--> ABSTRACT: Stratigraphic Correlation of Carboniferous Carbonate Reservoirs In the North-East Caspian Sea Region, by S. Warshuer, O. Skarpnes, S. Umirshin, and A. Negri; #91021 (2010)

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Stratigraphic Correlation of Carboniferous Carbonate Reservoirs In the North-East Caspian Sea Region

WARSHAUER, STEVEN,  ODDVAR SKARPNES,  SALIMZHAN UMIRSHIN, and ALBERTO NEGRI

Stratigraphic correlation of Carboniferous Carbonate rock units in the subsurface of the north-east Caspian Sea region was accomplished by the development of a correlation framework based solely on well-log responses. Most important was the response of the Gamma Logs, although Sonic Logs and Neutron Logs were also utilized. A key observation for the development of this methodology was the occurrence of a Highly Radioactive Zone (HRZ) in all wells drilled to a sufficient depth to intersect it. Gamma Log character for the HRZ is remarkably consistent across an 80 km transect extending from the Yuzhnaya structure in the south to the Karaton structure in the north. For wells located near the tops of the carbonate platforms at Tengiz and Karaton1 preliminary well log analysis indicates that the carbonate units found between the top of the Carboniferous and the HRZ display better reservoir characteristics than those units found below the HRZ. Included in this upper interval is the main portion of the producing reservoir in the Tengiz area. Generation of synthetic seismograms for the Tengiz and Karaton areas indicates that the HRZ can be recognized on seismic data and is widely mappable. Therefore, it is possible to map from seismic data the main reservoir interval in the north-east Caspian Sea region as both the top of the Carboniferous Carbonates and the HRZ can be recognized on seismic sections. Examination of core data for several wells indicates that the HRZ consists of extensive ash and associated vitroclastic material and is the result of a major volcanic event. Paleontological data from various sources indicates that the HRZ is a Visean event (Aleksinian or Tulian).

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.