Experimental investigation and thermodynamic modeling of asphaltene precipitation

Asphaltene precipitation may occur during pressure depletion or gas injection processes in a reservoir. This phenomenon is an important problem during oil production, because it can result in formation damage and the plugging of wellbore and surface facilities. In this work, the precipitation of asphaltenes in an Iranian crude oil, under different pressures, is measured, using an experimental set up based on high-pressure isothermal expansion and also atmospheric titration. For the particular oil investigated, compositional data, precipitation phase diagrams, and bubble point and onset pressures are reported. Also, in this work, the Perturbed Chain form of the Statistical Associating Fluid Theory (PC-SAFT), the Solid model and the Flory-Huggins model are used, to correlate onset pressures and solvent ratios at the onset point of precipitation for different solvents. The results show that the PC-SAFT EOS correlates more accurately with the experimental results over a wide composition interval.