GEOCHEMICAL CHARACTERISTICS OF THE DOMANIKOID-TYPE LATE DEVONIAN STRATA OF THE KOBLANDY-TAMDY UPLIFT

The article presents the lithological and geochemical characteristics of the Upper Devonian sediments of the Koblandy structure in the northeastern part of the Precaspian Basin. Based on the core data from the Koblandy-3 well from the Upper Devonian strata of the presalt complex, the results of RockEval and isotopic analysis are presented. Intervals of kerogen-siliceous-carbonate rocks enriched in organic matter have been established, which, according to a complex of microand macrocharacteristics, can be attributed to domanikoid-type sediments. The Domanikoid highcarbon formation of the neighboring Volga-Ural Basin is an effective source rock. The generative potential of the established domanikoid-type sediments of the Koblandy-3 well is characterized by high TOC values of 0.1-5.7%, the Production Index (PI) varies from 0.1-0.3, which corresponds to the oil window. Three lithotypes of domanikoid-type sediments deposited in predominantly deep marine environment have been established. The association of potential reef bodies in the vicinity of domanikoid-type source rocks indicate in favor of petroleum system within the upper Devonian presalt complex of the Koblandy-Tamdy uplift zone