An Integrated Model for Asphaltene Deposition in Oil Well Column Simulation

In this study, an innovative approach is presented for modeling asphaltene deposition in the well column. The presented model predicts the time, location and amount of asphaltene deposited in the well column as a function of well, fluid and reservoir properties. The model is formulated based on thermodynamic equilibrium, heat transfer, mass transfer and empirical multi-phase flow equations. Asphaltene-containing oil is sampled from an oil well suffering from periodic deposition problems. The thermodynamic behavior of the oil and depositional characteristics of asphaltene have been determined via laboratory experiments and modeled accordingly using the Peng-Robinson equation of state and the modified solid model, respectively. The pressure profile in the well column was determined based on Duns and Ross two-phase flow model. The temperature profile in the well column has been determined based on a developed model derived from field measurements. Fluid flow and heat transfer equations have been solved simultaneously based on pressure and temperature profiles in the well column. The Escobedo-and-Mansoori model which has been used for mass transfer calculations was used to evaluate the rate of asphaltene deposition onto the wellbore at various depths. The simulated and reported field values of wellhead pressure and temperature were used for evaluation of model predictions. The model had over 95.5% and 99.1% accuracy in predicting the wellhead pressure and temperature, respectively, in a time window of over three months in the studied well.