Transit to Site 1128

The 76-nmi transit to Site 1128 required 8.5 hr at an average speed of 8.9 kt. A beacon was launched at 1100 hr on 3 November initiating Site 1128. Its signal was erratic, however, and another beacon was deployed.

Hole 1128A

The ship was stabilized on position and an APC/XCB BHA was run to the seafloor. Hole 1128A was spudded at 1900 hr on 3 November, recovering 9.31 m in Core 1H. The hole was terminated at 1930 hr on 3 November because the recovery was excessive for establishment of a good mudline.

Hole 1128B

The ship was not moved, and Hole 1128B was spudded at 1955 hr on 3 November. The bit was positioned at 3882 mbrf and Core 1H recovered 5.66 m, indicating a water depth of 3874.6 mbsl. APC coring advanced to 137.8 mbsf and ceased when a partial stroke on Core 15H bent the APC shoe. Cores 3H–15H were oriented, and coring continued with the XCB advancing from 137.8 to 280.6 mbsf. The DVTP temperature probe was deployed after Core 16X at 145.8 mbsf. It became apparent that the jet nozzles in the bit were plugged sometime after running the DVTP. The resulting increased pump pressure required to maintain circulation may have caused reduced recovery in Cores 17X and 18X. Recovery dropped to 28.9% in the last four XCB cores (27X–30X), probably as a result of the bit overheating, despite attempts to increase circulation and pressure. Coring was terminated because of the low recovery in the last four cores and increasing drilling times. The bit cleared the seafloor at 1515 hr on 5 November, ending Hole 1128B.

Hole 1128C

The ship was moved 20 m east, and Hole 1128C was spudded with the APC at 1640 hr on 5 November. The bit was positioned at 3884 mbrf, and Core 1H recovered 7.95 m, indicating a water depth of 3874.3 mbsl. APC coring advanced to 138.3 mbsf, ceasing again with a partial stroke at Core 15H and a bent APC shoe. Cores 3H–15H were oriented and Adara tool heat-flow measurements were taken at Cores 4H, 8H, and 12H. A special nonmagnetic assembly was run on the bottom two-thirds of the APC inner core barrel on Cores 3H, 5H, 7H, 9H, 11H, and 13H. Coring resumed with the XCB to the depth objective of 240.1 mbsf. The drill string was recovered at 0330 hr on 7 November, terminating Hole 1128C.

Hole 1128D

The ship was moved 20 m north of Hole 1128C, and an RCB BHA was run to the seafloor. Hole 1128D was spudded at 1115 hr on 7 November, and the hole was drilled ahead with a center bit to 231.2 mbsf. RCB coring advanced from 231.1 to 452.6 mbsf with 35.7% recovery. Coring was terminated when drilling times increased and recovery decreased to unacceptable levels. The hole was prepped for logging, and the end of the drill pipe was placed at 92 mbsf. The triple combo tool string was run but was unable to pass 96 mbsf. The tool was pulled out, and the pipe run to 112 mbsf. The triple combo was rerun through a tight spot at ~250 mbsf from 428 mbsf (24 m off bottom) to the mudline. The FMS/Sonic tool string was deployed and logged from 424 mbsf to the end of the pipe. Operational time constraints precluded deployment of the WST. The hole was displaced with mud, the drill string retrieved and secured, and the ship was under way to Site 1129 at 0130 on 11 November.

To 182 Summary of Engineering and Drilling Operations for Site 1129

To 182 Table of Contents