--> Abstract: Methodology for Minibasin Ranking in the Deepwater Gulf of Mexico, by A. Koch, V. Mathur, R. Nagy, and F. Snyder; #90923 (1999)

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KOCH, AL,VINOD MATHUR, RICK NAGY,* and FRANK SNYDER

Abstract: Methodology for Minibasin Ranking in the Deepwater Gulf of Mexico

Deepwater northern Gulf of Mexico is characterized by extensive allochthonous salt sheets with isolated minibasins.Assessing the exploration potential of these minibasins requires an integration of all the petroleum systems elements.An analysis of minibasins in the Garden Banks, Green Canyon, Keathley Canyon and Walker Ridge protraction areas shows the relationship of stratal and structural architecture to the interaction of sedimentation and salt movement. Minibasins are broadly classified using stratal and allochthonous salt geometries into five basin types: (1) Ramp, (2) Welded, (3) Welded Listric, (4) Primary, and (5) Salt-floored. Basins that lack data for classification into the five types are carried as unclassified. The five basin types vary in their efficiency to collect and trap hydrocarbons, ramp basins being the most effective and salt-floored the least.

Ramp basins predominate on the slope in Garden Banks and Green Canyon.They are characterized by a south-bounding, north-dipping salt ramp. Most ramp basins have young thick depocenters adjacent to the counter regional ramp. Ramp basins tend to be asymmetric and larger in areal extent.Welded basins were previously underlain by allochthonous salt that has been fully or partially evacuated. They increase in frequency southward into the Walker Ridge and Keathley Canyon protraction areas. Welded listric (Roho) basins have south-dipping arcuate faults that sole into the evacuating salt.Welded basins have a multitude of patterns of internal faulting and sediment fill, some are symmetrical with bowl-shaped fill, others have multiple depositional axes and bi-directional stratal fill. Primary basins show no evidence of allochthonous salt and display continuous sedimentary fill from Cretaceous to Recent. Salt-floored basins are underlain by continuous allochthonous salt which shields them from the underlying petroleum kitchens. Salt-floored basins occur along the down dip edge of allochthonous salt near the Sigsbee escarpment and above very young salt sheets in Garden Banks and Green Canyon.

AAPG Search and Discovery Article #90923@1999 International Conference and Exhibition, Birmingham, England