Previous   |    Next

doi:10.2204/iodp.proc.342.106.2014

Operations

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

Hole U1405A summary

• Latitude: 40°08.3001′N
• Longitude: 51°49.1996′W
• Water depth below sea level (m): 4285.8
• Date started: 0745 h, 25 June 2012
• Date finished: 1120 h, 27 June 2012
• Time on hole (days): 2.1
• Seafloor depth (m drilling depth below rig floor [DRF]): 4297.3
• Seafloor depth estimation method: mudline core
• Rig floor to sea level (m): 11.5
• Penetration depth (m drilling depth below seafloor [DSF]): 308.6
• Cored interval (m): 308.6
• Recovered length (m): 270.34
• Recovery (%): 88
• Total cores (number): 33
• Advanced piston corer (APC) cores (number): 26
• Extended core barrel (XCB) cores (number): 7
• Drilling system: 11 inch APC/XCB bit with 136.00 m bottom-hole assembly (BHA)
• Objective: core from seafloor to ~250 m DSF
• Result: target exceeded; objectives met

Hole U1405B summary

• Latitude: 40°08.2995′N
• Longitude: 51°49.1845′W
• Water depth below sea level (m): 4284.5
• Date started: 1120 h, 27 June 2012
• Date finished: 1610 h, 28 June 2012
• Time on hole (days): 1.2
• Seafloor depth (m DRF): 4296
• Seafloor depth estimation method: mudline core
• Rig floor to sea level (m): 11.5
• Penetration depth (m DSF): 223.5
• Cored interval (m): 218.5
• Recovered length (m): 219.6
• Recovery (%): 101
• Drilled interval (m): 5
• Drilled interval (number): 1
• Total cores (number): 23
• APC cores (number): 23
• 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 U1405C summary

• Latitude: 40°08.2890′N
• Longitude: 51°49.1847′W
• Water depth below sea level (m): 4287.3
• Date started: 1610 h, 28 June 2012
• Date finished: 0200 h, 30 June 2012
• Time on hole (days): 1.4
• Seafloor depth (m DRF): 4298.8
• Seafloor depth estimation method: mudline core
• Rig floor to sea level (m): 11.52
• Penetration depth (m DSF): 232.0
• Cored interval (m): 232
• Recovered length (m): 227.77
• Recovery (%): 98
• Total cores (number): 25
• APC cores (number): 25
• Drilling system: 11 inch APC/XCB bit with 136.00 m BHA
• Objective: repeat cored sequence from Holes U1405A and U1405B
• Result: target reached; objectives met

Description

The vessel arrived at Site U1405 after a 7.5 nmi transit from Site U1404. The transit was made in dynamic positioning mode at a speed of 0.8 kt with the drill pipe suspended below the vessel. The vessel stabilized over Site U1405 at 0745 h on 25 June 2012. The plan for this site called for drilling three holes to a depth of ~250 m DSF. Holes U1405A–U1405C were successfully cored to depths of 308.6, 223.5, and 232.0 m DSF, respectively, without any significant problems.

Hole U1405A coring

Hole U1405A was spudded at 1140 h on 25 June 2012, and a 6.2 m mudline core established seafloor depth at 4297.3 m below rig floor (DRF; 4285.8 mbsl). Cores 342-U1405A-1H through 26H were recovered from the seafloor to 241.9 m DSF using nonmagnetic core barrels and the FlexIT core orientation tool. Advanced piston corer temperature tool (APCT-3) measurements were taken on Cores 4H, 7H, and 10H with good results. The first partial stroke was experienced with Core 26H, and the liner and core had to be pumped out of the core barrel. The XCB was deployed for Cores 27X through 33X to a total depth of 308.6 m DSF. The seafloor was cleared at 1120 h on 27 June, ending Hole U1405A. Overall core recovery for Hole U1405A was 270.34 m for the 308.6 m interval cored (88% recovery). Total time spent on Hole U1405A was 51.6 h.

Hole U1405B coring

The vessel was offset 20 m east, and Hole U1405B was spudded at 1305 h on 27 June. A 9.5 m mudline core established seafloor depth at 4296.0 m DRF (4284.5 mbsl). Cores 342-U1405B-1H through 24H were recovered from the seafloor to 218.5 m DSF using nonmagnetic core barrels and the FlexIT core orientation tool. An interval of 5 m was drilled without coring in an attempt to cover coring gaps in Hole U1405A. The seafloor was cleared at 1610 h on 28 June, ending Hole U1405B. Coring the 218.5 m interval yielded 219.60 m of core (101% recovery). The total time spent on Hole U1405B was 29.0 h.

Hole U1405C coring

The vessel was offset 20 m south. Hole U1405C was spudded at 1915 h on 28 June and a 6.7 m mudline core established seafloor depth at 4298.8 m DRF (4287.3 mbsl). Cores 342-U1405C-1H through 25H were recovered to a total depth of 232.0 m DSF using nonmagnetic core barrels and the FlexIT core orientation tool. The cored interval of 232.0 m yielded 227.77 m of core (98% recovery). The total time spent on Hole U1405C was 33.75 h. The seafloor was cleared at 0200 h on 30 June, ending Hole U1405C.

After clearing the seafloor, the drill string was tripped to ~3500 m DRF and the vessel began moving in dynamic positioning mode to the next site at a speed of 1.5 kt. The positioning beacon was left on-site to minimize the risk of losing it during recovery in difficult weather conditions. The beacon was recovered after operations at Site U1406 were complete. The total time spent at Site U1405 was 114.25 h (4.8 days).

Top of page   |    Previous   |    Next