To estimate reserves and optimize the development of hard-to-recover hydrocarbons from Middle-Upper Jurassic deposits reliable information on the ownership of the reservoir to certain strtonum is necessary. The question of the dismemberment of the hydrocarbon deposits Naunak and Tyumen suite in the South-East of Western Siberia is still controversial.
Material for study is based on samples from core 7 wells: No. 1, 2, 5 (Dvoinoye field) and No. 446, 170, 430, 301 (Snezhnoye field). The relevance of research is caused by necessity of using the results to update the geological model, calculation of the declared reserves of hydrocarbons and to optimize development of the hard deposits on the Dvoinoye and Snezhnoye fields. Guide fossils for the Tyumen suite (Tomsk phyto-horizon) are the ferns (Coniopteris vialovae, Raphaelia diamensis); czekanowskiales (Czekanowskia irkutensis, Cz. rigida, and Phoenicopsis mogutchevae); equisetaceous plants (Equisetites lateralis). The guiding forms for Naunak suite (Naunak phyto-horizon) in the studied wells are czekanowskiales Czekanowskia tomskiensis. Productive deposits of the Tyumen suite are characterized by a high degree of heterogeneity, lithological variability, with predominance of more interlayers of mixed breeds (are sandstones are mudstones). According to hydrolysate module values Tyumen suite is composed of continental sediments with the participation of products redeposition weathering and Naunak suite, with a reduced value of the modulus is composed of terrigenous rocks with the participation of volcanic-clastic material. Titanium module values show that Tyumen suite formed in the semi-arid climate. On the background of the prevailing semi-arid conditions at the end of the middle Jurassic era in the study area there were episodes of humidity.
An integrated lithogeochemical, biostratigraphic and facies studies allowed to carry out the dismemberment of the Middle-Upper Jurassic sediments in the studied sections and to clarify the boundary between Naunak and Tyumen suite, as well as to separate deposits of different genesis: the inland waterways (Tyumen suite) and coastal plains, occasionally flooded by sea.
References
1. Shurygin B.N., Nikitenko B.L., Devyatov V.P. et al., Stratigrafiya neftegazonosnykh basseynov Sibiri. Yurskaya sistema (Stratigraphy of oil and gas bearing basins of Siberia. Jurassic system), Novosibirsk: Publ. of SB RAS, 2000, 480 p.
2. Perevertailo T., Nedolivko N., Dolgaya T., Vasyugan horizon structure features within junction zone of Ust-Tym depression and Parabel megaswell (Tomsk Oblast), URL: http://dx.doi.org/10.1088/1755-1315/24/1/012023.
3. Resheniya 6-go Mezhvedomstvennogo stratigraficheskogo soveshchaniya po rassmotreniyu i prinyatiyu utochnennykh stratigraficheskikh skhem mezozoyskikh otlozheniy Zapadnoy Sibiri (Decisions of the 6th Interdepartmental Stratigraphic Meeting to Review and Adopt Refined Stratigraphic Schemes of Mesozoic Deposits in Western Siberia), Novosibirsk, 2004, 114 p.
4. Kirichkova A.I., Kostina E.I., Bystritskaya L.I., Fitostratigrafiya i flora yurskikh otlozheniy Zapadnoy Sibiri (Phytostratigraphy and flora of the Jurassic sediments of Western Siberia), St Petersburg: Nedra Publ., 2005, 378 p.
5. Alekseev V.P., Litologo-fatsial’nyy analiz (Lithofacies analysis), Ekaterinburg: Publ. of Ural State Mining University, 2003, 147 p.
6. Shaminova M., Rychkova I., Sterzhanova U., Paleogeographic and litho-facies formation conditions of MidUpper Jurassic sediments in S-E Western Siberia (Tomsk Oblast), URL: http://dx.doi.org-10.1088-1755-1315-43-1-012001.pdf.
7. Interpretatsiya geokhimicheskikh dannykh (Interpretation of geochemical data): edited by Sklyarov E.V., Moscow: Intermet Inzhiniring Publ., Part 1, 2001, 288 p.
8. Yudovich Ya.E., Osnovy litokhimii (Fundamentals of lithochemistry), St Petersburg: Nauka Publ., 2000, 479 p.
9. Yudovich Ya.E., Ketris M.P., Geokhimicheskie indikatory litogeneza (Geochemical indicators of lithogenesis), Syktyvkar: Geoprint Publ., 2011, 740 p.
10. Maslov A.V., Osadochnye porody: metody izucheniya i interpretatsii poluchennykh dannykh (Sedimentary rocks: methods for studying and interpreting received data), Ekaterinburg: Publ. of USMU, 2005, 289 p.
11. Gol’bert A.V., Markova L.G., Polyakova I.D. et al., Paleolandshafty Zapadnoy Sibiri v yure, melu i paleogene (Paleolandscapes of Western Siberia in the Jurassic, Cretaceous and Paleogene), Moscow: Nauka Publ., 1968, 152 p.
12. Shaminova M., Rychkova I., Sterzhanova U., Dolgaya T., Lithologo-facial, geochemical and sequence-stratigraphic sedimentation in Naunak suite (south-east Western Siberia), URL: http://iopscience.iop.org/article/10.1088/1755-1315/21/1/012001/pdf.