The structural and tectonic schemes on reference levels of the Mesozoic-Cenozoic sedimentary complex of eastern part of the Yenisei-Khatanga regional trough are presented. As a result of re-interpretation of all available seismic data and its coordination with the well data the structural map on the scale 1:750 000 of the Mesozoic-Cenozoic terrigenous complex bottom, of the Triassic-Jurassic terrigenous complex top, of the Berriasian-Lower Aptian complex top and of the Aptian-Albian-Senomanian complex top were constructed. Based on these schemes the maps of thickness of these complexes were created. The top of the Triassic-Jurassic complex was chosen as an object for tectonic zoning because this level most completely highlights the principle features of the all Mesozoic-Cenozoic sedimentary complex structure. Analysis of the made structural and tectonic maps indicates that the principle features of the tectonic construction of the research area are remained on the all considered levels. However, there are some differences between them due to tectonic processes in the history of sedimentary covering forming and largely influencing on the presence of oil-and-gas.

Neocomian reservoirs in the Mesozoic sedimentary cover of West Siberia have a complex geological structure. Their wedge-like (clinoform) geometry, with abrupt thickness changes and facies diversity (continental, shoreface, and pelagic deposits), causes difficulty in correlation between drilling- and seismics-based sand formations and clay caps. East-wedging (west-dipping) clinoforms consisting of interbedded clay and sand have the greatest reservoir potential in the West Siberian basin. Prediction of new oil and gas plays and their reservoir potential assessment require regional reconstructions in addition to local contour maps of individual zones and fields. However, the simulation technology which has been applied for years to Jurassic regional reservoirs is not fully applicable to the Neocomian clinoform sequences. Therefore we have adapted it correspondingly and suggest new tools to make due regard for the clinoform reservoir structure. The new approach has been tested through computing several structure and thickness contour maps of clinoform sequences for three largest regional Neocomian reservoirs (sub-Sarman, sub-Pim, and sub-Alymka) in northern and arctic West Siberia.

To predict the petroleum potential, we used stratigraphic, tectonic, lithological and facies, and geochemical criteria. We have considered their significance and estimated the petroleum potential from a total of criteria. The structures of the Toarcian, Pliensbachlan, and Hettangian-Sinemurian regional reservoirs of the Lower Jurassic have been characterized. The low petroleum potential of the reservoirs is due to the following factors: intricate structure, low and very low values of capacity-filtration parameters of reservoir rocks, widespread sealing beds of poor and very poor quality, low oil-generating potential of oil source rocks, and a high degree of catagenetic transformation of OM, as well as nearly ubiquitous saturation of reservoirs with formational waters.

From the analysis of considerable geological and geophysical evidence for the Lower Jurassic-Middle Jurassic deposits of the southeastern part of the Nyurolsk Trench adjacent to the Pudin megabar, we have first revealed large zones of possible hydrocarbon transfer from the Urman Formation sandstones to the Salat and Tyumen' Formation sandstones via permeable weathering crusts or pre-Jurassic complex rocks. Such zones can exist provided that some factors are present, including the presence of distinct negative Local structures at the surface of pre-Jurassic formations. A geological mode: for these zones is proposed. It is shown that if the above-mentioned transfer took place, the hydrocarbons migrating from the Urman Formation were most likely to accumulate in the macroreservoir traps of the Salat Formation and lower subformation of the Tyumen' Formation.