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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 68 (1984)

Issue: 4. (April)

First Page: 516

Last Page: 516

Title: New Ulm Previous HitFieldNext Hit: An Previous HitExampleNext Hit of Cretaceous Shelf-Slope Instability in East Texas: ABSTRACT

Author(s): Edwin Pinero


The New Ulm Previous HitfieldNext Hit in Austin County, Texas, is an Previous HitexampleNext Hit of the structural and stratigraphic complexity above the Cretaceous Edwards shelf margin of east Texas. Deep wells and improved seismic Previous HitdataNext Hit provide documentation of structural patterns and deepwater facies not previously considered in Gulf Coast reservoir play modeling.

Study of the Previous HitdataNext Hit implies the Late Cretaceous to Eocene section was deposited along a shelf-slope break. Late Cretaceous, pre-Midway sedimentation was affected by structurally induced slope instability, and consequent gravity faulting and slumping resulted in an irregular sea-floor surface. Paleocene Midway sands were carried onto this surface by storm-generated density currents where the uneven topography caused deposition in constructional channels. Continued deposition of the fluvio-deltaic Wilcox on this surface caused faulting and folding by differential compaction. The folds are minor and the faults small and steep, not like the typical large growth faults of the Gulf Coast. Upper Wilcox sediments were progressively less disturbed as the region stabilized.

New Ulm Previous HitfieldNext Hit production includes gas from the Midway Formation and oil and gas from the Wilcox Group. Midway reservoirs are stratigraphic, consisting of turbidite channel sandstones; Wilcox reservoirs are structural, consisting of fluvio-deltaic sandstones within faulted anticlines.

This study adds evidence to Previous HitdataTop describing shelf-slope geology along the Edwards margin. The setting can be a new type of hydrocarbon play in the Gulf Coast.

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