A Solution Model for Predicting Asphaltene Precipitation

Formation of asphaltene deposition during oil production, processing and synthesis is known as a fundamental problem of petroleum reservoir worldwide. Asphaltene is a petroleum fraction that can lead to increasing the operating costs in these industries. Variations in operational pressure, temperature and fluid composition are generally the significant cause of asphaltene precipitation. In this study, a regular solution model with liquid-liquid equilibrium criteria between asphaltene-rich phase and solvent-rich phase (maltene phase) is presented in order to calculate asphaltene precipitation. As a result, to achieve this objective, the Flory-Huggins (F-H) theory is applied and the definition of the interaction parameter in the traditional form of F-H model is modified. In this work, an empirical correlation is adapted using regular solution theory to predict the solubility parameters and eventually the DE (Differential Evolution) optimization strategy is applied to calculate optimum values of the justifiable parameters in the model. The results of the developed model are finally compared with the existing asphaltene precipitation data in various solvent ratios from the literature and it is shown that they are in acceptable agreement with the experimental data. Hence, the proposed model is capable of good prediction of asphaltene precipitation in a widespread range of the solvent ratios.