The lithological typification of the section was carried out, the conditions for the formation of deposits were identified, and maps of facies heterogeneity for each horizon of the terrigenous thickness of the Lower Carboniferous within the Republic of Bashkortostan were constructed. Using the data of wells with high core removal, microscopic description of the thin sections and granulometric studies of the samples, structural-lithological typification of terrigenous and carbonate deposits of the terrigenous thickness of the Lower Carboniferous was carried out. The granulometric composition and textural features revealed in the visual description of the core are taken as a basis for isolating lithotypes. Based on a detailed analysis of the core for the depositions of the terrigenous thickness of the Lower Carboniferous, a number of facies features were identified that allowed these deposits to be assigned to a delta complex of river type. The main diagnostic features that characterized this type of sedimentation environment have been identified. The main facies zones are the delta channels and secondary channels of the promontine, the delta plain, the delta dying, the mouth bars, the delta front, the prodelta and the shallow-marine carbonate sediments. Descriptions are given for each facies zone, its core characteristics that are characteristic for it, which make it possible to identify these complexes with confidence. In order to increase the detail of the maps of facies heterogeneity, wells with a GIS complex were involved in the wells with a core, for which an electrofacial analysis was performed, based on the methods of spontaneous potential log and Gamma ray log.
The created geological framework will serve as the base for petrophysical typing of deposits. Facies features revealed during the work can serve as a basis for constructing conceptual models of local objects, and also will allow to compare different objects according to the conditions of their formation at the regional level.
References
1. Rykus M.V., Rykus N.G., Sedimentologiya terrigennykh rezervuarov uglevodorodov (Sedimentology of terrigenous hydrocarbon reservoirs), Ufa: Mir Publ., 2014, 324 p.
2. Baraboshkin E.Yu., Prakticheskaya sedimentologiya. Terrigennye kollektory (Practical sedimentology. Terrigenous reservoirs), Moscow: GERS Publ., 2011, 152 p.
3. Botvinkina L.N., Zhemchuzhnikov Yu.A., Timofeev P.P. et al., Atlas litogeneticheskikh tipov uglenosnykh otlozheniy srednego karbona Donetskogo basseyna (Atlas of lithogenetic types of carboniferous deposits in the middle carboniferous of the Donetsk Basin), Moscow: Publ. of USSR AS, 1956, 368 p.
