Modeling Asphaltene Phase Behavior in Crude Oil Systems Using the Perturbed Chain Form of the Statistical Associating Fluid Theory (PC-SAFT) Equation of State

Asphaltene precipitation and deposition can occur at different stages during petroleum production, causing reservoir formation damage and plugging of pipeline and production equipment. Predicting asphaltene flow assurance issues requires the ability to model the phase behavior of asphaltenes as a function of the temperature, pressure, and composition. In this paper, we briefly review some recent approaches to model asphaltene phase behavior. We also present a method to characterize crude oil, including asphaltenes using the perturbed chain form of the statistical associating fluid theory (PC-SAFT). The theory accurately predicts the crude oil bubble point and density as well as asphaltene precipitation conditions. The theory is used to examine the effects of gas injection, oil-based mud contamination, and asphaltene polydispersity on the phase behavior of asphaltenes. The analysis produces some interesting insights into field and laboratory observations of asphaltene phase behavior.