Competitive interactions between components in surfactant–cosurfactant–additive systems

Advances of microemulsion and its applications for improved oil recovery

Microemulsion, because of its excellent interfacial tension reduction and solubilization properties, has wide range of applications in the petroleum industry, especially in improved oil recovery (IOR). Herein, the concept, types and formation mechanism of microemulsion were primarily introduced. Then, the preparation and characterization methods were illustrated. Additionally, several effect factors were elaborated specifically based on the composition of microemulsion. Finally, the application of microemulsion in IOR was addressed, including IOR mechanism analysis based on sweep efficiency and displacement efficiency, injection method (microemulsion flooding, in-situ microemulsion formation) and field tests. Furthermore, the current challenges and prospects of microemulsion on IOR were analyzed.

A Comparison Study on the Phase Behavior and Solubilization between Cn(Bim)2-2Br-Butyric Acid and CnmimBr-Butyric Acid Microemulsion Systems

The solubility, interfacial composition and solubilization ability of microemulsions containing gemini 1,4-bis(3-alkylimidazolium-1-yl) butane bromide [Cn(Bim)2-2Br]/butyric acid were studied and compared with that of microemulsions containing 1-alkyl-3-methylimidazolium (CnmimBr)/butyric acid. The solubilities of butyric acid (SA), and the mass fractions of butyric acid in the interfacial layer(AS) decrease, while the solubilization parameters (SP*) increase with the increase in the carbon chain length of the surfactants in Cn(Bim)2-2Br based and CnmimBr based microemulsions. A comparison of the gemini Cn(Bim)2-2Br microemulsions with CnmimBr microemulsions indicates that the values of SA and AS are in the order: Cn(Bim)2-2Br < CnmimBr, while SP* values are Cn(Bim)2-2Br > CnmimBr. With salinity increasing, the values of SA and AS decrease, while SP* values increase. With the increase in the alkyl chain length of the oil molecules, the SA values increase, AS and SP* values decrease. Temperature has less influence on the values of SA, AS and SP* of microemulsions containing Cn(Bim)2-2Br/butyric acid.

Phase Behavior and Solubilization of Microemulsion Systems Containing Imidazolium Type Surfactant CnmimBr and Butyric Acid as Cosurfactant

The phase behavior and solubilization of two microemulsion systems 1-alkyl-3-methylimidazolium bromide (CnmimBr, n = 12,14,16)/butyric acid/hexane/brine (5% NaCl) and CnmimBr/1-butanol/hexane/brine (5% NaCl) were studied and compared. The physico-chemical parameters, such as the solubility (∊ B ) of the cosurfactant, the mass fraction of the cosurfactant in the interfacial layer (AS ), and the solubilization ability (SP*) of the two microemulsion systems were calculated and discussed. As the carbon chain length of CnmimBr molecules increases, SP* increases, and the difference of SP* values between the two microemulsion systems is reduced. The effects of aqueous and oleic phases and temperatures on the phase behavior and solubilization of C14mimBr/butyric acid/alkane/aqueous phase microemulsion systems were also discussed.