Revisiting Asphaltene Precipitation from Crude Oils: A Case of Neglected Kinetic Effects

The precipitation of asphaltenes from crude oils can lead to serious challenges during oil production and processing. This research investigates the kinetics of asphaltene precipitation from crude oils using n-alkane precipitant. For several decades, it has been understood that the precipitation of asphaltenes is a solubility-driven phenomenon, and the previous studies on the effect of time are usually limited to short time scales. By using optical microscopy and centrifugation-based separation, we have demonstrated that the time required to precipitate asphaltenes can actually vary from a few minutes to several months, depending on the precipitant concentration used. Our results demonstrate that no single concentration can be identified as the critical precipitant concentration for asphaltene precipitation. On the basis of long-term experiments, we have also been able to establish the solubility of asphaltenes as a function of the precipitant concentration, and it is shown that the short-tern) experiments overpredict the Solubility. Similarities between the current work and other research areas are also discussed briefly, This research opens up a new paradigm for understanding asphaltene precipitation.