Characterization of Macromolecular Structure Elements from a Green River Oil Shale, I. Extracts

This paper is the first of two associated papers describing the structural details of three sections of an oil shale core taken at the Skyline 16 mine in the Utah Uinta Basin. Bitumen was extracted from the shale using methanol/dichloromethane. Kerogen was isolated from the shale, using a nine-step extraction procedure using HCl and HF. Bitumen samples from the three cores were analyzed using high-resolution 13C NMR liquid-state spectroscopy, showing carbon aromaticities of 7%–11%. Aliphatic carbons were dominated by methylene structures, with average aliphatic chain lengths of 24 carbons. The three parent shales and the demineralized kerogens were each analyzed with solid-state 13C NMR spectroscopy. Analysis of the carbon structure in the shale was hindered by the large amount of carbonates and ferri/ferro magnetic material present, but the organic structure of the shale was shown to be almost identical to the structure of the demineralized kerogen. Carbon aromaticity of the kerogen was 23%–24%, with 10–12 aromatic carbons per cluster and estimated molecular weights of 776–946, side chain molecular weights of 131–148, and side chain lengths of 11–13 carbons.