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doi:10.2204/iodp.proc.341.104.2014

Operations

Transit to Site U1418

After a 137 nmi transit from Site U1417 averaging 10.3 kt, the vessel arrived at the second expedition site. The vessel stabilized over Site U1418 at 1455 h (UTC – 8 h) on 23 June 2013, and the positioning beacon was deployed at 1515 h.

Site U1418

Site U1418 consists of six holes (Table T1), ranging in depth from 17.0 to 948.7 m drillers depth below seafloor (DSF) (Fig. F7). A total of 185 cores were recovered at the site. The interval cored with the advanced piston corer (APC) system was 810.0 m, with 819.08 m recovered (101%). The interval cored with the extended core barrel (XCB) system was 48.5 m, with 22.80 m recovered (47%). The interval cored with the rotary core barrel (RCB) system was 688.7 m, with 495.20 m recovered (72%). The overall recovery for Site U1418 was 86%. Total time spent on Site U1418 was 16.1 days.

Hole U1418A

Hole U1418A was spudded at 0015 h on 24 June 2013. The mudline core recovered 4.87 m of sediment, and the seafloor was calculated to be 3668.2 m drillers depth below sea level (DSL). Nonmagnetic core barrels and the APC system were used for Cores 341-U1418A-1H through 13H. Temperature measurements were taken with the advanced piston corer temperature tool (APCT-3) shoe on Cores 4H, 7H, 10H, and 13H. APC coring with wireline continued through Core 33H with the half APC coring system using steel core barrels. Partial APC strokes were recorded on Cores 11H, 12H, 13H, 32H, and 33H. Hole U1418A was terminated after Core 33H (209.9 m DSF). The drill string cleared the seafloor 1155 h on 25 June, ending Hole U1418A. A total of 33 piston cores were taken over a 209.9 m interval, with 216.85 m recovered (103%). Total time spent on Hole U1418A was 45.0 h.

Hole U1418B

After clearing the seafloor, the vessel was offset 20 m east of Hole U1418A. Hole U1418B was spudded at 1355 h on 25 June 2013. The mudline core recovered 7.57 m of sediment, and seafloor was calculated to be 3667.5 m DSL. Nonmagnetic core barrels and the APC system were used for Cores 341-U1418B-1H and 2H. Hole U1418B was terminated after two cores. These cores overlap with a cored interval that was disturbed in the first two cores from Hole U1418A. At the conclusion of coring, the bit was pulled clear of the seafloor, ending Hole U1418B at 1525 h on 25 June. A total of two piston cores were taken over a 17.0 m interval, with 17.08 m recovered (101%). Total time spent on Hole U1418B was 3.5 h.

Hole U1418C

After clearing the seafloor, the vessel was offset 20 m south of Hole U1418B. Hole U1418C was spudded at 2030 h on 25 June 2013. The mudline core recovered 8.67 m of sediment, and seafloor was calculated to be 3666.0 m DSL. Nonmagnetic core barrels were used and FlexIT orientation was performed for Cores 341-U1418C-1H through 7H. The liner from Core 7H had to be pumped from the core barrel, and the decision was made to drill ahead 2.5 m and change to the half APC coring system. The hole was advanced from Core 9H through Core 19H to 118.2 m DSF. Core barrels were then switched back to the full stroke, nonmagnetic core barrels, and the hole was advanced through Core 33H to 230.7 m DSF. Partial strokes of the coring system occurred on every core after Core 18H, but recovery was adequate until Core 33H. Hole U1418C was terminated at 230.7 m DSF. The seafloor was cleared at 0710 h on 27 June, ending Hole U1418C. A total of 32 piston cores were taken over a 228.2 m interval, with 229.48 m recovered (100.6%). Total time spent on Hole U1418C was 39.75 h.

Hole U1418D

After clearing the seafloor, the vessel was offset 20 m west of Hole U1418C. Hole U1418D was spudded at 0855 h on 27 June 2013. An offset water depth of 3666.5 meters below sea level (mbsl) was used after averaging the tide-corrected water depths from the first three holes. After spudding Hole U1418D, the hole was washed down to 3 m DSF and coring began with Core 341-U1418D-2H and continued with nonmagnetic core barrels through Core 26H to 230.0 m DSF. Partial strokes were recorded on Cores 12H, 13H, 16H, and 19H through 29H. After Core 26H, the half APC coring system was deployed, and coring continued to Core 32H (257.3 m DSF). The XCB coring system was deployed for Cores 33X through 37X to 305.8 m DSF. Total depth was reached at 0725 h on 29 June. The drill string was then pulled from the hole, and the seafloor was cleared at 0900 h, ending Hole U1418D. A total of 31 piston cores were taken over a 254.3 m interval, with 256.97 m recovered (101%). A single 3 m interval was drilled without coring. A total of five XCB cores were cut over a 48.5 m interval, with 22.8 m recovered (47%). Total core recovery for Hole U1418D was 279.77 m for the 302.8 m cored interval (92%). Total time spent on Hole U1418D was 49.75 h.

Hole U1418E

After clearing the seafloor, the vessel was offset 20 m south of Hole U1418D. While servicing the rig, a broken strand of wire was detected on the drilling line. Rather than risk a more severe problem, the decision was made to slip and cut the drilling line to remove the damaged section. Hole U1418D was spudded at 1755 h on 29 June 2013. A tide-corrected offset depth of 3667.7 mbsl was established for seafloor depth. The hole was advanced to 78.0 m DSF without coring, and the wash barrel was pulled. APC coring continued for Cores 341-U1418E-2H through 13H to 181.6 m DSF. Total depth was reached at 1000 h on 30 June. After laying out the final core, the drill string was tripped back to 133.4 m DSF and the top drive was set back. The drill string was then tripped back to surface, and the bottom-hole assembly (BHA) was set back in the derrick. The bit cleared the rotary table at 1900 h, ending Hole U1418E. A total of 11 APC cores were taken over a 100.6 m interval, with 98.7 m recovered (98%). Two intervals were drilled without coring. The first interval was 78.0 m, and the second was 3 m. Total time spent on Hole U1418E was 34 h.

Hole U1418F

After clearing the seafloor, the vessel was offset 20 m west of Hole U1418E. Hole U1418F was spudded at 0445 h on 1 July 2013. A water depth of 3677.0 mbsl was estimated using an offset depth, which was calculated using tide-adjusted depths for the first three holes at the site. After spudding Hole U1418F, the hole was drilled without coring to 260.0 m DSF. The wash barrel was then pulled, and Cores 341-U1418F-2R and 3R were cut to 279.4 m DSF but were empty when recovered on the rig floor. The core barrel, which had been dropped to cut Core 4R, was retrieved, and a core barrel with a bit deplugger was deployed. RCB coring with nonmagnetic core barrels resumed, and Cores 4R through 72R were cut to 948.7 m DSF. A total of 71 RCB cores were cut over a 688.7 m interval, with 495.20 m recovered (72%).

A total of 265 bbl of high-viscosity mud were used during and at the conclusion of the drilling/coring process in Hole U1418F. Following a short wiper trip from 830.0 to 945.0 m DSF, an additional 50 bbl sweep of high-viscosity mud was pumped to condition the hole for logging. After pumping the final sweep, the rotary shifting tool was deployed by wireline and the shifting sleeve inside the mechanical bit release was pulled, releasing the bit at the bottom of Hole U1418F. After releasing the bit, the sleeve was shifted back and the top drive was set back. The drill string was then tripped out of the hole, and the end of pipe was set at 98.6 m DSF for logging.

The triple combo logging string was then rigged up and run into the hole, reaching a total depth of 599 m wireline log depth below seafloor (WSF) at 2333 h on 7 July. The Schlumberger wireline winch experienced a transmission problem during the logging run and had to be repaired. The hole was then logged up, and the tools were pulled to surface and rigged down. After rigging down the triple combo tool string, the Versatile Seismic Imager (VSI) tool string was then rigged up and run into the hole. Protective Species Observation watches began at 0900 h 8 July. No protected marine species were observed within the 940 m diameter exclusion zone for 1 h, so the seismic source (a parallel cluster of two 250 in³ Sercel G. Guns) was ramped up. Watches continued throughout the VSI run, with the guns fired manually every 5 min as the tool string was run into the hole. Once the VSI tool string was in the hole, firing control was delivered to the Schlumberger engineer. Attempts were made to collect data over several hours, but the tool had problems clamping onto the borehole wall. The tool string was pulled out of the hole and back to the surface and rigged down. The guns were secured and the Protective Species Observation watches ceased at 1530 h.

The Formation MicroScanner (FMS)-sonic tool string was then rigged up and deployed to a depth of 582 m WSF. A single pass was made before the tool string became stuck in the BHA. After trying unsuccessfully to free the tool string, the Kinley crimper was rigged up and deployed to crimp the logging cable inside the BHA before severing the cable. The pressure spike experienced with the line under tension was enough to free the logging tool string, which was then pulled to the surface and rigged down. All logging equipment was rigged down by 0845 h on 9 July, and the knobbies were removed from the drill string. The drill string was then pulled from the hole and the BHA set back and secured for transit at 1630 h on 9 July, ending Site U1418. Total time spent on Hole U1418F was 213.5 h.

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