Lithology, facies and dynamics of formation of the albian-cenomanian reservoir rocks of the Pokuttya-Bukovyna part of the Carpathian autochthon

https://doi.org/10.23939/jgd2023.01.037
Received: April 19, 2023
1
Institute of Geology and Geochemistry of Combustible Minerals of National Ukrainian Academy of Sciences
2
Institute of Geology and Geochemistry of Combustible Minerals of National Ukrainian Academy of Sciences

The purpose of this work is to study the Upper Albian-Lower Cenomanian psammitic complex of the platform basement of the Pokuttya-Bukovyna part of the Carpathian Foredeep, which is one of the main reservoir strata of the Lopushna oil field. Methodology. The complex of investigations includes correlation of the well-log data, lithological studies of core material, mineralogical and petrographic analysis of rocks, and paleogeographic studies of the sedimentary basin. Results. On the basis of the analysis of all existing wells, it was established that the deposits of the Late Albian-Early Cenomanian age within the entire territory of the autochthon of the Pokuttya-Bukovyna Carpathians are mostly represented by sandstones. They are composed of quartz (50-80%), feldspar (1–5%), muscovite (0.1-3%), pyrite (0.1-3%) and accessory minerals – zircon and epidote. A significant part of sandstone is composed of the authigenic minerals – glauconite (10-15%, sometimes up to 45%) and phosphate (1–3 up to 10%). The matrix in the rocks is mainly porous and contact-porous (10-15% of the rock volume), which provides these psammites with good reservoir properties. On the basis of paleogeographic reconstructions, it was established that in the Late Albian-Early Cenomanian, terrigenous sedimentation prevailed within the entire shelf basin of the Carpathian branch of the Meso-Tethys, which caused the accumulation of the thick sandstones’ strata. The burial history and post-sedimentary evolution of rocks took place under the influence of the thrusting of the Carpathian Fold Belt. This resulted in the formation of reservoir rocks and traps in the Upper Albian-Lower Cenomanian sequence. The peculiarities of hydrocarbon migration in the studied region indicate a high probability of discovering new deposits in the autochthon of the Pokuttya-Bukovyna Carpathians. Originality. The applied complex of lithological, geological-geophysical and paleogeographical studies made it possible to investigate the features of distribution of the Albian-Cenomanian psammite complex of rocks, both laterally and in section, their mineralogical and petrographic characteristics, sedimentary environments. The post-sedimentary evolution of the study strata and features of hydrocarbon migration were caused by the dynamics of the Carpathian Flysch Belt thrusting over the margin of the East-European platform. Practical significance. The obtained results show that the Upper Albian-Lower Cenomanian sandstones, which are oil and gas-bearing in the Lopushna field, represent the potential reservoirs in terms of both thickness and mineral composition within the entire autochthon of the Pokuttya-Bukovyna Carpathians. Since the Pokuttya fault could serve as a migration path for the hydrocarbons from the Carpathian flysch sequence into the platform basement strata, there is a high probability of the discovery of new accumulations in the structures similar to the Lopushna, revealed by seismic studies in the autochthon of the Pokuttya-Bukovyna Carpathians.

  1. Gavrylyshyn, V. I. (1998). Stratigraphy of Mesozoic platform sediments of the Ukrainian Carpathians subthrust. Geology and geochemistry of combustible fossils, 3, 81-90.
  2. Dulub, V. G. (1965). On the Lower Cretaceous age of the Stavchany Formation. Paleontological collection, 2(2), 113-115.
  3. Fedyshyn, V. O. (Chief editor) (1998). Atlas of oil and gas fields of Ukraine: Volume IV. Western oil and gas region. Lviv: Center of Europe, 328 p.
  4. Havenzon, I. V., Pylypyshyn, B. V., Gnevush, O. S. Huk, I. V., & Denys, M. V. (2011). Prognosis of oil- and gas-bearing of the Lopushna oil field using the technique of seismolithmological analysis. Geodynamics, 2(11), 317-319. https://doi.org/10.23939/jgd2011.02.317
  5. Koltun, Y., Espitalie, J., Kotarba, M., Roure, F., Ellouz, N., & Kosakovski, P. (1998). Petroleum generation in the Ukrainian External Carpathians and the adjacent foreland. Journal of Petroleum Geology, 21(3), 265-288.  https://doi.org/10.1111/j.1747-5457.1998.tb00782.x
  6. Kotarba, М., Więcław, D., Bilkiewicz, E., Radkovets, N., Koltun, Y., Kmiecik, N., Romanowski, T., & Kowalski, A. (2019).  Origin of oil and natural gas and influence of secondary processes in the western part of the Ukrainian Outer Carpathians: geochemical and geological approach. Marine and Petroleum Geology, 103, 596-619. https://doi.org/10.1016/j.marpetgeo.2019.02.018
  7. Kotarba, М, Więcław, D., Bilkiewicz, E., Radkovets, N., Koltun, Y., Kowalski, A, Kmiecik, N., & Romanowski, T. (2020). Origin and migration of oil and natural gas in the central part of the Ukrainian outer Carpathians: Geochemical and geological approach. AAPG Bulletin, 104(6), 1323-1356. https://doi.org/10.1306/01222018165
  8. Kruglov, S. S., Smirnov, S. E., Spitkovskaya, S. M., Filshtynsky, L. E., & Khizhnyakov, A. V. (1985). Geodynamics of the Carpathians: Monograph. Kyiv: Naukova dumka, 136 p.
  9. Krupskyi, Yu. Z. (2001). Geodynamic conditions of formation and oil and gas bearing of the Carpathian and Volyn-Podillya regions of Ukraine: monograph. Kyiv: UkrDGRI, 144 p.
  10. Linetska, L.V., & Utrobin, V.M. (1965). On finds of Tintinnidae, Cadosina, Stomosphaera and Globochete in the Mesozoic of the Soviet Carpathians and the Carpathian foredeep. Reports of the Academy of Sciences of the Ukrainian SSR, 6, 782-785.
  11. Oszczypko, N., Krzywiec, P., Popadyuk, I., & Peryt, T. (2006). Carpathian Foredeep Basin (Poland and Ukraine) – its sedimentary, structural and geodynamic evolution. AAPG Memoir, 84, 293–350. . https://doi.org/10.1306/985612M843072
  12. Pasternak, S. I., & Ulizlo B. M. (1980). Neocomian of Fore-Carpathians. Geology and geochemistry of combustible fossils, 55, 22-30.
  13. Picha, F. J. (1996). Exploring for hydrocarbons under thrust belts – a challenging new frontier in the Carpathians and elsewhere. AAPG Bulletin, 80, 1547-1564. https://doi.org/10.1306/64EDA0A0-1724-11D7-8645000102C1865D
  14. Pilipchuk, A. S., Karpenchuk, Y. R.(1988).  Prospects of oil and gas bearing block structures of the Bylche-Volitsa zone of the Carpathian foredeep. Geology and geochemistry of combustible fossils, 71, 30-38.
  15. Radkovets, N. (2017). Early Cretaceous anoxic sedimentogenesis within the Carpathian segment of the Mesotethys. Geology and geochemistry of combustible fossils, 1-2, 149. http://nbuv.gov.ua/UJRN/giggk_2017_1-2_80.
  16. Radkovets, N., Kotarba, M., Koltun, Y., Kowalski, A., Kosakowski, P., & Więclaw, D. (2016). Origin and migration of oil from the Ukrainian Outer Carpathians to their Mesozoic basement: a case of Lopushna traps. Geological Quarterly, 60(1), 88-103. https://doi.org/10.7306/gq.1256
  17. Radkovets, N., & Yaremchuk, Ya. (2007). Features of the structure of authigenic glauconite of the Albian-Cenomanian sandstones of the autochthon of the Pokuttya-Bukovyna part of the Ukrainian Carpathians in the context of oil and gas bearing. Geology and geochemistry of combustible fossils, 1, 59-64.
  18. Senkovsky, Y. N. (1977). Lithogenesis of siliceous strata of the southwestern USSR: monograph. Kyiv: Naukova dumka, 280 p.
  19. Senkovskyi, Y., Hryhorchuk, K., Hnidets, V., & Koltun, Y. (2004). Geological Paleoceanography of the Tethys Ocean: monograph. Kyiv: Naukova dumka, 172 p.
  20. Shakin, V., Burov, V., Vyalov, O., Glushko, V., Kruglov, S., Petrashkevich, M., & Temniuk, M. (1976). Geological map of the Ukrainian Carpathians and adjacent territories 1: 200,000. Kyiv: Geologiya.
  21. Tolwinski, K. (1950). Karpaty Pokuckie. Acta geologica polonica, 1(3), 159-255