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doi:10.2204/iodp.proc.324.105.2010

Operations

Times in this chapter are given in local ship time. During transit to Site U1346, shipboard clocks were advanced 1 h, resetting local ship time to Sydney Standard Time (Universal Time Coordinated + 10). No further adjustments to the clock were made during the expedition.

Seafloor at Site U1348 was tagged at 3275.0 m drilling depth below rig floor (DRF) (Table T1; 2.7 m shallower than the corrected precision depth recorder depth of 3277.7 m DRF), and Hole U1348A was spudded at 1245 h on 3 October 2009. The hole was washed ahead with a wash barrel in place to 84.2 m drilling depth below seafloor (DSF) where rotary coring was initiated. Coring proceeded from 84.2 to 189.9 m DSF (105.7 m) with a poor average recovery of 3.5%, due mostly to the prevalence of soft pelagic ooze and chert. Once past this depth and starting with Core 324-U1348A-13R, recovery improved markedly as the sediment transitioned to more solid sandstone and then to volcaniclastics. The bottom 134.2 m of the hole was cored at an average rate of penetration (ROP) of 8.9 m/h with an average recovery of 57.5%. The average recovery for the 239.9 m cored interval was 33.7%. The washed interval was 84.2 m. This hole was terminated at 324.1 m DSF subsequent to a science meeting during which it was collectively decided to stop further drilling at this site because igneous basement was apparently not within reach (see Fig. F4 for overview).

The hole was prepared for logging operations with a wiper trip and displacement with 86 bbl of heavy mud (10.5 ppg). Following the release of the bit at the bottom of the hole, the drill string was pulled back and the end of pipe placed at 97.6 m DSF. At 2030 h on 5 October, the Schlumberger equipment was rigged up and the first tool string (triple combination [triple combo]) was successfully deployed to ~322 m DSF. Once the triple combo was recovered, the second logging suite (Formation MicroScanner [FMS]-sonic) was made up and deployed at 0700 h on 6 October. This tool was also able to reach within 2 m of the bottom of the hole. As the tool was being drawn back into the drill string, it became firmly stuck in the bottom-hole assembly (BHA) with the calipers at the level of the top connector of the mechanical bit release. For 1.5 h, the logging winch operator attempted to advance the tool with no success (see "Downhole logging").

The only option remaining was to use the Kinley crimper and cutter system to recover the recalcitrant instrument. The Kinley crimper was deployed on the logging line, followed 45 min later by the hammer which triggered the crimper charge. A positive indication of the firing of the crimper was indicated by the expected loss of signal voltage from the logging tool. The next step was the deployment of the cutter tool and hammer, which went as planned and neatly severed the logging line just above the cable head of the tool suite. The severed end of the logging line was recovered at 2030 h, after which the drill string was retrieved. When the BHA was at the surface, the FMS-sonic tool was still firmly pinned by the caliper arms inside the top connector of the mechanical bit release.

Once the FMS-sonic was rigged down, the drilling equipment was secured and the beacon recovered. The vessel departed for the next site at 0845 h on 7 October.