--> Abstract: Stratigraphy of Pleistocene Upper Slope Sands in the Green Canyon Block 184 Federal Unit, Gulf of Mexico, by D. J. Cook, M. E. Richards, and W. D. Edelman; #91012 (1992).

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ABSTRACT: Stratigraphy of Pleistocene Upper Slope Sands in the Green Canyon Block 184 Federal Unit, Gulf of Mexico

COOK, DOUGLAS J., MATTHEW E. RICHARDS,* and WILLIAM D. EDELMAN, Conoco, Inc., New Orleans, LA

The Green Canyon Block 184 Federal Unit lies 100 mi offshore Louisiana, off the present-day shelf edge on the upper continental slope. During Pleistocene glacial lowstands, sediments cascaded down multiple feeder channels to form coalescing fans in interdomal slope basins. Up to 25,000 ft of Pleistocene sediment was deposited in less than 3 m.y. in the four main salt withdrawal basins in the unit.

Sequence stratigraphy of the area integrates well data with 3-D seismic. Fining-upward graded beds based with cobble-sized shale clasts are evidence for high energy gravity flow deposits. Seismic sequence boundaries correlate to interglacial shale intervals with paleontologic evidence for warmer seas and a fossil-rich condensed section. Stacked reservoir-quality sands are coincident with glacial sea level lowstands. Reservoir sand packages are generally fining upward and do not fit classic basin floor fan models. Well cross sections and 3-D seismic sections demonstrate upper slope fan and channel morphology. Seismic amplitude maps delineate sand depositional trends and facies relationships within fan lobes. Amplitude maps and stratigraphic dipmeter interpretation have been used to con train reservoir net maps in the Federal Unit.

Reservoir sands are medium to most commonly very fine grained litharkoses. Shale laminations greatly reduce vertical permeability. Horizontal permeabilities average around 100 md, but range up to 3000 md. Reservoir heterogeneity and faulting resulting from tectonism generally limit reservoirs to depletion drive. Individual well rates in excess of 2000 BOPD have been sustained in the Jolliet and Marquette fields in the Federal Unit.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)