Microstructure of Heavy Oil Components and Mechanism of Influence on Viscosity of Heavy Oil

The composition of heavy oil is complex, and it is difficult to develop the heavy oil due to its high viscosity and poor fluidity. Therefore, it is very important to clarify the viscous mechanism of heavy oil. In this paper, typical ordinary heavy oil, extra heavy oil, and super heavy oil samples were selected to study the microstructure of heavy oil components and the mechanism of influence on viscosity of heavy oil. The molecular weight, element composition, and polarity of each SARA (short for Saturates, Aromatics, Resins and Asphaltene) component of heavy oil samples were measured and analyzed. The viscosity of heavy oil increases with the increase of the aggregate contents of resins and asphaltene. Resins and asphaltene in heavy oil have a high polarity, high heteroatomic content, and complex molecular structure, which are the key factors affecting the viscosity of heavy oil. On the basis of the experimental results, through simulation calculation and modeling, the microstructure and molecular formula of each component of different heavy oils are obtained, which provides a quantitative reference for revealing the viscosity mechanism of heavy oil. There is little difference in the elemental composition of resins and asphaltene, but the structure is very different and the difference in structure is the key factor leading to the difference in the properties of resins and asphaltene. The content and structure of resins and asphaltene in heavy oil are the key factors leading to the big difference in viscosity of heavy oils.