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The problem of forecast of the largest (giant) oil and gas deposits arises not from insufficient empirical knowledge (most recoverable HC resources of the world have been prospected) but from the necessity of its generalization and theoretical justification. Transition from empirical to theoretical level of knowledge requires a deeper integration of oil geology as a special study into the general structure of natural sciences, which requires formalization of a special knowledge in accordance with general principles and laws of the natural science. Inductive analysis traditionally used in oil geology in the context of historical and genetic approach must be complemented with deductive analysis based on static approach. Particular methodological forms of the latter approach are techniques of mathematical simulation, based on regularities in distribution of HC resources of oil and gas basins (OGB) among deposits of various sizing classes, and techniques of analogous structurization, based on regularities of distribution of giant deposits in the planetary system of OGB.

Astronomical and geochronological substantiation of galactic years and the orbital geochronological scale are considered. Climatic seasons of Phanerozoic galactic years are recognized. The dependence of various geochemical and biological phenomena and events, as well as formation of mineral deposits, on the position of the Sun in its galactic orbit and the related galactic climatic seasons is discussed.

The paper considers the criteria of influence of trappean magmatism on the petroleum potential of sedimentary basins. Particular emphasis is placed on the thermal effect of intrusive bodies on organic matter and hydrocarbons. The principles of classification of sedimentary basins are presented based on the degree of maturity by the time of the most intense stage of trap intrusion. The foundations of the technique of calculation of the predicted hydrocarbon resources are given for the basins of different types.

Studies of the traces of Riphean and Phanerozoic earthquakes in the Caucasus, West Siberian Plate, and Siberian Platform, as well as their comparison with the geological evidence of modern earthquakes, show that they may have played a role in the formation of oil and gas traps and accumulation zones. The seismogenic zones of oil and gas accumulation, which are of three main varieties (autochthonous, allochthonous, or transit), are considered in terms of their formation mechanisms and prediction. For such zones in the Caucasian foredeep, West Siberian Plate, and Siberian Platform, probable stratigraphic levels, locations, and types are outlined and example predictions are suggested.

In many regions of the world, including West Siberia, deposits of hydrocarbons in hydrate state are considered to be petroliferous formations. As to methods of search, prospecting, and exploitation of this kind deposits, however, the state-of-the-art is not satisfactory.
In Russia, the problem of existence of gas hydrate deposits is usually discussed in the context of hydrate saturation of the Cenomanian gas pool at the Messoyakha deposit. One more producing horizon has been recognized in the north of West Siberia, which is related to the Gazsalin Member of the Kuznetsov Formation of Turonian-Coniacian age, lying above the Cenomanian deposits and having more favorable PT-conditions for hydrate formation.
Analysis of specific features of geologic structure, temperature regime of the section, gas composition, mineralization of formation waters, logging data, seismic prospecting materials, and sampling suggests that gas hydrates can exist in the Gazsalin Member of the East Messoyakha deposit.
One of the possible directions of further study of genesis of natural gas hydrates and estimation of the effect of gas hydrate processes on the structure of gas deposits and gas resources is study of the hydrocarbons accumulated in the Gazsalin Member of the East Messoyakha deposit with sampling of core by a sealed thermostatically controlled corer.

The paper deals with the problem of bacterial oxidation (biodegradation) of crude oil hydrocarbons. The review of the literature on natural biodegraded oils and laboratory experiments suggest that the normal and branched alkanes are susceptible to microbiological degradation, as well as polycyclic saturated biomarker hydrocarbons (steranes, hopanes, and cheilanthanes). The homologous series of demethylated hopanes are assumed to be of different genesis: 28-norhopanes have the precursors in membranes of prokaryotes, i. e., they are "primary" biomarkers, while 25-norhopanes result from bacterial oxidation of regular hopanes in oil pools. Homohopanes close to "biological" structures (22R) are the first to be assimilated by bacteria. At the final stages of biodegradation, demethylation of cheilanthanes occurs at C-10. All this allows construction of the stage scale of hydrocarbon biodegradation.

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.