The Hydrocarbon System of Blocks II and III in the Eastern Black Sea Offshore the Republic of Georgia

By

Mark Frishman¹, Brian Locke¹

(1) Anadarko Petroleum Corporation, The Woodlands, TX

 Anadarko Georgia Company and the Georgian National Oil Co have completed seismic, gravity, and aeromagnetic surveys in two blocks offshore Georgia in the Black Sea.

The geological history of the area is complex because of the repeated opening and closing of various portions of the Tethyan seaway since the Early Triassic. The onshore geology is dominated by two fold and thrust belts, the Greater Caucasus to the north and the Achara-Trialet to the south. The thrust fronts are separated by a series of Neogene foreland basins, the Kura, the Kartli and the Rioni in the west.

The interpretations show that the Achara-Trialet complex terminates very abruptly close to the coastline. Offshore, the long axis of some of the Neogene to recent folds are over 50 kilometers long and change trend from east-west in the northern and eastern portion of the study area to southwest-northeast in the southern and western portion of the blocks. The structural deformation decreases basinward.

The sedimentary package contains strata that are younger and thicker than those onshore and some have seismic characteristics that are attributable to reservoir facies, especially in the Miocene and Plio-pleistocene sections. The Maykop Formation (Oligocene-Miocene) is recognized regionally as a very productive, oil prone source rock that is identified in the offshore by its distinctive seismic character where it is up to 5000 meters thick. Basin models indicate that at present the Maykop Formation is in the oil window throughout most of the two blocks. Vertical migration is expected via faults. Oil seeps were identified on repeated satellite images over the crests of two of the anticlines.