Isolated carbonate platforms — characteristic carbonate bodies of the Frasnian age on the southeast Volga-Ural hydrocarbon province

Aim. The presentation of the latest results on the studying of Frasnian isolated carbonate platforms in the southeast of the Volga-Ural oil and gas province is the purpose of this publication.

Materials and methods. The results of interpretation of 3D seismic data and core study of deep exploration wells served as source materials for the work. Sedimentological studies with facies diagnostics were performed on the core of deep wells in the interval of the Frasnian Stage.

Results. A group of Middle-Late Frasnian isolated carbonate platforms is identified to the north and northwest of the Sol-Iletsk Arch. These platforms are characterized by steep slopes with coarse clastic carbonate deposits, which is explained by the dominance of reef builders such as stromatoporoids and corals in frame limestones.

Conclusions. In the southern part of the Volga-Ural Paleobassin, isolated carbonate platforms were common forms of large carbonate bodies in the Middle and Late Frasnian of the Late Devonian. Subsequent accretion of isolated carbonate platforms resulted in the formation of long, rimmed carbonate platforms. Isolated platforms are complex carbonate reservoirs with a variety of void forms. The use of 3D seismic data can provide excellent detail of the structure of the Frasnian carbonate complex. This will allow us to adjust the directions of geological exploration in the region in order to search for missed hydrocarbon accumulations both in the carbonate reservoirs of the isolated platforms themselves and in siliciclastic deposits of the Kolganian Formation.

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