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

4
A
1 e
n
.' 2
n
.
El%
MATCH PARAMETERS
AP
= 1.0 psi
I
= 1.0 hr
PO = 0.079
3 ' tD/CD = 6.918
(C,eZ'), = 12
.
ICDezs),-m = 0.12
Ae-Zs = 0.11
1
+ DATA
- SIMULATION
/
0
1 I 1 I
0 1 2 3 4 5
DIMENSIONLESS SUPERPOSITION FUNCTION: FLOW PERIOD 2
Figure 5-78. DOE-l/Culebra Pumping Test Recovery Dimensionless Horner Plot with INTERPRET' Simulation
on. This difference between the observed and
simulated static formation pressures may indicate
that the Culebra pressure was not at equilibrium at
the start of the test, and may be related to the
observed late-time decline of the recovery pressure
derivative.
Figure 5-79 shows a linear-linear plot of the entire
DOE-I testing sequence, along with a simulation of
that sequence generated using the model derived
from the recovery analysis. The shape of the
simulation differs considerably from the drawdown
data, but the simulation accurately predicts the total
amount of drawdown (given that the simulation uses
a starting pressure 4.0 psi lower than that measured).
The simulation fits the recovery data quite well.
The overall hydraulic behavior of DOE-1 during the
pumping test remains anomalous. One explanation
for the discrepancy between the drawdown and
recovery behavior is that the well may have been
undergoing development during pumping, so that
the hydraulic properties governing the pressure
response were changing as pumping progressed.
The well-development activities performed during
March and April 1983 preceded knowledge of the
high Culebra transmissivity at DOE-I, and involved
only bailing and low-volume pumping with a pump
jack (see Section 3.21). The only high-volume
pumping that occurred before the pumping test was
an 8-hr step-drawdown test. These activities may
have been inadequate to clean and develop the
perforations in the well casing, and to clean the
fractures in the Culebra that might have gotten
plugged during drilling and cementing operations.
The 440-hr pumping test should have done a much
better job of well development. Once the pump was
turned off, the hydraulic properties of the well and
nearby aquifer probably stabilized, allowing the
recovery data to show an unchanging doubleporosity
system. For this reason, the analysis of the
recovery data is believed to provide the more
representative understanding of the hydraulic
behavior of the Culebra at DOE-I.
105