Asphalt Formation and Precipitation: Experimental Studies and Theoretical Modelling

Extensive new experimental data are presented for the amount of precipitated asphalt and asphaltene aggregates formed with crude oil and various precipitating agents, and their molecular weight (MW) distributions. A new scaling equation is proposed for predicting the onset and amount of the precipitates, which is similar to those encountered in aggregation phenomena. The scaling function takes on a very simple form, and its predictions are in very good agreement with the data. Small-angle X-ray and neutron scattering data are analyzed to delineate the structure of the asphalt and asphaltene aggregates. The analysis suggests that asphalt and asphaltene aggregates are fractal structures with welldefined fractal properties. The mechanisms that give rise to such fractal aggregates are identified, based on which a new analytical equation for the MW distribution of asphalt and asphaltene aggregates is proposed which provides accurate predictions for the data.