A Comparative Study of Different Quality Oil Shales Developed in the Middle Jurassic Shimengou Formation, Yuqia Area, Northern Qaidam Basin, China

Yueyue Bai, Zhaojun Liu, Simon C. George and Jingyao Meng
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Yueyue Bai: SinoProbe Center-China Deep Exploration Center, Chinese Academy of Geological Sciences, Beijing 100037, China
Zhaojun Liu: Key-Laboratory for Oil Shale and Coexisting Minerals Mineralization & Exploration and Exploitation, Jilin University, Changchun 130061, China
Simon C. George: School of Natural Sciences, Macquarie University, Sydney, NSW 2109, Australia
Jingyao Meng: Geology and Mineral Resource Program, Virginia Department of Energy, Charlottesville, VA 22903, USA

Energies, 2022, vol. 15, issue 3, 1-23

Abstract: Oil shales are developed in the Shale Member of the Middle Jurassic Shimengou Formation in the Qaidam Basin, China. The oil shales can be classified into three quality groups (low-, medium-, and high-quality oil shales) through a comprehensive analysis protocol that includes Rock-Eval pyrolysis, total organic carbon (TOC) content, proximate analysis, gas chromatography-mass spectrometry (GC-MS), X-ray diffraction (XRD), major and trace element analyses, and maceral analysis. The low-quality oil shales mainly contain type II 1 kerogen, the medium-quality oil shales mainly contain type I-II 1 kerogen, and the high-quality oil shales mainly contain type I kerogen. All are immature to early thermally mature. The oil yield of the oil shales is directly related to their quality and are positively correlated with TOC content and calorific value. All studied samples were deposited under anaerobic conditions but in different paleoenvironments. The low-quality oil shales were mainly deposited in fresh-water environments, whereas the high-quality oil shales were usually developed in highly saline and reducing environments. Salinity stratification and evidence of algal blooms that are conducive to organic matter enrichment were identified in both medium- and high-quality oil shales, the latter having the highest paleoproductivity and the best preservation conditions. In summary, shale quality is controlled by a combination of factors, including algal abundance, preservation conditions, the existence of algal blooms and salinity stratification, and paleoproductivity. This study reveals how these different factors affect the quality of oil shales, which might provide an in-depth explanation for the formation process of lacustrine oil shales.

Keywords: oil shale quality; organic matter enrichment; preservation conditions; Middle Jurassic; Qaidam Basin (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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