Environmental-Geochemical Transformation of the Supergene Zone under the Effect of an Oil-Producing Complex

摘要

General trends in variations of the hydrogeological conditions at oil and gas fields, developed with the use of reservoir pressure maintenance by water injection, are discussed. The issues considered in the study include the vertical hydrogeochemical zonality of the Volga-Ural oil and gas basin, the composition of fresh water and oilfield brines, the character of their mixing under the effect of oil-production activities at oil deposits of roof and depression types. Data of many-year (1971-2011) hydrolithomonitoring with the use of trend analysis of hydrogeological data were used to reveal the direction of ecological-geochemical transformation of fresh groundwater and clay rocks in the aeration zone. New water-helium method was proposed to differentiate pollution sources between surface and deep and to identify the penetration pathways of oil brines into freshwater in the supergene zone.