Oil & Gas Geology ›› 2004, Vol. 25 ›› Issue (4): 377-384.doi: 10.11743/ogg20040404

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Possible chemical constitutions and original biological materials of various vitrinites in coal measure strata

Liu Dayong, Peng Ping'an   

  1. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, Guangdong
  • Received:2004-05-15 Online:2004-08-25 Published:2012-01-16

Abstract:

Chemical constitutions of vitrinites in Jurassic coal measures in eastern Junggar basin and Turpan-Hami basin,and Permo-Carboniferous coal measures in Ordos basin,are studied through solid-state 13C NMR and transient pyrolysis-GC/MS. The aliphatic carbons in Jurassic hydrogen-rich desmocollinites have relatively high proportion of methylene carbon(-CH2-),and the proportion of aliphatic hydrocarbons in pyrolysis products are relatively high. Being compared with desmocollinites, although the Jurassic telocollinites are also hydrogen-rich, their aliphatic carbons have even higher proportion of methyl(-CH3),methine(-CH-) and quaternary carbon, and their pyrolysis products are mainly phenols and alkylbenzenes, with more branched substitiuents but shorter chain length. Though the Permo-Carboniferous vitrinites in Ordos basin are mostly composed of desmocollinites, they contain a relatively small proportion of aliphatic carbons, and most of which are gas-prone carbons. The pyrolysis products are mainly phenols and aromatic hydrocarbons, thus they are typical gas source rocks. With similar maturities, the structures of vitrinites are determined by sedimentary environments and original bilological materials. Ultramicroliptinites might have contributed to the relatively high constitutions of long chain aliphatic hydrocarbons in hydrogen-rich vitrinites in eastern Junggar and Turpan-Hami basins. Based on comparison with pyrolysis products of phycoplast,cutinites, sporinites and suberinite, and in combination with other evidences, it is believed that exinites of higher plants are more likely to be the main components of Ultramicroliptinites.

Key words: vitrinite, solid 13C NMR, pyrolysis, chemical structure, parent material of hydrocarbons

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