The mechanistic investigation on the effect of the crude oil /brine interaction on the interface properties: A study on asphaltene structure

• The Asphaltene molecular Structure was determined by ATR and EDAX analysis. • the Asphaltene adsorption rate at the interface highly depends on the brine salinity. • compaction of the Asphaltene molecules Structure significantly affects the adsorption behavior of the Asphaltene. • The concentration of Asphaltene fraction in the crude oil has a key role in fluid–fluid interaction. • Asphaltene molecules accumulate at the oil-brine interface and perform the Asphaltene-ion-bound with the dissolved ions. Despite many attempts to study the interaction of fluids in low-salinity flooding, they do not examine the principles of interphasic transition phenomena. This study aims to provide a new understanding of liquid–liquid interactions during the low-salinity water interaction through a series of experiments on the oil, emulsion, and aqueous phase. Three samples of crude oils with different asphaltene concentrations and structures with known physical properties are in contact with different solutions. The brine pH, conductivity, and crude oil viscosity experiments before and after contacting the oil with brine showed that the heteroatom concentration and compaction of crude oil asphaltene fraction and the brine salinity affect the rate of the migration of crude oil polar component toward the interface. Moreover, the IFT measurement illustrated that interface interactions are affected by several parameters such as dissolved ion type, the concentration of the brine, and the concentration of the polar components in crude oil. The solubility of crude oil polar species such as naphthenic acids in the brine does not always increase by decreasing the salinity of the aqueous phase. To verify this important finding, UV–Vis spectroscopy and FTIR were performed on the brine and crude oils before and after in contact with each other.