Previous   |    Next

doi:10.2204/iodp.proc.342.107.2014

Operations

All times are local ship time (UTC – 2.5 h). See Table T1 for coring summary.

Hole U1406A summary

• Latitude: 40°20.9992′N
• Longitude: 51°38.9994′W
• Water depth below sea level (m): 3814.8
• Date started: 1435 h, 30 June 2012
• Date finished: 1920 h, 2 July 2012
• Time on hole (days): 2.2
• Seafloor depth (m drilling depth below rig floor [DRF]): 3826.3
• Seafloor depth estimation method: mudline core
• Rig floor to sea level (m): 11.5
• Penetration depth (m drilling depth below seafloor [DSF]): 283.3
• Cored interval (m): 283.3
• Recovered length (m): 267.3
• Recovery (%): 94
• Total cores (number): 34
• Advanced piston corer (APC) cores (number): 25
• Extended core barrel (XCB) cores (number): 9
• Drilling system: 11 inch APC/XCB bit with 136.00 m bottom-hole assembly (BHA)
• Objective: core from seafloor to ~250 m DSF or until science objectives are met.
• Result: target reached; objectives met.

Hole U1406B summary

• Latitude: 40°20.9995′N
• Longitude: 51°38.9851′W
• Water depth below sea level (m): 3813.7
• Date started: 1920 h, 2 July 2012
• Date finished: 1435 h, 4 July 2012
• Time on hole (days): 1.8
• Seafloor depth (m DRF): 3825.2
• Seafloor depth estimation method: mudline core
• Rig floor to sea level (m): 11.5
• Penetration depth (m DSF): 253.6
• Cored interval (m): 253.6
• Recovered length (m): 241.34
• Recovery (%): 95
• Total cores (number): 30
• APC cores (number): 22
• XCB cores (number): 8
• Drilling system: 11 inch APC/XCB bit with 136.00 m BHA
• Objective: core from seafloor to ~250 m DSF
• Result: target reached; objectives met

Hole U1406C summary

• Latitude: 40°20.9892′N
• Longitude: 51°38.9853′W
• Water depth below sea level (m): 3813.0
• Date started: 1435 h, 4 July 2012
• Date finished: 1600 h, 6 July 2012
• Time on hole (days): 2.1
• Seafloor depth (m DRF): 3824.6
• Seafloor depth estimation method: mudline core
• Rig floor to sea level (m): 11.6
• Penetration depth (m DSF): 241.4
• Cored interval (m): 236.4
• Recovered length (m): 223.02
• Recovery (%): 94
• Drilled interval (m): 5
• Drilled interval (number): 2
• Total cores (number): 27
• APC cores (number): 17
• XCB cores (number): 10
• Drilling system: 11 inch APC/XCB bit with 136.00 m BHA
• Objective: repeat cored sequence from Hole U1406B
• Result: target reached; objectives met

Description

The vessel arrived at Site U1406 after a 14.9 nmi transit from Site U1405, which was made in dynamic positioning mode at a speed of 1.4 kt with the drill pipe suspended below the vessel. The vessel stabilized over Site U1406 at 1435 h on 30 June 2012. The plan for this site called for drilling three holes to a depth of ~250 m DSF. Holes U1406A, U1406B, and U1406C were successfully cored to a depth of 283.3, 253.6, and 241.4 m DSF, respectively, without any significant problems. The total time spent at Site U1406 was 145.5 h (6.1 days).

Hole U1406A coring

The calculated precision depth recorder depth for the site was 3810.4 m DRF. Two water cores were shot before the mudline was recovered, establishing seafloor depth at 3826.3 m DRF (3814.8 mbsl). Hole U1406A was spudded at 1950 h on 30 June, and Cores 342-U1406A-1H through 25H were retrieved using nonmagnetic core barrels for all cores and the FlexIT core orientation tool on the first 17 cores. The first partial stroke was experienced with Core 16H, and the APC was advanced by recovery for this and subsequent cores. The XCB was deployed for Cores 26X through 34X to a total depth of 283.3 m DSF. The seafloor was cleared at 1920 h on 2 July, ending Hole U1406A. Overall core recovery for Hole U1406A was 267.30 m for the 283.3 m interval cored (94% recovery). The total time spent on Hole U1406A was 52.75 h.

Hole U1406B coring

The vessel was offset 20 m east. Hole U1406B was spudded at 2055 h on 2 July, and a 6.5 m mudline core established seafloor depth at 3825.2 m DRF (3813.7 mbsl). Cores 342-U1406B-1H through 22H were retrieved from the seafloor to 188.8 m DSF using nonmagnetic core barrels and the FlexIT core orientation tool. The XCB was deployed for Cores 23X through 30X to a total depth of 253.6 m DSF. The seafloor was cleared at 1435 h on 4 July, ending Hole U1406B. Recovery for Hole U1406B was 241.34 m over the 253.6 m cored (95% recovery). The total time spent on Hole U1406B was 43.25 h.

Hole U1406C coring

The vessel was offset 20 m south. Hole U1406C was spudded at 1630 h on 4 July, and a 9.4 m mudline core established seafloor depth at 3824.6 m DRF (3813.0 mbsl). Cores 342-U1406C-1H through 18H were recovered from the seafloor to 161.4 m DSF using nonmagnetic core barrels. Core orientation was not performed in Hole U1406C. The XCB was deployed to a final depth at 241.4 m DSF. Two intervals were drilled without coring (2 and 3 m) in an attempt to cover coring gaps in the previous two holes. The seafloor was cleared at 0500 h on 6 July.

After clearing the seafloor, the drill string was tripped to the surface. The BHA was set back in the derrick with the exception of the lower seal bore drill collar plus subs. Schlumberger logging tools were then rigged up to conduct a pass-through check on the lower portion of the BHA. At the conclusion of the test, the remaining BHA components were secured. The drill floor was secured at 1600 h on 6 July, ending Hole U1406C.

The acoustic positioning beacon was recovered, and the vessel began the move to Site U1405 to recover the beacon left behind there. The total time spent on Hole U1406C was 49.5 h.

Top of page   |    Previous   |    Next