Understanding the polydisperse behavior of asphaltenes during precipitation

Asphaltenes are a polydisperse fraction of the crude oil, the phase behavior of which is significantly affected by the changes in pressure, temperature and composition. The focus of this study is to model the polydisperse asphaltenes’ precipitation onset condition and the amount of precipitate from solvent-diluted crude oils using the Perturbed Chain form of the Statistical Associating Fluid Theory (PC-SAFT) over a wide range of crude oil density. Heavy oil and bitumen production can involve diluting with paraffinic solvents. Different fractions of the polydisperse asphaltenes thus precipitated are predicted and when compared to the experimental data show a remarkable matching for different solvents. A comparison of monodisperse and polydisperse modeling is also performed. This work illustrates the successful application of PC-SAFT for predicting the phase behavior of polydisperse asphaltenes and in particular from heavy oil and bitumen.