--> ABSTRACT: Seismic Stratigraphy and Geomorphology of the Tengiz Isolated Carbonate Buildup: Utilization of Datumed Horizon Slices to Understand Platform Margin and Slope Complexity, by Posamentier, Henry W.; Bachtel, Steve ; Playton, Ted; Kenter, Jeroen; Jenkins, Steve ; Iskakov, Elrad; Katrenov, Zhanibek; Jazbayev, Kairat ; Harris, Paul (Mitch); #90142 (2012)

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Seismic Stratigraphy and Geomorphology of the Tengiz Isolated Carbonate Buildup: Utilization of Datumed Horizon Slices to Understand Platform Margin and Slope Complexity

Posamentier, Henry W.*1; Bachtel, Steve 1; Playton, Ted 1; Kenter, Jeroen 2; Jenkins, Steve 3; Iskakov, Elrad 3; Katrenov, Zhanibek 3; Jazbayev, Kairat 3; Harris, Paul (Mitch) 2
(1) Chevron ETC, Houston, TX.
(2) Chevron ETC, San Ramon, CA.
(3) TengizChevroil, Atyrau, Kazakhstan.

A newly acquired 3D seismic dataset over the Tengiz Field, Kazakhstan, has been interpreted to better understand the heterogeneity and complexity of carbonate margin, slope, and basinal environments. Initial iterative plan-view and cross-sectional mapping approaches coupled with better seismic imaging revealed features that are novel and impact reservoir characterization.

Large-scale truncation features observed at the outer platform are interpreted as catastrophic collapse unconformities and highlight the often discontinuous nature of the platform-slope boundary. They seem to be coincident with timing of observed onlapping basinal wedges and apparently link to sequence stratigraphic surfaces on the platform top that are critical for the reservoir framework and identification of flow units.

Closely-spaced (200-300 m), low-relief, ‘gullies’ with highly serrated morphologies, suggestive of erosion from tractive sediment gravity flows, are observed in the northwestern margin. The east/southeast margin is characterized by km-scale, concave, irregular reentrants that are interpreted to be a result of failure of early cemented microbial boundstone deposits. Such variation in margin features has implications for downdip prediction and modeling of the platform to slope transition.

Weakly-developed lineations of small circular amplitude anomalies parallel to the platform margin are interpreted to be vertical dissolution conduits and cavernous porosity that developed from corrosive burial fluid flow along fracture networks. These features appear to be related to the sites of major margin and upper slope collapse based on relationships observed in sequential horizon slices.

The integration of these new seismic observations with concepts from outcrop analogs, well logs, and production data will improve aspects of the next generation geological models, including the sequence stratigraphic framework, lithofacies distributions, and the population of fractures and cavernous porosity. In particular, better understanding of the distribution of the potential high porosity and permeability anomalies defined from seismic will greatly impact development and drilling decisions.

 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California