Wide and new data on hydrogeology on one of the largest artesian basins of the world have been summarized. Basic features of the groundwater and WDG formation, reservoir water zoning, P-T conditions and hydrogeological regime have been established. WSAB is proved to be favorable for the generation, accumulation, and preservation of hydrocarbon accumulations. Groundwater composition of the lower hydrogeological stage in the study area was formed in a sedimentary basin, being dominated by the expulsion regime with minor infiltration type common for the marginal parts of the basin. Connate waters are predominant in the basin formed by sea basins with moderate to low salinity (Aptian-Albian-Cenomanian, Neocomian, and Upper Jurassic complexes). Fossil meteoric infiltration waters penetrated into the sedimentary cover by infiltration in the sea basin regression epoch (Lower-Middle Jurassic and Triassic formations) are of minor distribution. Condensation water only in local sites are distributed formed by condensation from water vapor when hydrocarbon deposits generating. Particular attention is paid to identifying features of the interaction in the "water-rock-gas" system.