Use of Spectral Decomposition Data in a 3d Geomodel of OMV Operated Gas Field

Volker Otto, Erwin Rieser, Muhammad Ibrahim, Thomas Kuffner, and Helmut Rüppel
OMV Exploration & Production GmbH, Vienna, Austria

Spectral Decomposition (SD) is a seismic attribute where frequency cubes instead of time volumes are generated. Making use of the characteristic tuning frequency for each thickness, SD data represent a qualitative thickness measure. This methodology is known in the E&P industry since roughly a decade. However, it has not been widely established as part of a standard seismic interpretation workflow or in 3D reservoir modeling.

This study underscores the value of SD data especially as to how subtle geologic features as e.g. slope canyons can be made visible and in raising the vertical resolution to a subseismic thin bed scale. Moreover, composite plots of RGB-colored frequency bands provide an overview on the spatial distribution of reservoir bodies.

A conceptual integrated approach is presented where SD data have been combined with additional seismic attributes as Acoustic Impedance resulting in an innovative first-order porosity-thickness map. It is commented on how to theoretically calculate absolute thickness from SD frequency data and likewise on the calibration of SD with petrophysical data. Such procedure can lead to a more meaningful, rather semi-quantitative interpretation of a SD data set within the frame of a 3D static geomodel.
It is concluded that SD can provide a relatively fast methodology that adds to reservoir characterization and thus to positioning new production wells at comparably low costs.

AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery