Experimental and mechanism study of asphaltene on formation and stabilization of oil-based foam

Stable foam will be generated in the separation equipment after pressure reduction of crude oil, which reduce the separation efficiency and damage the power equipment. It is found that the foam formed by asphaltene-rich crude oil is particularly stable in oilfield production, and the action mechanism of asphaltene for foam remains unclear. Hence, a self-made foaming device was performed to investigate the foamability and foam stability of oil-based foam, and the impact of asphaltene concentration and oil phase composition on foam properties was elucidated from the interfacial properties, viscosity, foam structure and the microstructure of asphaltene. Results show that low asphaltene concentrations promote foaming and mitigate the foam destruction. In contrast, high asphaltene concentrations are detrimental to foaming and reduce foam stability. The changes in interfacial properties and viscosity caused by asphaltene are not the main factors affecting foam performance. Besides, we proposed that asphaltene present in the oil phase as non-adsorbed particle, and the foam stability is influenced by the shape, volume fraction and size distribution of the particles. Furthermore, the boundary conditions for the effect of asphaltene on foam performance are innovatively put forward. This work contributes to understand the mechanism by which the asphaltene enhances foam stability and provides theoretical support for defoaming techniques in crude oil foam.