Geology, geography and global energy

Scientific and Technical Journal

Hydrogeochemical Features of Brines in Subsalt Complex of Caspian Syneclise

2012. №4, pp. 28-31

Myazina Natalya G. - C.Sc. in Geology and Mineralogy, "Technoprojekt NVTISIZ" Ltd., 108 Yeletskaya st., Volgograd, Russian Federation, 400120, nvtisiz@list.ru

The article describes the basic laws of formation and distribution of pre-salt chloride brines in the Caspian syncline. It also considers the genetic characteristics of the main geochemical and genetic types of brine. Subsequently, the paper indicates the chemical composition of the brines and the possibility of them appearing during the development of oil and gas fields. The Caspian sedimentary basin, for instance, one of the major geological structures of the East European plateau, has a vast diversity of hydro-geochemical and lithophyte features. Moreover, the North Artesian section of that basin contains a complex salt dome structure. In the lower section of the basin, there is a subsalt hydro-geodynamic system, which probably has an ultra-subzone with a semi-built-up water exchange. The critique says that a distinctive feature of the basin is the presence of chloride-, sodium- and calcium-sodium (soda) brine (Type IIIb by EV Posokhova VA Sulin). Within the North Caspian basin, there is a Permian halogen spread-area formation having a chemical composition of ground water and brines. The latter, which are derived from the southeastern margin of the East European plateau, are found in subsalt areas that hinder the water exchange. The semi-built-up regime includes two principal geochemical and genetic types of brine: the sodium chloride sort, appearing in conjunction with infiltrated sedimentary diffusion leaching rock salt; and the calcium chloride, sedimentary sodium (soda) type.

Key words: Caspian sedimentary basin,chemical composition and salinity,chloride brines,major geochemical and genetic types,sedimentary and subsalt diffusion leaching-type brines

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