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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 57 (1973)

Issue: 9. (September)

First Page: 1837

Last Page: 1837

Title: Modern Wellsite Evaluation of Eocene Wilcox in Texas: ABSTRACT

Author(s): A. L. Schultz

Article Type: Meeting abstract

Abstract:

Present exploration efforts in the Eocene Wilcox of Texas are being conducted in areas with varied depositional environments and associated significant changes in sedimentary facies. The facies changes that most affect quantitative log interpretation are sediment size, sorting, and composition. Variable lithologic fabric and the wide range of connate waters present in the various intervals can cause difficult and unreliable interpretation when applying conventional methods for Sw and productivity Previous HitanalysisNext Hit.

Supplemental methods are used to (1) locate zones of interest, (2) gain an idea of whether hydrocarbon production can be expected, and (3) provide porosity and saturation information.

Zones of interest are detected by the Rxo/Rt Previous HitQuickNext Hit-Previous HitLookNext Hit curve as compared to the S.P. curve. Changes in connate water and/or shaliness do not affect this method. Zones so located are then analyzed by using the dual-induction data to verify productivity.

Finally, an Ro curve is obtained by positioning a density-derived formation-factor curve in water-bearing sands, aided by information gained by the Rxo/Rt Previous HitQuickNext Hit-Previous HitLookNext Hit curve. This permits verifying the constants needed for water-saturation evaluation. In the pay zones, both porosity and water saturation can be scaled off this overlay.

This simultaneous display for visual Previous HitanalysisTop, available on the basic resistivity log, provides a convenient way to compare the quality of the zones of interest. The interpretational aids are mutually supplemental and lead to significant improvements in formation evaluation.

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Copyright 1997 American Association of Petroleum Geologists