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Outcrop Analogs for Reservoir Characterization and Modeling of Smackover Microbial Reefs in the Northeastern Gulf of Mexico Area

E. A. Mancini and W. C. Parcell
Center for Sedimentary Basin Studies and Department of Geological Sciences, University of Alabama, Tuscaloosa, AL

Upper Jurassic (Oxfordian) Smackover reef buildups in the Northeastern Gulf of Mexico consist primarily of shallow-water thrombolitic microbolites that develop on hardgrounds or rockgrounds associated with Paleozoic basement features. These microbial buildups are typically associated with late transgressive to early highstand systems tracts deposits and range from 10 to over 100 feet in thickness. Because the Smackover strata are not exposed at the surface in this region, determination of the geometries and extent of these buildups, which are critical to developing hydrocarbon exploration and development strategies for these reservoirs, is difficult.

Upper Jurassic (Oxfordian and Kimmeridgian) microbial buildups are exposed in western Europe where they are also associated with late transgressive to highstand systems tracts deposits. In France, these microbial reefs have been observed in outcrop to consist of layered to dendroidal thrombolitic buildups that generally do not exceed 10 feet in thickness. In Portugal, microbial reefs consist primarily of thrombolitic buildups that attain thicknesses in excess of 100 feet. These buildups are associated with hardgrounds and occur in early highstand systems tracts deposits.

The use of Upper Jurassic microbial reef outcrops in Europe to characterize and model the Smackover reefs in the subsurface of the Northeastern Gulf of Mexico greatly facilitates the design of hydrocarbon exploration and development strategies for identifying and delineating Smackover microbial reefs through 3-D geologic and seismic modeling.

AAPG Search and Discovery Article #90901©2001 GCAGS, Annual Meeting, Shreveport, Louisiana