Seismic Stratigraphy and Regional Prospectivity of the Offshore Extension of the South Mangyshlak and North Caspian

The regional prospectivity of the South Mangyshlak, North Caspian and North Ustyurt basins is hereby presented based on seismic stratigraphic interpretation of 2D seismic lines acquired by CGGVeritas between 2006-2009 in both the central and northern Caspian Sea. The seismic dataset covers part of the offshore extension of each basin. We have identified four mega-sequences within the North Caspian Basin, two mega-sequences within the North Ustyurt basin and three mega-sequences within the South Mangyshlak Basin. The mega-sequences represent discrete phases of basin-fill mainly caused by a combination of tectonic subsidence, sedimentation rate and relative sea level change. These mega-sequences were identified based on seismic reflection terminations on bounding regional unconformities and their correlative conformities. These represent key plate re-organisation episodes and relative sea level change. In the North Caspian Basin, we have identified Devonian-Carboniferous, Permian-Triassic, Jurassic-Cretaceous and Tertiary mega-sequences. The Jurassic-Cretaceous and Tertiary mega-sequences occur in all three basins with similar depositional facies. The Permian-Triassic sequence is different in both depositional history and petroleum play elements in all three basins whilst the Devonian-Carboniferous sequence has been drilled only in the North Caspian basin.