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

4.0 I I I
3.0
MATCH PARAMETERS
AP
= 1.0 psi
t
= 1.0 hr
- PO = 0.155
fdco = 1250
Coca 60
P* = 158.6 psla
2.0
1 .o
+ DATA
-SIMULATION
1
0.0
0.0 0.5 1 .o 1.5 2.0
DIMENSIONLESS SUPERPOSITION FUNCTION: FLOW PERIOD 3
Figure 5-55. H-l8/Culebra First Buildup Dimensionless Homer Plot with INTERPRET Simulation
The log-log plot of the SBU data (Figure 5-56) also
shows overpressure skin effects as a decline in the
derivative at late time. The simulation shown is
similar to that developed for the FBU, and is
representative of a single-porosity medium with a
transmissivity of 2.2 ftZ/day (Table 5-3). The skin
factor for this simulation is -1.0, showing increased
stimulation during the DST's. The overpressure skin
caused the pressure to peak at 155.0 psia after
70 minutes of the SBU (Figure 5-53). The
dimensionless Horner plot of the SBU data
(Figure 5-57) shows that the overpressure skin was
initially driving the recovery toward a static formation
pressure of 156.1 psia, but that at late time the data
deviated toward a lower pressure as the rates of
pressure-skin dissipation and pressure recovery
became more equivalent.
Figure 5-58 is a semilog plot of the rising-head slugtest
data, along with the best-fit type-curve match.
This match provides a transmissivity estimate of
1.7 ftz/day, slightly lower than those provided by the
DST buildup analyses (Table 5-3). During the slug
test, the pressure appeared to be recovering to a
value of 154.5 psia, slightly lower than the final SBU
value.
The transmissivity values provided by the DST's and
slug test of about 2 ftZ/day indicate that H-18 lies in a
transitional region between the higher
transmissivities to the north and the lower
transmissivities to the south. Based on experience
with similar transmissivities at H-3 (Beauheim,
1987a), the Culebra at H-18 might be expected to
show double-porosity effects in its hydraulic
responses. Fractures in the Culebra core from H-18
further indicate a potential for double-porosity
behavior. No double-porosity behavior was
observed, however, perhaps because the small
spatial scale and the short test durations involved in
DST's and slug tests allow for little interaction
between fractures and matrix. A pumping test of
several days' duration would provide a more
definitive indication of whether or not the Culebra
behaves hydraulically as a double-porosity system at
H-18.
88