Purpose. Demonstration of the lithofacial structure and reconstruction of the sedimentation conditions of the Eifelian deposits of the Biloliskyy block of the Dobrudja foredeep in the aspect of the formation of productive horizons and the localization of perspective objects. Methods. The complex of lithological, paleo-oceanographic, lithophysica, and well logging explorations. Results. Five sedimentary cyclites of regressive nature, which are traced throughout the study area, were identified in the section of the Eifelian deposits of the Biloliskyy block of the Dobrudja foredeep. Cyclites have a two-membered structure: the lower part is represented by carbonate or terrigenous-carbonate rocks, the upper part is represented by marl- sulphate and sulphate (anhydrites). Characteristic changes in the content of the main lithological differences of cycles in space and time and the rhythmic nature of their sedimentation conditions have been determined. The sedimentation features of the development of biostromic bodies during the Eifelian age were reconstructed. The study localized the areas of their maximum development which tend to the slopes of the Skhidnosaratske and Zhovtoyarske uplifts. The features of the lithophysical structure of the Skhidnosaratske deposit are clarified. The main reservoirs (anticlinal and lithological types) of all the five identified productive horizons of the deposit were discovered to tend not to the modern arch of the structure, but to its south-western pericline. Based on the lithological and facial features of the region's Eifelian sediments, prospects for lithological-type traps within the southern, eastern, and northern slopes of the Zhovtoyarska structure are highly estimated. Scientific novelty. The construction of lithological, paleo-oceanographic, lithophysical models made it possible to determine the peculiarities of the spatial-temporal heterogeneity of the Eifelian deposits lithological structure of the Biloliskyy block of the Dobrudja foredeep and to correct the current estimation of their oil and gas prospects. Practical significance. The study of the features of the lithological structure of the strata, the creation of lithological, lithophysical, and paleo-oceanographic models will help to clarify the nature of the spatial-temporal development of sedimentary solids of various composition and genesis. All this will serve as a lithological basis for a more reasonable forecast of the distribution of oil and gas prospective objects.
- 1. Bесker F., Bechstädt T. Sequence stratigraphy of a carbonate‐evaporite succession (Zechstein 1, Hessian Basin, Germany). Sedimentology. 2006 53(5). P.1083 -1120
https://doi.org/10.1111/j.1365-3091.2006.00803.x
2. Botvinkina, L. N., Alekseev, V. P. (1991). Cyclicity of sedimentary strata and methods of its study. Sverdlovsk, Ural Federal University (in Russian)
3. Garland, J. (1997). Middle to Upper Devonian (Givetian and Frasnian) shallow-water carbonates of Western Europe: fades analysis and cyclicity. A thesis submitted in partial fulfillment of the degree of Doctor of Philosophy at the Department of Geological Sciences, University of Durham.
4. Grishchenko, V. P., Gurevich, K. Ya., Polukhtovich, B. M. (1986). New data on the Paleozoic deposits of the Western Black Sea. Tectonics and stratigraphy, 27, 52-59.
5. Hnidets, V. P., Hryhorchuk, K. H., Polukhtovych, B. M., Fedyshyn, V. O. (2003). Lithogenesis of Devonian deposits of Dobrogean foredeep (paleoceanography, sedimentary cyclicity, reservoir rocks' formation). Kyiv, UkrDHRI (in Ukrainian)
6. Hnidets, V. P., Hryhorchuk, K. H., Koshil, L. B., Tsizh, N. V., Yakovenko, M. B. (2016). The lithofacies zonality and lithmological structure of eifelian deposits of Dobrudja foredeep. Geodynamics, 1(20), 50- 62. https://doi.org/10.23939/jgd2016.01.050
https://doi.org/10.23939/jgd2016.01.050
7. Hnidets, V., Hryhorchuk, K., Koshil, L., Yakovenko, M. (2018). Lithofacies features and accumulating conditions of middle Devonian basal layers of Dobrudja foredeep. Visnyk Taras Shevchenko National University of Kyiv. Geology, 2(81), 6- 11. http://doi.org/10.17721/1728-2713.81.01
https://doi.org/10.17721/1728-2713.81.01
8. Hozhyk, P. F., Chebanenko, I. I., Yevdoshchuk, M. I., et al. (2007). Oil and gas prospective objects of Ukraine. Scientific and practical basis for the search for hydrocarbon deposits in the northwestern shelf of the Black Sea. Kyiv, EKMO.
9. Ivanyuta, M. M., Fedyshyn, V. O., Deneha, B. I., Arsirii Yu. O., Lazaruk Ya. H. (1998). Atlas of oil and gas deposits of Ukraine: in 6 Vol., Vol. 3. Southern oil and gas region. Lviv, Tsentr Yevropy, UNHA. (in Ukrainian)
10. Konyukhov, A. I. (2013). Oil and gas basins on the outskirts of the continents in the Paleozoic paleomors. Communication 1. Oil and gas basins on the outskirts of the continents of Japetus and Pantalassa. Lithology and minerals, 4, 1-26.
11. Makhnach, A. S., Moskvich, V. A., Kruchek, S. A., et al. (1984). Organogenic constructions of the Devonian of Belarus. Minsk: Science and technology.
12. Obrovets, S. M., Yashin, I. A. (2018). Non-traditional oil and gas-perspective reservoirs of the inter-salt complex of the Pripyat trough. Reports of the National Academy of Sciences of Belarus, 3(62), 3, 335-340.
https://doi.org/10.29235/1561-8323-2018-62-3-335-340
13. Oсakoğlu F. Repetitive Subtidal-to-Coastal Sabkha Cycles from a Lower-Middle Miocene Marine Sequence, Eastern Sivas Basin. Turkish Journal of Earth Sciences, 2001.Vol. 10, P. 17-34.
14. Polukhtovich, B. M., Bukatchuk, P. D., Genik, I. V. (1971). New data on the Middle and Upper Devonian sediments of the Pre-Dobrudge trough (within the Moldavian SSR). University proceedings. Series Geology and exploration, 12, 149-152.
15. Reding, H. G., Reding, D. D., Kollinson, X. G., & Allen, F. A. (1990). Sedimentation environments and facies.
16. Saraev, S. V. (2015). The litho-facies characterization of the Usol suite (Lower Cambrian) and its age-related analogues of the Pre-Yenisei sedimentary basin of Western Siberia. Geology and geophysics, 6(56), 1173-1188.
https://doi.org/10.1016/j.rgg.2015.05.008
17. Schröder S., Schreiber B. C., Amthor J. E., Matter A. A depositional model for the terminal Neoproterozoic-Early Cambrian Ara Group evaporites in south Oman. Sedimentology. 2003 Vol.50, Issue5. P. 879-898
https://doi.org/10.1046/j.1365-3091.2003.00587.x
18. Skachedub, Ye. O. (1998). Sedimentation conditions and oil and gas content of the Middle Devonian-Lower Carboniferous Evaporite Formation of the Predbrudzka Strait. Geology and geochemistry of combustible minerals, 102, 41-52.
19. Strahov, N. M. (1962). Fundamentals of the theory of lithogenesis. Volume III Patterns of composition and placement of arid sediments. Moscow, Publishing House of the Academy of Sciences of the USSR (in Russian).
20. Taninskaja, N. V. Sedimentological criteria of reservoirs forecast of the Middle Ordovician and Lower Devonian deposits of Timan-Pechora province. Oil and gas geology. Theory and practice, 5(4). 1-29.
21. Uilson Dzh. L. (1980). Carbonate facies in geological history. Moscow, Nedra (in Russian).