Play Types and Hydrocarbon Potential of the Deepwater Black Sea, NE Bulgaria
Structurally, the Bulgarian segment of the Western Black Sea Basin is in a lower plate position, in relation to the opening of the basin during mid-Cretaceous times. The paleo-shelf edge of the basin is marked by a major syn-rift hinge-zone. The basinward flank of the hinge zone formed a major submarine escarpment throughout much of the basin's history with a different shallow-water stratigraphy from that of the deepwater. The major erosional unconformities documented onshore and/or on the shelf do not exist in the deepwater as sedimentation was uninterrupted since early post-rift times.
At least six different deepwater play types have been identified in the northeastern Bulgarian offshore. Most of these plays are related to the prominent syn-rift Polshkov High, either in intra-Tertiary closures in the compactional anticline above, or within the Mesozoic syn-rift or early post-rift sequence. The deepest target is the Polshkov High itself, where the trap is defined by several fault blocks in which the assumed Jurassic carbonate platform sequence may have a reservoir facies suitable for deepwater gas production. The target of this play is identical to the ones targeted over the mid-Black Sea High (Andrusov Ridge) offshore Turkey or over the Tetyaev High offshore Ukraine.
Until recently, exploration efforts in the entire Black Sea were largely restricted to the shelf, due to the lack of access to deepwater drilling technology in the area. Therefore the deepwater Bulgarian Black Sea remains untested in spite of the significant exploration potential.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009