The effect of aromatic solvents on the onset and amount of asphaltene precipitation at reservoir conditions: Experimental and modeling studies

High-pressure filtration and standard IP-143 were employed to determine the amount of precipitated asphaltene for a live oil sample and its mixtures with toluene and p-xylene. To find the upper AOP of each mixture, the obtained precipitations curves were extrapolated. PC-SAFE and solid model were used to predict the effects of several aromatic solvents on the onset and amount of asphaltene precipitation. Both models were tuned to the experimental amount of precipitated asphaltenes in the original oil and AOP of the oil mixed with toluene. The results of this study suggest that PC-SAFT can reasonably predict the effects of aromatic solvents on the asphaltene phase behavior. The accuracy of PC-SAFT predictions was not greatly affected by the concentration and type of solvent. While solid model gave good predictions of the precipitated asphaltene for one mixture with low concentration of toluene, the prediction accuracy dropped with solvent concentration and change of solvent. Whereas PC-SAFT showed a positive correlation between the dissolving power and solubility parameter of aromatic solvents, no general correlation between these two parameters was predicted by solid model. Both models, nonetheless, predicted an almost linear relationship between the upper AOP and solvent concentration, consistent with experimental results. (C) 2016 Elsevier B.V. All rights reserved.