Engineering and Geological Studies of the Tengiz Deposit

Abstract

In this article, a study of geological and ecological loads on the geological environment at the Tengizfield, located in the Zhyloy district of Atyrau region of the Republic of Kazakhtan, is carried out. Soil tests by dynamic sounding (STDS) were performed on all drilling wells for sandy soils. In the process of performing engineering and geological exploration, static sounding of soils was performed at the projected sites of GDP-1 (gas distribution plant) and Torch, with the measurement of hydrostatic pore pressure. Physical and mechanical properties of soils, chemical properties of soils and chemical properties of groundwater were determined during laboratory studies. In the studied territory, the soils composing the engineering-geological section to a depth of up to 25 m are saline with an average degree of salinity. All lithological-facies groups of soils also contain a significant amount of carbonates and gypsum in their composition. For loamy silt (IGE-1b), according to the combination of physico-chemical and mechanical characteristics (fluid consistency, high degree of salinity, high degree of compressibility and low strength, the possibility of manifestation of thixotropic properties under dynamic influences), this soil belongs to the category of weak water-saturated clay soils. Weak soil (IGE-1b) is observed at a shallow depth in some areas. The available geotechnical data is not enough to accommodate areas of weak soils. At the same time, heavy sandy loam (IGE1a) and light sandy clay (IGE-8) have swelling properties of a weak degree. Chemical analysis of groundwater samples taken within the studied territories showed a high degree of mineralization, groundwater belongs to the brackish group, a subgroup of strongly brackish waters. Dangerous geological processes that could negatively affect the construction conditions are characterized by the processes of secondary salinization of soils.