Ul'nyrov I.L.

ulnyrov_iv@mail.ru

Graduated from the State University (2017), specialization "geologist".
Junior Researcher of the Institute of Geology of Komi Science Centre of the Ural Branch of the Russian Academy of Sciences, Syktyvkar.
Area of scientific interests: geology of oil and gas, lithology, carbonate rocks, reservoir rocks.
Author of 17 publications.
Stratigraphy and lithology
Article # 26_2025 submitted on 04/29/2025 displayed on website on 07/24/2025
44 p.
pdf The role of epigenesis in the formation of the Lower Devonian carbonate reservoir of the Gamburtsev swell (Timan-Pechora petroleum province)
Based on lithological and mineralogical studies and the distribution features of C, O isotopes and Sr, Ba, F elements in the carbonate strata of the Lower Devonian reservoir of the swell, the main epigenetic processes in the rocks were determined, the conditions of their occurrence were characterized, and conceptual models of epigenesis that satisfy these conditions were proposed. The studies demonstrate a significant contribution to the formation of the modern appearance and properties of rocks by the processes of dolomitization, sulfatization, dedolomitization, karstification, etc. To model the results of these processes in the Lower Devonian strata of the Gamburtsev Swell (Varandey-Adzva structural-tectonic zone), it is proposed to use reaction-transport models of reflux dolomitization, hydrothermal dolomitization, and models of diagenesis by meteoric and other reaction fluids unsaturated with carbonates.

Keywords: carbonate and carbonate-sulfate rocks, Lower Devonian reservoir, epigenetic processes, C and O isotopes, Sr, Ba, F microelements, epigenesis model, Gamburtsev Swell, Varandey-Adzva structural-tectonic zone, Timan-Pechora oil and gas province.
article citation Maydl' T.V., Ul'nyrov I.L., Nechaev M.S. Rol' epigeneza v formirovanii nizhnedevonskogo karbonatnogo rezervuara vala Gamburtseva (Timano-Pechorskaya neftegazonosnaya provintsiya) [The role of epigenesis in the formation of the Lower Devonian carbonate reservoir of the Gamburtsev swell (Timan-Pechora petroleum province)]. Neftegazovaya Geologiya. Teoriya I Praktika, 2025, vol. 20, no. 3, available at: https://www.ngtp.ru/rub/2025/26_2025.html EDN: IQFVGP
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Regional petroleum geology
Article # 22_2024 submitted on 06/21/2024 displayed on website on 08/22/2024
21 p.
pdf The influence of the reservoir brines composition on epigenetic changes in the Upper Silurian-Lower Devonian carbonate rocks of the Gambutsev swell (Timan-Pechora petroleum province)
The results of a comprehensive interpretation of lithological and geochemical studies of core material and modeling of geochemical interaction processes in the formation water-rock system for Lower Paleozoic productive strata of the Gamburtsev swell Varandey-Adzva tectonic zone are presented. The effects of sodium chloride brines on carbonate, sulfate-carbonate rocks are discussed for the first time. The calculations of the degree of saturation of waters in relation to carbonate and sulfate minerals and their comparison with the epigenetic mineralization of rocks allowed us to identify the main processes contributing to the formation of neo-minerals in the Lower Paleozoic reservoir. As a result, new data were obtained that contribute to a more accurate prediction of the reservoir properties of rocks of the Lower Paleozoic carbonate strata in the north-east of the Timan-Pechora petroleum province.

Keywords: carbonate rock, sulfate-carbonate rock, reservoir sodium chloride brines, epigenetic change, Gamburtsev swell, Varandey-Adzva tectonic zone, Timan-Pechora petroleum province.
article citation Maydl' T.V., Mityusheva T.P., Ul'nyrov I.L., Nechaev M.S. Vliyanie sostava plastovykh rassolov na epigeneticheskie izmeneniya verkhnesiluriysko-nizhnedevonskikh karbonatnykh porod vala Gamburtseva (Timano-Pechorskaya neftegazonosnaya provintsiya) [The influence of the reservoir brines composition on epigenetic changes in the Upper Silurian-Lower Devonian carbonate rocks of the Gambutsev swell (Timan-Pechora petroleum province)]. Neftegazovaya Geologiya. Teoriya I Praktika, 2024, vol. 19, no. 3, available at: https://www.ngtp.ru/rub/2024/22_2024.html EDN: BOOZTS
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Stratigraphy and lithology
Article # 15_2024 submitted on 04/10/2024 displayed on website on 05/29/2024
21 p.
pdf The characteristics of boundary strata of the pre-Greben regional unconformity from Upper Silurian of the Chernov Swell (Sizimselebeyshor creek) according to the conodonts chronostatigraphy
Upper Silurian conodonts from the outcrop of the Sizimselebeishor Creek were studied for the first time. A sequence of four associations conodonts of different taxonomic structure has been established throughout the boundary of the pre-Greben regional unconformity in the Sizimselebeyshor Creek. Association 1 with the dominant regional species Ctenognathodus (?) sp. A is dated below the surface of the unconformity. Association 2 with Ozarkodina confluence (Branson et Mehl, 1933), Oz. cornidentata Viira, 1983 and Coryssognathus dubius (Rhodes, 1953) was fixed in section, which directly underlying the unconformity. Association 3 with Panderodus equicostatus (Rhodes, 1953) and Wurmiella excavata (Branson et Mehl, 1933) was established directly overlapping the discordance. Both borderland associations 2 and 3 are represented by species of wide geographical and long-term stratigraphic distribution. Association 4 with species Zieglerodina cf. ivochlupaci Carls, Slavik, Valenzuella-Rios, 2007 and Oz. denticulata Viira, 2000 Pridoly age is dated above the pre-Greben unconformity also.
An auxiliary biostratigraphic division - layers with Ctenognathodus (?) sp. A of Gerdyu time (Ludlow) was identified as a result of correlation the studied interval with the boundary strata of Gerdyu regional stage (Ludlow) and Greben regional stage (Pridoli) of the reference section of the Kozhym River of the western slope of the Subpolar Urals. The layers are characterized by the joint presence of conodonts Ctenognathodus (?) sp. A and Ozarkodina confluens (Branson et Mehl, 1933), zonal brachiopod species Didymothiris didyma (Dalman, 1828) and the development of stromatolites interlayers.

Keywords: conodonts, Upper Silurian, Gerdyu regional stage, Greben regional stage, pre-Greben regional unconformity, Sizimselebeyshor Creek, Chernov Swell.
article citation Sokolova L.V., Dan'shchikova I.I., Ul'nyrov I.L. Kharakteristika po konodontam pogranichnykh otlozheniy predgrebenskogo nesoglasiya v verkhnem silure podnyatiya Chernova (ruchey Sizimtselebeyshor) [The characteristics of boundary strata of the pre-Greben regional unconformity from Upper Silurian of the Chernov Swell (Sizimselebeyshor creek) according to the conodonts chronostatigraphy]. Neftegazovaya Geologiya. Teoriya I Praktika, 2024, vol. 19, no. 2, available at: https://www.ngtp.ru/rub/2024/15_2024.html EDN: UJJBXO
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Stratigraphy and lithology
Article # 26_2023 submitted on 05/19/2023 displayed on website on 08/01/2023
36 p.
pdf Sedimentation conditions, petrography and formation of reservoir rocks of the Upper Silurian Carbonate strata of the Cherpayu area on the Gamburtsev Swell (Timan-Pechora petroleum province)
This article presents the results of studies of poorly investigated Upper Silurian carbonate strata of the Gamburtsev Swell using the Cherpayu area as an example. Methods of lithofacies analysis, scanning electron microscopy, data of petrophysical and geophysical studies of wells were used. In the Upper Silurian strata, nine microfacies types have been identified that characterize four facies’ zones: 1) littoral and flooded coast, 2) shelf lagoon, 3) shallow-water shelf zone, and 4) shallow sublittoral open shelf environments. Reconstruction of Late Silurian sedimentation showed that sediments accumulation in the Ludlowian time occurred mainly in the accumulative silty littoral conditions, and in the Pridolian time, in the conditions of the shallows on the open sea basin, where carbonate sands and small bioherms accumulated.
Five petrotypes of reservoir rocks have been identified, differing in structural (crystal size) and petrophysical (porosity and permeability) properties. The best properties of porosity and permeability are found in dolomites with a grain size of 20-100 µm, with a shady microbial clot structure, which is characteristic of “algae laminites” (petrotypes 1 and 2). Voidness is cavity-porous-fracture with a predominance of secondary leaching voids. A successive series of important stages in the reservoirs formation of the Upper Silurian in the Cherpayu area of the Gamburtsev Swell was identified: 1) the stage of sedimentation and diagenesis, which ensured primary voidness; 2) the stage of the Middle Devonian structural transformation and the regional pre-Upper Devonian hiatus, which is associated with the formation of surface (epigene) karst, which is not currently functioning, and 3) the stages of the Ural and Pay-Khoy tectonic phases, which ensured the activation of ascending fluid flows and the development of localized and diffusely manifested porosity deep hypogene karst.

Keywords: Carbonate Upper Silurian sedimentation, formation reservoir rocks, Cherpayu area, Gamburtsev Swell, Timan-Pechora petroleum province.
article citation Ul'nyrov I.L., Maydl' T.V. Litologiya, usloviya osadkonakopleniya i formirovanie porod-kollektorov verkhnesiluriyskikh karbonatnykh otlozheniy vala Gamburtseva (Timano-Pechorskaya neftegazonosnaya provintsiya) [Sedimentation conditions, petrography and formation of reservoir rocks of the Upper Silurian Carbonate strata of the Cherpayu area on the Gamburtsev Swell (Timan-Pechora petroleum province)]. Neftegazovaya Geologiya. Teoriya I Praktika, 2023, vol. 18, no. 3, available at: http://www.ngtp.ru/rub/2023/26_2023.html EDN: ZQRFWL
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