The Tertiary Petroleum System of the Eastern Black Sea Basin, Offshore Georgia Part I: Basin Configuration and Sediment Fill
Petroleum exploration within the Black Sea has historically been limited to the shallow waters of the shelf. To date, three exploration wells have been drilled in water depths over 300 m; one located in the Eastern Black Sea Basin. This well data along with 3D seismic data has resulted in new interpretations of the Tertiary petroleum system of the Eastern Black Sea Basin.
Prior to the opening of the Black Sea, the area was part of the Scythian Platform extending to the northern edge of the Tethys Ocean. Northward subduction of the Tethys Ocean during the latest Cretaceous to early Tertiary resulted in back-arc extension and the formation of the Eastern Black Sea (EBS) Basin. Continued northward movement of Arabia relative to Asia resulted in the complete closure of the Tethys, continental collision and uplift of the Pontides, Adjara-Trialet and Greater Caucasus Mountains. Presently, the EBS Basin is bound to the west by the Andrusov Ridge (Mid Black Sea High), to north by the Shatsky Ridge and Greater Caucasus Mountains, to the east by the suture of the Shatsky Ridge and Adjara-Trialet range and to the south by the Pontides.
These tectonic events have resulted in a complex basin configuration, sediment fill history and petroleum system. The EBS source rocks are assumed to be deepwater marine shales deposited in a restricted anoxic basin much like the present day Black Sea. The sediment fill history of the basin and provenance evolution is tied closely to the tectonic history of the area. The acquisition of 3D seismic data has resulted in a better understanding of the sediment fill history of the basin.
The basin fill history is dominated by three phases: syn-rift, post-rift and syn-orogenic. Phase one is characterised by syn-rift fill during the main back-arc extension. The second phase of sediment fill from Oligocene to mid-Miocene is referred to as post-rift and is characterised by passive, continuous, parallel deposition with meandering deepwater channel-levee systems. The third and current phase of sediment fill is the Late Miocene to present day syn-orogenic fill. This section is characterised by high rates of sedimentation and an abundance of deepwater channel-levee and canyon systems.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009