INFLUENCE OF ASPHALTENES AND RESINS CONTENT ON HEAVY OIL RHEOLOGY

摘要

Because of very large reserves, heavy oils are considered as a strategic and relevant source of hydrocarbons. Anyhow, their production faces the problem of their very high viscosity. The success of the exploitation of these petroleum products requires new treatments to improve their transport. Such a target implies to better understand the relationship between the composition of heavy oils and their flow properties. The influence of asphaltenes content in the crude has been particularly studied in our lab : the experimental work revealed the existence of a critical concentration C~* above which the asphaltenes entangle. This structural change dramatically increases the viscosity and intensifies the elastic character of heavy crude oils. A further series of experiments has focused on the influence of resins : they show that in dilute regime (CC~*) they lower the asphaltenes effect on viscosity. Experiments were first carried out in organic solvents with asphaltenes and nonylphenol as a model of resins and followed by experimental work on real crude that confirmed the trends. With this study, we have shown that to understand the rheological behavior of a heavy crude oil in relation with its internal structure, asphaltenes and resins have to be simultaneously considered.