Minireview on Salinity-Responsive Emulsions in Petroleum Engineering: Recent Progress, Key Challenges, and Future Perspectives

Abstract

Salinity-responsive emulsions can achieve phase inversion between oil-in-water and water-in-oil emulsions solely by adjusting the salinity. This offers significant advantages, including a simple regulation method, sensitive response, and potential recyclability, and has therefore attracted considerable attention in the field of the petroleum industry. Compared with phase inversion strategies triggered by temperature, pH, or other factors, salinity-responsive emulsions exhibit superior potential for field-scale applications. This paper systematically reviews the research progress and application status of the salinity-responsive emulsions. First, the types of emulsion phase inversion and their influencing factors are summarized, indicating that salinity-induced phase inversion essentially represents a transitional phase inversion process. Second, phase inversion mechanisms of salinity-responsive emulsions are analyzed, and the research status of four types of salinity-responsive emulsions is comprehensively reviewed. Third, the applications of salinity-responsive emulsions in drilling and completion operations, profile control and water shutoff, and hydraulic fracturing are discussed and analyzed. Finally, the key challenges and future perspectives of their development and field applications in the petroleum industry are identified.