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

Estimates of the static formation pressure of the
Forty-niner clay at H-16 were obtained from the
analyses of the DST and slug-test data, and from the
transducer installed to measure the Forty-niner
pressure as part of the H-16 5-packer system. The
static formation pressure indicated by the slug-test
analysis is 116.1 psia. This is 1 psi lower than the
value indicated by the DST’s, but is consistent with
the dissipation of a slight overpressure skin. With the
test transducer set at a depth of 542.5 ft in a hole
containing fluid with a specific gravity of 1.2, and a
measured atmospheric pressure of 14.3 psia, a
pressure of 116.1 psia corresponds to a pressure of
about 11 5 psig at the midpoint of the Forty-niner clay
about 568 ft deep. In comparison, the Forty-niner
transducer of the 5packer system, which is set at a
depth of 548.1 ft, showed a stabilized pressure of
105 psig within several weeks after installation
(Stensrud et al., 1988). This also corresponds to a
pressure of about 115 psig at the midpoint of the
Forty-niner clay, indicating that the value is
representative of the formation pressure existing in
mid-1987. As noted with regard to the other Rustler
members tested at H-16, however, the fluid pressure
within the Forty-niner clay could be artificially low
because of drainage of water from that unit into the
WlPP shafts.
5.3 Dewey Lake Red Beds
Little testing of the Dewey Lake Red Beds near the
WlPP site has ever been attempted, primarily
because of a lack of evidence of continuous zones of
saturation (Mercer, 1983). The Dewey Lake Red Beds
are permeable, however, as evidenced by losses of
circulation fluid during drilling of holes such as DOE-
2 and H-3d, and therefore the unit remains of interest
when considering groundwater-transport pathways in
the event of a breach of the WlPP facility. Beauheim
(1986) reported on unsuccessful attempts to test the
lower Dewey Lake at DOE-2. The only other Dewey
Lake testing attempted on behalf of the WlPP project
was performed at well H-14. No information was
obtained during the drilling of H-14 pertaining to the
presence or absence of a water table in the Dewey
Lake at that location. Nevertheless, limited testing of
the lower portion of the Dewey Lake Red Beds was
planned based on the supposition that either a water
table did exist in the lower Dewey Lake, or sufficient
water would have infiltrated into the Dewey Lake
during drilling and Rustler testing to allow at least
qualitative testing. Descriptions of the test
instrumentation and the test data are reported in
Stensrud et al. (1987).
For the tests at H-14, an interval of the lower Dewey
Lake from 327.5 to 356.0 ft deep was isolated with a
DST straddle tool. The testing was performed on
October 15 and 16, 1986 (Figure 5-107). Testing
proceeded without a preliminary equilibration period
because of assumed very low permeability. An initial
13-minute flow period resulted in very little fluid
entering the tubing. The pressure rose about 3 psi
during a subsequent 6-hr buildup period.
PULSE
/
100-
: 68
L
.I
: -?
-
PRESSURE BELOW TEST INTERVAL
.....
128 Figure 5-107. H-l4/Lower Dewey Lake Drillstem and Pulse Testing Unear-Linear Sequence Plot