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The history of investigation into the petroleum potential of deep-seated horizons of the Uralian region is reviewed. Two major objects for oil and gas prospecting are considered: 1) Late Precambrian (Riphean and Vendian) deposits in the platform part of the Bashkir Autonomic Republic and 2) Paleozoic and Precambrian underthrust series in the fold-nappe zone of the Urals. The petroleum potential is justified by numerous oil shows on the territory of Bashkiria and in adjacent areas and by the world data on the presence of abundant underthrust petroleum deposits in many countries.

The maturity of organic matter (OM) has been investigated according to vitrinite reflectance (R^o). This index has been modeled within the sedimentary cover. The depth dependence of R^o has been studied for the first time in the region. Model curves of OM maturation have been constructed for prospecting and test boreholes. This allows prediction of R^o at depths of to 10-12 km. Maps of OM maturity have been compiled for three OM-rich sequences: Carboniferous-Permian terrigenous-carbonate, Upper Triassic and Upper Jurassic terrigenous. The degree of OM conversion varies from protocatagenesis (PC) in the Cretaceous and Upper Jurassic deposits to apocatagenesis (AC) in the Permian ones. Structural and catagenetic levels are conformable in depressions, whereas mismatches of structural and catagenetic surfaces are observed in the terrigenous-carbonate complex and Lower-Middle Triassic deposits on uplifts, particularly, on the western flank of the Barents Sea megatrough and, to a lesser extent, on the Admiralteiskii megarampart.
The catagenetic model suggests a large-scale hydrocarbon generation in the sedimentary deposits of the deep-seated Barents Sea megatrough from Early Paleozoic to Late Mesozoic. During the last 250 Ma, the greatest petroleum catchment area has occurred in the zone of uplifts on the western flank of the Barents Sea megatrough. The potential of this area is comparable with that of the structures of the Shtokman-Lunin megasaddle, proven by exploration drilling.

The Famennian intersalt and uppersalt petroliferous deposits in the Pripyat' basin (Byelorussia) formed during the main rifting stage of its evolution. The related lithologically and facially diverse sections, cut by synsedimentary and postsedimentary faults, contain a broad variety of oil and gas traps and pools, including lithologically confined ones. All lithologically confined traps in the Pripyat' paleorift are grouped into zones; eleven zones have been discovered to date, and economic oil pools were found in four of them.

The results of generalized regional studies of the West Siberian geosyneclise are presented. The structural maps for the bottom of the plate complex and top of the Jurassic and Cenomanian complexes were compiled at the modern informative and technological level. The refined classification of the tectonic elements allowed comilation of tectonic maps for these levels, in which the tectonic elements and faults differentiated by the time of their formation and depth of occurrence are shown.
The structural and tectonic maps for the top of the Jurassic structural stage are presented and briefly.
Analysis of the structural and tectonic maps, isopach maps, and seismic profiles enabled description of the tectonic history of the West Siberian geosyneclise during the Cretaceous and Cenozoic in relation to its petroleum potential.

A map of deep heat flow of West Siberia has been compiled on the basis of over 6000 heat flow determinations, and the present temperature field has been analyzed in terms of the role of various factors forming the geothermal regime.
Analysis of local temperature fields in the vicinity of 340 hydrocarbon pools shows that almost 80% of them are associated with considerable heat flow variations, of which some are positive anomalies.

Integral methodology of geological survey, exploration, and production for Russia as a whole is in progress. Criteria for recognition of petroliferous megacomplexes and their basic elements are described. It is demonstrated that oil pools of Jurassic and older deposits are confined to large "hot" fields (regions), whereas gas accumulations exist under more moderate bed temperatures. This regularity is used for predicting oil and gas deposits.

The West Siberian basin formed as a result of the Early Triassic rifting and downwarping of the Earth's crust during the Mesozoic and Cenozoic. Three stages are recognized in this process: early (postrift, Middle Triassic-Middle Jurassic), middle (platform, late Middle Jurassic-Eocene), and late (neotectonic, late Eocene-Quaternary). In this paper, the regularities and conditions of sedimentation are described concisely, and the potential of Lower-Middle Jurassic petroleum-bearing complexes (Zimnii, Sharapov, Nadoyakh, Vym', and Malyshev) and Neocomian cllinoforms is estimated. The conclusion is made that the further increase in reserves of hydrocarbons in the West Siberian petroliferous province in a sufficient volume is possible at the cost of these two petroleum-bearing stories. A program of their further study on a regional scale is proposed. This program will be a base for a more complete estimation of resources of the complexes under study, for determination of areas for detailed seismic prospecting and parametric drilling, and for their geological and economical estimation aimed at a necessary licence.

Based on generalization of 1500 measurements of vitrinite reflectance, deep zoning of organic-matter (OM) catagenesis in Mesozoic deposits has been established, and schemes of catagenesis were constructed for the top and bottom of the Jurassic deposits. The OM catagenesis is within the range of grades PC₃ to MC₃² in the Upper Jurassic deposits and PC₃-AC₃ in the basal Jurassic horizons. Throughout most of the West Siberian megabasin, OM reached the end of mesocatagenesis and apocatagenesis. Regionally, the degree of OM catagenesis of the Jurassic deposits increases from the margins to the central and northern, most buried, areas of the West Siberian megabasin. The level of OM maturity ubiquitously increases with depth, but the rate of these changes varies throughout the area. The highest deep gradient of variations in OM catagenesis was identified in the Yamal and Gydan regions. Depth ranges of the main zone of oil generation (oil window) were determined from vitrinite reflectance values in different petroliferous regions. In the Nadym-Pur region, the main zone of oil generation is identified in the depth range 2.9-3.8 km, in the Pur-Taz region, at 2.8-3.6 km, in the Gydan region, at 2.4-3.3 km, and in the Yamal region, at 2.0-2.8 km. The Jurassic deposits to depths of about 4.0 km have not passed out of the oil window yet and can be of interest for oil and gas exploration. Down the section, the sequences are in the zone of intense gas generation, and, therefore, preservation of only dry and fat gas accumulations is possible at great depths. The same is true for the Triassic and Paleozoic sediments, in which the organic matter underwent significant thermobaric changes (grades MC₃² – AC₃).

The structure, composition, and formation settings of the Callovian-Oxfordian deposits of the Pur-Irtysh, Taz-Kheta, and Silgin facies districts of West Siberia are considered. In the first of them the Callovian-Oxfordian deposits include the Vasyugan and Abalak Formations; in the second, the Tochino and Sigovsk Formations; and in the third, the Naunak Formation. The variability of the Vasyugan Formation in the southeastern areas of the West Siberian Plate, in the latitudinal Ob' region, and in the Nadym-Taz interfluve has been shown by lithological and mineralogy-petrographical studies invoking production geophysics and geochemical and paleontological evidence. This allows recognition of three facies subdistricts: Ob'-Tara, Ob'-Agan, and Nadym-Pur. In addition, the Yamal-Nadym facies subdistrict, where the Abalak Formation occurs, has been recognized.