The Neopleistocene Aquifer System in the Region of the Development of the Astrakhan Gas Condensate Field: Characteristics, Structures, and Formation Models

• Published in: Moscow University geology bulletin 2021-11, Vol.76 (6), p.646-655
• Main Authors: Golovanova, O. V., Pitieva, K. E.
• Format: Article
• Language: English
• Subjects: Aquifer systems; Aquifers; Deltas; Earth and Environmental Science; Earth Sciences; Geology; Geomorphology; Hydrosphere; Lithology; Marine sediments; Pollution control; Risk reduction; Rocks; Sedimentary facies; Streams; Tectonophysics
• ISSN: 0145-8752; 1934-8436
• DOI: 10.3103/S014587522106003X

—This paper reports the results obtained during studies of Neopleistocene sedimentary aqua-rock complexes: lithological, mineralogical-geochemical, hydrogeochemical, hydrogeofiltration, and hydrogeomigration studies in the region of the development of the Astrakhan Gas Condensate Field (AGCF). The main concepts of the models of the formation of groundwaters, as well as the characteristics of their balance, chemical composition, hydrogeodynamics, and hydrogeomigration have been stated and the main governing factors, have been revealed. It has been established that marine sediments predominate, where clay strata play a significant role. Facies and sedimentation environments of large avandeltas and shallows of the Northern Caspian have been identified. To develop a model of the formation of the studied sequence, a system of deltas and avandeltas of large and small streams has been considered with the involvement of geomorphological, landscape-climatic, and geodynamic factors. A specific landscape-geomorphological pattern has been revealed in the upper part of the litho- and hydrosphere of the AGCF region. The pattern reflects systems of unstable, in terms of geodynamics, zones with a scale of several hundred of meters–kilometers. An association of areas characterized by the greatest thickness and conductivity of the aquiferous strata of the Neopleistocene complex with intradome depressions of deep-seated structures of halokinesis has been revealed in a significant part of the study area. The results are relevant for the development of a model of the formation of the Neopleistocene aqua-rock complexes and for AGCF management, which includes identifying the paths of spreading pollution, reducing the risk of accidents due to instability of the foundations of facilities, and many other issues.