The
319-nmi voyage to Site 1120 (proposed site
SWPAC-6B) was accomplished through calm seas at an
average speed of 11.0 kt. The vessel proceeded
directly to the Global Positioning System
coordinates of the location. The positioning
beacon was dropped at 0045 hr on 28 August 1998.
The advanced hydraulic piston core/extended core
barrel (APC/XCB) bottom-hole assembly was
assembled using a 9
-in PDC bit with a lockable float valve (LFV) and
deployed. Hole 1120A was spudded with the APC at
0550 hr on 28 August. The recovery indicated that
the water depth was 542.9 m below sea level (mbsl).
The hole was scheduled for only a mudline sample
and the single APC Core 1H was taken from 0 to 4.6
meters below seafloor (mbsf) (Table
T1, also
in
ASCII
format).
The second hole of the site was spudded with the APC at 0650 hr on 28 August. The seafloor depth inferred from recovery was 544.2 mbsl. APC coring advanced to 68.3 mbsf when Core 8H did not achieve a full stroke. Cores were oriented starting with Core 3H. Coring was continued with the XCB and deepened the hole to 188.0 mbsf (Table T1) when operations were put on standby because of excessive heave (2 m with an occasional 3-m event) generated by 2.0- to 2.5-m seas combined with a 4.0-5.5-m swell from the southwest. The hole was abandoned, the bit clearing the seafloor at 2020 hr on 28 August.
A force 9 gale, with sustained winds up to 45 kt and gusts to 60 kt (force 10), prevailed in the drilling area from the evening of 28 August until 0045 hr on 30 August, when it was decided to continue site operations even though environmental conditions were borderline for shallow-water operations. After positioning the bit at 543 mbsl, Hole 1120C was spudded with the APC at 0613 hr on 30 August. The seafloor depth based upon recovery was 545.9 mbsl. Piston coring advanced to 44.6 mbsf (Table T1) when an incomplete stroke was encountered at Core 5H. While recovering the core, the wireline broke. In an attempt to fish the parted wireline, monel sinker bars, and APC assembly, the drill pipe was pulled back. The bit cleared the seafloor at 0613 hr on 31 August.
A wireline spear was made up and run in the pipe. It tagged the broken wireline at 183 mbsl. Attempts to work the broken wireline back up the pipe were unsuccessful and the spear slipped off. The drill pipe was pulled back in stands until the broken end of the wireline was found. After the broken wireline was recovered, the APC core barrel containing Core 5H was retrieved at 1055 hr. Environmental conditions were too extreme to continue, and operations were placed in standby mode while awaiting improved weather.
At 1600 hr on 31 August, Hole 1120D was spudded and drilled ahead to 157.4 mbsf, where XCB coring was initiated. XCB coring advanced from 157.4 to 220.7 mbsf (Table T1) when operations again had to be terminated because of excessive heave. It was decided to discontinue coring at this location and move on to Site 1121. As the drill string was being retrieved, the beacon was recalled and recovered. At 0600 hr on 1 September, the vessel began the transit to Site 1121.
