In the south-eastern part of the Caspian depression the Devonian-Carboniferous carbonate deposits contain proved commercial oil and gas reserves. The reservoirs are confined to the ancient carbonate platforms which had been developed on the high-amplitude structures of the Primorsky Uplift Zone such as Kashagan, Tengiz, Korolevskaya. An effective developing these reserves needs new discoveries as well as more detailed investigations of old fields. The sub-salt Carboniferous and Devonian deposits contain carbonate rocks of the isolated platform with the high variety of facies: biogenic build-ups, their edges (grainstones, boundstones), lagoons, slope, and deep basin (wackestones, packstones, mudstones). An integrated interpretation of the deep drilling data, 3D and regional 2D seismic survey allowed refining of the carbonate structure internal heterogeneity and the reef zones delineating in the Karaton-Birlestik Area. According to the seismic survey data the Upper Devonian carbonate structure is well distinguished high surrounded by the slopes. In the Visean-Bashkirian deposits a few high-amplitude reef structures (up to 300 m) are recognizable that might contain the traps for hydrocarbons. As concluded the reservoir properties forecast to be more precise, it is necessary to take the environments of deposition in consideration. These properties have a great variation depended on the facies zone belonging to. For example, the grainstones and boundstones of the build-up zones have the highest porosity and permeability values in the result of secondary alterations.
References
1. Abilkhasimov Kh.B., Osobennosti formirovaniya prirodnykh rezervuarov paleozoyskikh otlozheniy Prikaspiyskoy vpadiny i otsenka perspektiv ikh neftegazonosnosti (Features of the formation of natural reservoirs of the Paleozoic sediments of the Caspian basin and assessment of the prospects of their oil and gas potential), Moscow: Publ. of Academy of Natural Sciences, 2016, 244 p.
2. Abilkhasimov Kh.B., Osobennosti formirovaniya prirodnykh rezervuarov paleozoyskikh otlozheniy Prikaspiyskoy vpadiny i otsenka perspektiv ikh neftegazonosnosti (Features of the formation of natural reservoirs of the Paleozoic sediments of the Caspian basin and assessment of the prospects of their oil and gas potential), Moscow: Publ. of Academy of Natural Sciences, 2016, 244 p.
