MACERAL COMPOSITIONS OF MIDDLE AND UPPER JURASSIC COALS IN THE SOUTHEAST OF THE WEST SIBERIAN MEGABASIN
А.N. Fomin. G.A. Lobova
1Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Novosibirsk, Russia, e-mail: fominan@ipgg.sbras.ru
2Tomsk Polytechnic University, Tomsk, Russia, e- mail: lobovaga@tpu.ru
Keywords: Western Siberia, Tyumen Formation and Vasyugan Formation, maceral composition of coals, formation conditions.
Abstract
The maceral composition of borehole coal cores from the Tyumen and Vasyugan Formations in the southeastern West Siberian megabasin (Tomsk and Novosibirsk regions) was determined using reflected light microscopy. We have identified and described the groups, classes, subclasses, types, and subtypes, with the most typical macerals photographed and their percentage shares determined from some samples. The maceral compositions are shown to be largely identical in the studied coals of the Tyumen and Vasyugan Formations. The revealed variations in the maceral groups for these formations are as follows (%): vitrinite - 27-100 (averaging 77); inertinite - 0-73 (18); liptinite - 0-33 (8) for the Tyumen Formation, and vitrinite - 52-100 (averaging 82); inertinite - 0-44 (14); liptinite - 0-48 (12) for the Vasyugan Fm (%), thus suggesting a close similarity in the facies conditions of the formation of their coals. The higher plant inputs — lignocellulose tissues, and more rarely, lipid components — served as their source material. In this regard, Upper and Middle Jurassic coals have been extremely underexplored within this area.Analysis of the maceral composition of coals, along with lithological studies, contribute to understanding the facies conditions of the formation of coal-bearing strata. These data may also be useful for petroleum producers in developing hydrocarbon deposits for efficient underground coal gasification, to alleviate the tight supply of natural gas.
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