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Abstract: Petroleum Geochemistry of the Kura/Iori Interfluve

Gianfranco G. L. Rinaldi, Akif A. Narimanov

Plate tectonic reconstructions suggest that the Kura/Iori Interfluve was located in a back-arc during the Paleocene when the main sources, reservoirs and seals were deposited and structural traps created. The Lower and Upper Eocene and, to a much lesser extent, the Lower Oligocene transgressive shales are the most probable candidates for effective oil-source rocks in the area. A source evaluation was made for selected core samples from Upper Eocene, Oligocene, and Lower Miocene shales. TOC, extractable organic matter, and the Rock-Eval genetic potential for these mudstones are high enough to consider them excellent potential source rocks.

Oil-oil correlations carried out via biomarkers and other conventional geochemical techniques show that both the Middle Eocene and Lowermost Upper Eocene reservoired oils are very similar to each other and suggest that they are derived from common source facies.

Oil-source correlations suggest that oils were generated from Eocene shales, off- structure, and that updip migration of hydrocarbons into anticlines having middle Eocene reservoirs, was fault controlled. Thinning of the Upper Eocene section on anticlines indicates that structural growth occurred contemporaneously with trap formation. The Upper Miocene and Pliocene orogeny breached, via thrust faulting, Eocene reservoirs with hydrocarbon accumulations already in place. Such breaching caused "selective" re-migration of "light ends" into shallower Miocene reservoirs or to the surface. Oil re-migration is particularly evident in traps located close to the thrust of the Greater Caucasus.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France