Geological structure and detailed correlation of Osinsky horizon sediments at the central part of Nepsky arch of Eastern Siberia Part 2. Detailed correlation and basic distribution patterns of productive reservoirs in the Osinsky horizon

UDK: 550.8:553.98

DOI: 10.24887/0028-2448-2025-9-14-19

Key words: Eastern Siberia, Nepsky arch, Osinsky horizon, natural radioactivity, detailed correlation, core studies, cavernous-porous reservoir, tectonic fracturing

Authors: E.A. Romashev (Tyumen Branch of SurgutNIPIneft, Surgutneftegas PJSC, RF, Tyumen); R.V. Malkosh (Tyumen Branch of SurgutNIPIneft, Surgutneftegas PJSC, RF, Tyumen); M.A. Shubina (Tyumen Branch of SurgutNIPIneft, Surgutneftegas PJSC, RF, Tyumen); M.G. Lebedeva (Tyumen Branch of SurgutNIPIneft, Surgutneftegas PJSC, RF, Tyumen); S.Y. Ageichenko (Tyumen Branch of SurgutNIPIneft, Surgutneftegas PJSC, RF, Tyumen); E.A. Kondakov (Tyumen Branch of SurgutNIPIneft, Surgutneftegas PJSC, RF, Tyumen)

The article reflects the experience of studying carbonate deposits of the Osinsky productive horizon (O-1, B1 formation) within several areas located in the central part of the Nepa-Peleduy arch of the Nepa-Botuoba anteclise, which are the main resource base of Surgutneftegas PJSC in the territory of the Republic of Sakha (Yakutia). In the course of the research, a large amount of factual material was studied, including exploration and production data, transit drilling, core studies, the results of interpretation of 3D-seismic data, as well as the analysis of the main indicators of the development of hydrocarbon deposits of the O-1 formation. The second part of the article presents the results of a detailed correlation of the Osinsky horizon, as well as the main factors influencing the formation of reservoir rocks with increased filtration and capacitance properties. In the section of O-1 formation, four cyclic sequences were identified. It was established that in the central and northern parts of the studied area, the organogenic buildup of the Osinsky horizon developed in two stages, which led to the formation of two intervals of the reservoir layers separated by a package of low-permeability rocks and acting as independent targets for development. The combined influence of sedimentation heterogeneity of rocks and subsequent epigenetic processes - dolomitization, recrystallization, and selective leaching determines the development of high-capacity pore space in the reservoirs of the Osinsky horizon. The best reservoir properties are found in secondary dolomites of organogenic buildups, in which inherited cavernous-porous void space is formed.

References

1. Milovanova E.V., Postnikova O.V., Kitaeva I.A., Mechanism of formation of increased natural radioactivity of deposits of the Osinskiy horizon in the south of the Siberian platform (In Russ.), Trudy RGU nefti i gaza (NIU) imeni I.M. Gubkina, 2020, no. 2(299), pp. 16-27, DOI: https://doi.org/10.33285/2073-9028-2020-2(299)-16-27

2. Gubina E.A., Vinokurova O.A., Belomestnykh A.A., Quantitative assessment of bitumen content in oil deposits of the Osinsky productive horizon of Eastern Siberia (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2024, no. 1, pp. 42-46, DOI: https://doi.org/10.24887/0028-2448-2024-1-42-4

3. Gurova T.I., Chernova L.S., Potlova M.M. et al., Litologiya i usloviya formirovaniya rezervuarov nefti i gaza Sibirskoy platformy (Mingeo SSSR, SibNPO po geologo-razvedochnym rabotam) (Lithology and conditions of formation of oil and gas reservoirs of the Siberian platform (Mingeo of the USSR, SibNPO for geological exploration)), Moscow: Nedra Publ., 1988, 254 p.

4. Nikulina M.Yu., Nikulin E.V., Luk'yanov V.V. et al., Prospects for searching for oil and gas deposits in the Osinsky pay zone in the territory of Nepa-Botuoba anteclise of Eastern Siberia (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2023, no. 9, pp. 85-89, DOI: http://doi.org/10.24887/0028-2448-2023-9-85-89

5. Kuznetsov V.G., Ilyukhin L.N., Postnikova O.V. et al., Karbonatnye tolshchi Vostochnoy Sibiri i ikh neftegazonosnost' (Carbonate strata of Eastern Siberia and their oil and gas potential), Moscow: Nauchnyy mir Publ., 2000, 104 p.

6. Malkosh R.V., Romashev E.A., Lebedeva M.G., Ageychenko S.Yu., The studying of fracturing of O-1 layer of the Osinsky productive formation deposits of the central part of Nepa arch of Eastern Siberia (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2024, no. 3, pp. 35-40, DOI: https://doi.org/10.24887/0028-2448-2024-3-35-40