F-31 SARA Crude Oil Characterization: A Critical Review
The refining industry has long sought to understand how the chemistry of crude oil relates to fouling. Crude oil is composed of thousands of chemical species, so identifying and quantifying each of them individually would be impractical. Instead, different laboratory techniques are used to group species with similar chemical characteristics into a minimum number of pseudo-components. One of the most common methods used in the oil industry is SARA analysis, the separation and quantification of crude oil into four pseudo-components, namely saturates, aromatics, resins, and asphaltenes. However, each fraction possesses widely different properties, and relative amounts can vary dramatically from one crude to another. Moreover, because crude oil is a continuum of molecular sizes and structures, nuances in the methods used to fractionate and quantify these pseudo-components can produce significantly different results. These issues make comparison and use of results from different methods challenging. This report explains these challenges in detail with supporting data, as well as SARA analysis results for HTRI crude oils. Alternative methods for crude oil characterization are also described.