Study on the effect and mechanism of temperature and shear on the stability of water-in-oil emulsion stabilized by asphaltenes

As a complex component of crude oil, asphaltenes determine the stability of emulsion. However, the mechanism of asphaltenes stabilize emulsion is still insufficient recognition due to the complexity of the molecular structure of asphaltenes. In this paper, the experiments and dissipative particle dynamics simulations were used to study the interfacial properties of asphaltenes. The adsorption of asphaltenes at the oil-water interface was studied by interfacial tension (IFT) experiments. A realistic molecular structure of asphaltene was constructed on the results of the characterization of the asphaltenes. The effects of asphaltenes concentration, temperature, and shear on the formation and stability of emulsion based on this molecular structure were investigated by simulations. The results show that the IFT decreases as asphaltenes concentration increases, while the droplet size of the emulsion decreases and becomes more uniformly distributed. Increasing the temperature enhances the interfacial activity of the asphaltenes, but also promotes its dissolution in the oil phase, which has a negative effect on reducing the IFT value and the stability of the emulsion. As the shear rate increases, the configuration of the emulsion changes from droplets to ellipsoids and rods, and the structure of the interfacial film is disrupted. This work provides useful insights into the mechanisms of asphaltenes concentration, temperature, and shear on the stability of the emulsion.