Chapter from:
AAPG Memoir 68:Regional and Petroleum Geology of the Black Sea and Surrounding Region, Edited by A.G. Robinson
AAPG Memoir 68: Regional and Petroleum Geology of the Black Sea and Surrounding Region. Chapter 18: Petroleum Geology of the Georgian Fold and Thrust Belts and Foreland Basins, by Andrew G. Robinson, Eric T. Griffith, Andrew R. Gardiner, and Andrew K. Home, Pages 347-367

Copyright © 1997 by The American Association of Petroleum Geologists. All rights reserved.

Chapter 18
Petroleum Geology of the Georgian Fold and Thrust Belts and Foreland Basins

Andrew G. Robinson
Eric T. Griffith
JKX Oil & Gas plc
Guildford, United Kingdom

Andrew R. Gardiner
Andrew K. Home
Robertson Research International
Llandudno, Gwynedd, United Kingdom

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ABSTRACT

Numerous, mainly small, oil discoveries have been made within the foreland basins and fold and thrust belts of Georgia. The largest field in Georgia (Samgori) contained ~200 MMbbl (million barrels) recoverable reserves reservoired in fractured middle Eocene volcaniclastics--the main proven reservoir in Georgia--trapped in a compressional fold of the Achara-Trialet belt. Where the Achara-Trialet deformation extended into the foreland basins, frontal folds with Miocene-Pliocene clastic reservoirs are known to be oil-bearing (e.g., Supsa field). Within the foreland basins in areas unaffected by Neogene compression, structural closures related to pre-Neogene extensional faulting may include draping lower Miocene and Mesozoic reservoirs: these are largely untested. The frontal folds of the Greater Caucasus have yielded small oil discoveries in lower Miocene fluvial to shallow marine clastic reservoirs. The widespread oil discoveries along the Achara-Trialet frontal folds demonstrate the presence of a working oil sourcing system from the Black Sea through to the Kura Basin. Gas chromatography-mass spectrometry and carbon isotope analyses indicate that a single source rock was responsible for generation of many of the oils in the foreland basins; oil source correlations suggest that this was late Eocene in age, deposited within the Paleogene Achara-Trialet Basin. Further, oil-prone source rocks appear to be present locally within the Greater Caucasus.