Influence of interactions between asphaltenes on heavy oil rheology:

application to the dilution with selected solvents

I. Henaut, J-F. Argillier

Institut Français du Petrole, France

Heavy crude oils represent a strategic source of hydrocarbons and give rise to many experimental works dedicated to decrease their viscosity. Their main chemical characteristic is their high asphaltene content. We have shown that these petroleum macromolecules mainly contribute to the high viscosity of heavy oils thanks to a fractal organization. This description was established using SAXS and rheology. The rheological characterization enabled to determine the interaction parameter k' corresponding to the Huggins theory, usually applied to polymers. This parameter allows to quantify the attractive interactions between asphaltenes in different conditions and various organic solvents. It was shown that the strength of the interactions between asphaltenes strongly depends on solvent quality, particularly its polarity. Relationship between the action of polar solvent on asphaltenes and macroscopic effect on dilution efficiency will be discussed. This kind of experiments enables to better select the solvent to be used to dilute heavy crude oils.