Novel insights into the effects of asphaltenes on oil phase properties: Crude oil, oil-water interface, and graphene oxide synergistic demulsification

Abstract

In this work, quantum chemical calculations and molecular dynamics simulations were employed to investigate the aggregation structure of asphaltene (a key component in heavy oil) and the influence of its molecular structure and content on the viscosity of heavy oil. Research suggests that the C5Pe molecules have a strong potential to bind together through π-π interactions (face-to-face). The angle between the two plane normal vectors was 1.4°. The mechanism of asphaltene-oil phase assembly can be succinctly summarized as the “rebar-cement” mode of action. The viscosity of heavy oil increases with the increase of asphaltenes, which can be attributed to the more complete construction of the three-dimensional network structure of asphaltene with the increase of asphaltene mass fraction (especially exceeding 35 wt%). The steered molecular dynamics simulation confirmed that reducing the concentration of asphaltenes in emulsified heavy oil droplets leads to increased susceptibility to mechanical destruction. This observation implies that asphaltenes negatively impact the demulsification and viscosity reduction of crude oil. The findings in this work can contribute to the development of efficient strategies for viscosity control and enhanced production of heavy oil resources.