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The results of study of hydrogeological conditions of oil and gas bearing deposit of the southern areas of Ob-Irtysh interfluves (southern regions of West Siberian basin) are presented. The hydrodynamic field is characterized by direct dependence and the presence of normal and increased pressure (formation anomalous pressure factor not exceed 1.13) is common in Apt-Alb-Cenomanian, Neokomian, Jurassic and pre-Jurassic complexes. The results of study of the reservoir properties and hydrodynamic conditions indicated that the elision water exchange play the dominant role in the modern hydrogeological structure formation. Two types of water drive system is established: elisional (lithostatical and termodehydrational) in the inner areas (southern part of Koltogor-Nyurolsky trench, Nyurolskaya megadepression, Verkhnevasyugansk anteclise and other structures) and infiltrational within the territory of Baraba-Pikhtovo monocline. Elisional system is replaced by the elisional-termodehydrational at the depth 2.0-2.2 km. Large piezo maximum zones (southern part of Koltogor-Nyurolsky trench and Nyurolskaya megadepression) become the inner regions of water pressure generation (the inner feed areas) with the maximal degree of hydrogeological closure of the interior. The region of piezo minima, tracing the structures of the Barabinsk-Pikhtovskaya megamonocline, relates to the external feed area. The hydrodynamic model of the southern areas of Ob-Irtysh interfluves is building for the first time and allow to predict the pressure change trends in the areas with poorly provided with the actual data.

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––For the first time in the last 35 years, hydrogeochemical data on pre-Jurassic complexes in West Siberia have been generalized. Groundwater and brines of Cl–Na and Cl–HCO3–Na type with total salinity (TDS) varying from 4 to 330 g/L are found to be widespread in the area under study, with the former type dominating. A detailed analysis of the hydrogeochemical data allowed us to assume the presence of three genetic groups of groundwater and brines in the hydrogeologic section: (1) sedimentogenic, (2) lithogenic (revived) and ancient infiltrogenic, and (3) condensatogenic. An integrated analysis of coefficients rNa/rCl, Ca/Cl, (Br/Cl)·10–3, and (Sr/Cl)·10–3 and integrated index S of brine metamorphization in the Siberian sedimentary basins has corroborated the fact that groundwater and brines in West Siberia are at the initial stage of metamorphization of their chemical composition. Groundwater and brines in the studied Siberian sedimentary basins show an increase in the degree of metamorphization (catagenetic changes) of their chemical composition in transition from the areas of igneous and metamorphic deposits at the base of the Meso–Cenozoic sedimentary cover of the young West Siberian sedimentary basin to the structures of the ancient Siberian Platform, where ultrastrong Ca–Na and Ca chloride brines are widespread.

The article is devoted to the approach to geothermal zonality. The results of geothermal studies of oil and gas bearing deposits in the northern territory of Novosibirsk region and adjacent areas are presented. Geothermal zoning was carried out, and the major geothermal anomalies were determined. The features of the geothermal zonality of Mesozoic sediments in the region under investigation are first of all defined by the material composition of the Paleozoic basement, the structural arrangement, and the warming effect of ground water during its crossflows from deeper lying horizons. Formation temperatures get leveled within the boundaries of Aptian-Albian-Cenomanian sediments, and no anomalies are distinguished. The highest geothermal gradients sup to 3,6-4,6 °C/100 m and correspond to the edge zones of the development of intrusive formations of pre-Jurassic rocks. Lower gradients sup to 2,4-3,0 °C/100 m and characterize the regions, in which Paleozoic carbonate rocks occur.

The paper discusses the pioneering results of comprehensive hydrogeochemical studies of natural waters of the Baydar valley (southwestern parts of the Crimean Peninsula), whose major aquifers are confined to the upper Jurassic sediments (karst limestone) representing the most important hydrogeological feature of the study area. Fresh and ultra-fresh waters of predominantly bicarbonate calcium composition with total mineralization in the range from 194 to 1137 mg/dm3 are most widespread in the region. The analyzed waters (surface, ground and artesian) differ significantly in chemical composition and their basic characteristics have been arranged in the following patterns: mineralization of 254-832 mg/dm3 and neutral pH (6.98-7.54) for artesian waters; higher mineralization level (up to 1137 mg/dm3) and wide variations of pH values (from 7.18 to 8.31) for ground waters; mineralization from 194 to 288 mg/dm3 and a slightly alkaline pH (between 8.02 and 8.04) for surface waters collected in the Chyornaya river basin and Chernorechensk reservoir. The studied waters display a unique spectrum of trace elements and REE distribution.

Results of thermodynamic calculations of the interactions of radon waters from the Zaeltsovsky field with the minerals of host rocks are presented for the first time. It was established that waters under study are supersaturated with respect to calcite and siderite, and to a smaller extent with respect to magnesite and dolomite. No saturation of radon waters with respect to primary aluminosilicate minerals (albite, anortite, microcline, ferrosilite) is observed. The points are located in the fields of stability of clayey minerals (kaolinite, Ca- and Mg-montmorillonite, Fe-sepiolite), gibbsite and leptochlorite. In the evolution of the water-rock system, they correspond to the siallite type of interaction with rocks.