LOCI OF GENERATION OF BAZHENOV- AND TOGUR-TYPE OILS IN THE SOUTHERN NYUROL'KA MEGADEPRESSION
V.I. Isaev and A.N. Fomin*
Tomsk Polytechnical University, 30 ul. Lenina, Tomsk, 634050, Russia
* Institute of Petroleum Geology and Geophysics, Siberian Branch of the RAS,
3 prosp. Akad. Koptyuga, Novosibirsk 630090, Russia
Keywords: Dispersed organic matter, Bazhenov-type oil, Togur-type oil, thermodynamic model for sedimentary section, locus and time of oil generation, deep heat flow, paleocryolithozone, Nyurol'ka depression, Tomsk Region
Pages: 731-743
Abstract
The dispersed organic matter of the Bazhenov Formation and Togur Member was correlated with the Bazhenov- and Togur-type oils in the southern Nyurol'ka megadepression, the Tomsk Region. On the basis of lithostratigraphic columns, data of testing and sampling of nineteen prospecting-exploratory boreholes, and vitrinite reflectance, the Mesozoic-Cenozoic sedimentary section was mathematically simulated in the form of a 3D-2D thermal model. According to the temperature zoning of oil and gas formation in the Bazhenov and Tyumen' Formations, loci of oil generation were established and the time of their joining the major zone of oil formation was determined. The locus of generation of the Bazhenov-type oils appeared at 32-24 Ma. In plan, it coincides with local folds in the Upper Jurassic sediments of the Igol'sk-Talovaya uplift, Karai-Aisaz trough, and northwestern Aisaz bank. The locus of generation of the Togur-type oils originated at 24 Ma and is associated with the Karai fold and local uplifts of the Karai-Aisaz trough. The possible effect of nonstationary deep heat flow, Pleistocene-Holocene cryogenic processes, and Miocene erosion on the forecast model for oil generation loci has been quantitatively estimated.
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