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

Two factors raised questions about these
datafinterpretations. First, reported Culebra
transmissivities are higher at holes northwest (P-l4),
southwest (H-7), northeast (H-3, DOE-l), and east (H-
11) of H-4 than at H-4. Second, early tests of the
Culebra at well DOE-2 appeared to indicate the
presence of a recharge boundary, which was later
shown to be simply poor hydraulic communication
between the well and the formation. Good hydraulic
communication was established by acidizing DOE-2,
and subsequent tests revealed a transmissivity
higher than previously estimated (Beauheim, 1986).
Hence, concern arose as to whether the reported
Culebra properties for H-4 were real, or were affected
by poor communication between the H-4 wells and
the formation.
To resolve this question, H-4c was acidized and a
falling-head slug test was performed to evaluate
whether or not the acidization had resulted in an
increase in the apparent transmissivity of the
Culebra. Well H-4c was selected as the test well
1 .o
because it is a cased hole with perforations providing
access to the Culebra, similar to DOE-2. The well
was acidized on July 16, 1986, by injecting nearly
200 gallons of a 20% hydrochloric acid solution at the
Culebra level over a period of about 2 hr. After a
waiting period of over an hour, the spent acid was
swabbed from the well. The well was then
developed over a 7-day period by repeatedly
pumping most of the water from the well and
allowing the water level to recover (Stensrud et al.,
1987).
On July 31, 1986, a falling-head slug test was
initiated in HAC. The test continued tor about 45 hr
until August 2, 1986. The data from this test are
reported in Stensrud et al. (1987). A plot of the test
data and the best fit to a slug-test type curve are
shown in Figure 5-20. The good fit between the data
and the type curve indicates that on the scale of the
test, the Culebra at H-4c behaves hydraulically as a
single-porosity medium. No evidence of a recharge
boundary is observed in the data.
0.9
0.8 p* = 59.47 psig
pi 103.90 psig
0.7
0.6
0
T 0.5
I
0.4
t
= 1.2hr
0.3
0.2
0.1
0.0
10'3 10-2 lo-' 100 10' 102
ELAPSED TIME, hours
Figure 5-20. H+c/Culebra Post-Acidiration Slug-Test Plot
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