Study of lithological and facies sedimentation conditions in the salt complex of the south of the Caspian Basin in connection with the assessment of oil and gas potential

Abstract

A description of the level of knowledge and regional features over the complex southern region of the Caspian basin is given. Modern ideas about the characteristics of the load and the total salt-dome tectonics on the supports of local structures and the oil and gas accumulation zone are presented. Based on the disclosure of data on the internal structure, the need for a detailed study of the “salt dome - trough”, the patterns of distribution of salt-bearing thickness over the area, and its manifestation on the overlying types of Triassic, Jurassic and Cretaceous are substantiated. The analysis of data on the structure and oil and gas content of salt dome structures of the southern interfluve of the Ural-Volga and the Yuzhno-Embinsky district is carried out. The factors determining the degree of complexity of the structure of the post-salt strata are substantiated. Including: the relationship between the activity of dome growth and the changes over time in the structural plan along horizons IV, V, and III within the supra-dome, peri-dome areas, and the periphery of the dome, as well as the overall evolution of the 'salt dome – basin' system. The wide strip along the contour of the southern framing of the Caspian basin, which is characterized by a sheet-like and weakly faulted salt occurrence, is emphasized as the most promising in terms of oil and gas bearing. In this strip on the southern framing of the Caspian basin, using the example of the fields of the Prorva group, Borankol, Kisimbay and others, it is shown that promising local structures are characterized by the preservation of the completeness of the section in the supra-dome and sub-dome parts, which provides relatively more favorable conditions for the formation of hydrocarbon traps in them.