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

The South Pass Block 65 oil field is about 25 miles east of the mouth
of the Mississippi River in the Gulf of Mexico. Water depth is about
300 feet. The field lies within the Pliocene belt of offshore
Loui s iana ..
The productive sands are Pliocene in age and range from 6,500 to 8,500
feet in depth. There are ten or so sands in the F, G, and H ser1es.
They range from very fine to fine grained and from clean to very shaley.
Most of the sands are deltaic river mouth deposits, but some are
localized channel sands.
The structure at South Pass Block 65 is caused by a fairly circular
deep-seated shale dome. There are numerous normal faults. The accumulations
are controlled by the structure, by faults, and by bottom
water. One of the principal accumulations is a channel sand which is
stratigraphically controlled. There are eleven sands in nine fault
blocks or sub segments. Of the total 26 recognized separate reservoir
units, 19 are producing, one is shut-in, and six are untested. Over 80
percent of the reserves are in four principal segments. The productive
area is 2,600 acres (4 square miles). Eighty-five wells have been
drilled from two platforms for 103 zonal-completions.
The hydrocarbons originally in place were calculated using the volumetric
method. This requires careful structural and isopach mapping
and analyses of core and logging data. These requirements apparently
have been met.
One of the major zones and one of the minor zones had original gas caps.
All of the other reservoir segments appear to have been undersaturated.
The primary oil recovery mechanism in most of the reservoir segments
was a water drive; however, the extent of water encroachment was not
sufficient to maintain pressure. A few of the reservoir segments,
including the channel sand segment were sufficiently isolated from an
active aquifer that the primary recovery mechanism was classed as
pressure depletion and dissolved gas drive. Pressure is being maintained
by water injection into most all of the reservoir segments,
including all of the important ones.
Ultimate oil recovery at South Pass Block 65 is estimated at 45 percent
of the oil originally in place. About 60 percent of the ultimate
recovery has a'l ready been produced. Mos t of the reservoi r segments
are experiencing oil production decline. The recovery efficiency of
gas is estimated at 54 percent of the gas originally in place.
The FEA report on the South Pass Block 65 Field was prepared by the
U.S. Geological Survey under Interagency Agreement CG-05-50059-00.
150
r.