New Colloidal Stability Index for Crude Oils Based on Polarity of Crude Oil Components

In the oil industry, colloidal stability indices based only on the crude oil composition are used to evaluate asphaltene stability. However, as shown in the literature, such indices are unable to correctly determine the behavior of asphaltenes in crude oils. In this study, the dipole moments of the model structures of asphaltene molecules were calculated, and it was found that asphaltenes from unstable crude oils are more polar than those from stable crude oils. Thus, asphaltene precipitation and deposition depend on the polarity of asphaltenes. On the basis of obtained results, a new colloidal stability index for crude oils is proposed. It takes into account both the crude oil composition and the polarity of crude oil components. Using sixteen crude oils as an example, it was shown that the new index is capable of predicting asphaltene precipitation.