The data on the location of the study area (western part of the West Siberian megabasin), hydrogeological stratification with separation of three overlapping basins - Cenozoic, Mesozoic, and Paleozoic. The issues of paleohydrogeological reconstructions with separation of piezomaximum and piezominimum zones are considered. It is shown that as a result of the evolutionary development of the Mesozoic hydrogeological basin, the studied area has turned into a regional piezomaximum zone due to the thick strata of clayey Neocomian deposits and is located within the development of infiltration, elision lithostatic and elision geodynamic water pressure systems. Groundwater has different ion-salt composition. The processes of elision water exchange, actively occurring in the study area, are closely connected with oil-and-gas formation and oil-and-gas accumulation.
