PSGeologic Framework for Korolev Field, Kazakhstan - A Carboniferous Isolated Carbonate Platform*
Paul M Harris1, Raymond A. Garber1, and Michael E. Clark2
Search and Discovery Article #20062 (2008)
Posted July 1, 2008
*Adapted from poster presentation at AAPG Annual Convention, New Orleans, April 16-19, 2000.
1 Chevron Petroleum Technology Company, Houston, TX; currently ETC, Chevron, San Ramon, CA, USA. ([email protected])
2 Tengizchevroil, Tengiz, Kazakhstan
Core and log data are combined into cross sections and maps to develop a geologic framework for Korolev field, a Carboniferous isolated carbonate platform located in western Kazakhstan adjacent to the giant Tengiz Field. From these results, the following observations can be made:
Platform Growth - Major changes occurred in the Korolev platform from its inception in the Devonian through the Carboniferous. In each stage, there was a change in configuration and significant decrease in size of the platform. A widespread Devonian shallow platform was much larger than the present Korolev structure. During the Tournaisian and Visean the shallow platform decreased in size in all directions. The platform edges are abrupt, showing a relatively rapid change from platform top to slope environments. Serpukhovian environments indicate the platform constricted significantly from the north and south to become relatively equidimensional and centered about the present structure. The platform thickened dramatically during the Serpukhovian, either responding to a rapid sea level rise or due to tectonic movement. The platform decreased farther in an east-west direction during the Bashkirian. Artinskian (Permian) deposits in all of the off-structure wells are interpreted as slope and basin deposits, whereas the environment in the wells over the platform is questionable.
Reservoir Quality - Facies recognized in Korolev samples are generally similar to those observed at nearby Tengiz field. Grainstones and packstones are generally widely distributed but are of very limited extent in the Bashkirian. A thick, but narrow, reef margin is confirmed for the Serpukhovian. Porosity within the Korolev samples ranges from 0% to 27%, and permeability ranges up to 1060 md. Better reservoir properties, defined for Korolev as >7.5% and/or k >2 md, are common in Bashkirian, Serpukhovian, and Tournaisian-lower Visean samples.