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Technical Tips: Tip #2

Working in the Frequency Domain - Spectral Decomposition

Spectral decomposition allows us to generate higher resolution in our seismic images. We can compare images from different frequencies to clarify geological relationships and illustrate subtle variations produced by reservoir heterogeneity and, thus, enhance our understanding of the reservoir.

Spectral decomposition is best applied to thinly bedded reservoirs, resolving channel, turbidite, and reef related plays by helping the geoscientist to recognize areas with similar physical characteristics that might be related to the geology.

Although spectral decomposition allows us to tune into specific frequencies to reveal zones with similar physical characteristics, these zones rarely tune at just one frequency. VisualVoxAt, Geomodeling's seismic interpretation software, allows you to visualize multiple frequencies using our color cube feature.

In the following figures, we will take you through an example of spectral decomposition and the color cube.



Figure 1. Spectral decomposition at 30 Hz allows you to visualize a channel feature. You can see the feature - it is not completely clear because parts of the channel are tuning at different frequencies.

Figure 2. This is the same channel feature illustrated in a color cube. The color cube allows you to visualize multiple spectral decomposition frequencies in the same volume. Note the detailed resolution of the entire channel. This color cube was computed on a strata-grid so that, as you scroll up and down through the volume, you will see many more details of the main channel and the smaller channels associated with it.



Figure 3. In the set-up for this color cube, one frequency in the red channel, one in the green, and a third in the blue allow you to see these different frequencies at which the event tunes. Semblance in the opacity channel allows you to see distinct channel edges and to see exactly where a better well placement will be.

Comments or questions? Please contact us at info@geomodeling.com - we look forward to hearing from you.