Abstract
The pre-Caspian basin is a low-lying flatland region encompassing the northern part of the Caspian Sea. The Pre-Caspian Basin, which lies to the north of the Caspian Sea partly within Russia and partly within Kazakhstan, with its southern margin beneath the North Caspian. The pre-Caspian basin has been formed from Paleozoic to Cenozoic time and the Kashagan field is situated in the southern part of Pre-Caspian depression. The Kashagan field is one of the world's largest oil discoveries of the last forty years. Administratively the field of 820 km2 belongs to Atyrau region and is situated in the North-East sector of the Kazakhstan part of the Caspian Sea. The interpretation of the structures affecting on the field was based on 3D seismic and drilling data from KE-1, KE-2, KE-3, KE-5 for East Kashagan, 2D seismic for West Kashagan where one well KW-1 was drilled and 3D seismic data also provided more detailed data about geology, structure, facies distribution and main layer thickness variations. The study area is composed of Upper Devonian deposits were represented by two wells this is pre-salt section; salt section structurally is anticline folds and Permian-Triassic sediments these are Post-salt section.