Objective To study the interfacial activity between crude oil components and surfactants, the crude oil components were separated, and their interfacial tension and characteristic structure composition were analyzed.

Methods The crude oil components were separated by preparative liquid chromatography. The variation tendency of interfacial tension between different components of crude oil and anionic surfactant such as sulfonate, and zwitterionic surfactant such as betaine was investigated. The main structure characters of different crude oil components were analyzed and compared based on gas chromatography-mass spectrometry.

Results Using hydrophobic reversed-phase chromatographic packing and mobile-phase gradient elution, crude oil can be separated into six different components with obvious differences of structure by preparative chromatography. When using the heavy alkylbenzene sulfonate as the surfactant, four components without aromatic hydrocarbon can obtain ultralow interfacial tension(< 1.0×10^-3 mN/m), one component with a small amount of aromatic hydrocarbon was close to ultralow interfacial tension (~1.0×10^-3 mN/m). When using sulfobetaine 12 (S-12) as the surfactant, one component rich in aromatic hydrocarbon can obtain ultralow interfacial tension(< 1.0×10^-3 mN/m).

Conclusions The structure types of surfactants are different, and the crude oil components corresponding to ultra-low interfacial tension are also different. The interfacial activity relationship between crude oil components and surfactants is complicated.