IAMG 2001--Cancún Technical Program--Session J

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Wireline Logs for High-Resolution Subsurface Stratigraphy by Ricardo A. Olea, Jorgina A. Ross, John C. Davis, David R. Collins, Daniel F. Merriam, and W. L. Watney, Kansas Geological Survey, USA Computer correlation and computing mapping systems are used to prepare a cross-section displaying stratigraphic correlations from well to well along a 202 mile (323 km) traverse from northwestern Kansas to south-central Kansas near the Oklahoma border. The correlations are denoted by a color-coded line from each point in a well to the correlated point in the adjacent well. The color coding indicates the amount of shale in the interval, based on the response of the gamma-ray logs. Correlations are based on the petrophysical characteristics of the correlated intervals, using well log traces digitized on a 6-inch spacing. Correlations have been determined by a computer program that finds the greater similarity between intervals in one well and intervals in a second well, then uses artificial intelligence to select the most feasible correlations according to stratigraphic principles. Once a pair of wells is correlated from top to bottom, the process moves to the next pair in the traverse, repeating the correlation process. After all wells along the line of section have been correlated, key stratigraphic intervals are identified and traced throughout the extent of the cross-section. During the construction of the cross-section, numerous checks on reliability and consistency are made by back correlating and by correlating in loops in the same manner that surveyors check for closure. After completion of the correlation process, results were thoroughly checked against preexisting information about the subsurface geology of Kansas.