The main petroleum and gas objects in Tomsk region are terrigenous rocks of upper-Jurassic and under chalk age. However, the hydrocarbon deposits in rocks of the settled cover are at the last stages of development now. Therefore, the pre-Jurassic deposits, where oil and gas deposits have been found out, become more important, but their models, trap occurrence conditions, ways of hydrocarbon migration are not studied very well at present time. As deep wells (more than 3000 m) drilling under low degree of geologic and geophysical studying of Paleozoic rocks of foundation is not the priority tendency today for Petroleum and Gas Extracting Companies, the complex approach to development and basis forecast system and estimation of oil and gas bearing prospects is required considering the set of criteria which can show the most reliable conclusions for every territory separately. The author offers the estimation of availability of south-eastern slope of Aleksandrovskiy megashaft with the help of paleofacies reconstruction of sedimentation ancient conditions. The main aim of the study is to disclose rock complexes, which sedimentation conditions could promote the formation of ancient carbonate blast. The latter can form traps, accumulate and keep oil and gas deposits on the territory of south-eastern slope of Aleksandrovskiy megashaft. Determination of area spreading of rock "lid" deposit complexes, with features of fluid traps is one more important thing. The methods used in the study: analysis of description of cores and joints of deep wells in south-eastern slope of Aleksandrovskiy megashaft (Tomsk region), comparison of the results of the carried out analysis of well core with lithological and paleogeographic maps of the USSR maps, edited by A. P. Vinogradov (1968-1969) and the material composition map of Tomsk region foundation surface by M. P. Nagorskiy (1977). The results. The author corrected the paleofacies conditions and climate zones of sedimentation in south-eastern slope of Aleksandrovskiy megashaft in pre-Jurassic period. The paleofacies and paleogeographic conditions of sedimenattion were analyzed and the localities and rock complexes, which are profitable for further formation, stocking and keeping of hydrocarbon deposits, and stratigraphic subdivisions and regions of the rock"lid" formation were revealed.