VYSSOTSKI, ALEXEI V.¹ and DAVID B. ROSENTHAL^2
1Rice University, Houston, TX
²Pennzoil Exploration and Production Company, Houston, TX

Abstract: Depositional Model of Upper Miocene Shelf Margin Deposits in Eastern South Marsh Island and Western Eugene Island Areas, Offshore Louisiana

A high resolution sequence-stratigraphic study was conducted on the upper Miocene section of eastern South Marsh Island and western Eugene Island areas. The study area provides a superb opportunity to analyze shelf edge and slope depositional environments.

Paleontological data were used to identify the location of the paleoshelf break during the upper Miocene. Depositional fairways were recognized using isochron thickness maps, seismic facies analysis, seismic amplitude attributes, and well log character. A large number of wells support location and orientation of the depositional fairways in the area.

Migration of the shelf edge due to relative sea level change produced a complex facies architecture consisting of upper bathyal deposits and middle to outer neritic deposits. Structural highs created by salt diapirism redirected sediment fairways and, in some cases, oriented them in a direction parallel to shelf edge. Gravity flows add complexity to the stratigraphic succession.

Hydrocarbon discoveries in the area were made in channels, channel/levee complexes and upper slope fan deposits. High resolution studies of paleo-shelf edge depositional environments can provide more accurate reservoir prediction.

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