Black Sea has two extensional basins of different ages, the West and East Black Sea basins, separated by the Mid-Black Sea Rise which is called Andrusov Ridge in the Ukrainian sector. These two sub-basins subsided simultaneously during the last 30 Ma.
A regional study of the eastern part of the Ukrainian Black Sea has been carried using regional 2D seismic lines. To the south of the Crimean peninsula there have been mapped out 20 large structures with closures of 50-200 km2. All structures are within the Miocene-Pliocene sediments. Mega structures are also mapped out, with an areal closure in the excess of 350 sq. km. These structures are found within the Tertiary and older Cretaceous sediments further to the east within Sorokin Trough and on the Andrusov Ridge itself. In the easternmost part of the Ukrainian Black Sea a number of anticlines have been mapped out in shallow water depth and in addition a huge Mesozoic structure of 400 km2 is identified within water depth of 150-700 meters.
The West Black Sea Basin includes about 50.000 km2 of shelf located mainly within the Ukrainian territory. The sea depth over the majority of shelf is less than 100 meters. The Odessa Bay is a confirmed gas province with one exploited deposit and six deposits in the exploitation preparation stage or development. The total surveyed resource of gas comprises approximately 53 TCF. The Karkinitsk Basin includes several gas deposits with reservoirs confined to coarse-grained sandstone of the Aptian, Pliocene, and Oligocene overlaid by marl of the Upper Cretaceous and Eocene and clay of the Oligocene. The main type of traps is anticlines formed during the Late Eocene and later phases of compression.
Eocene, Oligocene and Miocene sediments are considered as source rocks with good potential for generation of hydrocarbons. Potential direct hydrocarbons indicators are observed on 2D seismic data sets throughout various areas within the Black Sea.
Major Upper Mesozoic-Cenozoic leads within water depths of 100 m to 2000 m has the potential to contain hundreds of million of barrels of recoverable hydrocarbons.