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Process-Based Modeling of Aptian Turbidites in the Buchan Graben, Outer Moray Firth, UK North Sea

Aas, Tor E.1; Howell, John 1; Janocko, Michal 1; Jackson, Chris 2
1 of Earth Science, University of Bergen, Bergen, Norway.
2 Royal School of Mines, Imperial College, London, United Kingdom.

Process-based forward modeling of turbidity currents is a powerful approach for predicting the distribution of reservoir sands and can be used for hydrocarbon exploration in a variety of settings. The distribution of sand that results from the modeling is highly sensitive to the shape of the seafloor and initial parameters defined for the turbidity currents, such as height, width, sediment concentration, fluid density and velocity.

The turbidites of the Aptian aged Britannia Sandstone Fm of the Buchan Graben, Outer Moray Firth, UK North Sea, were axially transported along the ENE-WSW trending Kopervik fairway. The sands are up to 160 m thick and cover 600 km2 of the basin. Processed based modeling of the turbidites was undertaken to match the observed distribution of sand and predict sand extent and pinch-out.

A key part of this modeling was the re-creation of the Aptian paleobathymetry. The sands, which are currently buried to c.3000 m have been subjected to post depositional, tectonic deformation. In order to remove the effects of compaction and the deformation a 3D model comprising key stratigraphic and structural surfaces was generated and subsequently backstripped of overburden and structurally restored.

The re-creation of paleobathymetry is associated with uncertainties, which results in a range of paleobathymetric surfaces. Three of these re-created paleobathymetric surfaces were used as input for turbidity modeling. The resulting sand distributions were compared to the available well data and indicate that: 1) realistic distributions can be created; 2) input parameters used during the re-creation of palaeobathymetry can significantly shift the main focus of sand distribution.

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009