Relative compatibility index for evaluation of the compatibility of crude oil blends

Abstract

A new relative compatibility index is proposed to evaluate the compatibility of blends of crude oils. The approach considers the calculation of solvent power of individual crude oil and their blends, the critical solvent power for blends of crude oils with required amount of n-heptane when precipitation of asphaltenes begins, and a graphical comparison of both parameters (solvent power and critical solvent power) to determine the maximum proportion of crude oils in the blend to avoid incompatibility problems. The proposed method requires experimental data that are commonly available, such as specific gravity, TBP (True Boiling Point) distillation, and S-value (fuels stability determination according ASTM D 7157). Eight crude oils with a wide range of API (American Petroleum Institute) gravity (10–52°) were used to validate the method. It was demonstrated that the proposed approach accurately predicts the compatibility of blends of crude oils, and that relative compatibility index is an effective parameter to define appropriate amounts of crude oils to avoid asphaltenes precipitation during blending.