October 31, 1975 - Gerald R. Ford Presidential Library and Museum

The Eugene Island Block 32 oil and gas field is located 15 miles offshore
from St. Mary Parish of southern Louisiana in 16-20 feet of water. The
location is 95 miles west southwest of New Orleans in the offshore
Miocene belt.
The producing formations consist of 21 separate sands in a thick Miocene
sand-shale sequence at depths from 6,400 to 12,800 feet.
The structure at Eugene Island Block 32 field is a slightly elongated dome
with an east wes.t axis. The dome was caused by deep seated salt intrusion.
The Jurassic Louann salt has been encountered at about 17,000 feet. There
are several northeast southwest faults that cross the field which, together
with partial withdrawal of the salt, have caused a series of graben blocks
over the center of the dome. The sands are overlain and underlain by shale,
and bottom water is present in most reservoirs. A tendency for some of the
sand members to shale-out provides additional reservoir delineation. There
are 17 productive and 4 depleted oil reservoirs occurring from 6,400 to 10,400
feet. There are six productive and three depleted nonassociated gas reservoirs
from 10,100 to 12,800 feet. The productive area of the field is 2,000 acres
(3 square miles).
Hydrocarbons originally in place were estimated by the volumetric analysis method.
The report is very well documented with structure and isopach maps as well
as with reservoir rock and fluid parameters for the important zones. The
study team, in some instances, could not determine the exact position of
the gas/oil contact in reservoir segments containing original gas caps.
The oil reservoirs produce with combinations of water drive and gas cap drive.
A water injection project is active in one reservoir and secondary recovery
reserves are indicated for five reservoirs. The nonassociated gas reservoirs
produce with combinations of pressure depletion and water drive.
Ultimate recovery and proved reserves at Eugene Island Block 32 field have
been estimated by determination of recovery efficiency factors based on
empirical methods, with adjustments based upon judgment of the study team.
The report mentions that there is a higher probability of the estimates
being optimistic than pessimistic. Furthermore, the report mentions that
the production of the proved reserves will require workovers, recompletions,
drill"ing of new wells, and secondary recovery projects--the economics of
which have not been considered. Again, the report states that recoveries
from some of the smaller reservoirs may be overly optimistic. The recovery
from the nonassociated gas reservoirs, producing with pressure depletion,
was determined from study of pressure data versus cumulative production
relationships.
The FEA report on the Eugene Island Block 32 field has been prepared by
the U.S. Geological Survey, Department of the Interior, under Interagency
Agreement CG-05-50059-00.
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