Spider Maps: Linking Structural Subtleties to Stratigraphic Intervals

By

Nicholas K. Boyd and Ronald C. Surdam

Innovative Discovery Technologies, Laramie, WY

In the mapping of reservoir intervals using 3-D seismic data, the identification of localized faulting and fracturing is important for understanding the internal architecture of the reservoir. Recently, statistical summaries of seismic attributes and the Hilbert transform of the seismic trace have gained popularity as tools for this mapping. These attributes identify stratigraphic features that are too subtle to be easily observed in the seismic data.

The use of trace-to-trace similarity is a statistical summary method that identifies both stratigraphic and structural features. When used for structural mapping, trace-to-trace similarity identifies not only major faults, but also less obvious internal faulting and fractures. Flattening on a horizon to minimize the effects of regional dip in the similarity calculation, followed by the similarity calculation creates a volume of data where each slice is a chrono-stratigraphic measure of similarity. By picking the dissimilarities on multiple slices through an interval of interest, a map is created that shows features most likely associated with faults and fractures in the interval.

Discounting those events associated with regional faulting creates a clearer picture of internal faulting and fracturing. These maps of faulting and fracturing can then be superimposed on other attribute maps to help clarify the relationship between structural and stratigraphic elements in the interval. Examples of this technique are from datasets in the Wind River and Greater Green River basins.

AAPG Search and Discovery Article #90004©2002 AAPG Rocky Mountain Section, Laramie, Wyoming