Eugene Island Block 330 Field: an Update

David S. Holland, David R. Lammlein, John B. Leedy

The Eugene Island Block 330 field ranks third in cumulative hydrocarbon production on the federal Outer Continental Shelf of the United States and at peak production was the largest O.C.S. oil-producing field. This giant field, located offshore Louisiana, covers parts of seven blocks in the Eugene Island area, South Addition. The field was discovered by the Pennzoil 1, OCS-G 2115 well, in March 1971. Production commenced in September 1972, only 20 months after leasing in December 1970. Ten production platforms have been set in the field. Cumulative production is over 250 million bbl of liquids and 1.24 tcf of gas. Estimated recoverable reserves are 307 million bbl of liquid hydrocarbons and 1.65 tcf of gas.

The field is a faulted, rollover anticline structure on the downthrown side of a large growth fault. Production is from more than 25 Pleistocene, delta-front sandstones sourced by deeply buried pre-Pleistocene shales. Trapping mechanisms are combinations of structural and stratigraphic varieties including four-way dip closure, fault closure, and facies changes. Over 100 separate oil and gas reservoirs occur with a complex spatial distribution. Reservoir energy results from a combination water-drive and gas expansion system.

The field has experienced several phases of exploration and development. Initial mapping utilized reconnaissance seismic and lithofacies data. Over time, the data base has expanded to include 258 exploratory and development wells and three-dimensional seismic surveys. Ongoing evaluation has continually refined our geologic understanding and, although the field is mature, exploration and development continue.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.