Geology Reference
In-Depth Information
Dip-Sequence Analysis
9.1
Introduction
The three-dimensional geometry of a structure can be determined from the bedding
attitudes measured in a single well bore or on a traverse through a structure. The method
of dip sequence analysis presented here was developed for the structural analysis of
dipmeter logs by Bengtson (1981a) but is equally informative whether the traverse is
down a well or along a stream. Major problems with the structural interpretation of
dip data are the high stratigraphic noise content and the complexity of the structures
to be interpreted. Dip sequence analysis techniques, called Statistical Curvature Analysis
Techniques (SCAT or SCAT analysis) by Bengtson (1981a), are particularly good for
extracting the structural signal from the noise. Using SCAT it is possible to determine
the plunge of folds, the locations of fold axial surfaces, crests, and troughs, to infer the
strike and dip directions of faults, and to separate regional fold trends from local fault
trends. The power of the technique derives from (1) the noise-reduction strategy of
examining the data as dip components in both the strike and dip directions of folding
and (2) providing models for the SCAT responses of the geometry to be interpreted.
Fig. 9.1. Railroad Gap Field, California, predicted longitudinal and transverse cross sections and struc-
ture contour map on the top Carneros sandstone, based on the SCAT analysis of a single well at the crest
of the anticline. O/W: oil-water contact. (After Bengtson 1981a)
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