The Pre-Caspian megabasin is a large oil and gas basin with a unique geological structure. However, the region remains poorly studied, with uneven drilling and seismic sections limited in length. The presence of thick salt strata and morphological features create difficulties during geological exploration, their interpretation and forecasting of hydrocarbon potential. The results of the study allowed authors to establish the complex structure of the depression, including the Archean and Baikal basement. The study of geophysical materials, especially seismic data, makes it possible to revise the concept of the structure and history of the development of the southeastern margin of the Pre-Caspian depression. Within the limits of the North Caspian and Temir uplifts of the depression, numerous protrusions of the foundation have been revealed, which are overlain by Paleozoic sedimentary rocks. These protrusions contain promising traps for hydrocarbons at depths up to 7–8 km. The block structure of the foundation determines the features of the subsalt sedimentary complex of the basin. The study of the Pre-Caspian basin showed the presence of isometric uplifts, such as Kashagan and Tengiz, as well as a system of narrow uplifts of the eastern side zone. As a result of modeling the migration of oil and gas from source strata, it was revealed that about 4,70 trillion tons of hydrocarbon fluids emigrated, mainly liquid. The analysis of structural maps has shown the possibility of migration and filling of potential traps in the Lower Permian, Visean-Bashkir and French-Famen oil and gas complexes. The obtained simulation results made it possible to successfully reproduce the main deposits in the studied area, reflecting real data. The deposits in the west of the depression are characterized by a high content of gaseous hydrocarbons, while in the east the liquid fraction predominates, corresponding to the more oil potential of the eastern side of the Pre-Caspian depression. In the central part of the depression, exclusively gas accumulations are formed associated with the migration of gas from the oil and gas source strata. In the northern side zone, there is an increased content of liquid components. An increased content of gaseous hydrocarbons was detected on the Astrakhan platform. In the south of the Caspian sea, accumulations of hydrocarbons are observed in all the complexes under consideration. Modeling also showed the presence of new promising zones at various stratigraphic levels. Particular attention is paid to the formation of gas condensate accumulations in the central part of the depression.
References
1. Volozh Yu.A., Abukova L.A., Antipov M.P. et al., Autoclave type of the hydrocarbon systems in the Pricaspian oil-and-gas province (Russia): Conditions of formation at great depth (In Russ.), Geotektonika = Geotectonics, 2022, no. 6, pp. 59–77, DOI: https://doi.org/10.31857/S0016853X22060078
2. Bakirov A.A., Bordovskaya M.V., Mal’tseva A.K., Tabasaranskiy Z.A., Geologiya i geokhimiya nefti i gaza (Geology and geochemistry of oil and gas), Moscow: Nedra, 1982, 288 p.
3. Voronov G.V., Kuantaev N.E., Paleozoyskie karbonatnye otlozheniya Prikaspiyskoy vpadiny: nadezhdy, real’nost’, perspektivy (Paleozoic carbonate deposits of the Caspian basin: hopes, reality, prospects), In: Osobennosti karbonatnykh porod i voprosy modelirovaniya rezervuarov (Features of carbonate rocks and reservoir modeling issues), Proceedings of Kazakhstan Society of Petroleum Geologists, 2022, V. 9, pp. 27-37.
4. Zhuravlev V.S., Sravnitel’naya tektonika Pechorskoy, Prikaspiyskoy i Severomorskoy ekzogonal’nykh vpadin Evropeyskoy platformy (Comparative tectonics of the Pechora, Caspian and North Sea exogonal depressions of the European Platform), Moscow: Nauka Publ., 1972, pp. 399.
5. Abilkhasimov Kh.B., Osobennosti formirovaniya prirodnykh rezervuarov paleozoyskikh otlozheniy Prikaspiyskoy vpadiny i otsenka perspektiv ikh neftegazonosnosti (Features of the formation of natural reservoirs of the Paleozoic sediments of the Caspian basin and assessment of the prospects of their oil and gas potential), Moscow: Publ. of Academy of Natural Sciences, 2016, 244 p.
6. Antipov M.P., Bykadorov V.A., Volozh Yu.A., Leonov Yu.G., Problems of origin and evolution of Pre-Caspian depression (In Russ.), Geologiya nefti i gaza, 2009, no. 3, pp. 11–19.
7. 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.
8. Petrovskiy V.B., Opyt primeneniya novykh tekhnologiy obrabotki dannykh distantsionnogo zondirovaniya Zemli v komplekse s geofizicheskimi metodami pri reshenii zadach neftegazovoy geologii (Experience in using new technologies for processing Earth remote sensing data in combination with geophysical methods in solving problems of oil and gas geology), In: Neftegazonosnye basseyny Kazakhstana i perspektivy ikh osvoeniya (Oil and gas basins of Kazakhstan and prospects for their development), Almaty: Publ. of Kazakhstan Society of Petroleum Geologists, 2015, pp. 442-453.
9. Voronov G.V., Kuantaev N.E., Eskozha B.A., Glubinnaya neft’ Prikaspiya: Predposylki, osobennosti, vyzovy i perspektivy (Deep oil of the Caspian region: Prerequisites, features, challenges and prospects), In: Kaspiyskiy region: Problemy stroeniya i nefteganosnosti glubokozalegayushchikh kompleksov i geneticheskaya priroda uglevodorodov (Caspian region: Problems of the structure and oil potential of deep-lying complexes and the genetic nature of hydrocarbons), Proceedings of Kazakhstan Society of Petroleum Geologists, 2015, V. 5, pp. 15-23.
10. Voronov G.V., Kuantaev N.E., Konusy vynosa i turbidity Prikaspiyskoy vpadiny – novye ob»ekty, osobennosti i perspektivy poiskov nefti i gaza (Alluvial fans and turbidites of the Caspian basin - new objects, features and prospects for oil and gas exploration), In: Kaspiyskiy region: Perspektivy neftegazonosnosti Kazakhstana, problemy, puti izucheniya i osvoeniya trudnoizvlekaemogo, netraditsionnogo uglevodorodnogo syr’ya (Caspian region: Prospects for the oil and gas potential of Kazakhstan, problems, ways of studying and developing hard-to-recover, unconventional hydrocarbon raw materials), Proceedings of Kazakhstan Society of Petroleum Geologists, 2017, V. 6, pp. 311-321.
