Beauheim 1987 - Waste Isolation Pilot Plant - U.S. Department of ...

The simulation is representative of a singleporosity
medium with a transmissivity of 0.31 ftzfday
(Table 5-3). Assuming a Culebra porosity of 20%, a
total-system compressibility of 1 .O x 10-5 psi-1, and a
fluid viscosity of 1.0 cp, the skin factor for this
simulation is about -1.8. These values are in
excellent agreement with the FBU results, and
indicate possible slight well development during the
DST's. Again, the decline in the pressure derivative
in Figure 5-33 at late time shows the continuing
influence of the overpressure skin on the data.
Figure 5-34 shows a semilog plot of the rising-head
slug-test data, along with the best-fit type curve. This
fit provides a transmissivity estimate of 0.30 ftz/day
(Table 5-3). which is in excellent agreement with the
FBU and SBU results. This fit was achieved using a
static formation pressure estimate of 90.0 psia,
slightly below the pressure measured at the end of
the SBU. The transducer used for the DST's and
slug test was set at a depth of 514.7 ft. The fluid in
the hole during the testing had a specific gravity of
1.003, and the transducer measured an atmospheric
pressure of 12.3 psia before testing began. Hence,
90.0 psia at the transducer depth corresponds to a
static formation pressure of about 96.5 psig at the
midpoint of the Culebra about 558 ft deep.
Conclusions: The Culebra is 26.5 ft thick at H-14.
The transmissivity of the upper 5.8 ft is 0.10 ftZ/day,
while that of the entire unit is 0.30 ftz/day. Hence, the
average hydraulic conductivity of the upper 5.8 ft of
the Culebra appears to be about 1.8 times greater
than that of the lower 20.7 ft. This difference does
not represent a great degree of heterogeneity. Left
unresolved by this testing is the distribution of
hydraulic conductivity within the Culebra on a finer
scale, such as hydraulic-conductivity differences
between those portions that are less competent and
core quickly, and those that are more competent and
core more slowly.
1 .o
0.9
0.8
0.7
0.6
0
F
I
0.5
0.4
0.3
0.2
0.1
0.0
I,-, = 295:17:3555
10-3 10-2 lo-' 100
ELAPSED TIME, hours
10' 102
Figure 5-34. H-I4/Culebra Slug-Test Plot
73