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Abstract: Gulf of Mexico Oil and Gas Atlas Series: Chronostratigraphically Bound Reservoir Plays in Texas and Federal Offshore Waters

Steven J. Seni, Bruce A. Desselle, Allan Standen

The search for additional hydrocarbons in the Gulf of Mexico is directing exploration toward both deep-water frontier trends and historically productive areas on the shelf. The University of Texas at Austin, Bureau of Economic Geology, in cooperation with the Minerals Management Service, the Gas Research Institute, and the U.S. Department of Energy, is responding to this need through a coordinated research effort to develop an oil and gas atlas series for the offshore northern Gulf of Mexico. The atlas series will group regional trends of oil and gas reservoirs into subregional plays and will display graphical location and reservoir data on a computerized information system. Primary defining attributes for plays include chronozone, depositional style, structural style, hydrocarbon typ , and reservoir properties. Play methodology includes constructing composite type logs with producing zones for all fields, identifying progradational, aggradational, and retrogradational depositional styles, and displaying geologic data for type fields. Deep-water sand-rich depositional systems are identified separately on the basis of faunal ecozones, chronostratigraphic facies position, and log patterns.

To date, 4 Oligocene, 19 lower Miocene, and 5 upper Miocene plays have been identified in Texas state offshore waters. Texas state offshore plays are gas prone and are preferentially trapped in rollover anticlines. Lower Miocene plays include deep-water sandstones of Lenticulina hanseni and jeffersonensis;

progradational sandstones of Marginulina, Discorbis b, Siphonia davisi, and Lenticulina; transgressive sandstones associated with a barrier-bar system in the Matagorda area; and transgressive sandstones below Amphistegina B shale. Particularly productive gas-prone plays are progradational Siphonia davisi, shelf-margin deltas in the High Island area, and progradational Marginulina shelf and deltaic sands in association with large rollover anticlines in the Matagorda Island and Brazos areas.

AAPG Search and Discovery Article #90983©1994 GCAGS and Gulf Coast SEPM 44th Annual Meeting, Austin, Texas, October 6-7, 1994