Experimental investigation of different characteristics of crude oil on the interfacial activity of anionic, cationic and nonionic surfactants mixtures

Abstract

The current study investigates the synergistic/antagonistic effect of cationic (octyl pyridinium chloride [C8Py][Cl]), anionic (sodium lauryl sulfate (SLS)), and nonionic (octyl phenol ethoxylate (Triton-X100)) surfactants on the interfacial tension (IFT) reduction. The performance of the mixture of surfactants in the presence of different electrolytes on the IFT values of five crude oil samples are evaluated. To better understand the molecular interaction between surfactant solutions and oil samples, the important parameters such as °API, total acid and base numbers, asphaltene and resin weight percent, resin to asphaltene ratio, weight percent of oxygen, nitrogen and sulfur elements, and aromaticity of asphaltene and resin fractions are thoroughly examined. It is found that the synergistic effect between crude oil and surfactant solutions depends on the crude oil and surfactant types and salinity of brine. In this way, the mixture of anionic-cationic had the best results with an IFT value lower 0.1 mN/m. Although no specific trend was observed for the effect of oil type on the IFT of mixtures, the results showed that the ionic strength and surfactant type had a more dominant effect than the oil type. The mechanisms of IFT reduction for each binary mixture are also thoroughly discussed.