Abstract <p>The paper investigates the effects of the salinity and pH of an aqueous phase, as well as the influence of asphaltene content in crude oil, on emulsification—specifically on the formation of an interfacial layer and the stability of emulsion. The oil–water interfacial tension, water droplet size, and emulsion stability were characterized using the bottle test method. The oil–distilled water interfacial tension in emulsions varies widely. Compared to distilled water, emulsions with high-salinity reservoir waters are distinguished by high stability and a lower interfacial tension. Asphaltenes that are concentrated in the interfacial layer of an emulsion with high-salinity reservoir water have a higher molecular weight than asphaltenes of crude oils and of emulsions with distilled water. Elemental analysis and IR spectroscopy show an increase in sulfur content in asphaltenes adsorbing at the oil–distilled water interface, and an increase in oxygen content in asphaltenes from emulsion with high-salinity-waters.</p>