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

The West Cote Blanche Bay oil and gas field is located in West Cote
Blanche Bay, St. Mary Parish in extreme southern Louisiana. The
field is 65 miles south of Baton Rouge in the onshore Miocene Belt.
The producing formations are sands in a thick sand-shale sequence of
Pliocene and Miocene age. Depths to the sands range from 1,400 to
10,200 feet.
The structure at West Cote Blanche Bay is related to a shallow piercement
type salt dome. The shallowest salt is at about 7,700 feet.
There are numerous faults associated with the field and over 200
separate reservoir segments are believed to exist. Some reservoirs
are superdomal and are related entirely to the anticlinal structure.
Other reservoirs are controlled by truncation of the sands by salt or
shale as the salt intruded. Some sands pinch out stratigraphically
as deposition approaches the salt mass. Faults and bottom water also
delineate the accumulations in most instances. The field has about
2,860 productive areas (4 square miles).
Hydrocarbons orig'inally in place at West Cote Blanche Bay were estimated
by means of a "broad" or 'coarse II volumetric analysis. A sampling
of logs was examined to determine net oil and gas sand thickness and
a composite isopach map was prepared. Average reservoir and fluid
characteristics were selected.
The predominate recovery mechanism is a water drive. Also there are
eleven active water floods, all of which have been in operation long
enough to be assessed. The field has been on production decline since
1971. The proved reserves have been estimated by analysis of production
history and by analogy with overall performance characteristics
of water drive reservoirs. The specific manner in which the shut-in
reserves were estimated was not mentioned in the report. Presumably
a method similar to that described in the Bay de Chene field summary
was followed.
The FEA report on the West Cote Blanche Bay Field was prepared by
Keplinger and Associates, Inc., under Contract No. CO-05-50l84-00.
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