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doi:10.2204/iodp.proc.327.105.2011

Operations

Following operations in Hole U1301B (see “Operations” in the “Site U1301” chapter), the ship was offset in dynamic positioning mode to Hole 1027C. At 1000 h on 18 August 2010 a CORK recovery tool was slipped onto the CORK head, and engagement of the J-slots with the CORK lugs was verified by 1015 h. Another 3.5 h was spent in an unsuccessful attempt to recover the CORK, including pulling to 140,000 lb of overpull. Ultimately, we realized that in order to release this type of CORK another set of lugs below the CORK platform had to be engaged, but this required a release tool that had not been brought to sea. The recovery tool used for the initial recovery attempt during Expedition 327 was not long enough to reach the second set of lugs, so the drill string was recovered to the surface while options were considered. Finally, we decided that the crew could fabricate an appropriate CORK recovery tool using the existing tool as a basis. This fabrication took 36 h to complete: a test-fitting jig was built to emulate the CORK head to be recovered, a section of 20 inch casing was used to extend the length of the recovery tool so it could reach deep enough to engage the lower set of CORK lugs, the lower section of the tool was enlarged to the correct inside diameter, and the small reverse cone used to enhance the tool’s ability to get over the CORK head was cut down to a 32 inch diameter. Everything was welded back together, doubler plates were added for extra strength, and the tool was fit over the test jig for the final time.

The drill string was tripped to the seafloor, and at 1200 h on 20 August the new recovery tool was slipped over the CORK head. The tool was lowered down through the 48 inch hole in the center of the CORK platform, and by 1245 h the lower latches on the CORK head were engaged with the modified recovery tool J-slots. The next 3.5 h was spent trying to pull the CORK, but the latching mechanism still would not release. Attempts were cycled between allowing the recovery tool to hammer down on the CORK head with 10,000 lb to exerting an overpull up to 100,000 lb, again without success. It is unclear why the CORK could not be released from the hole once the proper recovery tool was deployed, but with limited time available to complete other high-priority activities and no additional options for resolving the problem, the attempt to recover the CORK from Hole 1027C was abandoned. At 1615 h the recovery tool was disengaged from the CORK head and the drill string was recovered back to the surface. The subsea TV was recovered, and at 2130 h on 20 August the recovery tool cleared the rotary table, ending operations in Hole 1027C.

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