Date of Award
Doctor of Philosophy (PhD)
Chemistry and Biochemistry
John R. Donat
Lesley H. Greene
Oil shale is a promising source of hydrocarbon fuel that is distributed throughout the world. The petroleum generating potential of oil shale is related to the molecular structure of the organic matter in source rock. The major fraction of organic matter of oil shale is termed kerogen, and due to its insolubility in organic solvents, 13C solid-state nuclear magnetic resonance (NMR) spectroscopy is one of the best ways to directly measure the insoluble organic matter without changing its chemical structures. This dissertation investigated oil shale samples using advanced solid-state 13C NMR spectroscopy techniques and high resolution magic angle spinning (HRMAS) NMR spectroscopy, and studied bitumen samples extracted from oil shales using liquid-state NMR spectroscopy. Quantitative 13C solid-state NMR spectra were generated for 22 shale samples and their percentages of different carbon moieties were integrated and aromaticities were calculated. Aromaticity was considered as a supplemental indicator of the thermal maturity and hydrocarbon generating potential of the oil shale. By investigating quantitative structural characteristics of three shales with extreme heteroatom contents, we found out that he high oxygen content in organic matter in the Kukersite shale sample indicated more non-protonated aromatic carbons, which were substituted with oxygen. An improved structural model of Kukersite kerogen was constructed based on one from literature and refined using our spectral data. The high organic sulfur content in the organic matter present in the Jordanian Ghareb shale sample was mostly contributed to the high aromaticity of the organic matter in the sample. The Glen Davis shale sample contained organic matter with a relatively low total heteroatom content and produced comparatively simpler spectra due to the presence of few oxygen-containing functional groups. A comparative study showed that Kimmeridge and Phosphoria formation had similar solid-state 13C NMR spectra from shale, kerogen, and extracted rock samples, and they exhibited almost the same signals in liquid-state 2D 1H-13C HSQC spectra from bitumen samples, indicating their similar structural characteristics, in spite of their differences in geologic age and depositional location. By examining shales samples with advanced solid-state 13C NMR, quantitative data can be obtained and could be used for constructing more reliable kerogen structural models and for predicting petroleum generating potential.
"Structural Characterization of Organic Matter in Oil Shales Using Multiple Nuclear Magnetic Resonance Spectroscopic Techniques"
(2020). Doctor of Philosophy (PhD), Dissertation, Chemistry and Biochemistry, Old Dominion University, DOI: 10.25777/1bq4-6j64