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doi:10.2204/iodp.proc.320321.109.2010

Operations

Honolulu port call

Expedition 321 officially began at 0736 h (Hawaii Standard Time; Universal Time Coordinated [UTC] – 10 h) on 4 May 2009, with the first line ashore Pier 2B in Honolulu, Hawaii (USA). The JOIDES Resolution arrived a full day early, having been scheduled in at 0700 h 5 May. The early arrival added a bonus day to a schedule that already was planned as a 4 day port call.

The ship arrived with two propulsion motors out of service, requiring field coil replacement. This was the first priority activity upon arrival. The first day also included offloading all refrigerated core sections and replacement of the logging winch transmission. During port call, vendor representatives were aboard to replace the elevator mechanical interlocks with a solenoid-actuated variety, balance the heating/ventilation/air conditioning system, and repair and calibrate the Rigwatch rig instrumentation system (RIS). Normal on- and offloading activities took place, including loading of 10 short tons of attapulgite drilling mud left over from the Expedition 320 Honolulu port call, and 1537 metric tons of marine gas oil were bunkered. Training was conducted on the Rigwatch RIS and on operation of the Schlumberger logging line winch and wireline heave compensator (WHC) systems. Other activities included a Det Norske Veritas International Safety Management audit of the ship and the arrival of Center for Deep Earth Exploration engineers to discuss the JOIDES Resolution's core winch regenerative braking system and coring tools.

Public relations activities were conducted dockside at the Pier 2B cruise ship terminal, the Waikiki Aquarium, and the Marriott Hotel Waikiki. Several high-level dignitaries and other management personnel, including the directors of the National Science Foundation, Ocean Leadership, the University of Hawaii, and Texas A&M University, were in attendance. Ship tours were conducted for dignitaries as well as University of Hawaii faculty and students and high school students and teachers.

The ship departed Honolulu with the last line away from Pier 2B at 0512 h on 9 May. At ~10 nmi offshore the ship switched from cruise mode to dynamic positioning (DP) control and lowered thrusters. DP trials were conducted for 7.75 h to optimize system performance after changes in the ship profile were made during the Singapore refit. During this period a representative from L3, the Nautronics parent company, collected data and made adjustments to the internal windage modeling program that impacts the anticipatory commands of the system. The vendor was transferred from the JOIDES Resolution to the V/L Karake at the Honolulu Harbor outer sea buoy. At 1636 h the vessel got under way for Site U1336.

Transit to Sites U1336 and U1337

The transit to Site U1336 (proposed Site PEAT-5C) began at 1636 h on 9 May 2009. Transit speeds varied considerably as a result of fluctuating currents and eddies surrounding the Hawaiian Islands with average transit speeds from 9.9 to 10.7 kt with 135 turns on both shafts. One propulsion motor remained offline as field coil replacement continued. On the morning of 11 May, after several days of discussions with the science team, the decision was made to divert our course from Site U1336 to Site U1337 (proposed Site PEAT-7C). The decision was driven by several issues including (1) slower than anticipated transit speeds, (2) time spent conducting automated stationkeeping sea trials took longer than planned, (3) addition of VSI to the suite of wireline logging tools to be deployed at Site U1337, (4) depth to basement projections deepened by 50 m because of results from Expedition 320, and (5) scientific tradeoffs in general between additional operations at Site U1336 versus conducting a more complete program at Site U1338. During the transit, routine readiness inspections were conducted by the drill crew on all of the drilling equipment. During the inspection it was discovered that the passive heave compensator rod seals were burned up and required replacement. The clocks advanced by 3 h during transit (1 h increments on 13, 16, and 17 May). From here onward, times are local ship time, which was U.S. Pacific Daylight Savings Time (UTC – 7 h). The ship arrived on location the morning of 19 May. The total 2320 nmi transit was accomplished in 9.8 days at an average speed of 10.0 kt.

Site U1337

Although the Global Positioning System (GPS) was the primary positioning reference used for this site, a new-generation acoustic beacon was also deployed at 1250 h on 19 May 2009. The automated stationkeeping system can be configured to accept position inputs from both the GPS and the seafloor acoustic beacon. Both inputs were used for Expedition 321.

Four holes were drilled at this site using the APC/XCB coring systems (Table T1). One hole (U1337B) was terminated early when the XCB core barrel became stuck in the bit seal. This necessitated the drilling of the fourth hole. The cause of the stuck barrel was later identified as an APC shear pin stub. The first hole was successfully wireline logged using the triple combo, VSI, and FMS-sonic tool strings. Overall recovery for Site U1337, using both APC and XCB coring systems, was 96.0%. The basement contact was recovered in three of the four holes drilled at the site.

Hole U1337A

Rig floor operations commenced at 1200 h after the ship was stationary over the location coordinates. The pipe trip to the seafloor was slow because of the need for measuring (strapping) and drifting (internal diameter verification) of all tubulars and the picking up of the drill collars from the main deck storage rack. At 0300 h on 20 May, the top drive was picked up; however, the tilt/counterbalance feature was not functional. Troubleshooting and repairing the top drive took 4 h before spacing out the drill string and deploying the first APC core barrel. With the bit positioned at 4467.0 m drilling depth below rig floor (DRF) the first APC barrel was pressured up and fired. Upon recovery, the leading edge of the APC cutting shoe was found severely damaged and the core barrel was empty. To confirm the approximate seafloor depth the drill string was lowered and the mudline was "tagged" twice at about the same depth of 4472.0 m DRF. This depth was taken as the official seafloor depth for the hole, the bit was repositioned 1.0 m lower at 4468.0 m DRF, and Hole U1337A was spudded at 1115 h. Core 1H recovered 0.19 m (Table T1) of core, and once again the APC cutting shoe showed signs of having impacted something very hard. APC coring continued normally from there, however, and was suspended at 195.5 m DSF because of a 90,000 lb overpull. Nonmagnetic core barrels were used for all cores except Core 21H. A 60,000 lb overpull for Core 20H led to a return to steel core barrels. Average core recovery for the APC was 102%. FlexIt core orientation was conducted for all cores except Core 1H with apparent good success. In addition, five successful APCT-3 measurements were taken with Cores 5H, 7H, 9H, 11H, and 13H at 43.5, 62.5, 81.5, 100.5, and 119.5 m DSF, respectively. Only one core liner split (Core 8H), coincidently the first barrel shot with all three speed control holes open. XCB coring continued with Cores 22X through 48X, achieving an average recovery of 87%. Two split core liners occurred during XCB coring (Cores 37X and 38X). There was nothing significant noted in the coring parameters for these two cores other than the fact that Core 38X achieved only 53% recovery compared to Core 37X, which had 101% recovery. The sediment/basement contact was recovered at the base of Core 48X. Total depth of Hole U1337A was 4921.8 m DRF (449.8 m DSF). Overall recovery for the hole using both APC and XCB coring systems was 93%. Rig-up for wireline logging began at 1130 h on 23 May. Logging was successfully concluded and all logging equipment was rigged down by 0900 h on 25 May. Three logging strings were deployed. The triple combo reached total hole depth of 449.8 m DSF and obtained good-quality logs. The second logging string consisted of the VSI. This tool also reached total hole depth, and shooting stations were conducted at ~15 m intervals. VSI logging was conducted during daylight hours to conform with established IODP mammal watch protocols, including a preshooting mammal watch and soft start procedures for the air guns. The third logging string (FMS-sonic) reached a depth of 440.0 m DSF (<10 m off bottom). With the end of pipe positioned at 82.6 m DSF, there were no reported issues with logging tools reentering the pipe. The drill string was pulled back until the bit cleared the seafloor at 0930 h on 25 May, ending operations in Hole U1337A.

Hole U1337B

The ship was offset 20 m west of Hole U1337A, and the bit was positioned at a depth of 4473.0 m DRF. This was to offset the core breaks between the two holes, maximizing the chances to recover a complete section. The seafloor "tag" depth of 4472.0 m DRF for Hole U1337A was used for Hole U1337B. APC coring continued through Core 27H to 245.2 m DSF. The FlexIt core orientation system was deployed successfully for all but two APC cores (17H and 18H). Nonmagnetic core barrels were used through Core 20H and successful APCT-3 measurements were obtained with Cores 15H, 17H, and 19H at 143.5, 162.5, and 181.5 m DSF, respectively. Overpull for the APC ranged from 20,000 to 90,000 lb and all but five barrels (Cores 21H, 23H through 25H, and 27H) achieved full stroke. Two cores (16H and 22H) were recovered with split liners. The first split occurred after recovery with the sectioned cores in the rack. The latter split occurred in the core barrel prior to extraction. Average core recovery for the APC was 99%. Coring continued with a single XCB core (28X) to 251.9 m DSF; however, this barrel could not be recovered, forcing Hole U1337B to be abandoned prematurely. The drill string was recovered and further analysis indicated that a shear pin stub from an earlier piston core had caused the XCB core barrel to jam in the bit seal assembly; the core barrel was empty. Operations in Hole U1337B officially ended at 2245 h on 27 May. Total depth achieved was 4723.9 m DRF (251.9 m DSF). Overall recovery for the hole using both APC and XCB coring systems was 97%. The single XCB core (28X) recovered nothing.

Hole U1337C

The ship was offset 20 m west from Hole U1337B, and the drill string was tripped to the seafloor. Hole U1337C was spudded with the bit positioned at 4471.0 m DRF. Recovery from APC Core 1H established a seafloor depth of 4478.6 m DRF. Core 2H extended the hole to 11.4 m DSF using nonmagnetic core barrels and the FlexIt core orientation system. A wash barrel was deployed, and the hole was washed to a depth of 169.4 m DSF. APC coring resumed at that depth and continued through Core 9H to 221.3 m DSF. Steel core barrels were used at this point because of high overpull >70,000 lb. Full stroke was achieved with all cores except Core 6H, which was advanced by recovery. Average core recovery for the APC was 103%. Coring with the XCB system continued with Cores 10X through 33X, recovering 95% of the section. Total depth of the hole was 4918.9 m DRF (440.3 m DSF), and overall recovery, using both APC and XCB coring systems, was 97%. The drill string was pulled clear of the seafloor at 1400 h on 30 May, officially ending operations in Hole U1337C.

Hole U1337D

The plan for this hole was to duplicate recovery through those sections of the formation already recovered to provide additional sample material. In addition, the goal was to use a more focused coring approach to target once again the few remaining areas that had yet to be fully recovered. The most troublesome material was the large intervals of diatom mats and a porcellanite ("baby chert") layer. Hole U1338D was spudded at 1645 h on 30 May. Recovery of APC Core 1H placed the seafloor depth at 4476.5 m DRF. APC coring continued through Core 26H to 237.7 m DSF. Nonmagnetic core barrels were used through Core 20H, and Core 21H was shot with the bit 4.5 m off bottom to set up the first target area of interest. The first XCB core (27X) was designed to only core through the hard ~0.5 m thick porcellanite (baby chert) layer but not into the material below. The APC was once again deployed, and Cores 28H through 30H were cut to 267.0 m DSF. At this point the XCB coring system was once again deployed for Cores 31X through 49X to a total depth of 442.9 m DSF. The FlexIt core orientation system was deployed successfully with all APC cores, and all barrels were fully stroked except for Core 22H. Total recovery for the APC in this hole was 103%, and recovery with the XCB coring system was 90%. Total recovery for the hole was 98%. A much higher incidence of imploded or split liners plagued this hole, and we were unable to identify the reason. The drill string was recovered, the bottom-hole assembly was racked back in the derrick, and the rig floor was secured for transit. Once the bit cleared the seafloor the positioning beacon was recovered and thrusters and hydrophones were raised. At 1625 h on 2 June, control was switched from DP to cruise mode and the ship got underway for the next site.

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