Summary

On the southwestern margins of the Black Sea several Tertiary lowstand-events, of likely Eocene to Late-Miocene age, have eroded canyons and incised-valleys. Reservoirs that were formed during intervals of rapidly changing relative water levels reside in canyons, valleys, and on interfluves. Thus, the same systems evolve paleogeographically from submarine canyons, to incised valleys. Finally when the basin fills with fresh water, these systems become sublacustrine canyons. The resultant stratigraphy is heterogeneous, evolving from pre-canyon marginal marine and marine deposits to marine turbidites to marine and lacustrine deltaics, to fluvial sediments and back to lacustrine deposits. Canyon reservoirs are ultimately sealed by transgressive fine-grained lacustrine sediments.

Exploration targets comprise a variety of non-marine and/or marine sands overlain and sealed by fine-grained, deep-water lacustrine strata. These include lowstand deposits such as: canyon fill sediment; incised-valley fill; toe-of-slope fan (proximal turbidite) facies; and lowstand fluvio-deltaic reservoir. Transgressive system deposits comprise upper shoreface reservoir in proximal positions. However in more distal or basinal settings transgressive deposits can be fine-grained seal and source rock deposits. Proximal, coarse-grained highstand deposits (near upland areas) comprise fluvio-deltaic reservoir. Distal, fine-grained highstand deposits in basinal areas can include source rock and seal.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah