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

The Tijerina-Cana1es-B1ucher (T-C-B) oil and gas field is located in
Jim Wells and K1eberg Counties of South Texas. The field is in the
onshore Oligocene belt of the Texas Gulf Coast 45 miles southwest of
Corpus Christi.
The producing formations are loosely consolidated sands of the Frio
and Vicksburg series of the Middle and Lower Oligocene age. The
depth ranges from 5,500 to 11,000 feet.
T-C-B is an anticlinal structure with a north-south axis. The field
is separated from the See1igson Field to the north by a unit boundary.
The productive area is 6,800 acres (11 square miles). The structure
is relatively unfau1ted. The sands are highly lenticular. There
are many shale-outs. Over 72 reservoirs are believed to exist. The
report treats 12 different nonassociated gas entities and 6 different
oil reservoir groupings in the producing category and 12 shut-in
nonassociated gas reservoirs.
Hydrocarbons originally in place were calculated by the volumetric
analysis method. The report is well documented with structure and
isopach maps, as well as with listings of reservoir rock and fluid
characteristics for the important reservoirs.
The oil reservoirs have gas cap and solution gas drives supplemented
by water injection. Pressure has been maintained by means of reinjection
of produced gas into the associated gas caps. The principal
oil reservoirs are now in the final depletion stages and gas cap
production has begun. The nonassociated gas reservoirs produce by
pressure depletion except for a water drive in one minor reservoir.
Proved reserves of crude oil were estimated by extending production
decline trends. The proved reserves of associated gas were estimated
by comparing calculated current gas saturation in the reservoir with
estimated residual saturations at time of abandonment. This approach
appears advisable because cumulative associated gas production minus
injection records are not considered reliable. Proved reserves of
nonassociated gas were apparently estimated, principally, by production
decline curve extension methods. These estimates were tested
for reasonableness by observing the recovery efficiency factors.
The FEA report on the Tijerina-Cana1es-B1ucher Field was prepared by
James A. Lewis Engineering under Contract No. CO-05-5018l-00.
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