Hole 1123B
To obtain stratigraphic overlap with the previous hole, the bit was raised by 3 m from the
spudding depth of Hole 1123A, and Hole 1123B was spudded with the APC at 0110 hr on 15
September. The recovery of the mudline core indicated a seafloor depth of 3289.9 mbsl. APC
Cores 181-1123B-1H through 15H were recovered from 0 to 136.4 mbsf. While attempting to
retrieve Core 181-1123B-16H from a depth of 145.9 mbsf, the wireline parted at the sinker bar
assembly socket. An eight-finger hard formation core catcher was used as an overshot in order to
latch onto the core barrel. The overshot was run in and engaged on the first attempt and the core
barrel was retrieved to the surface. Piston coring resumed in Hole 1123B with a full stroke of Core
181-1123B-17H. The core barrel could not be extracted from the sediment and had to be drilled
over. The Adara heat-flow shoe was deployed with Cores 181-1123B-5H (41.4 mbsf), 6H (60.4
mbsf), 7H (79.4 mbsf), and 11H (98.4 mbsf). These runs failed to provide heat-flow data because
of the frictional heat that was generated by the vertical motion of the vessel (heave). Coring was
switched to the XCB and advanced without incident to 182.0 mbsf with >100% recovery. While
retrieving Core 181-1123B-21X the core-winch operator noticed that the line on the drum was
slack and that there was no line tension on the weight indicator. This was an obvious indication that
the wireline and sinker bars were caught on an obstruction in the drill pipe. The obstruction turned
out to be the core barrel which had stuck in the pipe 124 m below the drill floor. As a result of
running into the core barrel, the wireline on the drum backlashed. After respooling the line and
after various attempts to free the stuck XCB barrel the drill string had to be retrieved to the level of
the stuck core barrel. There was nothing found on the inside of the drill pipe to suggest the cause of
the jamming. The drill string was run back in to the bottom and XCB operations recommenced at
0545 hr on 16 September. Coring advanced to 374.1 mbsf. While pumping down the XCB core
barrel to cut Core 181-1123B-41X, the barrel stopped at an obstruction in the bore of the drill pipe
at 645 mbrf. On tagging the stuck barrel with the sinker assembly, a number of loose wraps were
produced on the forward core winch drum before the brakes could be applied. Approximately 50
m of wire was spooled from the drum to remove the loose wraps. A fishing assembly was
deployed, and the core barrel was tagged at 645 mbrf. After the first hit of the wireline jars, the
stuck core barrel was freed and recovered to the rig floor. XCB coring again resumed at 0900 hr
on 17 September and advanced to 489 mbsf, which was the revised depth objective for this hole.
Logging Operations in Hole 1123B
In preparation for logging, an aluminum go-devil was dropped and the hole swept with 60
barrels of high viscosity mud. The bit was pulled back in the hole to 520 mbsf and the hole was
displaced with 175 barrels of sepiolite mud. The bit was then positioned at the logging depth of 83
mbsf. Logging operations began at 1100 hr and lasted for 20 hr. Logging was conducted from the
bottom of the hole at 489 mbsf to the bit at 84 mbsf. Three standard tool-string configurations
were run: the triple combination, the FMS-sonic (two passes), and the GHMT. The NMRS (total
field) tool on the GHMT failed to work. The condition of the borehole was good and the quality of
the data was excellent. After the logging equipment was disassembled, the bit was pulled out of the
hole and cleared the seafloor at 0955 hr on 19 September, ending operations at Hole 1123B.
Hole 1123C
The vessel was offset by 30 m to the north and Hole 1123C was spudded with the APC at
1130 hr. Piston coring advanced to 151.5 mbsf. A core barrel with a center bit was dropped and
the hole was deepened by drilling ahead to 230.0 mbsf. The center bit was retrieved and one XCB
core (Core 181-1123C-17X) was obtained from 230.0 to 239.6 mbsf with 67% recovery to
provide overlap with an interval of poor recovery in Hole 1123B. Following the recovery of the
XCB core barrel, the center bit was dropped again and the hole was drilled ahead from 239.6 to
484.0 mbsf. After the center bit was recovered, XCB coring resumed and advanced from 484.0
mbsf to the modified depth objective of 632.8 mbsf (Cores 181-1123C-18X to 33X), with
excellent recovery.
Logging Operations in Hole 1123C
In preparation for logging, an aluminum go-devil was dropped and the hole swept with 60
barrels of high viscosity mud. The bit was pulled back in the hole to 629 mbsf and the hole was
displaced with 213 barrels of sepiolite mud. The bit was then pulled back to logging depth of 68
mbsf. By the time the drill crew was preparing to rig up for logging, there were wind gusts of over
60 kt, seas of 3–4 m, and up to 12-m-high swells, which forced the decision to abandon planned
logging. At 1050 hr on 22 September, the bit was pulled clear of the seafloor. The pipe was
partially recovered, but by 1300 hr the maximum vessel pitch was over 9°. Pipe tripping was
suspended because of the hazard to men and material, and operations were placed in weather
standby. The storm abated by 0330 hr on 24 September, which allowed the drill crew to recover
the drill string and beacon. By 1000 hr the drilling equipment was secured and the thrusters and
hydrophones retracted as the vessel began the 269-nmi transit to Site 1124.
To 181 Summary of Engineering and Drilling Operations: Site 1124