Boundary Jurassic-Cretaceous sediments of the water area of the Middle Caspian: structure, stratification and prospects of oil and gas potential (on the example of the Sarmatian-Khvalyn Uplift zone)

UDK: 552.98(262.81)+551.762
DOI: 10.24887/0028-2448-2019-8-22-26
Key words: stratigraphic studies, boundary Jurassic-Cretaceous; biostratigraphy, paleo-and petromagnetic structure of the section, ratios of stable isotopes 87Sr/86Sr, δ13C, δ18O, traps of stratigraphic screening
Authors: M.V. Smirnov (VolgogradNIPImorneft Branch of LUKOIL-Engineering LLC in Volgograd, RF, Volgograd), S.Yu Shtun (LUKOIL-Nizhnevolzhskneft LLC, RF, Astrakhan), O.I. Smirnova (VolgogradNIPImorneft Branch of LUKOIL-Engineering LLC in Volgograd, RF, Volgograd), P.F. Popova (VolgogradNIPImorneft Branch of LUKOIL-Engineering LLC in Volgograd, RF, Volgograd)

The Russian sector of the Caspian Sea is one of the promising regions for the search for hydrocarbon deposits. The results obtained from the processing of seismic facies, lithological, geophysical, petrophysical and other researches indicate that the main prospects are connected with the carbonate Upper Jurassic-Lower Cretaceous complex of deposits. The development predicted at the initial stage of research in this (previously considered to be Tithonian) complex of rifogenic type traps has not been confirmed. Along with this, materials are accumulating that indicate the possible presence in this region of a significant number of non-structural oil and gas traps of lithological, stratigraphic and combined types. Search and exploration of deposits of this type dictate the need for a well-developed stratification scheme. The territory of the Northern Caspian Sea is of great scientific interest from the perspective of paleogeographic events that took place at the turn of the Jurassic and Cretaceous: it is through this region that water masses and marine biota were exchanged between the Boreal and Tethyan basins. The joint analysis of stratigraphic and paleogeographic data on the Northern Caspian Sea can provide key information for the Boreal-Tethys correlation and justification of the Jurassic-Cretaceous boundary in the boreal sections. In this regard, the initial figures about the structure of the Jurassic-Cretaceous sequence of the region that were obtained by drilling are of particular interest. It is established that the carbonate complex previously attributed to the formations of the titon tier should be considered as a transitional Tithon-Berriass, and the productive I layer, represented by fractured-cavernous dolomites, should be attributed to the Berriasian. Inter-well correlation of the refined roof of Jurassic system sediments was executed using three independent methods. The one-dimensional modeling performed taking into account the VSP and drilling data, made it possible to correctly stratigraphically link the reference horizons to the borehole data and unambiguously correlate the target horizons. The seismic facies analysis showed that in the upper part of the Upper Jurassic deposits there is a zone of the release of individual phases under the roof of the Upper Jurassic deposits. The obtained geological results confirm the assumption about the possible development of stratigraphic screening traps in this region.

References

1. Smirnov M.V., Baraboshkin E.Yu., Bogdanova T.N. et al., Tithonian and Neocomian of Northern Caspian (In Russ.), Byulleten' Moskovskogo obshchestva ispytateley prirody. Otdel geologicheskiy, 2004, V. 79, no. 2, pp. 30–39.

2. Guzhikov A.Yu., Molostovskiy E.A., Stratigraphic informativeness of numerical magnetic characteristics of sedimentary rocks (methodical aspects) (In Russ.), Byulleten' Moskovskogo obshchestva ispytateley prirody. Otdel geologicheskiy, 1995, V. 70, no. 1, pp. 32–41.

3. Guzhikov A.Yu., Geological informativeness of the magnetism of the core and sludge sedimentary rocks obtained during the drilling of exploratory wells (In Russ.), Pribory i sistemy razvedochnoy geofiziki, 2013, no. 4(46), pp. 51–61.

4. Kuznetsov A.B., Semikhatov M.A., Gorokhov I.M., Strontium isotope stratigraphy: Principles and state of the art (In Russ.), Stratigrafiya. Geologicheskaya korrelyatsiya = Stratigraphy and Geological Correlation, 2018, V. 26, no. 4, pp. 3–23.

5. Wierzbowski H., Anczkiewicz R., Pawlak J. et al., Revised Middle–Upper Jurassic strontium isotope stratigraphy, Chemical Geology, 2017, V. 466, pp. 239–255.

6. Kuznetsov A.B., Izokh O.P., Dzyuba O.S., Shurygin B.N., Sr isotope composition in belemnites from the Jurassic–Cretaceous boundary section (Maurynya River, Western Siberia) (In Russ.), Doklady RAN = Doklady Earth Sciences, 2017, V. 477, no. 4, pp. 455–460.

7. Baraboshkin E.Yu., Naydin D.P., Ben'yamovskiy V.N. et al., Prolivy Severnogo polushariya v melu i paleogene (Straits of the Northern Hemisphere in the Cretaceous and Paleogene), Moscow: Publ. of MSU, 2007, 182 p.

8. Baraboshkin E.Yu., Shtun' S.Yu., Guzhikov A.Yu. et al., Sedimentologiya i stratigrafiya pogranichnogo yursko-melovogo intervala karbonatnogo rampa Severnogo Kaspiya (Sedimentology and stratigraphy of the border Jurassic-Cretaceous interval of the carbonate ramp of the Northern Caspian), Collected papers “Melovaya sistema Rossii i blizhnego zarubezh'ya: problemy stratigrafii i paleogeografii” (The Cretaceous system of Russia and neighboring countries: problems of stratigraphy and paleogeography), Proceedings of IX All-Russian meeting, 17–23 September 2018, Belgorod: Politerra Publ., 2018, pp. 54–58.

9. Baraboshkin E.Yu., Rogov M.A., Guzhikov A.Yu. et al., Kashpir section (Volga River, Russia), the proposed auxiliary section for the J/K interval in Subboreal Realm, Proceedings of XII Jurassica Conference. Field Trip Guide and Abstracts Book, Smolenice, Slovakia: Publ. of Earth Science Institute, Slovak Academy of Sciences, Bratislava, 2016, pp. 109–112.


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