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doi:10.2204/iodp.proc.317.105.2011

Operations

Transit to Site U1353

After an 18 nmi transit from Site U1352, the R/V JOIDES Resolution was positioned over Site U1353 at 2320 h (all times are ship local time, Universal Time Coordinated [UTC] + 13 h) on 21 December 2009. At 2346 h, 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 U1353 overview

Three holes were cored or drilled at Site U1353 (Table T1). The first hole was cored with the advanced piston corer (APC) system to 56 m drilling depth below seafloor (DSF) to provide sufficient samples for microbiology, chemistry, and geotechnical studies. The second hole was cored with the APC/extended core barrel (XCB) systems to the target depth of 614 m DSF. The third hole was drilled as a dedicated logging hole to 529 m DSF with a center bit installed in the APC/XCB bottom-hole assembly (BHA).

At 84.2 m water depth, Hole U1353A is the shallowest hole drilled for science by the JOIDES Resolution. The only holes cored in shallower water by the JOIDES Resolution were located in the Eniwetok Lagoon during Ocean Drilling Program (ODP) Leg 143. Holes 870A and 870B were cored to 48.7 and 49.8 m DSF, respectively, with a total recovery for both holes of 0.6 m. Both holes were drilled to test the dynamic positioning (DP) system and were not drilled for scientific objectives.

Core recovery at Site U1353 was 100% for the APC system and 5% for the XCB system. The total cored interval for Site U1353 was 670.3 m, with 267.86 m (40%) of recovered core samples.

Hole U1353A

Rig floor operations commenced at 2320 h on 21 December when the vessel shifted to auto-DP control. The BHA was made up with an APC/XCB bit, and operations in Hole U1353A began at 0230 h on 22 December with the establishment of the mudline at 91.5 m drilling depth below rig floor (DRF; 84.2 meters below sea level [mbsl]). APC coring continued through Core 317-U1353A-8H to 56.0 m DSF using nonmagnetic coring assemblies. Orientation was taken on the first six cores. The third-generation advanced piston corer temperature tool (APCT-3) was deployed once (Core 317-U1353A-5H) without success. The type of formation encountered proved too difficult for our temperature measurement tools. Contamination testing was done on all cores with microspheres. Overall recovery for Hole U1353A was 56.38 m over an interval of 56 m (101%). The drill string was pulled back to the seafloor, and the bit cleared the seabed at 1115 h on 22 December.

Hole U1353B

The vessel was offset 20 m south of Hole U1353A, and coring in Hole U1353B began at 1115 h on 22 December. Hole U1353B was piston cored to 80.2 m DSF, with a total recovery of 80.74 m (101%). Because of the rough piston coring conditions noted in Hole U1353A, orientation and temperature measurement tools were not deployed in this hole. In an effort to maximize recovery and make progress in the hole, the XCB coring system was deployed intermittently from Cores 317-U1353B-14X through 60H (80.2–257.7 m DSF). In this interval, 69.7 m was cored in 9 XCB deployments, recovering 2.53 m of core (4%), and 107.8 m was cored in 38 APC deployments, recovering 107.6 m (100%). The superior recovery with the APC was not without penalty. Almost all of the piston cores were partial strokes (average = 3.7 m). Because the bit was advanced by recovery, the rate of penetration was very slow. Many cores had shattered core liners, and piston seals and core catchers were damaged. In addition, the recovered material included a large amount (>50%) of reworked or caved material.

Below 257.7 m DSF, Cores 317-U1353B-61X through 98X were taken to a total depth of 614.3 m DSF, recovering 20.55 m (6%).

The drill string was tripped back to 250 m DRF, and a 12 bbl, 14 ppg cement plug was pumped according to IODP policies for drilling on a continental shelf. The drill string was tripped back to just above the seafloor, and the bit cleared the seafloor at 2050 h on 26 December, ending Hole U1353B. A total of 211.48 m of core was recovered over an interval of 614.3 m (average recovery of 34%).

Hole U1353C

The ship was offset 20 m north of Hole U1353A, and drilling in Hole U1353C, a dedicated logging hole, began at 2050 h on 26 December. The hole was drilled to 626 m DSF, swept clean with a 50 bbl high-viscosity mud sweep, and displaced with 300 bbl of high-viscosity 10.5 ppg mud. The drill string was tripped out of the hole to 202 m DRF. The triple combination (triple combo) logging tool string was rigged up without nuclear sources (neutron porosity and gamma ray density) to minimize operational risk. The tool string was run into the hole, tagging the bottom at 621 m wireline log depth below rig floor (WRF); the hole was logged up from there. The logging string was pulled to the surface and rigged down, and the Formation MicroScanner (FMS)-sonic tool string was assembled and run into the hole to 343 m WRF, where an obstruction was encountered. The hole was logged up from 343 m WRF. A second attempt was made to run down with the FMS-sonic tool string, but the tool string was only able to reach ~300 m WRF. Hole conditions while the tool was logged upward continued to deteriorate until the hole collapsed completely below 202 m WRF. The drillers worked to free both the drill string and the logging string, and eventually the logging string partially reentered the drill string. The drill string and the logging line were pulled up onto the rig floor using T-bars from ~200 m DRF. Hole U1353C could not be cemented with the logging tools stuck in the drill string, and the hole completely collapsed as the BHA was pulled clear of the hole, making it impossible to cement. The logging tools were rigged down on the rig floor. The BHA was broken down and secured at 2100 h on 28 December, ending Hole U1353C and operations at Site U1353.

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