Typification of oils in Volga-Urals Petroleum Province has attracted the attention of researchers for many decades; however, a unified concept for the formation of hydrocarbon accumulations has not yet been developed. Both abiogenic and biogenic ideas of hydrocarbon accumulation are currently proposed. The authors discuss geochemistry of oils of South Tatarsky Arch (Republic of Bashkortostan). Differences between oils from the Koivensky-Takatinsky, Vorobyevsky, and Ardatovsky horizons and oils from the overlying formations are demonstrated. Two oil types are identified, they are: a vanadium-bearing sulphur-rich Domanik type and a predominantly nickel-bearing low-sulphur pre-Domanik type. The Domanik-type oil is the most common; it is pervasive and occurs throughout the Devonian Pashiisky, Timansky, and Domanik horizons, the Famennian Stage, the Lower Carboniferous Tournaisian and Visean stages, and the Lower Permian Asselian-Sakmarian stages. The pre-Domanik oil type is more mature compared to the Domanik one. Contribution of carbonates to the composition of pre-Domanik-type source rocks was probably significantly lower than in the case of the Domanik-type. Mixed-type oils were identified in the Devonian Ardatovsky, Pashiisky, and Timansky horizons of the central part of the South Tatarsky Arch. In terms of density, sulphur content, and trace-element composition (vanadium and nickel), these oils occupy an intermediate position between the Domanik and pre-Domanik oil types.

Aleksei A. Mitin ORCiD
Chief specialist
Branch of RN-GIR LLC in the city of Ufa – BashNIPIneft,
86/1, ul. Lenina, Ufa, 450064, Russia
e-mail: mitin2016@yandex.ru
AuthorID: 1219757

Rim K. Masagutov   ORCiD
Doctor of Geological and Mineralogical Sciences
Academy of Sciences Republic of Bashkortostan,
15, ul. Kirova, Ufa, 450008, Russia
e-mail: masagutovr@mail.ru
AuthorID: 881611

Elena A. Yaropolova   ORCiD
Candidate of Chemical Sciences
e-mail: yaropolovaEA@yandex.ru

1. Kontorovich A.E., Danilova V.P., Kostyreva E.A. et al. Source rock formations of Western Siberia: old and new perception of the problem. Organicheskaya geokhimiya nefteproizvodyashchikh porod Zapadnoi Sibiri: Tez. dokl. nauch. soveshch., Novosibirsk, 12–14 October, 1999. – Novosibirsk : Izd-vo SO RAN. pp. 10–12.
2. Sobornov K.O. Riphean Depocenters and Origin of Oil Deposits of the Romashkinskoye and Yaregskoye Fields. Georesursy = Georesources. 2025;27(1):35–50. DOI: 10.18599/grs.2025.1.10.
3. Chikhirin A.A., Shostak A.V. Lateral migration of hydrocarbons in terms of oil content of the terrigenous devonian section in the Kama region Nedropol’zovanie. 2022;22(3):116–125. DOI: 10.15593/2712-8008/2022.3.3.
4. Muslimov R.Kh. An in-depth study of the crystalline basement of sedimentary basins is a dictate of the time. Georesursy = Georesources. 2019;21(4):55–62. DOI: 10.18599/grs.2019.4.55-62. In Russ.
5. Kazantsev Yu.V., Kazantseva T.T. Vozmozhnost’ popolneniya zapasov uglevodorodnogo syr’ya v starykh mestorozhdeniyakh v svete seismotektonicheskikh issledovanii [The possibility of replenishing hydrocarbon reserves in old deposits in the light of seismotectonic studies]. Geologicheskii sbornik. 2007;(6):74–76.
6. Lozin E.V. Glubinnoe stroenie i neftegazonosnost’ Volgo-Ural’skoi oblasti i smezhnykh territorii []. Litosfera. 2002;(3):46–68.
7. Galimov Eh.M., Kamaleeva A.I. Source of hydrocarbons in the supergiant Romashkino oilfield (Tatarstan): Recharge from the crystalline basement or source sediments? Geochemistry International. 2015;53(2):103–122. DOI: 10.1134/S0016702915020032. In Russ.
8. Egorova N.P., Khalimov Eh.M., Ozolin B.V. et al. Zakonomernosti razmeshcheniya i usloviya formirovaniya zalezhei nefti i gaza Volgo-Ural’skoi oblasti [Regularities of placement and conditions of formation of oil and gas deposits in the Volga-Ural region. V. IV. Bashkir ASSR]. Moscow: Nedra, 1973. 293 p. In Russ.
9. Kiseleva Yu.A., Zheglova T.P., Dakhnova M.V., Mozhegova S.V., Nazarova E.S., Nechitailo G.S. The role of domanik deposits in the formation of oil pools in the central areas of the volga-ural petroleum province (Buzuluk depression). Russian geology and geophysics. 2017;58(3–4):384–397.
10. Kiseleva Yu.A., Mozhegova S.V. Genetic groups and sources of oils in the central part of the Volga-Urals petroleum province. Neftegazovaya geologiya. Teoriya i praktika. 2012;7(3). Available at: http://www.ngtp.ru/rub/1/36_2012.pdf (accessed 12.01.2026). In Russ.
11. Romanov A.G., Morozov O.N., Giruts M.V., Tikhomirov V.I., Gordadze G.N. Typification of samara oblast oils by hydrocarbon biomarkers. Neftekhimiya. 2010;50(6):424–430. DOI: 10.1134/S0965544110060022.
12. Orlova A.Yu., Poludetkina E.N. Geokhimiya neftei i organicheskogo veshchestva domanikovykh otlozhenii Yuzhno-Tatarskogo svoda [Oils geochemistry and Domanik formation organic matter of the South Tatar arch]. Neftegazovaya geologiya. Teoriya i praktika. 2023;18(1). Available at: http://www.ngtp.ru/rub/2023/11_2023.html (accessed 09.01.2026).
13. Smirnov M.B, Fadeeva N.P., Vanyukova N.A. Differentiation of oils in tatarstan based on the composition of saturated biomarkers. Geokhimiya. 2021;66(5):436–449. DOI: 10.1134/S0016702921050074.
14. Kozhevnikova E.E., Bashkova S.E., Yakovlev Yu.A. Formation of the oil and gas potential of the emsian-nizhnefrancian deposits in the north of the volga-ural oil and gas province. Geologiya, geofizika i razrabotka neftyanykh i gazovykh mestorozhdenii. 2024;392(8):5–19.
15. Kozhanov D.D., Bolshakova M.A., Khopta I.S. The role of proterozoic sediments in the formation of oil and gas content in the northern part of the Volga-Ural oil and gas basin (based on the results of basin modeling). Georesursy = Georesources. 2022;24(2):113–128. DOI: 10.18599/grs.2022.2.12. In Russ.
16. Masagutov R.Kh., Ilemenova O.D., Minkaev V.N. Geologiya i geokhimiya domanikovykh fatsii yugo-vostoka Volgo-Ural’skoi provintsii (na primere Bashkirskogo Priural’ya) [Geology and geochemistry of domanic facies in the South-east of the Volga-Ural province (on the example of the Bashkir Urals region)]. Ufa : Gilem, 2019. 160 p.
17. Mitin A.A., Masagutov R.Kh., Yaropolova E.A. Genetic typing of oils of the moscovian stage and underlying sediments in the northwest of platform. Vestnik Akademii nauk Respubliki Bashkortostan. 2023;(4):40–49. DOI: 10.24412/1728-5283-2023-4-40-49.
18. Erdman J.G., Morris D.A. Geochemical correlation of petroleum. AAPG Bull., 1974;58(11):2326–2337.
19. Dakhnova M.V. Use of geochemical investigations in exploration, assessment and development of hydrocarbon fields. Geologiya nefti i gaza. 2007;(2):81–89.
20. Peters К.E., Walters C.C., Мoldowan J.М. The Biomarker Guide: Biomarkers and isotopes in petroleum systems and Earth History. Cambridge University Press, UK, 2005. V. 2. 1155 p.
21. Walters C.C., Isaksen G.H., Peters K.E. Applications of Light Hydrocarbon Molecular and Isotopic Compositions in Oil and Gas Exploration. Analytical Advances for Hydrocarbon Research, 2003. pp. 247–266.
22. Vinogradova T.L., Chakhmakhchev V.A., Agafonova Z.A., Yakubson Z.V. Hydrocarbon and heteroatomic compounds as indices of thermal maturity of organic matter of rocks and naphthydes. Geologiya nefti i gaza. 2001;(6):49–55.
23. Chakhmakhchev V.A. Geokhimiya protsessa migratsii uglevodorodnykh system [Geochemistry of the migration process of hydrocarbon systems]. Moscow: Nedra, 1983. 231 p.