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Abstract: Chronostratigraphic Hydrocarbon Plays and Depositional Styles in the Northern Gulf of Mexico

Steven J. Seni, Jeff Brooke, David Marin, Eric Kazanis

Sand-body reservoirs in the Federal OCS of the northern Gulf of Mexico were classified into 98 chronostratigraphic plays by style, structural style, and engineering parameters. Cumulative gas production is apportioned to three primary depositional styles: progradational (65%), submarine fan (16%), and aggradational (12%). In contrast, cumulative oil production is distributed primarily as progradational (58%), aggradational (23%), and submarine fan (16%). On the continental shelf, progradational environments are hydrocarbon rich owing to favorable sandstone-to-shale ratios and traps over salt structures and faulted anticlines. Submarine fan plays dominate downdip of the modern shelf edge. Remaining recoverable gas reserves for progradational (48%), submarine fan (28%), and aggradational (16%) reveal a decline of progradational plays and an increase of submarine fan plays. Average porosity varies between fan plays (26%), progradational plays (29%), and aggradational or retrogradational plays (28%) (statistical significance, 85% to 98%), in part as a function of play depth, which is greatest for submarine fan plays (11,631 ft). Average pay thickness of fan (45 ft) and retrogradational (34 ft) plays is higher than that of aggradational and progradational plays (31 ft) (statistical significance, 85% to 99%).

Proved hydrocarbons are unequally distributed within chronozones in the Gulf. Forty-two percent of the original recoverable oil is concentrated in two chronozones--the lower Pleistocene Lenticulina 1 to Buliminella 1 (22.8%) and the upper Miocene Bigenerina A to Cristellaria K (20.4%). Gas is more uniformly distributed. Of the original recoverable gas, 29% exists in two chronozones--the lower Pleistocene Lenticulina 1 to Valvulina H (18.6%) and the upper Pleistocene Hyalinea balthica to Sangamon (10.6%). New discoveries will probably be made in submarine fan plays in Pleistocene to Miocene strata on the slope and in Miocene and older fan facies on the shelf.

AAPG Search and Discovery Article #90955©1995 GCAGS 45th Annual Meeting and Gulf Section SEPM, Baton Rouge, Louisiana