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doi:10.2204/iodp.proc.327.104.2011

Operations

Following the deployment of the Hole U1362A L-CORK (see “Operations” in the “Site U1362” chapter), the ship was offset in dynamic positioning (DP) mode to Hole U1301B (47°45.228′N, 127°45.827′W; 2671 m water depth), 800 m to the south-southwest. A bottom-hole assembly (BHA) that included a CORK recovery tool was made up and tripped to the seafloor by 1615 h on 17 August 2010. At 1730 h the recovery tool engaged the Hole U1301B CORK head, but before the J-slot tool could be engaged the recovery tool heaved off. This required a second engagement attempt, and by 1815 h the tool was back on the CORK head. Engagement of the J-slot tool was ineffectual, so 10,000 lb of weight was applied to the top of the CORK, allowing us to proceed with instrument string recovery operations. The CORK running tool used for operations was later determined to be incompatible with the wellhead, which had J-slot lugs that were too large. Fortunately, this did not prevent completion of planned work.

The sinker bars were lowered, and after multiple attempts the GS overshot engaged the instrument string top plug. Tension was applied to the instrument string, which was found to be stuck in place, as it had been during the Atlantis recovery effort in summer 2009. After working the sandline with various amounts of overpull, the cable stretched or the instrument string started creeping slowly upward. At 0920 h on 17 August the Spectra cable parted. The CORK recovery tool was disengaged, and a portion of the instrument string was recovered back to the surface. Upon recovery it was found that a splice in the Spectra rope had failed directly above the middle plug of the installed instrument string. Five temperature data loggers and 377 m of Spectra rope were recovered. After laying out the recovered portion of the instrument string the CORK head was reengaged at 2225 h. A temperature logger was deployed on sandline to obtain a temperature profile of the upper part of the CORK casing and to determine the depth of casing available for subsequent instrument deployment. This allowed proper configuration of the replacement instrument string. The logging tool was stopped for 5 min at 5 m increments in the uppermost 50 m of the CORK and subsequently at 25 m intervals. The bottom of the open CORK casing was tagged at 3037 meters below rig floor (mbrf; 370 meters below seafloor [mbsf]). The recovery tool was disengaged once again at 0130 h on 18 August.

Make-up of the replacement instrument string, including rigging of the Schlumberger electric logging line, began at 0145 h. The prototype Electronic “RS” (ERS; “RS” is an oil field designation for a particular geometry of fishing tool) tool system, under development by Stress Engineering for use with the developmental SCIMPI CORK system, was used for this deployment because the Hole U1301B CORK system was not configured with an instrument string latch-down system. Historically, there have been significant problems jarring off the instrument string without dislodging the upper CORK plug, which has tended to get pulled out of the wellhead during deployment. The replacement instrument string, which included three thermistor probes and extended to ~54 mbsf (end of sinker bar), was ready for deployment at 0330 h, and the CORK running tool was engaged once again at 0435 h. The instrument string was successfully landed and released using the ERS tool without incident, and the Schlumberger logging line was recovered and rigged down. At 0530 h on 18 August the CORK recovery tool was disengaged, ending operations in Hole U1301B.

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