Study on the Interactive Effects of Solid Particles and Asphaltenes on the Interfacial Structure and Stability of a Water-in-Model Oil Emulsion.

Asphaltenes and solid particles are common compositions in crude oil emulsions. They can be anchored at the oil/water interface, exerting significant effects on the strength of an interfacial layer. In this study, the interactive effects of the asphaltenes and solid particles on the interfacial structure are investigated. First, the solid particles and asphaltenes are proven to perform different roles in stabilizing the emulsion by influencing the strength of the interfacial layer with the change in asphaltene concentration. Subsequently, the competitive coadsorption process of the asphaltenes and particles is examined by measuring the dynamic interfacial tension. The adsorption of particles could occupy the interfacial area, postponing the adsorption of asphaltenes. The crumpling ratio of the interfacial layer formed by the asphaltenes and solid particles indicates that the composite layer should be more flexible with a higher compressibility compared to that formed by only asphaltenes. It is observed by SEM that the binary layer possesses a composite structure with the particles as the framework and the asphaltenes as the filling. The interactive mechanism between the asphaltenes and particles should lie in the adsorption of the asphaltenes on the particles. Systematic experiments on the contact angle, adsorbed amount, and desorption percentage reveal that asphaltenes could adsorb on the surface of the particles, modifying the wettability. The change in asphaltene concentration will result in the varying wettability modification due to asphaltene adsorption on the particles, leading to the different adsorption abilities and barrier effects of the modified particles at the interface.