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doi:10.2204/iodp.proc.329.105.2011

Operations

Transit to Site U1367

After a 100.75 h transit from Site U1366, covering 1019 nmi and averaging 10.1 kt, speed was reduced and thrusters were lowered. Speed was less than expected because two of the propulsion motors were offline, one on the starboard shaft and one on the port shaft, both with failed field coils. Dynamic positioning was initiated over Site U1367 at 2304 h on 4 November 2010. The position reference was a combination of GPS signals. No acoustic beacon was deployed, but a beacon remained on standby in the event of loss of GPS satellite coverage. Whereas automatic input into the dynamic positioning system was not possible because of a system malfunction, it was possible to manually hold the vessel in position to clear the seafloor with the bottom-hole assembly (BHA) if necessary.

Site U1367

Six holes were drilled or cored at this site (Table T1). The first hole was a washdown hole drilled with the center bit in order to establish the sediment depth of 21.2 meters below seafloor (mbsf). The next four holes were cored with the advanced piston corer (APC) system. The last remaining hole was drilled and cored with the rotary core barrel (RCB) system ~33.5 m into basement. The advanced piston corer temperature tool (APCT-3) was not deployed because of the sediment depths. Perfluorocarbon tracer (PFT) was pumped in for the entire drilling/coring interval until the last core was on deck. APC system recovery for Site U1367 was 98.1%. RCB system recovery was 11.2%. A total of 20 cores were attempted while coring 137.4 m. The total length of core recovered at this site was 101.34 m (73.8% recovery).

Hole U1367A

Rig floor operations commenced at 2300 h on 4 November 2010. The trip to the seafloor was uneventful. The top drive was picked up and the drill string was spaced out and spudded at 0740 h on 5 November. The PFT pump was turned on to displace the drill string with the contamination testing fluid. The washdown hole was drilled to determine depth of basement. Mudline was established at 4302.0 mbrf by tagging with the bit. After drilling down, basement was established at 21.2 mbsf. The bit was pulled back above the seafloor, clearing the seafloor at 0810 h on 5 November and ending Hole U1367A.

Hole U1367B

After clearing the seafloor, the center bit was pulled by wireline, the vessel was offset 20 m west, and the drill string was spaced out to spud Hole U1367B. After making up the first APC core barrel, the core barrel was run to bottom on the wireline and Hole U1367B was spudded at 1000 h on 5 November. Seafloor depth was established with a mudline core at 4300 mbrf. APC coring continued to 22.3 mbsf. Four cores were taken with a total recovery of 22.31 m (100.0% recovery). After Core 329-U1367B-4H, the bit was tripped back to just above the seafloor, ending Hole U1367B at 1440 h. PFT was mixed with the drilling fluid (seawater) and pumped on all cores for contamination testing.

Hole U1367C

Hole U1367C began at 1440 h when the APC assembly cleared the seafloor after completing Hole U1367B. After offsetting the vessel 20 m north, Hole U1367C was spudded at 1520 h on 5 November and advanced with the APC system to 26.7 mbsf before encountering basement. Seafloor was established at 4299.3 meters below rig floor (mbrf). PFT was mixed with the drilling fluid (seawater) and pumped on all cores for contamination testing. Four cores were taken with a total recovery of 27.01 m (101.2% recovery). The drill string was then tripped to just above the mudline, clearing the seafloor at 2005 h and ending Hole U1367C.

Hole U1367D

Hole U1367D began at 2005 h on 5 November when the APC assembly cleared the seafloor after completing Hole U1367C. After offsetting the vessel 20 m east, Hole U1367D was spudded at 2205 h and advanced with the APC system for four cores to 25.5 mbsf with a 24.54 m recovery (96.2%). Seafloor was established at 4299.1 mbrf. PFT was mixed with the drilling fluid (seawater) and pumped on all cores for contamination testing. The drill string was tripped to just above the mudline, clearing the seafloor at 0255 h on 6 November and ending Hole U1367D.

Hole U1367E

Hole U1367E began at 0255 h on 6 November when the APC assembly cleared the seafloor after completing Hole U1367D. After making up the first APC core barrel, the core barrel was run to bottom on the wireline and Hole U1367E was spudded at 0340 h. Seafloor depth was established with a mudline core at 4298.7 mbrf. The APC system was used to take three cores to 24.4 mbsf with a 23.15 m recovery (94.9%). PFT was mixed with the drilling fluid (seawater) and pumped on all cores for contamination testing. The drill string was tripped to the surface, clearing the rotary table at 1400 h and ending Hole U1367E.

Hole U1367F

After a 20 m offset to the south, Hole U1367F began on 6 November at 1400 h when the bit cleared the rotary table after tripping out of Hole U1367E. The BHA was set back, the APC bit was removed, and the rotary core bit and rotary coring system were assembled in preparation for running the new RCB BHA. The BHA was run into the hole followed by the drill pipe. The top drive was picked up and the drill string was spaced out to spud Hole U1367F. Water depth was recorded at 4300 mbrf using the BHA tag depth. The center bit was deployed and Hole U1367F was spudded at 2345 h. At 17 mbsf, the center bit was pulled and the RCB was dropped and coring began. RCB coring continued from 17 to 55.5 mbsf with poor recovery. A total of 38.5 m was cored with a recovery of 4.33 m of core. RCB system recovery in Hole U1367F was 11.2%. PFT was mixed with the drilling fluid (seawater) and pumped on all cores for contamination testing. Microspheres were also deployed on all RCB cores in Hole U1367E. The drill string was tripped back to the rig floor and secured for the 793 nmi transit to the next site, ending Hole U1367F and Site U1367 at 0545 h on 9 November.

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