Abbas Heshmati - Chemical Engineering Dept., Isfahan University of Technology, Isfahan, Iran.
Seyed Foad Aghamiri - Chemical Engineering Dept., University of Isfahan, Isfahan, ۸۱۷۴۶-۷۳۴۴۱, Iran.
Shapoor Roodpeyma - Chemical Engineering Dept., Isfahan University of Technology, Isfahan, Iran.

A molecular thermodynamic model has been proposed for asphaltene precipitation under live oil conditions, at wide range pressure (up to reservoir’s pressures) and different solvent ratios. In this model a VLE and then SLE calculation is performed separately and sequentially. Asphaltenes are assumed to be a single psoudocomponent, heaviest fraction of C7+, which it is precipitated free of other components. A two variable Gamma function has been employed to characterize C7+ fraction. It is found that asphaltene's critical temperature (Tca) is an important parameter for asphaltene phase behavior prediction. A new correlation is presented to calculate critical temperature of asphaltenes. According to this correlation Tca can be well related to crude oil and added solvent properties.

asphaltene precipitation, thermodynamic model, solid-liquid equilibria