Print this pageThe Use of Spectral Recomposition in Tailored 3-D Forward Seismic Modeling of Outcrop Analogs
Spectral recomposition, an improved methodology for generating three-dimensioinal forward seismic models of outcrop analogs, makes use of the full range of frequencies found within real-world seismic volumes. It overcomes the issue common to most current forward seismic modeling processes in which single peak frequencies are usually modeled, with the resultant models not capturing low or high frequency content that is found in the real world image. This variable frequency content of real-world seismic volumes has long been known to contain more detailed information within different spectral bands; this forms the basis of the spectral decomposition process, in which different spectral frequencies can correlate to different stratigraphic thicknesses, for example.
In this presentation, we introduce and illustrate the use of a new method, termed "spectral recomposition." Spectral recomposition is a post-stack method operating in the frequency domain. The frequency spectrum of a real-world seismic image, windowed around the reservoir of interest, is extracted, and the individual frequency peaks identified. Single frequency 1-D convolution and 3-D exploding reflector forward seismic models are generated for a high-resolution 3-D geological model of an outcrop analogous to that reservoir. These forward seismic models generated at separate peak frequencies are recomposed to derive a final image which has a frequency spectrum similar to that of the target real-world image. Using this method, 3-D forward seismic models of outcrops can be tailored to specific real-world images, and a more appropriate comparison made between the known outcrop geometries and those that are imaged in the subsurface.
As these forward models are fully three-dimensional seismic volumes, they can be interpreted and interrogated in the same way as real-world images, including the use of seismic attributes and spectral decomposition. This enables a greater degree of knowledge transfer from the outcrop analog to the real-world seismic image.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009