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

10’
1 I I I
n
a
w
5 100
v)
v)
W
a
v)
v)
W
-I
z
0
E lo-’
5
a
*,;v * *,Y
*y** MATCH PARAMETERS **
AP
1.Opsi
#
d
t 1.0 hr *
0.079
a
PD
~D/CD 6.918
(CDe2S), 12 *
0 PRESSURE DATA (Cne2s), 0.12
9 PRESSURE-DERIVATIVE DATA A e-2s 0.11
-
SIMULATIONS
PI
107.34 psig
1 I I I
10-2
- 10-1 100 10’ 102 103
DIMENSIONLESS TIME GROUP, tD/cD
104
Figure 5-77. DOE-l/Culebra Pumping Test Recovery Log-Log Plot with INTERPRFT Simulation
Several points are puzzling or inconsistent about this
interpretation, however. First, the occurrence of a
single fracture at this location seems inherently
unlikely. Second, evidence from many tests in the
Culebra (e.g., DOE-2, H-8b, H-1 1, WIPP-13) indicates
that transmissivities greater than 1 or 2 ftz/day are
related to extensive fracturing, and are not
representative of intact Culebra. Third, the
indications of hydraulic boundaries began at the
same time that the flow rate was increased. Fourth,
wellbore-storage effects in the pressure data [a unit
slope on a log-log plot at early time) should be more
evident than they are. A wellbore-storage coefficient
of about 8.5 gal/psi can be calculated for DOE-1
based on the size of the casing and discharge line,
and the specific gravity of the water being
discharged. This high a wellbore-storage coefficient
should cause observable effects. These effects are
not seen, and the wellbore-storage coefficient
obtained from the model used to generate the
simulation is only 0.7 gal/psi. Finally, the recovery
data show a completely different hydraulic behavior
than the drawdown data.
The log-log recovery plot (figure 5-77) includes a
simulation generated by INTERPRFT using a doubleporosity
model with restricted interporosity flow. The
model uses a transmissivity of 11 ftz/day and a
wellbore-storage coefficient of 6.8 gal/psi. The skin
factor for this simulation, using the same parameter
values used in the drawdown analysis presented
above, is -6.0. The simulation fits the data very well,
except for a sharp decline in the pressure-derivative
data at extremely late time. This decline was caused
by the rate of pressure recovery slowing significantly,
as if an overpressure skin were present and
dissipating. Why this decrease in the rate of
recovery occurred is unknown, but it is the opposite
of what would be expected if the no-flow boundaries
indicated by the drawdown analysis were present.
Figure 5-78 shows a dimensionless Horner plot of
the recovery data. The double-porosity simulation
again matches the observed data very well.
However, the static formation pressure (p*) specified
for this simulation, 149.6 psig, is 4.0 psi lower than
the pressure measured before the pump was turned
104