After
reviewing the pressure-data analyses presented by Orr and others
(1985), we chose to use 0.403 psi/ft as the slope of the pressure
function for the deep brine aquifer (Granite Wash) of the Palo Duro
Basin. We chose this value because it derives from the most consistent
data ("Class A") presented by Orr and others (1985). They
defined "Class A" pressure data as those values for which
both initial and final shut-in pressures were available and that
agreed within 10 percent. The original data came from drill-stem
tests of petroleum exploration wells. Orr and others (1985) obtained
them from Petroleum Information Service, Inc. Note that this value,
0.403 psi/ft, is below the estimated hydrostatic gradient of deep-basin
brines, 0.466 psi/ft. By choosing only the "Class A" data
of Orr and others, we hope to eliminate one possible reason for
the underpressuring of the saline aquifer, poor-quality drill-stem
tests. Therefore, according to Orr and others, there are two other
possible reasons for this underpressuring: (1) isolation from shallower,
hydrostatically pressured aquifers or (2)
potential for downward flow within the aquifer. Orr and others presented
evidence for both cases in the deep brine aquifer of the Palo Duro
Basin.
12b Map:
12b
Reference:
Orr,
E. D, Kreitler, C. W., and Senger, R. K., 1985, Investigation of
the underpressuring in the deep-brine aquifer, Palo Duro Basin,
Texas: The University of Texas at Austin, Bureau of Economic Geology,
Geological Circular 85-1, 44 p.
