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

Figure 5-42 shows a log-log plot of the FBU data
along with an INTERPRET-generated simulation.
The simulation shown is representative of a singleporosity
medium with a transmissivity of 0.85 ftZ/day
(Table 5-3). Assuming a Culebra porosity of 20%, a
total-system compressibility of 1.0 x 10-5 psi-', and a
fluid viscosity of 1.0 cp, the skin factor for this
simulation is about 0.0, indicating no wellbore
damage. The decline in the pressure derivative at
late time is indicative of a residual overpressure skin
created when the Culebra was cored and reamed on
August 6, 1987. The dimensionless Horner plot of
the FBU data (Figure 5-43) also shows the effects of
the overpressure skin as the data trend slightly
upward at very late time (lower left corner of the plot)
towards a pressure lower than the 136.2 psia
specified as the static formation pressure for that
simulation.
The log-log plot of the SBU data (Figure 5-44) shows
no overpressure-skin effects. The simulation shown
on the figure is representative of a single-porosity
medium with a transmissivity of 0.85 ftz/day
(Table 5-3), similar to the FBU simulation. The skin
factor for this simulation is 6.3, indicating very slight
stimulation of the wellbore. The SBU dimensionless
Horner plot (Figure 5-45) shows the data recovering
to a static formation pressure of 135.4 psia.
IO'
1 I I
II PRESSURE DATA
- PRESSURE-DERIVATIVE DATA
- SIMULATIONS
O
sa
w
a
3
v)
v)
W
a
n.
g 100
W
-I
2
0
v)
z
I"
E
t
= 1.0 hr
PD = 0.126
tdCD =2200
CDe2* = 20
PI
= 95.0 psia
4P*
*
*
lo-'
100
1 I I
10' 102 103
x
104
DIMENSIONLESS TIME GROUP, tD/CD
Figure 5-42. H-IG/Culebra First Buildup Log-Log Plot with INTERPRET Simulation
79