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doi:10.2204/iodp.pr.324.2010

Operations

Expedition 324 began in Yokohama, Japan, and drilled five holes at five sites at Shatsky Rise (Sites U1346–U1350) before transiting to Townsville, Australia. Times in this operations section are given in local ship time. During the transit to the first 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.

Yokohama port call

Expedition 324 started on 4 September 2009 at the port of Yokohama with the changing and crossover of Overseas Drilling Limited and Integrated Ocean Drilling Program personnel. Expedition 324 scientists boarded the ship on 5 September. In addition to the routine resupply of expendables and the offloading of Expedition 323 cores and returning freight, some items of note were the loading of 1800 MT of marine gas oil, overhaul of the passive heave compensator, and service visits by Novenco (air conditioning), RigNet (Very Small Aperture Terminal [VSAT]), and Hose-McCann (ship phone/intercom/alarm system) field engineers. This port call was also noteworthy for the extensive number of visitors that were treated to a tour of the vessel including visitors of the Museum of Nature and Sciences in Tokyo, members of the Japanese scientific community, and U.S. embassy personnel. A press conference for Japanese and international media was held on 5 September.

During this ~5 day port call, we were not able to send or receive e-mail or use the ship's phone system because of local electromagnetic interference, which prevented VSAT operation. Although some maintenance was possible on the aft antenna, the RigNet engineer was unable to perform a systems check and calibration to the VSAT system because of the interference.

Once the last line was released at 0950 h on 9 September, the vessel was under way to the pilot station. The RigNet engineer stayed aboard and attempted last-minute adjustments while working with rig-based technicians. The pilot and RigNet representative disembarked at the pilot station at ~1130 h. A short time after this, VSAT operation was restored and remained until the first course change. At this time, the signal was lost and in spite of the best efforts of onboard technicians communicating with the RigNet engineer in the hotel using the Inmarsat GMDSS satellite phone, the VSAT system could not be restored to normal working order. A decision was made to reverse course, return to a convenient rendezvous point close to the head of Sagami Bay, and bring the RigNet engineer back to work on the system.

The RigNet engineer was welcomed aboard shortly before 0600 h on 10 September and remained for nearly 2 h restoring the VSAT to operation. Once he departed at 0740 h, the vessel began its voyage to Site U1346.

Transit to Shatsky Rise and Site U1346 (Shirshov Massif)

After a transit of 4 days, the JOIDES Resolution set position on Site U1346 (proposed Site SRNH-2) at 0930 h on 14 September 2009. The RCB drilling assembly was prepared, the pipe lengths were measured, and the drillers proceeded to run pipe through the moonpool. At 0140 h on 15 September, the seafloor was tagged at 3630.0 m drilling depth below rig floor (DRF) and Hole U1346A was advanced without coring to 100.5 m drilling depth below seafloor (DSF). Rotary coring was initiated at 100.5 m DSF and deepened the hole to a total depth of 191.8 m DSF by 0915 h on 18 September (Table T1). Basaltic basement was contacted at 139.2 m CSF-A (total basement penetration = 52.6 m). The average penetration rate for basement coring was 1.3 m/h with an average recovery of 38.7%. Because of the slow penetration rate combined with the successful recovery of material suitable to address most of the objectives for this site, it was decided to end coring at this depth and prepare the hole for logging operations. An additional factor in the decision to cease coring operations at this site was the approach of Typhoon Choi-Wan. The hole was logged with triple combo on 18 September. Poor hole conditions, however, did not warrant deployment of the FMS tool string. The vessel departed for Site U1347 at 1800 h on 19 September. Because of the proximity of Sites U1348 and U1349 to the projected track of Typhoon Choi-Wan, it was decided to proceed directly to the more southerly and higher priority site.

Site U1347 (Tamu Massif)

The JOIDES Resolution established position on Site U1347 (proposed Site SRSH-3B) at 1730 h on 21 September 2009, and at 0500 the next morning, the seafloor was tagged at 3461.0 m DRF. Hole U1347A was drilled with a wash barrel in place to 71.0 m DSF, where rotary coring was initiated. Basaltic basement was reached at 157.6 m CSF-A (Table T1). Coring into basement continued until 2145 h on 25 September when operations were suspended in order to change to a fresh bit after the initial rotary bit had accumulated 60 rotating hours. A FFF was deployed and the bit was pulled out of the FFF early on the morning of 26 September. A new C-4 bit was affixed to the rotary drilling assembly and run through the moonpool toward the seafloor.

Hole U1347A was successfully reentered at 2250 h on 26 September. The drill string was advanced to the bottom of the hole where the driller found only 1 m of soft fill. At 0500 h on 27 September coring resumed but had to be suspended for 5.75 h to replace the broken core winch motor. Once the new motor was mounted and tested, coring resumed. From 1530 h on 27 September to 1230 h on 30 September rotary coring deepened the hole from 242.7 m DSF to a final depth of 317.5 m DSF. Operations were concluded when the last core was only able to advance 1 m in 3 h, possibly because of either a worn bit, an extremely hard formation, or a combination of both.

Total penetration into basement in Hole U1347A was 159.9 m cored at an average rate of penetration (ROP) of 1.5 m/h. While coring basement, the ROP for individual cores ranged from a lethargic 0.7 m/h to a more energetic 4.1 m/h. The average recovery for basement coring was 64.2%.

In preparation for logging, the bit was released at the bottom of the hole and the bore was displaced with 83.5 bbl of 10.5 ppg mud. The drill string was pulled back in the hole and set at a depth of 131.5 m DSF. The first logging run was made with the triple combo and succeeded in reaching within 2 m of the bottom of the hole. A preliminary analysis of the results of the first logging run indicated that the hole was in good condition and suitable for the additional measurement runs planned for this site. The second tool deployed was the FMS-sonic which was also successfully run (two complete passes). The third logging tool suite, which included the UBI, had to be cancelled because of hardware problems with the logging tools.

After the logging equipment was secured, the drill string and the beacon were retrieved in routine fashion. Once the drilling equipment was secured, the vessel departed for the next site at 0400 h on 2 October. The total time devoted to Site U1347 was 10.4 days.

Site U1348 (Tamu Massif)

The JOIDES Resolution established position on Site U1348 (proposed Site SRSH-6) at 1515 h on 2 October 2009. After a delay of 4 h to fix a problem with the drawworks clutch, the driller tagged seafloor at 1130 h on 3 October at 3275.0 m DRF. Hole U1348A was drilled with a wash barrel in place to 84.2 m 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% caused mostly by the prevalence of soft sediment and chert. Once past this depth and starting with Core 324-U1348A-13R, the recovery improved markedly as the sediments transitioned to sandstone and then to volcaniclastics. After discussion, the science party elected to terminate the hole at a depth of 324.1 m DSF (Table T1). The bottom 134.2 m of the hole was cored at an average ROP of 8.9 m/h with an average recovery of 57.5%. The average recovery for the cored interval of 239.9 m was 33.7%.

The hole was prepared for logging operations with a wiper trip and displacement with 86 bbl of heavy mud. 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 combo) was successfully deployed to ~322 m DSF, only 2 m above the bottom of the hole. Once the triple combo was recovered, the second logging suite (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 BHA with the electrical pad arms 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.

The only option remaining was to use the Kinley crimper and cutter system to recover the recalcitrant instrument. The Kinley crimper was deployed and severed the logging line just above the cable head of the tool suite. The severed end of the logging line was recovered and the drill string retrieved. When the BHA was at the surface, the FMS-sonic tool was still firmly pinned by the springs of the broken FMS pad arms inside the top connector of the mechanical bit release.

After the logging equipment was disassembled, the vessel departed for the next site at 0848 h on 7 October. The total time on site was 4.7 days.

Site U1349 (Ori Massif)

The JOIDES Resolution arrived at Site U1349 (proposed Site SRCH-5) at the summit of Ori Massif at 2145 h on 7 October 2009 after a transit of 12.9 h. The drill string was routinely deployed and after the driller tagged seafloor at 3138.0 m DRF, or ~5 m shallower than the corrected precision depth recorder depth, Hole U1349A was spudded with the rotary system at 0600 h on 8 October. The hole was drilled with a wash barrel to 116 m DSF, where coring was initiated. The sediment portion of the hole was cored with the usual low average recovery (23%) because of the prevalence of chert within the soft pelagic ooze. At 165.1 m CSF-A, basement was encountered. Coring in the hole continued into basement without incident to 250.4 m DSF (85.3 m into basement) (Table T1) by 1430 h on 11 October, when coring in the hole was terminated. The decision to stop coring at this site was made during a science meeting held earlier in the day. Hole U1349A was cored with an overall average recovery of 49.0%. The basement portion of the hole was cored at an average ROP of 1.8 m/h and with an average recovery of 67.4%.

The hole was prepared for logging with a 50 bbl mud flush followed by a round trip of the drill string from 250 to 86 m DSF. After one more 50 bbl mud treatment, the bit was released at the bottom of the hole with the rotary shifting tool on the coring line. Prior to tripping the drill string to the logging depth of 119.3 m DSF, the hole was displaced with 56 bbl of 10.5 ppg heavy mud. The first logging run of Hole U1349A was made with the triple combo, which was deployed at 2140 h on 11 October and retrieved at 0240 h the next morning. The second logging run was conducted with the FMS, which was deployed at 0355 h and recovered at 0930 h. The hole was found in good condition (except for one tight spot just below the end of the pipe) and both the triple combo and FMS runs retrieved excellent data.

After the logging equipment was secured and the drill string and beacon were recovered, the vessel departed for Site U1350 at 1930 h on 12 October. The time expended on Site U1349 was 126.8 h, or 5.3 days.

Site U1350

The vessel positioned on Site U1350 (proposed Site SRNH-2) at 0115 h on 13 October 2009 after a 53 nmi voyage from Site U1349. The driller tagged the seafloor at 4067.0 m DRF at 1030 h. Hole U1350A was spudded with a wash barrel in place and drilled to 104.6 m DSF, where rotary coring was initiated. The sediment portion (48.0 m) of the hole was cored with the usual poor recovery (1.6%) resulting from chert stringers intermixed with the host sediments, which likely consisted of soft ooze and chalk. Igneous basement was reached with Core 324-U1350A-6R at 143.1 m DSF, which was slightly higher than expected (~157 m below seafloor, calculated from the site survey seismic data).

Rotary coring deepened the hole to a final depth of 315.8 m DSF (Table T1) by 2015 h on 18 October when operating time expired. The final depth corresponds to a total penetration of 172.7 m in basement, which was cored with an average recovery of 43.2% and an average ROP of 2.0 m/h. The total interval of 315.8 m was cored with an average recovery of 35.6% at an average ROP of 3.5 m/h. When coring was halted, the bit had accumulated 91.2 rotating hours and was still viable.

In preparation for logging, the hole was flushed with a 50 bbl mud sweep followed by a wiper trip up to 84 m DSF and back to 316 m DSF. Following another 50 bbl sweep, the bit was released with the rotary shifting tool and the hole was displaced with 90 bbl of 10.5 ppg heavy mud. The pipe was then pulled back in the hole with the end of pipe placed at the logging depth of 117 m DSF.

The first of potentially two logging runs was attempted with the triple combo, which was deployed at 0640 h on 19 October and lowered at a speed of 2200 m/h to a depth of 3600 m DRF. At this depth, the head tension decreased dramatically and the cable speed was reduced to ~90–120 m/h to avoid potential damage to the wireline. The slow progress required pumping pressure down the drill pipe to aid the descent. After making very slow progress to a depth of 4000 m DRF it was decided to pull out of the hole to check the tool string and cable for damage. With the tool string on the rig floor, high volumes of water were pumped through the pipe to remove any potential obstruction. The tool string was deployed a second time with similar results, reaching 4122 m DRF. As time was running out and the weather was progressively deteriorating (initial ship heave conditions of ~2 m changed to ~4 m with wind gusts of up to 56 kt) and without knowing the cause of the low-tension problem, it was decided to terminate the logging operations. The tool was recovered at 2330 h and after the logging equipment was rigged down the drill string was pulled out of the hole, clearing the seafloor at 0125 h on 20 October. Following the securing of the drilling equipment and hydrophones and recovery of the beacon, the vessel departed for its long voyage to Townsville at 1245 h on 20 October. The total time at Site U1350 was 7.5 days.

Magnetic field data were collected during the transit to Townsville using the borrowed Geometrics magnetometer. On the way south, the ship was steered first across Helios Basin, south of Ori Massif, and along a gap between magnetic track lines on Tamu Massif. The ship continued to collect magnetic data after departing Shatsky Rise, including a north–south profile across western Ontong Java Plateau. The transit ended at 0800 h on 2 November, when the ship finally reached the sea buoy outside of Townsville.

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