Study On Interaction Between Ionic Liquids And Surfactants & Application Research In Enhanced Oil Recovery

The key of enhanced oil recovery (EOR) technology development is to explore the flooding which can improve the oil displacement efficiency, normally the most effective and feasible method to increase oil displacement efficiency is to reduce interfacial tension between the flooding and crude oil. The Gemini surfactants are a new type of surfactants, they are made up of two amphiphilic moieties connected at the level of the head groups or very close to the head groups by a spacer group, compared with single chain surfactants, Gemini surfactants possess much lower critical micelle concentration and higher surface activity. Ionic liquids are composed of anions and cations, they exist as salts near normal temperature, their cations mostly contain imidazole ring, pyridine ring head groups and relatively long alkyl chains, and the structures determine that they have certain amphiphilic properties, the surface activity of long chain ionic liquids is better than that of conventional surfactants. We assume to combine them to form a mixed solution, using the synergy effect to further improve the surface activity to meet the performance requirements of flooding. More importantly, the molecular structures of Gemini surfactants and ionic liquids are adjustable, the interfacial and bulk characters can be controlled through adjusting the structure of both surfactants, therefore, the mixed system of containing Gemini surfactants and ionic liquids is expected to become a new and efficient flooding system. However, so far, there is no corresponding research on this aspect.This paper explores the potential applications of the mixed system of Gemini surfactants and ionic liquids in EOR, firstly, the influence of ionic liquids on surfactant solutions is studied. The results show that the addition of a few of ionic liquids can improve the solubility of surfactants dramatically, acting as the co-solvent; ionic liquids can cooperate with the surfactants, the addition of a few of ionic liquids can reduce the water-oil interfacial tension above a magnitude than that of system without ionic liquids; At the same time, ionic liquids can alter the micelle morphology to change the apparent viscosity of mixed solutions. In addition, this paper also discusses the influence of ionic liquids on the system which contains polymer, studies the influence of the type and concentration of ionic liquids and conventional salts on water-oil interfacial properties, explores the influence rule to provide basic data and the theoretical guidance for the development of new type of oil displacement systems with high efficiency.