Geological structure and formation conditions of the Novoalekseevsky depression in relation to petroleum potential

UDK: 553.9: 550.8 (470.54/.56+57)

DOI: 10.24887/0028-2448-2025-6-16-23

Key words: Pre-Caspian depression, Pre-Ural trough, Ural fold system, Novoalexeevsky trough, seismic survey, reflecting horizon, structural, seismic stratigraphic analysis

Authors: A.A. Tkacheva (Geological Institute of the RAS, RF, Moscow); Yu.A. Volozh (Geological Institute of the RAS, RF, Moscow); S.F. Khafizov (Gubkin University, RF, Moscow); V.A. Schevyakov (Gubkin University, RF, Moscow)

The article presents the results of a seismic stratigraphic analysis of geological and geophysical data from the northeastern periphery of the Caspian Depression. Based on these findings, the geological structure of the Novoalexeyevskiy area within the Caspian oil and gas province was examined in detail. The study identified two distinct types of crust in the basement of the region which differ in consolidation age: ancient Archean–Early Proterozoic crust and younger Late Proterozoic (Riphean) crust, which is crucial for understanding the geodynamic evolution of the area. Six regionally traceable seismic stratigraphic complexes were distinguished within the sedimentary cover, each characterized by unique structural and formation features. Of particular note is the Ordovician–Silurian complex, the existence of which was previously debated. The research clarified the tectonic affinity of the area and established correlations with large-scale geodynamic events and the evolutionary history of the entire Caspian region. Paleogeographic settings and sedimentation conditions for the Riphean–Early Permian interval of sedimentary cover formation were substantiated. The obtained data indicate significant hydrocarbon potential in the Novoalexeyevsk area, previously underestimated in this regard. As a result, priority directions for further research were identified, opening new opportunities for hydrocarbon exploration along the Russian border with Kazakhstan.

References

1. Dzhamikeshov A.M., Kerimova I.K., Deep structure of the northeast Pricaspian basin pre-salt deposits (In Russ.), Georesursy, 2011, no. 1, pp. 38–41.

2. Zhanserkeeva A.A., Prospects of oil and gas potential of the junction zone of the north-east of the Precaspian basin and the southern segment of the Ural fold system (Aktobe Uralian foredeep) (In Russ.), Neft’ i gaz, 2022, no. 5, pp. 26–39, DOI: https://doi.org/10.37878/2708-0080/2022-5.02

3. Volozh Yu.A., Abukova L.A., Antipov M.P. et al., Geology and hydrocarbon potential of the subsalt deposits of the Astrakhan arch in the Caspian petroleum province: Results of comprehensive study (In Russ.), Geotektonika, 2024, no. 5, pp. 114–119, DOI: https://doi.org/10.31857/S0016853X20193323

4. Nevolin N.V., Tectonics of the Caspian Basin (In Russ.), Geologiya nefti i gaza, 1958, no. 9, pp. 4–11.

5. Antipov M.P., Bykadorov V.A., Volozh Yu.A. et al., Orenburgskiy tektonicheskiy uzel: geologicheskoe stroenie i neftegazonosnost’ (Orenburg tectonic knot: geological structure and oil and gas potential): edited by Volozh Yu.A., Parasyn V.S., Moscow: Nauchnyy mir Publ., 2013, 264 p.

6. Abilkhasimov Kh.B., Hydrocarbon potential of the Kobylandy-Tamdy upfold of the northern edge of Pricaspian basin (In Russ.), Vestnik neftegazovoy otrasli Kazakhstana, 2020, no. 1, pp. 4–18, DOI: https://doi.org/10.54859/kjogi95559

7. Slepakova G.I., Buried graben-like structures of the Caspian Basin (In Russ.), Geotektonika, 1983, no. 3, pp. 60–65.

8. Krylov N.D., Avrov V.P., Golubeva Z.V., Geological model of the subsalt complex of the Caspian depression and oil and gas potential (In Russ.), Geologiya nefti i gaza, 1994, no. 6, pp. 35–39.

9. Volozh Yu.A., Antipov M.P., Khafizov S.F., On the conditions of the Precaspian depression formation (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2024, no. 5, pp. 8–15, DOI: https://doi.org/10.24887/0028-2448-2024-5-8-15

10. Leonov Yu.G., Volozh Yu.A., Antipov M.P., Konsolidirovannaya kora Kaspiyskogo regiona: opyt rayonirovaniya (Consolidated crust of the Caspian region: zoning experience): edited by Leonov Yu.G., Moscow: GEOS Publ., 2010, 64 p.

11. Shlezinger A.E., Regional’naya seysmostratigrafiya (Regional seismic stratigraphy), Moscow: Nauchnyy mir Publ., 1998, 144 p.

12. Volozh Yu.A., Nekrasov G.E., Antipov M.P. et al., Novyy vzglyad na formirovanie konsolidirovannoy kory Prikaspiyskoy neftegazonosnoy provintsii (A new look at the formation of the consolidated crust of the Caspian oil and gas province), In: Tektonika i geodinamika Zemnoy kory i mantii: fundamental’nye problemy-2022 (Tectonics and geodynamics of the Earth’s crust and mantle: fundamental problems-2022), Materials of the LIII Tectonic Meeting, Moscow: GEOS Publ., 2022, pp. 114–119.

13. Zhukov I.M., Makarova S.P., Novitskiy Yu.V. et al., Ancient microaulacogens - new targets for oil and gas exploration (In Russ.), Geologiya nefti i gaza, 1990, no. 12,

pp. 2–4.

14. Politykina M.A., Tyurin A.M., Prospects for oil and gas potential of the Riphean-Lower Devonian deposits in the south of the Orenburg region (In Russ.), Geologiya nefti i gaza, 2002, no. 5, pp. 20–23.

15. Kan V.P., Deep structure of the Aktobe Urals and the adjacent zone of the Urals according to seismic data of the Common Point Method (In Russ.), Geologiya nefti i gaza, 1996, no. 7, pp. 39–44.