Some issues of the geological development and structure of the productive intervals of the section after the exploration work in the south-east of the South Tatar arch and the adjacent part of the Aktanysh-Chishmin depression have not been fully resolved. For example, the conditions of formation and the nature of the distribution of sandy-siltstone reservoir rocks in the kosvinsk-bobrikovsky deposits of the lower carboniferous terrigenous strata have not been fully clarified. At the same time, the reserves of most oil fields in the Paleozoic sedimentary cover of the designated territory have been significantly depleted during long-term production and therefore new sources of replenishment are required. Based on the study of geological and geophysical data, it was revealed that the accumulation of terrigenous rocks of the kosvinsk-bobrikovsky time occurred in the conditions of an alluvial delta extending in a southeastern direction into the shallow shelf area. In the well section, these deposits can be represented by distributive delta channels, estuarine bars of the delta front and sands of floodplain spills. Siltstone-sandy rocks of the delta channels and the proximal part of the bars are characterized by the best porosity and permeability properties, while sediments of floodplains and the distal part of the bars have lower values of such properties. During the detailed analysis, the paths of transfer of detrital material were mapped and the formed facies were shown on a detailed map of the facies zoning of the eastern part of the South Tatar arch at the end of bobrikovsky time. This map was compiled for the first time by the authors and, on its basis, the association of discovered fields and oil deposits with certain facies is compared and a forecast is given for the discovery of new oil deposits in the areas of intersection of delta channels, estuarine bars with slopes and arches of positive local structures.
References
1. Sedimentary environments: processes, facies and stratigraphy: edited by Reading H.G., Blackwell Publishing Limited, Second edition, 1986.
2. Valeeva I.F., Anisimov G.A., Anisimova L.Z., Geological aspects of oil and gas potential in the Upper Devonian and Lower Carboniferous sediments of Aktanysh-Chishminsky deflection of Kamsko-Kinelsky system of deflections (In Russ.), Georesursy, 2015, V. 2, no. 3(62), pp. 37–42.
3. Masagutov R.Kh., Tyurikhin A.M., Nasser Kh., Litologo-fatsial’naya kharakteristika radaevsko-bobrikovskikh otlozheniy osevoy zony Aktanysh-Chishminskogo progiba (na primere Ilishevskogo mestorozhdeniya) (Lithological-facial characteristics of the Radaevsky-Bobrikovsky deposits of the axial zone of the Aktanysh-Chishminsky trough (using the example of the Ilishevsky field)), Proceedings of RN-BashNIPIneft’ LLC, 2001, V. 108, pp. 44–52.
4. Masagutov R.Kh., Tektonicheskoe stroenie Bashkiro-Tatarskogo Pribel’ya (Tectonic structure of the Bashkir-Tatar region), Proceedings of RN-BashNIPIneft’ LLC, 2000, V. 100, pp. 44–56.
5. Krasnevskiy Yu.S., Lozin E.V., A new type of oil deposits: annular, encircling reef body (In Russ.), Oil&Gas Journal Russia, 2015, no. 1–2, pp. 38–42.
6. Komilov D.U., Maleev R.I., Masagutov R.Kh., Tomilin V.E., Late Tula delta geology and hydrocarbons occurrences in the Upper Kama depression and adjacent area
(In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2019, no. 12, pp. 86–90, DOI: https://doi.org/10.24887/0028-2448-2019-12-86-90
7. Komilov D.U., Geologiya i perspektivy neftenosnosti verkhnetul’sko-mikhaylovskikh otlozheniy platformennogo Bashkortostana (Geology and oil-bearing prospects of the Verkhnetula-Mikhailovsky deposits of platform Bashkortostan): thesis of candidate of geological and mineralogical science, Ufa, 2022.
