--> Abstract: Fan Fringe Reservoir Characteristics Of Fine-Grained Turbidite Systems, by A. H. Bouma and H. D. Wickens; #90928 (1999).

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BOUMA, ARNOLD H.1 and H. DeVILLE WICKENS2
1Louisiana State University, Baton Rouge, LA
2Consultant, Cape Town, South Africa

Abstract: Fan Fringe Reservoir Characteristics of Fine-Grained Turbidite Systems

Side-scan sonar images, high-resolution reflection seismics, and piston and gravity cores from the outer fringe of the Mississippi Fan result in the logical conclusion that the entire fan is controlled by channels. Sand would have been transported through channels and distributaries with deposition of sand in the levee-overbank areas. Cores reveal a mud fill of the channels. The above suggests that the outer sheet sand deposits (depositional lobes) are comprised of "finger-like" sands that have no lateral connectivity because of the channel muds.

Outcrop studies on the Permian Tanqua Karoo finegrained turbidite systems suggest another interpretation. Thickening-upward successions in the distal areas show that an upper thick layer, with parallel contacts, has a number of shallow depressions in its upper sandstone-shale contact. These can be interpreted as the contact zones where depositional finger sands onlap onto one another. This example shows that the onlapping sandstones form an extensive reservoir with good lateral connectivity.

Both types of investigations have their shortcomings. The observations on the Mississippi Fan only investigate the upper part of the fan: i.e. the waning phase of the depositional cycle. The Tanqua Karoo studies lack the horizontal axis of the third dimension, making the term "finger" interpretive. Combining both types of investigations offers a warning to subsurface investigators that either more than one interpretation can exist or that both lack sufficient information to be applicable. Integration of different data sources, therefore, is necessary.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas