Characterization of Uinta Basin oil sand bitumens

Abstract

Results of the analyses of the saturate and monoaromatic fractions of four Uinta Basin bitumens (southwest Whiterocks, northwest Whiterocks, Asphalt Ridge and Sunnyside) are presented in this paper. After separating the bitumen samples into several fractions using solvent extraction and elution chromatography, peak-by-peak analysis was performed on the saturate and monoaromatic fractions using GC-MS. The saturated compounds were predominantly polycyclic naphthenes, while the monoaromatics were mostly naphthenoaromatics. Samples from all of the deposits contained a significant number of compounds in the carbon-number range C{sub 27}--C{sub 30} due to the presence of steranes and hopanes. Carbon number and Z-number distributions were produced using sorting and quantitation procedures developed in this project. Although the four samples were believed to be of common origin and maturity, significant differences in carbon-number distributions and chemical-type distributions were shown to exist. Even two samples from the same deposit (Whiterocks) exhibited significant differences. Relative abundances of steranes and of hopanes with a carbon number greater than C{sub 30} were used as measures of the relative degree of biodegradation of the samples. It was found that biodegradation increased as follows: southwest Whiterocks < northwest Whiterocks < Asphalt Ridge < Sunnyside.