ORGANIC MATTER OF THE MIDDLE DEVONIAN-LOWER FRANSIAN DEPOSITS OF THE IZHMA-PECHORA BASIN BASED ON PYROLYTIC AND COAL PETROGRAPHIC STUDIES
D.A. Bushnev1, N.S. Burdelnaya1, N.V. Pronina2, O.S. Kotik1, P.V. Trushkov3
1Institute of Geology of Komi Scientific Center of the Ural Branch of the Russian Academy of Sciences, Syktyvkar, Russia
2Lomonosov Moscow State University, Moscow, Russia
3RN-Geology Research Development LLC, Tomsk, Russia
Keywords: highly paraffinic organic matter, Middle Devonian-Lower Frasnian oil and gas-bearing terrigenous complex, Timan-Pechora oil and gas province, coal petrography, pyrolytic studies, hydrocarbon potential
Abstract
The Middle Devonian-Lower Frasnian terrigenous complex of the Izhma-Pechora Depression of the Timan-Pechora petroleum province contains rocks with very good, good, and fair hydrocarbon potential. This article presents the results of organic petrography analysis of rock organic matter, including VRo determination, pyrolytic studies using pyr-GC and pyr-GC/MS, IR spectroscopy analysis, and a study of the kinetics of hydrocarbon formation using the Rock-Eval method and individual C1-C5 gases in stepwise pyrolysis. The main groups of hydrocarbon-generating macerals in the rocks are alginite and liptinite, represented by sporinite. The kinetic characteristics and chemical structure of the fossil organic matter resemble type I kerogen, despite the relatively low hydrogen index (HI) and the results of organic petrography studies. The organic matter of the rocks of the Middle Devonian-Lower Frasnian deposits is enriched in n-alkyl structures and realizes its hydrocarbon potential in the form of highly paraffinic oil at relatively high stages of thermal evolution, with EASY%Ro/EASY%RoDL values of about 1.2%.
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