- Copyright © 2000 Society of Exploration Geophysicists
Note: Because some of the graphics presented are part of animations, it is difficult to demonstrate the robustness of visualization techniques in printed form. To remedy the paper limitations, a fully animated version of the visualization figures can be viewed at www.hampson-russell.com/consult5.htm.
It is well known that determining if something is anomalous requires the ability to identify what is ordinary or routine. This is very true in our “relative seismic science,” where we routinely talk about anomalies and anomalous responses. For AVO analysis, the routine or ordinary response translates to identification of the background trend. These background trends can vary greatly from basin to basin.
Although the particular AVO attributes used and the means of viewing them will vary from individual to individual, the common denominator in all prestack attempts to extract more lithology or pore fluid information from seismic data is predicated on the ability to identify a background response. Better identification of a background trend can be facilitated with AVO crossplot techniques that use, in particular, the common AVO attributes intercept (A) and gradient (B). Identifying the background trend on an A-B crossplot can be straightforward for model data or a small number of CDPs (say from a 2-D line or an arbitrary line or one to two in-lines). However, when examining the larger volumes of 3-D data typically encountered in exploration and exploitation geophysics, background trends can be more difficult to recognize because of the large number of points in a single crossplot plane. Removing or reducing the number of points through filtering does not necessarily improve the interpretability of the data and may introduce a bias. Removing the “scatter of points” might improve the clarity of the crossplot at the expense of eliminating geologic information. While we recognize the trade-offs involved in accurately determining the …