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

The Brown-Bassett gas field is located in Terrell County, Texas, in
the Val Verde Basin.
The principal producing formation is the Ellenburger dolomite of
Ordovician agr.. The Ellenburger reaches about 1,500 feet in thickness
at Brown-Bassett and is encountered at a depth of about 14,000 feet.
There are minor amounts of gas in the Silurian, Pennsylvania-Strawn,
and Permian-Wolfcamp Formations.
The structure at Brown-Bassett is a highly faulted anticline. Bottom
water controls the lower limits of production. The Ellenburger productive
area is about 18,000 acres (28 square miles).
The bottom water in the Ellenburger appears limited in its activity
and the gas is believed to be produced through the process of pressure
depletion. The raw gas produced is about 54 percent C02 by volume.
Ultimate recovery and gas originally in place were estimated by extrapolating
a pressure data versus cumulative production trend to an
abandonment reservoir pressure of 500 psia and to a pressure of absolute
zero respectively. The study team encountered several problems
in this analysis which could affect the results. The highly faulted
nature of the Ellenburger structure seriously restricts pressure
communication throughout the field. The average pressure trend for
the reservoir does not extrapolate backwards to the correct original
pressure--the difference being 1,300 psia or about 20 percent.
Accordingly there is some risk that the incorrectly positioned line
might not extrapolate forward to the correct ultimate recovery.
Finally there is a problem of water production in the Ellenburger
gas stream, which was not investigated because of time restrictions.
The FEA report on the Brown-Bassett Field was prepared by the U.S.
Bureau of Mines, Department of Interior, under Interagency Agreement
CG-05-50058-00.
20