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Dalman, Rory1, Marinus Eric Donselaar1, Tom Dreyer2, Stefan Luthi1, Gerrit Toxopeus1
(1) Delft University of Technology, Delft, Netherlands
(2) Norsk Hydro Research Centre, Bergen, Norway

ABSTRACT: Integrated Sedimentological and Forward Seismic Modelling of the Cook Formation (Oseberg field, offshore Norway)

The Early Jurassic Cook Formation (Oseberg field, offshore Norway) is the focus for a new integrated technique of detailed sedimentological and forward seismic modelling. The real pre-stack time-migrated seismic data show very specific but ambiguous features. By using only well data, several models can reasonably fit the data. In order to construct an unambiguous quantitative sedimentological model, the elements which produce the seismic features need to be understood. The new forward modelling technique uses a resolution function that allows very efficient simulation of migrated seismics. Compared to the commonly used 1D convolution method, the horizontal resolution is quantified in addition to the vertical resolution. The depositional setting, genetic types and large-scale geometry of the Cook Formation are derived from analysis of available cores, wire-line logs and seismics. The Cook Formation is an estuarine funnel-shaped infill with tidal and fluvial influences. Using regionally correlated sequences as a framework, a detailed facies model of the internal architecture was built with sedimentological data of the Gironde tidal estuary (SE France) as an analogue. Log-derived impedance values were assigned to the facies models and were subsequently used to create 2D simulated migrated seismics. Comparison with the real seismics shows promising results that warrant further evaluation of the geological data. The facies model resulting in the best fit of synthetic and real seismics will, therefore, produce a high-resolution approximation of the internal geometry and the intrinsic properties of the layers in the subsurface.

 

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.