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Abstract: Regional Setting of Petroleum Producing Turbidite Systems, Northern Deep Gulf of Mexico

Weimer, Paul- University of Colorado

The petroleum producing Neogene turbidite systems in the northern deep Gulf of Mexico consist of four main elements that have characteristic stratal geometries based on wireline logs, 2-D and 3-D seismic, biostratigraphy, and cores. Depositional lobes (basins-floor fans) are characterized by roughly circular amplitude anomalies that onlap the flanks of the mini-basins. Sands tend to be well developed and blocky in log shape (50 to 150 feet thick). These sheet-like sands have good lateral continuity, and have the highest production rates. Channel deposits have parallel to hummocky reflections. On 3-D horizon slices, they consist of sinuous high and low- amplitude anomalies, reflecting both erosional and depositional channels. Channel widths are 0.5 to 1.2 miles, and channel-fill varies between 20 to 150 feet of sand and mud. Overbank deposits are dominantly muddy, and have laterally continuous low to moderate amplitude reflections. Slides have chaotic to mounded reflections; on 3-D they have an arcuate to discontinuous shape.

In the lower to middle bathyal settings, the sedimentary fill in these intraslope basins have a distinct evolution. Sheet sands and/or erosional channels overlie the sequence boundary. Erosional channels are interpreted to act primarily as a conduit for coarser grained sediments that bypass farther downslope. Overlying that are sinuous, depositional channels that regularly shifted their positions in the mini-basins by avulsion. These channels, and associated overbank deposits comprise the bulk of the sediment in any sequence.

AAPG Search and Discovery Article #90933©1998 ABGP/AAPG International Conference and Exhibition, Rio de Janeiro, Brazil