Distribution of Saturates, Aromatics, Resins, and Asphaltenes Fractions in the Bituminous Layer of Athabasca Oil Sands

The composition and distribution of saturates, aromatics, resins, and asphaltenes (SARA) fractions in the bituminous layer on the surface of Athabasca oil sands were identified using elemental analysis (EA), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (SEM) with an energy-dispersive spectrometer (EDS), and Fourier transform infrared spectrometry (FTIR). The contents of elements sulfur (S) and nitrogen (N) and the ratios of carbon/sulfur (C/S) and carbon/nitrogen (C/N) were characterized as potential indicators for evaluating the distribution of SARA fractions in the bituminous layer. Results indicated that saturates and aromatics tend to deposit at the outer bituminous layer, while asphaltenes and resins were inclined to distribute at the inner layer. Results also suggested that the distribution of SARA fractions was thermodynamically dependent and susceptible to thermal treatment. On the basis of the experimental results, a conceptual distribution model was proposed, which is supposed to serve as a basis for future studies on the liberation of bitumen from oil sands and the operation conditions for oil sands processing.