--> Systematic Wireline Log Predictions of Sequence Stratigraphic Units: A Case-Study from the Upper Pennsylvanian of Kansas, by W. L. Watney, G. C. Bohling, and J. H. Doveton; #90986 (1994).

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Abstract: Systematic Wireline Log Predictions of Sequence Stratigraphic Units: A Case-Study from the Upper Pennsylvanian of Kansas

W. Lynn Watney, Geoffrey C. Bohling, John H Doveton

High-resolution sequence stratigraphic analysis in subsurface studies relies heavily on interpretations from wireline logs to extend knowledge acquired from limited core data. However, sequence stratigraphers typically draw vague generalizations concerning shape, trends and values from SP, resistivity and gamma-ray logs that are starkly contrasted with their use of detailed geological observations and interpretations from core or outcrop. Contemporary logging suites routinely record continuous measurements that reflect both geochemical and mineral composition. Results presented here indicate that logs can also be used to systematically distinguish sequence components using the numerical information, once they are properly calibrated to cores.

In an exploratory case study, lithodensity-neutron and spectral gamma ray measurements were related to the sequence stratigraphic framework interpreted from a 330-meter core taken from a succession of Upper Pennsylvanian carbonate-dominated sequences in southwestern Kansas. The log values of the depositional facies, including paleosols, flooding units, condensed sections and late high-stand deep-water, peritidal and subtidal carbonate units were represented as data clouds in a six-log variable space. The cloud data-point densities were enumerated on a neural lattice framework and used for classification of facies by Bayesian probability methods.

The procedure is an interactive learning process which integrates core and log data in a consistent manner that is easily intelligible to the traditional geologist. The final classification based on probabilities and recognition of facies shift surfaces can then be applied to the sequence stratigraphy of equivalent successions that are logged but not cored.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994