PETROLEUM SYSTEMS IN THE RIONI AND KURA BASINS OF GEORGIA

The Neogene Rioni and Kura foreland basins in Georgia are located between the converging Greater Lesser Caucasus fold‐and‐thrust belts. Basin continues westward into Black Sea whereas extends eastward Azerbaijan Caspian Sea. “Pre‐” “post‐salt” petroleum systems distinguished separated by an Upper Jurassic evaporite succession of regional extent. pre‐salt system northern is still poorly understood. Bathonian shales have generated oil which has been recorded Middle sandstones. However, as origin sandstones (e.g. at Okumi discovery) problematic, remains constrained. Gas‐rich, high volatile bituminous coals age may represent a CBM play. post‐salt charged two prolific source rock units: Eocene Kuma Formation Oligo‐Miocene Maikop Group. potential Formation, about 40 m thick, classified good to very good. Oligocene part Group several hundred metres thick contains rocks with up 5 wt.% TOC its lower part. Additional present Cretaceous Paleogene levels. Oil produced from fractured carbonates anticlinal structures below unconformity Mio‐Pliocene siliciclastics fault‐related anticlines. Trap formation hydrocarbon accumulation interpreted occurred since Maeotian time. Proven reserves low (∼2 million tons) suggest charge efficiency. Several stratigraphic horizons containing eastern Georgia. Although oil‐source correlations yielded unsatisfactory results, most likely rock, despite relatively poor best “fair” Tbilisi area west basin. include shales. Fractured volcaniclastic producing reservoirs for hydrocarbons, but accumulations also found Lower Eocene, siliciclastics. Biomarker data Cenozoic (or Cretaceous) abundant terrigenous organic matter. Anticlines positive flower related compressional tectonics front belts form main trap types. Samgori‐Patardzeuli‐Ninotsminda region far largest field accounts nearly 90% cumulative production country (28.5 tons). was probably kitchen north. Strike‐slip faults played major role migration pathways. Despite presence many seeps, proven Georgian (2.4 This reflects traps seal integrity.