Predicting Asphaltene Precipitation by Simple Algorithm Using Solubility Parameter Calculated Based on Peng-Robinson Equation of State

Asphaltene precipitation is frequently the cause of increased cost of oil production in the petroleum industry. To avoid or minimize problems due to asphaltene precipitation, a model to predict the amount of asphaltene precipitation under the petroleum reservoir conditions is required. In this study, the Flory-Huggins solution theory with a correctly tuned equation of state for calculation of the solubility parameter of liquid oil and a second order polynomial equation for variations of asphaltene solubility with pressure were applied to model asphaltene precipitation. The advantage of this model is that expensive and time consuming experiments are not required to obtain the asphaltene and liquid oil solubility parameters. Routine pressure/volume/temperature (PVT) tests and the amount of asphaltene precipitated at the bubble point pressure are sufficient. Data generated by the model were compared to the experimental asphaltene precipitation data on two live oils under reservoir conditions, showing that the model could accurately represent the behavior of asphaltene precipitation in the reservoir.