IODP NanTroSEIZE Stage 1:
Expedition 314: NanTroSEIZE LWD Transect
Weekly Report #6
Date 02/Nov/2007
The operations to recover the dropped drill pipe and cementing continued this week. The Chikyu sailed 14 nm NNW to move away from the strong current and typhoon after the recovery assembly was pulled out of the hole at 00:00 a.m. on 27 October. At 16:00 p.m. of 27 October Chikyu sailed back to Site C0003A and a recovery assembly was made up again. After moving to the 6 nm upstream, the assembly began running into the water to about 1800 m, and ROV dived while drifting back to position. The hole was re-entered at 03:15 a.m. on 28 October, and run in to the 292.5 meter below seafloor.
After continuous attempts at recovering the disconnected section, JAMSTEC determined to abandon recovery operations on October 29th because of difficulties with the geological formation at the site and condition of the remaining disconnected pipe. At 19:00, Chikyu sailed 500 m upstream and sealed the borehole with concrete. Seawater was displaced with concrete and confirmed cement return to the seabed by ROV. After cementing, all assembly was pulled out of the hole, ROV recovered. Beginning at 16:00 p.m., beacons were picked up and Chikyu moved to the next site, NT2-01-I pilot hole location at 03:45 a.m. on 31 October and beacons were set. After making up pilot hole assembly, Chikyu drifted 4 nm upstream while running the assembly from 20:00 p.m. Position was confirmed at 04:30 a.m. and an pilot hole (2632 m water depth) was spudded at 04:45 a.m. on 1 November. It was jetted down from the seafloor to 75.5 meters below the seafloor (mbsf), and rotary drilling began. A short wiper trip was made between 222.5 to 70.5 mbsf. 400 m Target Depth was reached at 18:45 p.m. and the pilot drilling assembly pulled out of the hole.
After the pilot hole assembly was back on the drill floor, preparations began for the LWD assembly at 03:45 a.m. on 2 November.
Science party discussed the drilling plan for the remaining 3 weeks on the 26th Oct. On 27th Oct, final site summary meeting for Site C0002 was held and each group submitted their site reports on the 28th. On 29th, a science seminar was held on crustal structure in the Nankai Trough, and the science party continued working on the real-time MWD results from Hole C0003A. Site summary meeting for C0003 was held on 1 November and reports are due to be submitted on the 3rd. Continued the preparation for the coring expeditions: maintenance- cleaning microscopes; instrument setup- , X-ray CT, SQUID, canbonate analyzer, titrator and close-up photo system; and training- Xray CT operation and core rack handling. Discussion on lab measurements was made between Lab technicians and NanTroSEIZE Specialty Coordinators, working together for the preparation for the coming coring expeditions.
