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doi:10.2204/iodp.proc.317.106.2011

Operations

Transit to Site U1354

After a 7 nmi transit from Site U1353, the R/V JOIDES Resolution was positioned over Site U1354 at 2320 h (all times are ship local time, Universal Time Coordinated [UTC] +13 h) on 28 December 2009. At 0001 h on 29 December, the positioning beacon (FSI BAP-547W, SN 1025, 14.0 kHz, 200 dB) was deployed. The position reference was a combination of Global Positioning System (GPS) and an acoustic beacon on the seafloor, weighted heavily toward the acoustic beacon (80%).

Site U1354 overview

Three holes were cored with the advanced piston corer (APC)/extended core barrel (XCB) coring systems at Site U1354 (Table T1). The third hole (U1354C) was drilled to 65 m drilling depth below seafloor (DSF) with a center bit installed to advance the hole after severe weather ended Hole U1354B. Hole U1354C was then cored to 384.2 m DSF. Logging of Hole U1354C was successfully completed using a special tool configuration that combined the natural gamma ray tool, the sonic tool, and the resistivity tool. The Sediment Temperature (SET) tool was deployed twice without success. The type of formation encountered proved too difficult for our temperature measurement tools. Overall recovery for Site U1354 was 100% with the APC coring system and 39% with the XCB system. The total cored interval for Site U1354 was 479.8 m, with 294.50 m (61%) of recovery.

Hole U1354A

Rig floor operations commenced at 2345 h on 28 December when the vessel was stabilized over Hole U1354A. Coring in Hole U1354A (109.8 m water depth) began at 0415 h on 29 December, with 3.8 m of mudline core establishing the seafloor at 121.2 m drilling depth below rig floor (DRF). APC coring continued through Core 317-U1354A-19H to 85.4 m DSF using nonmagnetic coring assemblies. A 2 m section (64.9–66.9 m DSF) had to be drilled to advance through a section of shells and shell fragments. Core orientation was measured on the first three cores, but hard formation and incomplete piston strokes prompted a decision to remove the tool. Temperature measurements were not attempted in this hole because hole conditions were poor and waiting for 10 min without circulation in shallow water was deemed too risky. Overall recovery for Hole U1354A using the APC coring system was 84.43 m (101%). The drill string was pulled back to the seafloor, and the bit cleared the seabed at 2300 h on 29 December, officially ending the hole.

Hole U1354B

The vessel was offset 20 m south of Hole U1354A, and Hole U1354B was spudded at 2330 h. Hole U1354B was piston cored to 77.2 m DSF, with a total core recovery of 77.52 m (100%). Because of the rough piston coring conditions noted in Hole U1354A, the core orientation and downhole temperature tools were not deployed. Coring was terminated because highly variable winds from the south caused positioning problems. The ship could not be maintained in its required watch circle, so we decided to wait for the weather to improve. The drill string was tripped back to just above the seafloor, and the bit cleared the seafloor at 1245 h on 30 December, ending Hole U1354B.

Hole U1354C

Hole U1354C officially began at 0700 h on 31 December when the vessel could again be maintained in its watch circle over the new location. The ship was offset 20 m south of Hole U1354B, and coring began at 0715 h on 31 December. The hole was drilled with the center bit installed to 65 m DSF before two APC cores were taken. The core liner shattered on the second attempt, and the APC system was replaced with the XCB system to core through a particularly dense layer of shells. Core recovery with the XCB was initially very good but deteriorated downhole. Coring with the XCB continued to 384.2 m DSF (Core 317-U1354C-36X). The total cored interval for Hole U1354C was 319.2 m, with 133.37 m of core recovered (42%).

The hole was swept clean with a 50 bbl high-viscosity mud sweep and displaced with 320 bbl of high-viscosity 10.5 ppg logging mud. The drill string was tripped out of the hole to 225 m DRF (100 m DSF). A special logging string was made up in order to combine all basic sensors without nuclear sources into a single run. The tool string included resistivity (Dual Induction Tool [DIT]), sonic compressional and shear velocity (Dipole Sonic Imager [DSI]), and natural gamma ray spectroscopy (Hostile Environment Natural Gamma Ray Sonde [HNGS]) tools. The tool string was rigged up in the early morning of 2 January 2010 and tagged the bottom of the hole at ~505 m wireline log depth below rig floor (WRF). A short "repeat section" was recorded from there to ~440 m WRF. The tool string was returned to total depth, and then a main pass from total depth up to the seabed was recorded. The drill string was tripped back to 275 m DRF, and a 12 bbl, 14 ppg cement plug was pumped. At 0615 h on 2 January, the logging tools were rigged down, the drill string was tripped to the surface, and the bottom-hole assembly (BHA) was broken down and secured for transit. When the beacons were recovered and the rig was secured for transit, operations in Hole U1354C, at Site U1354, and on Expedition 317 ended at 1200 h on 2 January, and the vessel departed for the 24 h transit to Wellington.

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