Heavy oils and bitumens may be considered to be composed of chemical constitutive molecules belonging to two distinct categories, namely, the malthenes (soluble in 40 volumes of n-pentane) and the asphaltenes (soluble in toluene but insoluble in n-pentane).
The spatial organization of malthenes and asphaltenes leads to the macrostructural and microstructural properties of which viscosity is of paramount importance for production, transportation and processing considerations. Such spatial organization causes an increase in viscosity with an increase in asphaltene concentration. Hence the high viscosity of Athabasca bitumen is, at least. partly due to its high asphaltene content (>15 wt.%). Experimental results suggest that viscosity depends not only on asphaltene concentration but also on the molecular weight of the asphaltenes. For example, higher molecular weight asphaltene units have greater tendencies to form aggregates of larger sizes, and therefore, provide greater resistance to flow. The process of aggregate formation is a complex one and is not well understood. However, this process can be reversed by breaking up the aggregates with the application of energy in the form of high shear or heat. We have examined the effect of ultrasonic energy on the viscosity of Athabasca bitumen and its mixtures with other solvents and solutions via break up of asphaltene aggregates. In this paper, we report the results of our experimental work.
|Number of pages||4|
|Journal||Journal of Canadian Petroleum Technology|
|Publication status||Published - May 1993|