Technical approaches for optimizing the effectiveness of Gemini surfactants in enhanced oil recovery: a structural review

Gemini surfactants constitute a unique class of amphiphilic molecules in which two or more conventional surfactant moieties are covalently connected through a spacer positioned at or near their hydrophilic head groups. Compared to traditional surfactants, Gemini surfactants consistently demonstrate superior properties, including enhanced surface and interfacial activities, lower critical micelle concentrations (CMCs), unique micellar structures and aggregation behaviors, interesting rheological characteristics, high brine solubility, and excellent compatibility with other surfactants. These exceptional attributes have significantly broadened their applications in the petroleum industry, capturing the interest of both academic researchers and industry experts. This review examines systematic technical approaches to optimizing the performance of Gemini surfactants for enhanced oil recovery (EOR). Furthermore, it discusses the EOR mechanisms underlying surfactant flooding processes and reports the persistent challenges related to surfactant effectiveness in the field. Drawing on current insights, the review highlights pivotal strategies for maximizing the efficacy of Gemini surfactants. The objective is to provide valuable guidance for enhancing the performance efficacy of Gemini surfactants specifically designed for EOR applications.