Prediction of Asphaltene precipitation from live-oils

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.

Keywords:

asphaltene precipitation , thermodynamic model , solid-liquid equilibria