Reservoir oil interface with brine studied with real-component molecular model

Аннотация

This study presents a real-component molecular model for reservoir crude oil and investigates the interfacial tension (IFT) between the oil and brine using molecular dynamics simulations. The oil composition is characterized based on experimental data from the Yamburg oil field in Western Siberia, Russia. The model represents the oil as a mixture of aliphatic and aromatic compounds, with the alkane molecular weights (MW) following a gamma distribution and the aromatic content fraction increasing linearly with the alkane MW. Asphaltenes and methane are also included in the model. The simulations reveal several key findings on the factors influencing oil-brine IFT at reservoir conditions. Asphaltene presence strongly enhances the adsorption of aromatic compounds at the oil–water interface, amplifying the effect of aromaticity on IFT. Methane content increases IFT, with a more pronounced effect in the presence of asphaltenes. Pressure increase leads to IFT increase for oils with high methane and asphaltene content, while the pressure influence is negligible for deasphalted oil with low methane. The simulation results are used to develop a linear model that describes IFT dependence on temperature, pressure, gas content, and brine salinity. This work provides insights into the complex interplay between crude oil composition and reservoir conditions in determining interfacial properties, which is crucial for optimizing oil recovery strategies.