Aspects of Interaction of Surfactant—Acid Compositions at Phase Boundary with Hydrocarbons

Most part of all additives to technological fluids for acid treatments of oil-extracting wells are surfactants. One of approaches to assess the behavior of surfactants in these compositions is to determine the interfacial tension of their solutions at the interface with hydrocarbons. The interfacial tension of surfactant—acid compositions based on hydrochloric and sulfamic acids and also on distilled water without addition of acids. The interfacial tension was determined at the boundary with n-octane, kerosene, and oil with different polarities and contents of natural surfactants. It was shown that n-octane and kerosene are model systems that allow conditional comparison in activity between surfactants. A dependence was found of the interfacial tension of a surfactant—acid formulations on the nature of an acid: sulfamic acid affects the activity of surfactants positively, and hydrochloric acid, negatively. The interfacial tension parameter being determined is strongly affected by the type of a surfactant. It was shown that the nonionogenic surfactant Neonol AF 9–12 shows the smallest values of the interfacial tension in the formulations based on distilled water, and the anionic surfactant Nezhegol, in acid formulations, which is due to the interaction of the functional group of a surfactant with hydroxonium ions present in solution.