniquely stable micellar structure, favorable interfacial behavior, rock-wetting character, viscoelasticity and cost-profitability. Gemini surfactant-assisted EOR solutions are expected to provide enhanced stability in comparison to conventional fluids, with the added advantage of minor operating investments and significant returns for petroleum producing companies. Gemini surfactants form an intermediary between conventional surfactants and polymeric materials, with desirable traits of both kinds of chemicals. Mechanisms associated with gemini surfactant-assisted EOR have been reported. In this review, the status, developmental trends and prospects of gemini (dimeric) surfactants, with respect to the needs of the petroleum industry have been elaborated. Though gemini surfactants have been used in numerous sectors, their application in EOR has been limited owing to unfamiliarity and commercial unavailability. Prospective gemini surfactant systems have been discussed herein to identify technical risks, calibrate reservoir simulation models, contribute to environmental responsibility and develop operating strategies to improve oil recovery/economics. (C) 2021 Elsevier B.V. All rights reserved.