Seismic data: analyzing individual reflectors

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Exploring for Oil and Gas Traps
Series Treatise in Petroleum Geology
Part Predicting the occurrence of oil and gas traps
Chapter Exploring for stratigraphic traps
Author John C. Dolson, Mike S. Bahorich, Rick C. Tobin, Edward A. Beaumont, Louis J. Terlikoski, Michael L. Hendricks
Link Web page
Store AAPG Store

We can enhance our recognition of stratigraphic features by using seismic data attributes, reflection strength, coherence, and instantaneous phase. These attributes are well suited to stratigraphic interpretation and are an effective interpretive tool when displayed in map view.

Seismic data attributes

Seismic data attributes and their use in seismic facies analysis are listed in the following table.

Attribute Use
Reflection strength
  • Lithologic variation
  • Facies mapping
  • Porosity prediction
  • Thin-bed analysis
  • Character correlation
Instantaneous phase
  • Reflector configuration
  • Reflector continuity
  • Reflector terminations
3-D coherence

Reflection strength

Figure 1 A 3-D coherency slice of a Miocene channel complex in the Nile Delta, Egypt. From Wescott and Boucher;[1] courtesy AAPG.

Reflection strength is a measure of the total energy of a reflection, manifested in reflection amplitude. It is independent of phase. Reflection strength is also referred to as the instantaneous amplitude, or envelope amplitude. Analysis within specific reflectors can give us clues to changes in lithology or porosity.

Instantaneous phase

Instantaneous phase is an amplitude-independent attribute that highlights reflector continuity. It is useful for enhancing reflector terminations, particularly in areas with weak, low-amplitude events. Reflector terminations appear much clearer, which allows for an easier understanding of the geometry of individual packages of reflectors.

3-D coherence

Three-dimensional coherence is a measure of the similarity of neighboring seismic traces in 3-D data. It is useful for mapping paleogeomorphology and faults.[2]

Figure 1 is a 3-D coherency slice of a Miocene channel complex in the Nile Delta, Egypt.

See also

References

  1. ↑ Wescott, W. A., and P. J. Boucher, 1998, Paleohydraulic characteristics of Late Miocene–Early Pliocene submarine channels in the Nile Delta, Egypt: AAPG Bulletin, vol. 82, p. 695
  2. ↑ Bahorich, M., S., Farmer, S., L., 1995, 3-D seismic discontinuity for faults and stratigraphic features: the coherence cube: The Leading Edge, vol. 14, no. 10, p. 1053–58., 10., 1190/1., 1437077

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