The Modified Yen Model

Asphaltenes, the most aromatic of the heaviest components of crude oil, are critical to all aspects of petroleum use, including production, transportation, refining, upgrading, and heavy-end use in paving and coating materials. As such, efficiency in these diverse disciplines mandates proper chemical accounting of structure−function relations of crude oils and asphaltenes, the vision of petroleomics (Asphaltenes, Heavy Oils and Petroleomics; Mullins, O. C., Sheu, E. Y., Hammami, A., Marshall, A. G., Eds.; Springer: New York, 2007). Indeed, the molecular characterization of asphaltenes is required as well as the detailed understanding of the hierarchical colloidal structures of asphaltenes and petroleum. With great prescience, Professor Teh Fu Yen and co-workers proposed a hierarchical model of asphaltenes to account for many of their characteristics known at that time (Dickie, J. P.; Yen, T. F. Macrostrucutres of asphaltic fractions by various instrumental methods. Anal. Chem. 1967, 39, 1847−1852). This model is rightfully known as the Yen model. Nevertheless, at the time the Yen model was formulated, there were many order-of-magnitude uncertainties in asphaltene science that precluded establishing structure−function relations and causality, thereby rendering the Yen model somewhat phenomenological. Petroleum science has advanced greatly in recent years enabling development of a much more specific model yet still based on precepts of the Yen model; we call this the “modified Yen model”. The modified Yen model is shown to account for wide ranging, myriad properties of asphaltenes, including their dynamics. In addition, the modified Yen model has even proven successful for understanding interfacial phenomena involving asphaltenes. Moreover, the modified Yen model accounts for fundamental observations in oil reservoirs and is now propelling significantly improved efficiency in oil production. The modified Yen model is a simple, yet powerful construct that provides the foundation to test future developments in asphaltene and petroleum science; refinement of the modified Yen model is an expected outcome of this process.