SUMMARY OF LEG 183 ENGINEERING AND DRILLING
Hole 1142A (Proposed Site KIP-9E)
The positioning beacon was deployed on this site while the pipe was still being tripped back to the
drill ship. The beacon was deployed at 1500 hr on 5 February 1999 on the precise GPS coordinates
for Site 1142.
We spudded Hole 1142A at 2330 hr on 5 February 1999. The seafloor depth adjusted to the rig
floor was estimated at 1213.0 m, based once again on a hard tag indication by the driller. The 3.5-kHz
PDR had indicated an adjusted seafloor depth of 1216.4 m.
Because the objective was basalt and the sedimentary sequence had already been cored in Hole
1141A, we were given permission from ODP/TAMU to drill through the overlying sediments. The
driller washed/drilled with a wash barrel in place for 119-min rotating time (45.9 m/hr) until the
formation became firm at a depth of 91.0 mbsf. The wash barrel was recovered and Core 2R was cut
in aphyric to moderately plagioclase-phyric basalt. Coring continued in this formation, with much of
the recovered basalt totally altered to brown clay. Recovery was highly variable and generally low
(13.0% to 84.4%). Even cutting half cores only resulted in an overall recovery for the section of
34.4%. The ROP was also highly variable, ranging from 2.3 to 7.7 m/hr, and averaging 3.7 m/hr
Before completion of Core 10R, a 20-bbl sweep of sepiolite mud was circulated and displaced out
of the hole. The sinker bars were installed, and the core was retrieved without incident. After laying
out the core, the drill string was immediately made up, and circulation was established. As in the last
hole, upon picking the drill string up off the elevators, the pipe was stuck. This time rotation was
possible but upward travel of the drill string was not possible. The drill bit was at ~6.0 m above the
bottom of the hole when the drill string became stuck.
The stuck pipe was worked from 125.6 mbsf to 106.3 mbsf. Circulation and rotation was possible
with high erratic torque. We were unable to come up without stalling the top drive. Maximum
amperage on the top drive was 1000 and maximum overpull used was 80,000 lb. The pipe was
eventually worked free by going gradually down with the bit. At that point <3 hr of coring time
remained in the schedule, so further coring operations were suspended. TD of the hole was 141.9
mbsf, or 50.9 m into basement. A total of 17.54 m of core was recovered from the hole for an overall
average of 34.4%.
The pipe was pulled out of the hole using the top drive, clearing the seafloor at 0400 hr on 7
February 1999. The forward core line was subsequently run in the hole and coated with compound-L
corrosion inhibitor. The core barrels were stored away, and the drill string was tripped the remaining
distance out of the hole while corrosion inhibitor was applied. During the pipe trip, the positioning
beacon was released and recovered at 0615 hr. The bottom hole assembly was broken down, and all
drill collars were racked and secured in the forward collar rack. With the bit at the rig floor at 1055 hr,
the remaining thrusters were pulled and the rig was secured for transit.
At 1100 hr on 7 February 1999, we were under way for Fremantle, Australia.
Leg 183 Table of Contents