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A new tectonic map of the Vendian-Silurian stage in the Lena-Tunguska petroleum province has been compiled following special principles and methodology, on the basis of the pioneer digital version of the 1:1,000,000 structural map of the Vendian-Cambrian surface for the same region. Mapping revealed the distribution and morphology of tectonic elements of different hierarchies.

Riphean source beds much contributed to the high hydrocarbon potential of Precambrian deposits on the Siberian Platform. Large amounts of hydrocarbons were accumulated in reservoir traps of the Angara-Lena and Nepa-Botuobiya petroliferous provinces. In the Angara-Lena province, gas fluids played a leading role in the formation of hydrocarbon pools. We consider a geological model, formation conditions, porosity and permeability, and regularities of occurrence of sand reservoirs in the Parfenov producing horizon of the giant Kovykta gas-condensate deposit. The hydrocarbon resources of the deposit are estimated at 2.5-3 x 10¹² m³.
The Nepa-Botuobiya province is highly promising for large hydrocarbon accumulations. Considerable amounts of hydrocarbons are concentrated there in a subsalt carbonate complex. The geologic structure of the Verkhnechonskoe deposit is considered. The estimates show that the petroleum resources of the deposit can be increased 2-2.5 times, i.e., to 400-500 mln tons.
The discovery of large and giant petroleum deposits in the Precambrian deposits of the Siberian Platform provides a base for realizing a large-scale program on the development of new centers of oil and gas extraction in East Siberia.

A base of petroleum resorves has been constructed in the Sakha Republic (Yakutia), which is sufficient not only for satisfying the domestic needs but also for transporting oil and gas beyond the republic. The recentmost data dictate the trends of prospecting to enhance the base of oil and gas extraction. There exist specific conditions complicating the process of oil and gas extraction at the Yakutian deposits, which are due to the presence of permafrost in the sedimentary cover. The main problems of development of the Yakutian petroleum complex have been discussed.

Analysis of the formation of bitumoid pools in various regions of the Siberian Platform gives insight into the stages of evolution of hydrocarbons in areas of their accumulation and destruction.

Oil and gas pools in the Vendian section in the Baikit petroleum province may be associated with structural-depositional traps. These traps have been investigated through reference seismogeological modeling based on CMP profiling and log data. Different basic models correspond to structural-lithological traps in sandstones of different facies: Fluvial sandstones form traps in valleys incised into a pre-Vendian plateau, and large traps in deltas and embayments occur in shallow-sea environments near the pinchout of the Vanavara terrigenous section. Processing of over 150 well logs and 7000 km of CMP data revealed six oil and gas traps in Vendian sandstones, including two high-potential traps in the pinchout zone.

A system lithofacies analysis refined the role of primary sedimentogene factors in the formation of reservoir properties of carbonate rocks in the O-I producing bed of the Talakan petroleum deposit. The bed bears 11 microfacies and 3 mesofacies - algal-microbial organogenic buildings, accumulative bodies of peloid sediments, and small, periodically drying basins of elevated and high salinity made up of chemogenic carbonate-sulfate sediments. The best reservoir properties are observed for rocks of peloid microfacies.

The transitional region from Baltic Shield to Barents Sea petroliferous shelf, made up chiefly of Late Proterozoic sediments, is tectonically zoned. Three subparallel structural zones correspond to different parts of the large Timan rift trough of Riphean-Vendian age framing the Russian Platform in the northeast. The forecast of hydrocarbon deposits is different for each of the zones. It is important that the thrusts be of restricted occurrence and complicated structural traps of hydrocarbons be possible to exist, especially in the central zone and on its northeastern periphery. The correct forecast and prospecting require a considerable additional volume of geological and geophysical data obtained by the promising method of CMP-wave reflection over the entire transitional field, with the reported approach to their interpretation taken into account. Also, two parametric boreholes are required to be drilled northeast and southwest of the Trollfjord-Komagelv-Rybachii zone of deep disturbances.

The main factors that contribute to postsedimentary salinization of reservoirs are: contact, hydrochemical, and pressure-thermal metamorphism of underground waters and brines; an increase in mineralization of brines on evaporation, freezing, gas hydration, and membrane processes; role of connate waters and mother brine of halmeic basins; effect of trap magmatism; man-induced salinization. They have been discussed and quantitatively estimated.
It has been established that the main and virtually the only reason for regional salinization of subsalt terrigene reservoirs is pressure-thermal metamorphism of brines (decrease in pressure and temperature). All the above-mentioned natural processes contributed to the regional salinization of carbonate basins, and the main one was contact metamorphism of underground waters and brines (their interaction with halmeic-carbonate rocks). The buried brine of halmeic basins and other connate waters had no effect on salinization of reservoirs. The disjunctive activity of trap magmatism accelerated these processes, but thermal action of traps and their subsequent cooling promoted only slight salinization of reservoirs. Man-induced salinization can occur in reservoirs of any type, restricted to local zones around absorbing wells. Some recommendations are given with respect to further study.

We describe the technique and results of gas resources estimation in discovered and predicted gas pools in gaize (silica clay) and siliceous mudstones of the Lower Berezovskaya subformation of Cenomanian age in West Siberia. The estimation technique is based on complex geophysical studies of wells, data on stony material, and results of sampling from the study section in the Komsomol'skoe field. Also, data on the physical properties of gaize and gaize-like clays sampled from stratigraphic wells are analyzed. The results obtained show low coefficients of gas saturation, thus pointing to a low gas potential of gaize.

Infauna trails (trace fossils) have been identified in rocks of the Bazhenov and Georgiev Formations of the Upper Jurassic of the West Siberian Plate. Two types of trace fossils, Zoophycos and Chondrites, are found in deposits of the Bazhenov Formation, and three types of trails, Chondrites, Thalassinoides, and Skolithos, are recognized in the Georgiev Formation. Conditions of formation have been determined for each type of trace fossils.