3D geologic modelling of channelized reservoirs: applications in seismic attribute facies classification

Geological models are usually used qualitatively in seismic interpretation. This paper illustrates that quantitative representations of detailed geological models can significantly enhance seismic attribute interpretation through facies classification. When applying seismic attribute classification to reservoir facies mapping, one often faces such typical questions as:

  • Which attributes should be used as input to classification?
  • How many classes should be used in the unsupervised classification method?
  • How many levels of hierarchy should be selected in the hierarchical classification method?
  • Does the seismic facies correspond to the geological facies?
  • How can attribute-derived facies models be validated?

There are no unique and easy answers to the above questions. In this study, we aim to create a more accurate representation of the reservoir by using 3D synthetic Earth models to guide seismic attribute classification. We consider a channelized reservoir for which seismic attribute analysis has proven to be very useful, but results can be difficult to interpret. The next section describes a 3D stratigraphic modeling approach for the channelized reservoir. The major channel components and parameterizations are illustrated with examples. This is followed by a summary of seismic attribute analysis and classification workflow applied to a synthetic seismic volume. Results of attribute classifications using a self-organized map (SOM) (Kohonen, 1989) and waveform correlation maps are compared in relation to different input attributes and classification parameters. The lessons learned from this synthetic example are summarized and the selection of attributes for facies classification is discussed.

Renjun Wen, Geomodeling

Published in First Break December 2005

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