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Petroleum Systems of Deep-Water Basins - Gulf Coast Section SEPM

Petroleum Systems of Deep-Water Basins - Gulf Coast Section SEPM

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Stratigraphic and Tectonic Framework <strong>of</strong> the DeSoto<br />

Canyon and Lloyd Ridge Protraction Areas,<br />

Northeastern <strong>Deep</strong> <strong>Gulf</strong> <strong>of</strong> Mexico: Implications for the<br />

<strong>Petroleum</strong> System and Potential Play Types<br />

David R. Pyles<br />

dpyles@emarc.colorado.edu<br />

Paul Weimer<br />

Renaud Bouroullec<br />

Energy and Minerals Applied Research Center<br />

Department <strong>of</strong> Geological Sciences<br />

University <strong>of</strong> Colorado at Boulder<br />

Boulder, Colorado 80309-0399<br />

Abstract<br />

The deep water northeastern <strong>Gulf</strong> <strong>of</strong> Mexico reflects one <strong>of</strong> the last frontier exploration areas in the U.S. <strong>Gulf</strong>.<br />

Analysis <strong>of</strong> 5860 km <strong>of</strong> 2-D seismic data over the deepwater DeSoto Canyon and Lloyd Ridge protraction areas<br />

allows us to evaluate the stratigraphic and tectonic framework <strong>of</strong> the area and relate that history to the petroleum system<br />

and potential play types.<br />

The stratigraphic framework <strong>of</strong> the study area is divided into five informal stratigraphic units. Each <strong>of</strong> them contains<br />

unique lithologies, stacking patterns and depocenter locations. The stratigraphic units are: (1) Middle Jurassic<br />

salt; (2) Upper Jurassic through lower Oligocene carbonates, including the Early Cretaceous carbonate platform; (3)<br />

upper Oligocene through middle Miocene clastic submarine fans within a base-<strong>of</strong>-slope depocenter; (4) upper<br />

Miocene progradation <strong>of</strong> the Mississippi fan within a slope depocenter; (5) Pliocene to present high sediment accumulation<br />

rate section within a base-<strong>of</strong>-slope and basinal depocenter.<br />

The tectonic history <strong>of</strong> the area is divided into six different time units, based on the type, amount and rate <strong>of</strong> tectonic<br />

activity: (1) Late Triassic through Late Jurassic: rifting, (2) Early Cretaceous: basin subsidence, (3) Late<br />

Cretaceous through early Miocene: gravity-driven, extensional-contractional system related to the Early Cretaceous<br />

carbonate platform, (4) middle Miocene: tectonic quiescence, (5) late Miocene: contractional system linked to up-dip<br />

extension and allochthonous salt deformation to the northwest, (6) Pliocene to present: minor salt diapirism.<br />

The petroleum system in the area involves the complex relationship between reservoir rocks, seal rocks, trap formation<br />

and evolution, salt history, source rocks, overburden rocks and petroleum generation, migration and<br />

accumulation history. The source rocks in the area are interpreted to be Oxfordian, Tithonian, Cenomanian, Turonian,<br />

and lower Eocene. The exact nature <strong>of</strong> the potential source rocks is unknown as no wells penetrate them in the study<br />

area. However, several petroleum seeps are located in the study area, signifying the presence <strong>of</strong> mature source rocks.<br />

Six play types are defined in the study area. They are: (1) Mesozoic structural play, (2) carbonate slope apron play,<br />

(3) middle Oligocene structural play, (4) post-middle Oligocene onlap play, (5) post-middle Oligocene structuralstratigraphic<br />

play, (6) shallow salt play. Each <strong>of</strong> these play types reflects discrete phases <strong>of</strong> the structural and stratigraphic<br />

evolution <strong>of</strong> the area.<br />

Economic issues related to production from this frontier province are heavily affected by ultra-deep water depths,<br />

lack <strong>of</strong> production infrastructure, oil quality issues, reservoir quality and potential field size.<br />

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