In 2019, RN-Shelf-Arctic LLC, a subsidiary of Rosneft Oil Company, carried out a regional project on Cretaceous deposits (structural and depositional environment reconstruction) in the Russian territory of the Barents Sea in order to explore new potential objects and increase the resource base at Rosneft. The algorithm of the studies included the interpretation of seismic data, the analysis of well data and outcrops of the islands within the Barents Sea, the identification of typical seismic facies and their depositional interpretation, the choice of palaeoenvironmental reconstruction intervals, the analysis of thickness and seismic facies maps and finally, facies-palaeogeographic reconstructions. Sequence stratigraphy was used as the main interpretation method. Thus sequence boundaries and maximum flooding surfaces were justified and correlated as a chronostratigraphic framework. As a result, seven sequences were identified in the Lower Cretaceous interval: five sequences in the Neocomian interval (approximately the third order) and 2 sequences in the Aptian-Albian interval (2 orders). Mapping was carried out at two levels: combined LST + TST and HST.
One of the most interesting results of the study is the recognition and mapping of stepped-dipping steeply falling clinoform bodies associated with forced regression in three Neocomian sequences. These bodies were interpreted as deposits of deltas of shelf edges. According to the literature data, deposits of a similar genesis are characterized by a high content of sand material and have good reservoir properties.
The results of this study can significantly reduce the risks associated with the reservoir properties for the objects within the zone of distribution of these deposits.
References
1. Seldal J., Lower Cretaceous: the next target for oil exploration in the Barents Sea, Petroleum Geology Conference series, 2005, V. 6, pp. 231–240.
2. Zhuravlev V.A., Korago E.A., Kostin D.A. et al., Gosudarstvennaya geologicheskaya karta Rossiyskoy Federatsii. Masshtab 1:1 000 000 (State geological map of the Russian Federation. Scale 1: 1,000,000), Seriya Severo-Karsko-Barentsevomorskaya. List R-39,40 – o. Kolguev – proliv Karskie Vorota. Ob"yasnitel'naya zapiska (Series North-Kara-Barents Sea. Sheet R-39.40 - Kolguev Island - Kara Gate. Explanatory letter), St. Petersburg: Publ. of Kartograficheskaya fabrika VSEGEI, 2014, 405 p.
3. Burguto A.G., Zhuravlev V.A., Zavarzina G.A. et al., Gosudarstvennaya geologicheskaya karta Rossiyskoy Federatsii. Masshtab 1:1000000 (State geological map of the Russian Federation. Scale 1: 1,000,000), Ser. Severo-Karsko-Barentsevomorskaya. List S-36, 37. – Barentsevo more (zap. i tsentr. chasti). Ob"yasnitel'naya zapiska (Series North-Kara-Barents Sea. Sheet S-36, 37. Barents Sea (western and central parts). Explanatory letter), St. Petersburg: Publ. of Kartograficheskaya fabrika VSEGEI, 2016, 144 p.
4. Cherkesov O.V., Burdykina M.D., O stratifikatsii mezozoya Novoy Zemli po nakhodkam pereotlozhennoy fauny (On the stratification of the Mesozoic of Novaya Zemlya based on finds of redeposited fauna), In: Paleontologicheskaya osnova stratigraficheskikh skhem paleozoya i mezozoya ostrovov Sovetskoy Arktiki (The paleontological basis of the stratigraphic patterns of the Paleozoic and Mesozoic islands of the Soviet Arctic), Leningrad: Publ. of NIIGA, 1981, pp. 85–99.
5. Mordasova A.V., Usloviya formirovaniya i perspektivy neftegazonosnosti verkhneyursko-nizhnemelovykh otlozheniy Barentsevomorskogo shel'fa (Formation conditions and oil and gas prospects of the Upper Jurassic-Lower Cretaceous deposits of the Barents Sea shelf): thesis of candidate of geological and mineralogical science, Moscow, 2018.
6. Nikishin A., Petrov E., Cloetingh S. et al., Geological structure and history of the Arctic Ocean based on new geophysical data: Implications for palaeoenviroment and palaeoclimate. Part 2. Mesozoic to Cenozoic geological evolution, Earth-Science Reviews, 2019, DOI: 10.1016/j.earscirev.2019.103034.
7. Kairanov B., Escalona A., Mordasova A. et al., Lower Cretaceous tectonostratigraphic evolution of the Northcentral Barents Sea, Journal of Geodynamics, 2018, pp. 183–198, DOI: 10.1016/j.jog.2018.02.009.
8. Posamentier H.W., Allen G.P., James D.P., Tesson M., Forced regressions in a sequence stratigraphic framework: concepts, examples and exploration significance, AAPG Bull., 1992, v. 76, DOI:10.1306/BDFF8AA6-1718-11D7-8645000102C1865D.
9. Gurari F.G., Stroenie i usloviya obrazovaniya klinoform neokoma Zapadno-Sibirskoy plity (istoriya stanovleniya predstavleniy) (The structure and formation conditions of the Neocom clinoforms of the West Siberian Plate (history of the formation of representations)), Novosibirsk: Publ. of SNIIGGiMS, 2003, 141 p.
10. Nezhdanov A.A., Seysmogeologicheskiy analiz neftegazonosnosti otlozheniy Zapadnoy Sibiri dlya tseley prognoza i kartirovaniya neantiklinal'nykh lovushek i zalezhey UV (Seismogeological analysis of the oil and gas potential of sediments in Western Siberia for the forecast and mapping of non-anticlinal traps and hydrocarbon deposits): thesis of doctor of geological and mineralogical science, Tyumen', 2004.
11. Porebski S., Steel R., Shelf-margin deltas: their stratigraphic significance and relation to deep water sands, Earth-Science Reviews, 2003, v. 62, pp. 283–326, DOI: 10.1016/S0012-8252(02)00161-7.
12. Posamentier H.W., Morris W.R. Aspects of the stratal architecture of forced regressive deposits, In: Sedimentary responses to forced regressions: edited by Hunt D., Gawthorpe R.L., Geol. Soc. London, Spec. Publ., 2000, V. 172, pp. 19– 46.
13. Kolla V., Biondi P., Long B., Fillon R., Sequence stratigraphy and architecture of the Late Pleistocene Lagniappe delta complex, northeast Gulf of Mexico, In: Sedimentary responses to forced regressions: edited by Hunt D., Gawthorpe R.L., Geol. Soc. London, Spec. Publ., 2000, V. 172, pp. 291–327.
14. Aksu A.E., Piper D.J.W., Progradation of Late Quaternary Gediz delta, Turkey, Mar. Geol., 1983, V. 54, pp. 1–25.
15. Tesson M., Posamentier H.W., Gensous B., Stratigraphic organization of Late Pleistocene deposits of the western part of the Golfe du Lion shelf (Langedoc shelf), western Mediterranean Sea, using high-resolution seismic and core data, AAPG Bull., 2000, V. 84, pp. 119–150.
16. McMaster R.L., de Boer J., Ashraf A., Magnetic and seismic reflection studies on continental shelf off Portuguese Guinea, Guinea, and Sierra Leone, West Africa, AAPG Bull., 1970, V. 54, pp. 158–167.
17. Pegler E.A., Mid- to Late Quaternary environments and stratigraphy of the southern Sierra Leone shelf, West Africa, J. Geol. Soc. London., 1999, V. 156, pp. 977–990.
18. Nemec W., Steel R.J., Gjelberg J. et al., Anatomy of collapsed and re-established delta front in Lower Cretaceous of eastern Spitsbergen: gravitational sliding and sedimentation processes, AAPG Bull., 1988, V. 72, pp. 454–476.
19. Steel R.J., Crabaugh J., Schellpeper M. et al., Deltas versus rivers on the shelf edge: their relative contributions to the growth of shelf margins and basin-floor fans (Barremian and Eocene, Spitsbergen), Proceedings of GCSSEPM Foundation 20th Ann. Res. Conf., Deepwater Reservoirs of the World, Houston, 2000, pp. 981–1000.
20. Simonova V.A., Karyakin Yu.V., Kotlyarova A.V., Physical and Chemical Conditions of Basaltic Magmatism at the Franz Josef Land Archipelago (In Russ.), Geokhimiya = Geochemistry International, 2019, V. 64, no. 7, pp. 700–725.
21. Abashev V.V., Metelkin D.V., Vernikovskiy V.A. et al., Novye dannye o vozraste bazal'tovogo magmatizma arkhipelaga Zemlya Frantsa-Iosifa (New data on the age of basaltic magmatism of the Franz Josef Land archipelago), Proceedings of 51th Tectonic meeting “Problemy tektoniki kontinentov i okeanov” (Problems of tectonics of continents and oceans), Part 1, Moscow, 2019, pp. 3–8.
