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doi:10.2204/iodp.pr.325.2010

Offshore operations

Expedition 325 carried two types of coring tools: an extended nose corer (EXN; equivalent to the extended core barrel [XCB]; core type X) and a standard rotary corer (ALN; equivalent to the rotary core barrel [RCB]; core type R). See Table T1 for a summary of operations.

Mobilization of the Greatship Maya

Mobilization of the drilling platform Greatship Maya took place in two stages; the first stage occurred in Singapore (Japan) on 4–13 January 2010 and the second stage took place in Townsville (Australia) on 10–11 February. ESO personnel were also present onboard the Greatship Maya during her geotechnical sea trials (18–29 January), assessing operational capability.

Shipping of ESO laboratories, office, database, and refrigerated containers from ESO partners around Europe began in late August 2009 when three containers were dispatched from Germany. This was followed in late November 2009 by four containers from the United Kingdom. Once all the containers had cleared customs, they were delivered to the Keppel Shipyard, Singapore, where they were held until stage one of mobilization in January 2010. Downhole logging tools were air-freighted directly to Townsville in January 2010, where they were held by Westlink Logistics Pty Ltd, who acted as shipping agents, until the second stage of mobilization in February 2010. The staggered shipping of containers and equipment was unusual for a mission-specific platform (MSP) expedition and arose because of a change of vessel by Bluestone Offshore Pte Ltd in late August 2009, which occurred after the containers had left Germany but prior to any other shipment.

The first stage of mobilization was significantly reduced because of delays in the shipyard's schedule of work. Containers were loaded onto the Greatship Maya toward the end of the mobilization period, and power was provided to the containers to enable checking of all equipment. However, an unexpected dock move resulted in power being withdrawn from the two Expedition Drilling Information System (ExpeditionDIS) servers before ESO personnel could shut them down. This resulted in them failing completely. New servers accompanied ESO personnel to the mobilization in Townsville. The second stage of mobilization included installing a shipboard computer network and the new ExpeditionDIS servers, preparing equipment within the laboratories, providing power to the refrigerated container, and loading on and checking all the downhole logging equipment.

Transit to Townsville, Australia

The Greatship Maya departed Singapore at 1130 h on 30 January 2010, clearing customs in Singapore at the anchorage at 1330 h, and arrived alongside at Townsville at 1600 h on 9 February. One member of ESO personnel sailed on the transit, continuing to mobilize the containers and equipment where possible en route.

Port call in Townsville

The second stage of mobilization took place in Townsville on 10–11 February 2010. The remaining ESO personnel and members of the science party joined the Greatship Maya at 0815 h on 10 February. For this stage of mobilization, the complete ESO team was available. All laboratories and office spaces were networked with computers, the Drilling Information System (DIS) database system was set up, onboard equipment was laid out, and a satellite-based e-mail system was installed in the office containers and the client office inside the vessel's superstructure. New servers supporting the DIS were also installed, having been flown out with the ESO staff following complete failure of both original servers at Singapore during the first stage of mobilization.

At 1200 h on 11 February, the Co-Chief Scientists, Staff Scientist, Operations Superintendant, and ESO Outreach Manager attended a media launch at the Jupiters Hotel, Townsville. Following this, three television teams, local and regional print media, and a number of national radio reporters were invited to visit the Greatship Maya for a guided tour of the drilling platform and operational areas; the tour lasted ~1 h.

Transit to HYD-01C transect

The Greatship Maya departed for the first site at 2100 h on 11 February 2010 after spending 53 h in port and arrived at Site 5 at the HYD-01C transect, Hole M0030A, at 2315 h on 12 February. For the first 16 h, transit speed was a maximum of 5 kt because of water coming up through the moonpool door and ingressing into the engine room via a faulty hatch. Once the hatch was repaired, transit speed was slowly increased to 12 kt from 1300 h onward. There was also a problem with the vessels air conditioning system for 24 h after departing from Townsville, which was rectified by the engineering crew onboard.

Site 5

Hole M0030A

The Greatship Maya arrived on station over Hole M0030A at 2315 h on 12 February 2010 and proceeded to begin tests on the dynamic positioning (DP) system. The initial spin test revealed an offset of 12 m, as the center of the vessel had not been correctly set to rotate around the drill string in the moonpool. Corrections were made and further spin tests conducted until 0200 h on 13 February. The HiPap seabed transponder was deployed, and at 0223 h the bridge gave the go-ahead to commence coring operations. By 0520 h the API pipe had been run to 5 m above the seabed, and the downpipe camera was deployed for a precoring seabed survey to check that the position was devoid of live coral. It was noted that there were very strong currents present pushing the end of the API pipe.

At 0610 h the camera became stuck on recovery when the cable wrapped around the camera frame. By 0625 h the camera was at the top of the string but again caught, so the cable was cut and the camera recovered. By 0700 h API pipe was being run to tag the seabed, and the first core was on deck at 0945 h. Core Runs 1 and 2 were conducted using the ALN barrel and Run 3 using the EXN. However, during the EXN run the shoe became blocked with loose carbonate sand, so the coring strategy was altered, pumping the ALN barrel back down with seawater and coring with seawater flushing. However, at 1345 h the overshot wire became slack and entangled when deployed to recover the ALN barrel and had to be cut. By 1700 h the wireline had been recovered but the overshot had been left inside the API pipe, as the shackle had broken. This required tripping of the string to recover the barrel and overshot, thereby terminating the hole at 6 m CSF-A with an average recovery of 4%. Recovery of the barrel and overshot was completed by 1730 h, and it was found that the chaser on the overshot had jammed in the first API pipe. Repairs were conducted on the overshot chaser and the wireline between 1730 h and 2005 h. It was decided to core the same location (Hole M0030B).

Hole M0030B

By 2015 h on 13 February 2010 API pipe was being run, and the seabed was tagged at 2215 h. The first ALN core was recovered at 2240 h. At 0030 h on 14 February the vessel has to reposition to compensate for the strong current, bringing the API pipe back to vertical. Two more ALN cores were run, but on recovering the third at 0100 h, the barrel became stuck and the wireline winch cable snapped. This again required tripping the API pipe, so Hole M0030B was terminated at 9 m CSF-A with an average recovery of 6.1%. Between 0200 and 0250 h, operations were suspended while repairs to the roughneck jaw grips were undertaken, but by 0520 h the BHA was up at the drill floor. The barrel was still stuck, but flushing with water finally released it at 0545 h, when it was discovered that the ALN bit was split. The decision was taken to transit slowly to Site 6, Hole M0031A, while repairs to the wireline winch were made. The HiPap beacon was recovered, and the vessel departed for Site 6 at 0550 h.

Site 6

Hole M0031A

The Greatship Maya arrived on station at Site 6 at 0730 h on 14 February 2010. While the vessel established DP mode, the overshot tools were tested. Running of the API pipe commenced at 0830 h. The downpipe camera was deployed for the precoring survey at 1030 h but was found not to be working, probably because of a faulty light. The camera was recovered, repaired, and deployed again, but it was found to be sticking ~1 m from the end of the BHA because of a bent lifter loop jamming in the narrowest section of the BHA. The problem was finally rectified and the precoring survey completed by 1755 h.

The first ALN core was recovered at 1825 h on 14 February, and coring operations continued until 0140 h on 16 February. However, problems occurred throughout the operation with strong currents requiring vessel repositioning five times (each move between 2 and 5 m); hole collapse requiring reaming and flushing after Run 5 and during deployment of the barrel in Run 6 (9–12 m CSF-A); the inner barrel becoming stuck inside the outer barrel because of compacted sediment after Runs 6, 11, and 12; 2 h downtime between 0530 h and 0730 h to fix the mud pump; the barrel becoming stuck after Run 9, requiring three attempts to free it and retermination of the overshot wire (1015 h and 1155 h) and reaming prior to core Run 10; and further reaming following a hole collapse after core Run 15 with high pressure indicating a blocked bit during core Run 16, which had very limited recovery.

The hole was terminated after 17 core runs at 43 m CSF-A with an average recovery of 13.2%, and preparations were made to begin downhole through-pipe gamma logging. The through-pipe gamma sonde was deployed at 0230 h and was recovered back onto deck at 0755 h. The API pipe was then tripped to 7 m above the seabed by 0855 h, and a postcoring downpipe camera survey was conducted. The camera was left inside the API pipe for the transit. The Greatship Maya departed Hole M0031A at 0945 h on 16 February to transit slowly (under DP) to Hole M0032A, 15 m away.

Hole M0032A

At 0952 h on 16 February 2010 the Greatship Maya was settled on station over Hole M0032A and a downpipe camera survey was conducted. At 1050 h an additional API pipe was added, and coring operations commenced at 1115 h using metal splits. The string overpressurized on the first core run, and the ALN had to be tripped to free it. There was also evidence of hole caving and overpressurizing on the second core run. However, coring then progressed steadily until 2355 h, when the bit became heavily blocked with sediment on Run 12 (liner tube for Runs 5–15). Runs 14–16 (metal splits from Run 16) took from 0155 to 0515 h on 17 February to complete. Between 0515 h and 0555 h there was a delay in operations because of refueling the hydraulic powerpacks. Coring then continued to the end of hole at 0925 h at 36.7 m CSF-A (average recovery = 16.3%).

The API pipe was tripped to 5 m above the seabed, and at 1015 h the downpipe camera was deployed for a seabed survey. Once this was completed and the camera recovered at 1110 h, the hydraulic powerpacks were shut down for maintenance until 1330 h, when the vessel departed for Site 6, Hole M0033A.

Hole M0033A

The vessel was on station at 1353 h on 17 February 2010 after an additional 2 m move in a northeast direction from the original location to avoid the presence of live coral. At 1445 h the ALN core barrel and additional API pipe were run, and the first core run commenced at 1510 h after a slight delay because of a Differential Global Positioning System (DGPS) drop-out. Coring operations continued until 0000 h, when refuelling of the compressors and powerpacks took place until 0025 h on 18 February. Coring then restarted until 0530 h, when the barrel became stuck on core Run 16. It was recovered after 30 min but had a broken latch lug on recovery. Core Run 17 was recovered at 0745 h after the water pressure spiked. The liner tube was found to be crushed and stuck inside the barrel, with an extruded lug halfway down the barrel, taking operations to one fully functional core barrel while the liner is removed. Coring continued for another six runs before the hole was terminated at 1335 h at 32.8 m CSF-A with an average recovery of 40.9%.

API pipe was tripped to just above the seabed before the downpipe camera was deployed at 1435 h. However, the camera would not pass through the final 3–4 m of the BHA, and the wireline became twisted. The wireline was quickly untwisted from the top of the derrick, but the camera still could not pass through the BHA, so the camera survey was aborted at 1540 h without running a postcoring survey and recovered to deck by 1600 h. By 1725 h the remainder of the API pipe was tripped, and the vessel began a slow (1 kt) transit to Site 3 in order to allow time for repairs to the roughneck slips.

Site 3

Hole M0034A

The Greatship Maya was on station and settled on DP at 1825 h on 18 February 2010. Repairs to the roughneck slips continued while discussions about the best way to hang the HQ pipe were conducted. Between 1925 and 2100 h, the moonpool door was closed. This took longer than expected due to damage sustained during the initial transit out from Townsville. At 1900 h the API started being run to just above the seabed. A downpipe camera survey was conducted, and by 2305 h preparations to run the first core barrel were being made. The first ALN core was recovered at 0020 h on 19 February, and coring continued for another six core runs until 0515 h, when preparations began to change to HQ coring. Running of the HQ rods took from 0900 to 1047 h, when flushing of the hole lasted for 25 min.

The first HQ core (Run 8) was recovered at 1150 h, and HQ coring continued for another four runs until 1500 h, reaching a depth of 18.6 m CSF-A. The bit became blocked on Run 12, and freeing it took 25 min. Flushing then continued until 1525 h. However, currents had been increasing along with wind speed over the course of coring, and at 1525 h the HQ rods twisted off ~2 m below the drill deck. At 1530 h the vessel was moved to straighten the API pipe, and fishing for the end of the broken HQ pipe began using a casing recovery tap. The recovery tool broke off the rod at 1710 h and was manually recovered using a pup joint. At 1915 h an attempt was made to hammer the tap into the broken joint. At 2235 h an additional API was added, connecting to the joint above the moonpool door, and pulled back to the slips. Flushing and reaming continued in an attempt to lower the API pipe slightly in the hole, but the hole was by this point caving and forcing the API pipe periodically upward. By 0235 h on 20 February the fishing operation could restart, as the top of the API was safely set in the slips at the drill floor. However, another API pipe needed to be added at 0310 h, as the pipe was sinking in a softer lithology.

The HQ pipe was tagged at 0345 h, and recovery began. This was completed at 0734 h, when preparations began to change back to API coring using the ALN core barrel. The hole was open-holed with the API back down to 18.6 m CSF-A. When the ALN barrel was initially deployed, mud pressure spiked and the barrel was recovered without advancing. Two washers were removed from the inner barrel bearing head to increase the shoe/bit air gap, and the barrel was redeployed, with the first core being recovered at 1005 h. Core Run 15 had poor recovery, so a washer was added to the inner barrel bearing head again to reduce the effect of flushing, but this caused the pressure to spike again, so the barrel was tripped and a new impregnated bit was put on. Between 1235 and 1310 h, operations halted because of repairs being made on the mud pumps. Four further attempts were then made to core, all of which resulted in no advance and overpressurizing of the drill string. An infill sample from an unknown depth was recovered on one occasion and was curated as Run 16.

At 1518 h the Greatship Maya lost DGPS corrections, and the vessel moved 23 m off station in a water depth of 56 m. GPS was restored at 1520 h and DPGS at 1524 h. Although the vessel was manually moved back onto station within 10 min, the API pipe was bent, requiring a full trip. Once the API pipe was on deck (1810 h), three pipes were found to have been bent and were now unusable. Checks were run with the ALN and BHA in the slips, using both liners and metal splits, and no over pressurizing was noted.

Discussions took place between the Master of the Greatship Maya, Chief Engineer, Bluestone Party Chief, ESO Operations Superintendant, European Geophysical Society Surveyor, Chief Mate, and Chief Electrical Engineer as to why the GPS and DGPS signal had been lost. The Master contacted shore-based GC Rieber personnel for advice and stated that no further drilling operations were to take place until the problem had been rectified, thereby terminating Hole M0034A at 23.1 m CSF-A with an average recovery of 29.1%. Another GPS drop-out occurred at 2000 h for 10 min. A passing vessel was contacted, and they had not suffered any loss of signal.

During the early morning of 21 February the Greatship Maya suffered three power failures because of the bow thrusters ramping up to 100% without warning and tripping the generator because of overdemand. At 0945 h, it was decided that a secondary independent positioning system was required before further drilling could take place. This would hold the vessel on DP should a further GPS/DGPS signal drop-out occur. Permission was sought from GBRMPA to use the 3 m x 3 m seabed template with a HiPap beacon installed on it. The Environmental Management Plan (EMP) had previously only allowed a 1 m x 1 m template to be used, which was being pushed off location in the strong currents experienced at Hydrographer's Passage. Notice of permission granted was received from GBRMPA by 1005 h.

It was decided, however, that no coring operations could take place until the secondary power failure issue was rectified. Engine and DP data were downloaded and sent to GC Rieber, Singapore, who passed the information onto ConverTeam, who were responsible for the electrical and DP installation. By 2300 h the vessel crew had identified the problem, run a simulation to ascertain that this was a correct identification, and rectified the issue. At 2330 h the Master informed the drill floor operations team that he was satisfied that changes to the thruster settings had rectified the problem, and that the vessel could move to Site 11, Hole M0035A.

Site 11

Hole M0035A

The Greatship Maya arrived at Site 11 over Hole M0035A at 2345 h on 21 February 2010 and settled on DP. At 0045 h the moonpool door was opened, and running of the API pipe commenced at 0100 h on 22 February. Operations halted between 0200 and 0250 h to undertake repairs to the hydraulics on the roughneck. Once the API was just above the seabed, the seabed template was lowered to 20 mbsl to test the HiPap transponder and recovered back to the moonpool. At 0355 h the API was lowered further and the downpipe camera deployed for a precoring survey. The camera was recovered by 0550 h. The API was then run to tag the seabed and pulled back 0.5–1 m, with the aim that the end of the pipe would rest inside the seabed template when deployed but be free to move where the template guided it. The template was lowered onto the seabed at 0635 h. However, because of the template settling into the sediment, the first attempt at ALN coring showed that the API pipe and ALN core barrel were now outside the template entry cone. At 0730 h the ALN barrel and API pipe were tripped, and at 1015 h the seabed template was recovered. The ALN bit was found to be smashed, and the API bit was cracked in three places. Both were repaired, and the API pipe was rerun starting at 1100 h. The API pipe was in position just above the seabed by 1410 h, and the downpipe camera was deployed. However, at 1445 h the vessel again lost position with the camera still inside the API pipe. As the HiPap transponder was attached to the seabed template, which had not been deployed yet, the vessel started to drift.

At 1451 h the API pipe was raised by 2 m to avoid any obstacles on the seabed while the vessel regained station, and the camera was recovered. The GPS came back online at 1513 h. The Master of the Greatship Maya and the DPO Officer stated that they were happy with the DP model at 1555 h and were ready to restart operations, but the ESO Operations Superintendant required that a secondary positioning system was established, henceforth know as the seabed transponder. This was deployed over the side of the vessel prior to any operations beginning at any site from this point on to prevent any further positioning problems occurring during operations. At 2030 h the decision was made to abandon Hole M0035A and return to Townsville, where engineers for both the GPS and DP systems would be waiting. The remainder of the API pipe was tripped, and the drill floor secured for transit.

Port call at Townsville

The Greatship Maya departed HYD-01C transect Site 11 (Hole M0035A) at 2240 h on 22 February 2010 and arrived alongside in Townsville at 2050 h on 23 February. Engineers from Veripos (GPS) and ConverTeam (DP) boarded the vessel. Work to identify and rectify problems with both the DP and GPS systems continued overnight. The Greatship Maya departed Townsville at 1010 h on 24 February to begin sea trials of the DP and GPS systems. At 2350 h a supply boat arrived alongside the Greatship Maya. Additional core liner tubes and a new seabed frame for the HiPap transponder were taken onboard, and one Veripos surveyor and the ConverTeam engineer departed. One Veripos engineer remained onboard.

Transit to HYD-01C transect

The Greatship Maya departed for HYD-01C transect Site 11 at 0020 h on 25 February 2010 and arrived at Hole M0035A at 0100 h on 26 February, where she remained waiting on weather until 0405 h on 27 February.

Site 11

Hole M0035A

At 0330 h on 27 February 2010 the HiPap transponder was attached to the seabed frame in readiness for improved weather conditions. Permission was given to begin operations, and at 0430 h the vessel moved 10 m starboard of Site 11, Hole M0035A, under DP to deploy the seabed transponder. The vessel was back on station over Hole M0035A at 0530 h. The bridge confirmed that drilling operations could begin at 0605 h, and work began changing the API bit to a new stepped impregnated bit. Running API commenced at 0715 h, pausing at 0735 h while the seabed template was suspended in the moonpool before continuing until 0930 h. Between 0930 and 1010 h, a downpipe camera survey was conducted. Additional API pipe was then run, and ALN coring commenced at 1110 h.

At 1250 h the second core was recovered to deck. However, there were problems with the hole collapsing, and operations had to cease as power was lost to the drillers consol. Coring operations restarted at 1600 h, with the power problem now restricted to the mud pump number 1. The roughneck control box was also found to be leaking hydraulic oil. At 1740 h the bit became blocked. Pumping and reaming was unable to free the bit, so at 1915 h the hammer sampler was deployed, freeing the bit at 2215 h.

At 2325 h the decision was made to switch to HQ coring. Preparations continued until 0205 h on 28 February, including fitting a collar to the API pipe above the seabed template suspended in the moonpool. The API pipe and seabed template were very unstable within the moonpool because of strong currents pushing on the API pipe, and the API pipe was not reacting against the hole. At 0335 h the decision was taken to return to API coring. Repairs were made to the winch cable at 0425 h, which had been damaged during preparations for HQ coring, with coring operations restarting at 0440 h. Between 0800 and 1025 h, operations were halted because of a problem with the mud pumps caused by air entering the suction at the valve in the moonpool. Between 1200 and 1235 h, and again between 1600 and 1620 h, operations halted as repairs were made to the compressor because of it overheating. At 1625 h the bit became blocked on Run 14 but was freed by pumping water.

The bit became blocked again, accompanied by high pressure at 0240 and 0415 h on 1 March. The ALN barrel was recovered on both occasions. Sand was found to be jamming the inner and outer barrel. The barrel was stripped down, fully cleaned, and reassembled. Coring continued until 0740 h on 1 March, when coring of Hole M0035A was terminated at 29.9 m CSF-A with an average recovery of 40.9%. The API pipe was tripped to 5 m above the seabed, and a downpipe camera survey was conducted, finishing at 0850 h. The camera was left inside the API pipe for the move to the next coring location. The seabed transponder was recovered and a fully charged beacon attached to the frame.

Hole M0036A

At 0940 h on 1 March 2010 the seabed transponder was redeployed, and the vessel maneuvered under DP to Site 11, Hole M0036A. Between 0940 and 1055 h, the vessel undertook a series of small moves (<5 m) to target the top of a coral high and position the API pipe over an area devoid of live coral using the downpipe camera system to image the seabed. By 1100 h the downpipe camera was recovered and API pipe was being run, tagging the seafloor at 1135 h. The first core (ALN) was recovered at 1150 h, and operations continued until 0600 h on 2 March, with a total of 22 runs reaching 34 m CSF-A and an average recovery of 26.2%. On the penultimate core run at 0445 h, the barrel became blocked with sand, requiring the hammer sampler to free it.

At 0600 h preparations for downhole logging began. Between 0855 and 1115 h, the through-pipe gamma sonde was deployed, logging an interval of 33.26 m wireline log matched depth below seafloor (WMSF). At 1115 h circulation and conditioning of the hole commenced prior to three API pipes being tripped, bringing the pipe to 10 m CSF-A. At 1255 h lowering of the seabed template began, with the template on the seabed at 1400 h. Progress was slow because of strong currents pushing the electrical umbilical around the underside of the template. At 1510, 1630, 1900, and 2050 h, respectively, the resistivity, sonic, open hole gamma, and magnetic susceptibility sondes were deployed downhole, logging the intervals 7.5–25.87, 7.45–16.50, 10.66, and 7.47 m WMSF, respectively. A gradual collapse of the hole during this period was noted, with each successive tool only being able to penetrate to shallower depths. At 2145 h the calliper tool was deployed downhole. However, communication problems with the tool meant that at 2330 h the second caliper was tried downhole. Again, communications problems prevented logging using this instrument, so logging operations were terminated at 2340 h on 2 March. Demobilization of the logging equipment continued until 0040 h on 3 March, when we began to raise the seabed template. At 0130 h two API pipes were tripped, and a downpipe camera survey was conducted. Tripping of the API pipe continued from 0220 h and was completed by 0400 h, when the vessel moved to recover the seabed transponder. The Greatship Maya then moved slowly to Site 9, Hole M0037A, while maintenance of the drill floor hydraulics was carried out.

Site 9

Hole M0037A

The seabed transponder was deployed at 0640 h on 3 March 2010, and by 0700 h the vessel was in position above Site 9, Hole M0037A. Running of API pipe commenced at 0745 h; however, repairs to a hydraulic hose on the elevator after a collision with the roughneck halted operations between 0820 and 0950 h. Running of the API restarted at 0950 h and by 1100 h the API was situated 10 m above the seabed and the downpipe camera was being deployed. The camera survey was completed by 1140 h, and preparations to core began. The first ALN core was recovered at 1330 h, and coring continued successfully until 0055 h on 4 March, when the hole was terminated at 21 m CSF-A with an average recovery of 35.8%.

The API pipe was tripped to 10 m above the seabed between 0055 h and 0230 h, when the vessel moved to recover the seabed transponder. At 0250 h the Greatship Maya began to move slowly, under DP, to Site 8, Hole M0038A.

Site 8

Hole M0038A

The seabed transponder was deployed at 0320 h on 4 March 2010 prior to moving onto station by 0340 h. However, a mud pump suction failure at 0330 h prevented operations commencing until 1400 h, when API pipe was run to just above the seabed by 1430 h. A downpipe camera survey was completed by 1510 h, and API pipe tagged the seabed at 1535 h. However, on recovery of the first ALN core at 1540 h, the bit was found to have been completely destroyed. The decision was taken to lift the drill string, move across 2 m, and begin a new hole to avoid coring any remnants of the ALN bit. As this area was within the field of view from the camera survey for Hole M0038A, no new survey was required prior to coring operations in Hole M0039A.

Hole M0039A

Hole M0039A tagged seabed at 1625 h on 4 March 2010, and the first ALN core was on deck at 1700 h. Coring continued until 2340 h, when the driller noted high mud pressure, suggesting the barrel was blocked. On recovery, the latch head assembly was found to be blocked with sediment. This happened on three consecutive deployments, resulting in there being no advance in the drilled depth. At 0300 h on 5 March the barrel advanced slowly on core Run 10, and coring continued until 1400 h (with a break between 1130 and 1220 h for repairs to the latch head dog), when the hole was terminated at 28.4 m CSF-A with an average recovery of 36.6%. By 1420 h the API pipe was tripped to just above the seabed in order to run a downpipe camera survey. Tripping the API pipe then continued from 1455 to 1650 h, when the seabed transponder was recovered.

Transit to HYD-02A transect

The Greatship Maya transited to the next survey transect under guidance from the pilot. The vessel crossed Hydrographer's Passage in a southeastern direction and reached Site 10, Hole M0040A, by 1830 h on 5 March 2010.

Site 10

Hole M0040A

By 1925 h on 5 March 2010, the seabed transponder had been deployed and the Greatship Maya had settled on station over Hole M0040A. API pipe was run to just above the seabed by 2125 h, when the downpipe camera was deployed. The camera survey was completed by 2220 h, and API pipe continued to be run until the seabed was tagged at 2235 h. The first core was on deck at 2250 h, and coring continued until the end of Run 3, when repairs to the driller's shack electrics halted operations between 0030 and 0155 h on 6 March. Operations then restarted for another nine core runs until the hole was terminated at 0825 h at 21.5 m CSF-A with an average recovery of 54.6%.

Three API pipes were tripped to bring the drill string to ~4 m above the seabed. A downpipe camera survey was then conducted between 0850 and 0910 h prior to the vessel moving 10 m to starboard to the next hole.

Hole M0041A

The Greatship Maya was on station over hole M0041A by 0915 h on 6 March 2010, and a precoring downpipe camera survey was conducted. The camera was back on deck by 0925 h, and the API pipe tagged the seabed at 0955 h. Coring operations ran smoothly for 12 ALN runs before the hole was terminated at 1650 h at 22.1 m CSF-A with an average recovery of 45.5%.

The API pipe was tripped until it sat ~5 m above the seabed, and the downpipe camera was deployed. However, the camera became stuck in the BHA at 1720 h and could not be recovered. At 1745 h the decision was taken to cut the camera cable and trip the API pipe, passing the camera cable through each pipe successively in order to retain the camera should it become free while the API pipe was being tripped. At 2110 h the camera became free in the pipe above the collars and was recovered. By 2130 h all API pipe was in the rack/slips and retermination of the camera cable had begun. The seabed transponder was recovered, and the vessel began to transit 6 km landward to Site 2, Hole M0042A, at 2220 h.

Site 2

Hole M0042A

The Greatship Maya arrived at Site 2 at 2330 h on 6 March 2010 and began to settle on DP. The seabed template was secured in the moonpool, repairs to the camera cable continued, and the API pipe was run to just above the seabed. At 0145 h on 7 March the downpipe camera was deployed. The first ALN core was recovered at 0330 h, and operations continued until 0500 h, when repairs to a latch head dog stopped coring for 55 min. After ALN Run 5 was recovered at 0715 h, it was decided that the API was spudded into the seabed firmly enough to switch to HQ coring. By 1020 h the seabed template was secured in the moonpool with steel wires, the API pipe was set in the elevators, and the HQ rods were ready to be run. The first HQ core (Run 6) was recovered at 1240 h. However, the API pipe was sinking in the hole (1.5 m), presumably because of soft sediments, and so hole stabilization using a thicker mud continued until 1330 h. During Run 7, the bit became blocked requiring flushing. However, the API started sinking again, now resting on the elevators, and swabbing the hole was believed to be causing further instability. The decision was taken to trip the HQ rods and return to API coring until a harder formation was encountered in which to set the API pipe.

At 1500 h a sample was recovered from the HQ BHA and curated as a wash sample. Between 1540 and 1700 h the API pipe was reconnected and the elevator removed. ALN coring restarted at 1710 h and continued until 0705 h on 8 March, when the hole was terminated at 46.4 m CSF-A with an average recovery of 23.6%.

Downhole logging was conducted following coring operations, and mobilization of the drill floor and logging equipment continued until 1010 h. Between 1010 h and 1150 h the through-pipe gamma log was run. On completion, the API pipe was tripped to 7 m CSF-A, and conditioning of the hole continued until 1340 h. The seabed template was then lowered onto the seabed, and the dual induction logging sonde was deployed at 1410 h. Following this, the ABI, spectral gamma, magnetic susceptibility, sonic, OBI, and caliper sondes were deployed at 1530, 1710, 1845, 2000, 2125, and 2320 h, respectively. Some hole caving was noted, with the tools logging from 45.07, 43.98, 39.93, 38.49, 33.23, 38.84, and 38.58 m WMSF, respectively. By 0030 h on 9 March all downhole logging had been completed and demobilization of the equipment and securing of the drill floor for transit had begun. At 0130 h the seabed template was recovered, and by 0345 h all API pipe had been tripped. The seabed transponder was onboard and secured by 0400 h, and the vessel began the 6.5 km transit seaward to Site 12, Hole M0044A.

Over the course of coring and logging this hole, three separate remotely operated vehicle (ROV) dives were conducted, viewing the drill string, small entry hole, and the dispersion of drill cuttings.

Site 12

Hole M0043A

The seabed transponder was deployed at 0455 h on 9 March 2010, and by 0515 h the Greatship Maya was on station at Site 12 (Hole M0043A). The seabed template was adjusted in the moonpool, and at 0550 h the API was started to run to just above the seabed. A downpipe camera survey was conducted at 0740 h, and coring operations (ALN) started at 0815 h, continuing until 2350 h, when the hole was terminated at 35 m CSF-A with an average recovery of 17.3%. The API pipe was tripped to 7 m above the seabed, and a downhole camera survey was completed by 0115 h on 10 March. The camera remained inside the pipe for the vessel move (52 m) to Site 8, Hole M0044A. The seabed transponder was recovered at 0115 h, and the vessel moved slowly under DP to Site 8.

Site 8

Hole M0044A

The seabed transponder was deployed at 0140 h on 10 March 2010, and the vessel was on station over Hole M0044A by 0155 h. The downpipe camera survey was completed by 0225 h, and the barrel was prepared as API pipe was run to tag the seabed. The first core (ALN) was recovered at 0320 h. On recovering the second core at 0415 h, the ALN polycrystalline diamond drill bit (PCD) was found to be damaged and the stabilizer housing was deformed. The bit was changed for a short impregnated ALN bit, and coring continued. At 0800 h the vessel lost a forward thruster for 5 min without coring operations being affected. At 0905 h the seabed template was lowered in the moonpool in an attempt to dampen drill string vibration. At 1120 h the ALN barrel became stuck in the BHA during core Run 9. Attempts were made to recover the barrel, but at 1310 h the wireline failed. In order to recover the barrel and overshot, the API pipe had to be tripped, terminating Hole M0044A at 11 m CSF-A with an average recovery of 15.2%. The ALN was recovered from the BHA at 1645 h. The barrel and BHA were checked and the overshot wire repaired.

The API pipe was run in to just above the seabed by 1850 h, and a downpipe camera survey was conducted. The vessel was then moved over ~2.5 m, under DP, to Hole M0045A.

Hole M0045A

The Greatship Maya was on station over M0045A in 4 min, with the downpipe camera still deployed. A precoring camera survey was conducted and the camera recovered to deck by 1910 h on 10 March 2010. The seabed was tagged at 1945 h, and coring commenced. However, after initially appearing to core, the drill string then dropped 3 m abruptly. It was believed that the drill string was skipping down the side of a pinnacle, and so the vessel was moved 2 m closer to Hole M0044A before trying another core run. The seabed was again tagged, and the drill string appeared to be compensating at 2115 h. However, the first and second ALN core runs again appeared to "skip" down the side of the pinnacle, with the drill string dropping quickly and with no apparent force. The last 70 cm of the third core run appeared to drill very hard material. However, while recovering the barrel, the drill string fell abruptly 8 m—it was thought that the string had reentered Hole M0044A. If this was so, the drill string should have stopped at the total depth (TD) for Hole M0044A at 11 m CSF-A, but it continued to freefall until 14.6 m CSF-A. As it was not clear whether or not the API string had actually penetrated the target coral pinnacle or was "skipping" down its side, the decision was taken to abandon Hole M0045A and move the vessel. Two API pipes were tripped by 0025 h on 11 March, and the Greatship Maya was moved under DP 3 m to the opposite side of Hole M0044A.

Hole M0046A

The Greatship Maya was on station above Hole M0046A by 0050 h on 11 March 2010. The first three ALN core runs all appeared to "skip" down a slope, free-falling to 10.8 m CSF-A. However, coring then continued, with seabed corals appearing in the liner at ~10.8 m CSF-A in Run 4. While recovering Run 10 from a depth of 25.2 m CSF-A, there was a partial hole collapse, so the top 1 m of core from Run 11 represents infill. The hole was terminated after Run 13 at 1040 h at 31.20 m CSF-A with an average recovery of 8.9%. The API pipe was tripped back to joint 11 in preparation for transit to the next site, and the seabed transponder was recovered. The vessel began the move to Site 12, Hole M0047A, at 1145 h.

Core depths were taken from the first indication of the drill string tagging the seabed at the start of Run 1, as it is unknown whether or not the penetration was accurate from this point. It should therefore be noted that all depths may be 10.8 m shallower than recorded if the first presence of corals in the liner tubes at 10.8 m CSF-A represents the actual point of seabed penetration.

Site 12

Hole M0047A

The Greatship Maya came onto station over Hole M0047A at 1220 h on 11 March 2010. Retermination of the beacon transponder deployment wire delayed deployment until 1250 h. API pipe was run in to just above the seabed, and a downpipe camera survey was conducted. The camera was back on deck at 1335 h, and the API tagged the seabed at 1410 h. The first ALN core was recovered at 1430 h, and coring continued until 0030 h on 12 March, when the hole was terminated at 33.2 m CSF-A with an average recovery of 11.4%.

The API pipe was tripped to just above the seabed by 0055 h, and a downpipe camera survey was conducted. The seabed transponder was recovered by 0145 h, and the vessel departed for Site 12, Hole M0048A, under DP with the 11 API pipes deployed.

Hole M0048A

The Greatship Maya came onto station over Hole M0048A at 0220 h on 12 March 2010. The seabed transponder was deployed, and an additional API pipe was run to take the pipe to just above the seabed by 0305 h. A downpipe camera survey was completed by 0325 h, and the first ALN core was recovered by 0405 h. ALN coring continued until 0610 h, when the decision was made to halt operations at 7.1 m CSF-A after four runs because of winds in excess of 35 kt and heave >2.5 m, with an average recovery of 9.7%.

The API pipe was tripped by 0805 h, and the seabed template was secured by 0850 h. The seabed transponder was then recovered and secured on deck by 0910 h.

Waiting on weather and port call, Townsville

The Greatship Maya departed Site 12 (Hole M0048A) at 0910 h on 12 March 2010 to transit to sheltered waters within Hydrographer's Passage in order to conduct a ship to ship transfer of equipment, including a bumper sub, and drilling mud from the PMG Pride, which commenced at 1530 h. Because of the failure of previous HQ attempts using the seabed template suspended in the moonpool or water column as a guide for the HQ string and API "casing," a bumper sub was manufactured to facilitate further attempts at recovering HQ cores.

At 1645 h the Greatship Maya departed Hydrographer's Passage to transit northward using the inner passage because of deteriorating weather conditions offshore. At 1510 h on 13 March, the Greatship Maya dropped anchor at the Townsville Anchorage to wait on weather. Preparations continued to be made in advance of Cyclone Ului; all containers, equipment inside, cables, winches, and banners were securely fastened, and monitoring of the weather continued on a six hourly basis.

At 1916 h on 15 March the Greatship Maya weighed anchor, coming alongside in Townsville at 2100 h. Following rebunkering and a GC Rieber marine crew change, the Greatship Maya departed Townsville at 2035 h on 16 March and arrived at the Townsville Anchorage at 2205 h to continue waiting on weather. At 1600 h on 17 March a pilot boat came alongside with additional spares. The Greatship Maya continued to wait on weather at the Townsville Anchorage until 19 March.

Transit to RIB-02A transect

Following regular assessment of weather conditions at all three geographical drilling locations, the Greatship Maya departed Townsville Anchorage and began the transit to Ribbon Reef 3 at 2040 h on 19 March 2001, arriving at 1930 h on 20 March. At 2030 h the Greatship Maya began DP trials ~0.3 nmi seaward from RIB-02A transect Site 4. These trials continued to 21 March because of problems with the bow thrusters. At 1530 h on 21 March new DP software was installed, and testing continued until 1645 h, when the Greatship Maya began to move onto station at Site 4.

Site 4

Hole M0049A

At 1900 h on 21 March 2010 the Greatship Maya arrived on station and the seabed transponder was deployed. The anchor was also made ready for fast deployment as per the EMP for the Ribbon Reef sites. Running of API pipe commenced at 1950. Between 2225 and 2240 h, a downpipe camera survey of the seabed was conducted prior to tagging the seabed at 2300 h.

The first core arrived on deck at 2330 h. However, after two EXN core runs (3.5 m CSF-A), a problem with the water swivel/flush pipe at 0040 h on 22 March necessitated tripping the API pipe to ~7 m above the seabed. The vessel remained on DP and on station during the repairs.

Hole M0049B

Coring recommenced at Site 4, Hole M0049B, at 0400 h on 22 March and continued for 13 core runs (1–3 = EXN cores; 4–13 = ALN cores) until the hole was terminated at 15.6 m CSF-A at 1520 h with an average recovery of 17.9%. The API pipe was tripped to just above the seabed, and a downpipe camera survey was conducted between 1550 and 1610 h.

Hole M0050A

The downpipe camera was retained inside the API pipe while the vessel moved 4 m under DP to Site 4, Hole M0050A. A precoring seabed survey was completed by 1650 h on 22 March 2010, and the first core run (EXN) was started. ALN coring (Core 325-M0050A-2R onward) continued until 2120 h, when the hole was terminated at 10.5 m CSF-A because of entering Pleistocene sequences, with an average recovery of 17.8%. The API pipe was tripped to just above the seabed, and a downpipe camera survey was conducted between 2200 and 2220 h. Between 2220 and 2245 h the API pipe was tripped until there was ~60 m hanging beneath the drill floor. The seabed transponder was then recovered, and at 2305 h the vessel began moving under DP 78 m closer to the modern reef at Site 3.

Site 3

Hole M0051A

The seabed transponder was deployed at 2315 h on 22 March 2010 with the Greatship Maya coming onto station at Site 3 (Hole M0051A) at 2320 h. API pipe was run starting at 2330 h. A downpipe camera survey was conducted between 2255 and 0030 h (23 March). The first ALN core was on deck at 0105 h. However, the second core could not be recovered because of a hydraulic failure of the elevator and mud valve at 0230 h, effectively terminating the hole at 2.5 m CSF-A. At 0800 h the vessel was moved into deeper water for safety, having recovered the seabed transponder, while repairs on the hydraulics continued. However, by 0900 h the decision was taken to trip the API pipe using manual elevators. The core barrel was recovered from the BHA once in the slips, between 1315 and 1345 h; however, minimal core remained.

Another prerequisite of the EMP was for a GBRMPA Environmental Site Supervisor (ESS) to be onboard while Sites 1 and 2 at Ribbon Reef 3 were drilled. At 1300 h on 23 March the ESS came alongside in the Reef Charters vessel Hurricane. However, after numerous attempts at a boat to boat transfer, it was decided that the sea swell and winds were too high to enable any transfer to be carried out safely. The ESS and the Hurricane returned to Cooktown (Australia) at 1400 h, and the Greatship Maya began waiting on weather, as conditions prohibited starting a new hole. At 1530 h, following operational discussions regarding the limited drilling options at the Ribbon Reef sites with no ESS available, the seabed transponder was recovered and the drill floor and moonpool secured for transit. The Greatship Maya came off DP at 1645 h and departed for Noggin Pass.

Transit to NOG-01B transect and waiting on weather

The Greatship Maya departed RIB-02A transect Site 3 (Hole M0051A) at 1645 h on 23 March 2010 and arrived at the NOG-01B transect at 0910 h on 24 March.

Site 6

Hole M0052A

After going onto DP at 0910 h, the vessel moved slowly onto station at Site 6 (Hole M0052A), completing the maneuver at 1120 h on 24 March 2010. Following an assessment of weather conditions at 1145 h, the vessel moved 500 m seaward of Hole M0052A to wait on weather in deeper water. Operations continued to wait on weather on 25 March.

At 0655 h on 26 March the supply boat Acheron arrived alongside. Because of high winds and sea swell, it was not safe to conduct a boat to boat transfer of equipment at the location. At 0745 h both vessels departed NOG-01B Site 6 to transit to calmer waters inside Flora Passage and arrived at 1100 h. Following a successful transfer, the Greatship Maya departed Flora Passage at 1120 h, arrived back at NOG-01B Site 6 at 1645 h, and continued waiting on weather. At 1900 h permission was given for coring operations to start, and the seabed transponder was deployed at 1930 h. API pipe was run between 2045 and 2250 h, following which a downpipe camera survey was conducted. At 2355 h the first (EXN) core run commenced.

The core run was halted after 1.4 m because of a very hard lithology, and recovered. However, on recovery the liner was found to be crushed and the bit damaged. During recovery the API drill string came out of the hole because of vessel heave, and Hole M0052A was terminated at 1.4 m CSF-A.

Hole M0052B

Coring (ALN) recommenced at 0115 h on 27 March 2010 at the same location as Hole M0054A. The first core was recovered at 0200 h. The bit was found to be cracked and the hole collapsed back to 1 m. Coring continued for another three runs until 0430 h. However, weather conditions and large sea swells were causing the bit to bounce on the bottom of the hole, as well as DP deviation. At 0430 h the barrel became stuck in the BHA and could not be recovered without tripping the API pipe, so Hole M0052B was terminated at 6.9 m CSF-A. The barrel was recovered at 0745 h, and the bit was found to be bent so that it was catching on the BHA landing ring.

Hole M0052C

At 0815 h on 27 March 2010 API pipe was run in at the same location as Hole M0052B. Open hole coring down to 6.9 m CSF-A commenced at 0915 h. At 1020 h the first ALN core was recovered. On recovering the second core at 1130 h, the bit was found to be missing and the hole had to be terminated at 8.8 m CSF-A. Tripping the API pipe began at 1140 h, completing this operation at 1330 h. The BHA and API ALN systems were checked while the Greatship Maya moved to a new location within Site 6.

Hole M0053A

API pipe was run in Hole M0053A starting at 1400 h on 27 March 2010 in preparation for using the HQ coring system. Operations halted between 1510 and 1530 h to make repairs to the elevator. Between 1725 and 1800 h, operations had to stop because of a squall passing through the area. Between 1800 and 1900 h, the dies on the roughneck were checked prior to running the bumper sub and lowering the seabed template to ~10 m below the sea surface. At 2010 h the API string was lowered to the seabed and the bumper sub heave monitored. The heave was not sufficient, possibly because of soft sediment, and a 3 m pup was added. The bumper sub appeared to be compensating, and at 2130 h the seabed template was lowered to the seabed. However, at 2210 h the bumper sub stopped compensating. At 2300 h the decision was taken to abandon HQ coring and return to API.

The seabed template was recovered between 2300 and 0030 h on 28 March and the bumper sub between 0030 and 0110 h. Additional API pipe was run between 0110 and 0120 h. The first EXN core was recovered at 0210 h (all subsequent core runs used the ALN core barrel). Between 0520 and 0550 h on 28 March operations stopped while the latch head assembly was changed, and between 1330 and 1350 h coring operations again stopped because of heavy rain obscuring the driller's view of the derrick. ALN coring then continued for another 17 runs until the hole was terminated at 0250 h on 29 March at 37.3 m CSF-A with an average recovery of 32.7%.

At 0300 h on 29 March the API pipe was tripped to just above the seabed, and a downpipe camera survey was conducted. This operation was completed by 0335 h, with the camera being left in the pipe for the vessel move to the next site, 66 m away. The seabed transponder was recovered at 0355 h and the vessel began the move to Site 7 (Hole M0054A) at 0410 h.

Site 7

Hole M0054A

The Greatship Maya was on station over Hole M0054A at 0425 h on 29 March 2010, and the seabed transponder was deployed. The downpipe camera survey began at 0440 h but took until 0530 h to complete because an additional API pipe had to be run in, requiring the recovery and redeployment of the camera system. Time was needed to repair hydraulic fluid leaks on the roughneck and to conduct maintenance on the main power pack. After lowering the seabed template, the seabed was tagged at 1515 h, followed by washing down to set the API in the hole. HQ coring commenced at 1600 h and continued until 0425 h on 30 March.

The hole was terminated at 0425 h at a depth of 18.72 m after three consecutive core runs recovered no material. It was considered necessary to recover the BHA to deck, where it was discovered that 60 cm of cored material had become wedged in the BHA and was preventing the barrel from latching. The average recovery for Hole M0054A was 23.98%.

Hole M0054B

Operations in Hole M0054B commenced at 0545 h on 30 March 2010 following recovery of the blocked BHA which led to the termination of Hole M0054A. The HQ pipe was run down the API string, tagging the bottom of the borehole at 0830 h. The first core was recovered at 0915 h and consisted of wash material from the caving of Hole M0054A. Coring then continued until 1910 h, when Core 325-M0054A-12R was recovered and a TD of 33.2 m was achieved. The average recovery for Hole M0054B was 29.63%.

Following recovery of this core, the drill floor was prepared for wireline logging operations. Through-pipe gamma logging started at 2330 h and was completed at 0145 h on 1 April. The HQ string was tripped to swap the BHA with a shoe to allow the open-hole logging sondes to be run. At 0315 h a hydraulic fluid leak occurred, delaying the tripping of the HQ string. At 0520 h tripping recommenced, and the HQ BHA was recovered to deck at 0645 h. Following removal of the crossover sub from the top drive, half an API pipe was run in and the crossover reattached. At 0815 h the HQ string was run back into the hole and flushing with mud and water occurred. At 1530 h the HQ string was put into heave compensation. At 1600 h the conductivity sonde was run, followed by the ABI (1745 h), OBI (1900 h), spectral gamma (2145 h), sonic (2330 h), magnetic susceptibility (0110 h on 1 April), idronaut (0155 h), and caliper (0240 h). By 0335 h all wireline tools were recovered to the deck and the logging rooster box was demobilized.

At 0530 h tripping of the HQ string commenced and continued until 0800 h. This was followed by tripping of the HQ pipe to just above the seabed to allow deployment of the downpipe camera for posthole survey. This was interrupted by a further hydraulic fluid leak on the iron roughneck from 0840 to 0855 h, when tripping recommenced. By 0920 h the API pipe was in position just above the seafloor, and the seabed template was lifted to 7 m above the seafloor to allow the camera survey to commence. At 0940 h the camera was deployed. It is thought that the camera was caught on the steps inside the bumper sub, blowing the bulb and making it impossible to complete the survey.

The camera was recovered to deck by 1000 h. The remaining API pipe was tripped until the bumper sub was level with the drill floor for inspection by 1120 h. By 1140 h the seabed frame had been lifted to 20 mbsl and the seabed transponder recovered to allow transit to the next hole. At 1200 h the vessel commenced transit to Hole M0055A.

Site 5

Hole M0055A

The Greatship Maya was on station at Site 5, Hole M0055A, and deploying the seabed transponder at 1230 h on 1 April 2010. Once completed, the seabed template was lowered to ~10 m off the seabed, and API pipe was run to just above the seabed. The downpipe camera survey was conducted by 1530 h, and the API pipe tagged the seabed at 1545 h. By 1620 h the API pipe had been washed down 2 m. The API pipe was then disconnected and set on elevators on the drill floor. Following this, HQ rods were run, tagging the bottom (3.29 m CSF-A) at 1920 h. HQ coring operations continued until 0555 h on 2 April, when the hole was terminated at 31.29 m CSF-A with an average hole recovery of 32%.

The HQ rods were tripped by 0805 h, and the API pipes were clear of the seabed by 0845 h. The seabed template was lifted above the seabed, and the seabed transponder was recovered. The Greatship Maya departed Hole M0055A at 0920 h.

Hole M0056A

The Greatship Maya transited slowly to Site 5 (Hole M0056A), 66 m away from Hole M0055A, because of the seabed template being suspended in the water column. At 0935 h on 2 April 2010 the seabed transponder was deployed, and at 0945 h the template was lowered over Hole M0056A to 72 mbsl. Between 0955 and 1035 h the API pipe and seabed template were lowered to just above the seabed, at which point the downpipe camera survey was conducted. The seabed template was lowered onto the seabed, and the API pipe tagged bottom at 1120 h. The API was then washed in 1.3 m. At 1230 h the API pipe was broken and the elevators set on the slips prior to running HQ rods.

The HQ rods tagged bottom at 1415 h, at which point coring operations started, continuing until 2100 h when the HQ crossover and saver sub had to be replaced following failure of a weld. Coring restarted at 2140 h and continued until 0635 h on 3 April, when the hole was terminated at 41.29 m CSF-A with an average hole recovery of 30.8%. The HQ rods were tripped by 0840 h and the top drive reconnected to the API pipe. The seabed template and API were lifted to ~9 m above the seabed and a downpipe camera survey was conducted. At 0935 h the API pipe was tripped back to the bumper sub, and the seabed template was lifted into the moonpool in preparation for transit. At 1040 h the seabed transponder was recovered and the Greatship Maya departed Site 5 at 1050 h.

Site 2

Hole M0057A

At 1125 h on 3 April 2010 the seabed transponder was deployed, and by 1140 h the Greatship Maya had settled on station at Site 2, Hole M0057A. The transponder on the seabed template was changed prior to lowering the template to ~35 mbsl. At 1135 h API pipe was run to just above the seabed and a downpipe camera survey was conducted. Further API was then run, tagging the seabed at 1400 h. The API pipe was then set on the elevators and disconnected from the top drive at 1430 h in preparation for running HQ pipe. The seabed was tagged with the HQ pipe at 1520 h and coring operations began.

After core Run 3 it was noted that the hole was caving, possibly because of the string swabbing the hole. Coring operations continued after hole conditioning until 2325 h, when there was a twist off between the crossover sub and the top HQ pipe. Between 2325 and 0100 h on 4 April the crossover sub was tripped out for repairs and the core barrel recovered. On the next core run, damage to the threads on two HQ rods was sustained while running a new rod in, resulting in having to trip two rods and replace them. Coring then continued until 0440 h, when it was noted that mud was leaking from the repaired crossover sub/HQ pipe joint. To enable safe working on the joint, three HQ rods were tripped out. During the repair period the hole collapsed. Open hole drilling and flushing back down to the previously reached depth of 32.38 m CSF-A ran from 0610 to 0710 h, at which point coring operations restarted.

Operations were temporarily halted between 1040 and 1100 h because of a fire alarm caused by an oil leak dripping onto the exhaust pipe in the engine room. Operations then continued until 1230 h, when the hole was terminated at 41.78 m CSF-A with an average hole recovery of 45.5%. Between 1240 and 1520 h, the HQ rods were tripped, followed by the API pipe. A problem with the iron roughneck delayed lifting of the seabed template, which was completed at 1730 h. The seabed transponder was recovered by 1750 h and the template and drill floor secured in preparation for transit to Site 8, Hole M0058A.

Site 8

Hole M0058A

The Greatship Maya reached Site 8 at 1950 h on 4 April 2010, and the seabed transponder was deployed prior to the vessel settling on station over Hole M0058A by 2005 h. Between 2010 and 2240 h, repairs on the roughneck and roughneck hydraulics were undertaken prior to running API pipe. The first core run started at 0220 h on 5 April and continued for 15 runs; all runs were EXN with the exception of Run 5, which was ALN. Coring operations were going smoothly until problems with the powerpacks surging and cutting out caused operations to stop between 1035 to 1245 h and again between 1355 and 1425 h. The final hole was terminated after core Run 15 at 41.4 m CSF-A with an average recovery of 82%.

At 1515 h the powerpack stalled, delaying tripping of the API pipe. However, all API pipe was on deck by 1845 h, and the drill floor and template were secured ready for transit by 2105 h. At 2115 h the Greatship Maya came off DP, departing Site 8 (Hole M0058A) at 2130 h.

Transit to Townsville

The Greatship Maya departed the final site at 2130 h on 5 April 2010 and arrived at the port of Townsville at 1430 h on 6 April 2010. Demobilization of the vessel and clearances of the containers by the Australian Quarantine and Inspection Service (AQIS) and customs officials continued until 1130 h on 7 April, when all ESO personnel and science party members departed the vessel.

Onshore Science Party, Bremen

The cores collected offshore on the GBR were transported under refrigeration to the IODP Bremen Core Repository and Laboratories in the Center for Marine Environmental Sciences (MARUM) building on the campus of Bremen University. Frozen microbiology samples were shipped directly from Australia to scientists' laboratories in the United States and China by special courier service. Samples from 68 core catchers were also sent to laboratories in Japan and the United Kingdom for U-Th and ¹⁴C dating to be carried out in order to produce a preliminary shipboard chronology prior to the OSP. Thermal conductivity measurements and some computed tomography (CT) scans of selected cores were acquired before the start of the OSP.

Further analytical laboratories were accessed by agreement with the Department of Geosciences (geochemistry, paleomagnetism, and mineralogy [X-ray diffraction] laboratories) and MARUM (physical properties, micropaleontology, and nondestructive core logging laboratories) at Bremen University. During the Expedition 325 OSP (2–16 July 2010), the cores were described in detail and sampled, and minimum and some standard measurements were made (Table T2). In addition, sampling for postcruise scientific work was also undertaken.

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