Previous   |    Next

doi:10.2204/iodp.pr.339.2012

Operations

Port call

Expedition 339 began with the first line ashore at 0830 h, 16 November 2011, to Berth 12 in Ponta Delgada harbor on the island of Saõ Miguel, Azores. The IODP technical crew change occurred as scheduled on 17 November, although a group of IODP personnel arrived on 18 November because of weather-related travel problems. The scientific complement joined the vessel on 18 November. Education and public relation activities were carried out on Friday and Saturday, 18–19 November, and included tours of the R/V JOIDES Resolution for 175 students and 15 teachers from 4 local high schools (Escola Secundária Antero de Quental-Ponta Delgada, Escola Secundária das Laranjeiras-Ponta Delgada, Escola Secundária de Lagoa-Lagoa, and Escola Secundária da Ribeira Grande-Ribeira Grande), 12 students and professors from the Universidade dos Açores, 25 students and researchers from the Centro de Vulcanologia e Avaliação de Riscos Geológicos, 20 local visitors, 9 local government representatives, the Portuguese European Consortium for Ocean Research Drilling delegate, and 6 local journalists (press).

In addition to routine resupply of consumables and offloading of returning freight, the ship was loaded with ~600 MT of marine gasoil 60 ST of sepiolite, and 20 ST of barite drilling mud. Just prior to concluding the port call in Ponta Delgada, the home port of registry for the JOIDES Resolution was changed from Monrovia, Liberia, to Limassol, Cyprus. The port call concluded when the last line was released at 0800 h, 22 November.

Site U1385

We arrived at Site U1385 (proposed Site SHACK-04A) at 0400 h Universal Time Coordinated (UTC), 25 November 2011, after a 68 h, 741 nmi journey from Ponta Delgada. Five holes were cored at this site using the advanced piston corer (APC) system and nonmagnetic core barrels (Table T1). Four holes were cored to ~150 mbsf and one to just 9.5 mbsf (1 core). A total of 67 cores were required to obtain 621.8 m of sediment (103.2% recovery). The advanced piston corer temperature tool (APCT-3) was deployed 12 times.

Hole U1385A

The initial pipe trip was extended by routine measuring and “rabbiting” that occurs on the first deployment of the drill string. Following a 3 h survey of the seabed using the underwater camera system, during which no obstructions were observed, Hole U1385A was spudded with the APC at 2300 h, 25 November. Recovery of the first core established the seafloor depth at 2598 meters below rig floor (mbrf) (2587 mbsl). Piston coring with nonmagnetic core barrels advanced to a total depth of 151.1 mbsf (17 cores), which was the depth objective of the site. Total recovery in Hole U1385A was 155.9m (103%). Cores 339-U1385A-4H through 17H were oriented with the Flexit tool. The APCT-3 was deployed to take temperature measurements at 30 (Core 4H), 58.5 (Core 7H), 87 (Core 10H), and 115.5 (Core 13H) mbsf. The APC experienced partial strokes on Cores 14H and 17H. The last core advanced only 7.7 m when the formation became firm and abruptly stopped the APC. The drill crew experienced difficultly extracting the sinker bars from the drill string prior to pulling out of the hole, requiring 4.5 h of IODP rig time to remove a deformed section of coring line before operations could resume. This involved the removal of 100 m of coring line, reheading the line, and redressing the oil saver.

Hole U1385B

Following a vessel offset of 20 m east of Hole U1385A, operations in Hole U1385B began at 0030 h, 27 November. The water depth calculated from the recovery of the first core was 2598 mbrf (2587 mbsl). Piston coring using nonmagnetic core barrels continued to a total depth of 147.9 mbsf (16 cores). Total recovery in Hole U1385B was 150.7 m (103%). APCT-3 measurements were made at 34.6 (Core 4H), 63.1 (Core 7H), 91.6 (Core 10H), and 120.1 (Core 13H) mbsf.

Hole U1385C

Hole U1385C was spudded at 1830 h, 27 November. Because the core barrel was retrieved full of sediment (9.87 m), a mudline depth could not be determined and another hole was required to obtain a good mudline core. Total recovery in Hole U1385C was 9.9 m (104%).

Hole U1385D

Following a vessel offset of 20 m south, Hole U1385D was spudded at 2045 h. The first core established a seafloor depth at 2595 mbsf (2584 mbsl). Piston coring advanced without incident to a final depth of 146.4 mbsf (16 cores) with an average recovery of 105.2%. Cores were oriented starting with Core 4H. The APCT-3 was deployed at 35.4 (Core 4H), 60.9 (Core 7H), 89.4 (Core 10H), and 117.9 (Core 13H) mbsf. Cores 15H and 16H were partial strokes and advanced by recovery. All cores were obtained with nonmagnetic core barrels. The bit cleared the seafloor at 1255 h, 28 November.

Hole U1385E

After a vessel offset of 20 m west of Hole U1385D, piston coring in the last hole at Site U1385 began at 1520 h, 28 November, using nonmagnetic core barrels. Seventeen cores were taken to the total depth of 148.7 mbsf by 0730 h, 29 November. We recovered 151.3 m of sediment (102%). Cores were oriented starting with Core 5H. The last three cores (Cores 15H through 17H) were partial strokes and advanced by recovery. Two cores were intentionally repositioned (Core 8H and 10H) to maintain an offset relative to the previous holes on this site. All cores were obtained with nonmagnetic core barrels. This hole concluded operations at this site.

The drill string was recovered and the bit cleared the seafloor at 0850 h. Once the drilling equipment was secured and the beacon recovered, the vessel departed for the next site at 1515 h, 29 November. Total time on site was 4.5 days.

Site U1386

After a 150 nmi transit from Site U1385, the JOIDES Resolution, arrived at Site U1386 (proposed Site GC-01A; 560.4 mbsl) at 0415 h, 30 November 2011. We deployed the camera system and conducted a ~2 h survey of the seabed on a 30 m grid pattern to ensure that the seafloor was free of man-made obstructions. No obstructions were observed on the seafloor, but many shallow linear furrows were seen that were assumed to be the result of fishing trawls.

Three holes were drilled at Site U1386 (Table T1). Hole U1386A was cored using the APC system to 183.1 mbsf and then cored with the extended core barrel (XCB) system to 349.3 mbsf. Similarly, Hole U1386B was cored with the APC to 162.3 mbsf and then with the XCB to 464.9 mbsf. Hole U1386C was drilled to 405 mbsf and then cored using the rotary core barrel (RCB) system to the target depth of 526 mbsf. Two cores were taken in the initial drilled interval (Core 339-U1386C-2R, 165–174.6 mbsf, 40% recovery; Core 4R, 205–214.6 mbsf, 93% recovery) to try to fill in short gaps in APC cores recovered from Holes U1386A and U1386B. Downhole logging was carried out in Hole U1386C using the triple combination (triple combo), Formation MicroScanner (FMS)-sonic, and Versatile Sonic Imager (VSI) tool strings (see “Downhole logging at Site U1386”). Overall recovery at Site U1386 was 351 m (101.62%) with the APC, 417.63 m (89.1%) with the XCB, and 82 m (58.5%) with the RCB. The total cored interval for Site U1386 was 954.4 m, and total recovery was 850.64 m (89.1%).

Hole U1386A

Once the camera system was recovered at 1255 h, 30 November, we began piston coring in Hole U1386A. APC coring continued to refusal at 183.1 mbsf (Cores 1H through 21H). Recovery for this interval was 101%. Temperature measurements were obtained at 32.3 (Core 4H), 60.8 (Core 7H), 89.3 (Core 10H), 117.8 (Core 13H), 114.0 (Core 16H), and 167.2 (Core 19H) mbsf. Cores were oriented starting with Core 4H. The corer was advanced by recovery on Cores 16H to 19H and 21H. Nonmagnetic hardware was used on all cores. At 183.1 mbsf, the coring system was switched to the XCB and coring continued to a total depth of 349.3 mbsf (Cores 22X through 39X) by 0415 h, 2 December. The 166.2 m interval was cored with a recovery of 97%. The total recovery in Hole U1386A was 346.2 m, which represented 99% of the cored interval. The bit cleared the seafloor at 0620 h, 2 December, and the vessel offset 20 m east of Hole U1386A.

Hole U1386B

Piston coring in Hole U1386B began at 0825 h, 2 December, and advanced to an APC refusal depth of 162.3 mbsf (Cores 1H through 18H). Recovery for the APC interval was 100%. The calculated water depth from the recovery of the first core was 562 mbsl. Temperature measurements using the APCT-3 were taken at 16.8 (Core 2H), 45.3 (Core 5H), 73.8 (Core 8H), 102.8 (Core 11H), 130.8 (Core 14H), and 157.6 (Core 17H) mbsf. The cores were oriented starting with Core 3H. There were partial strokes with Cores 15H, 16H, and 18H. Nonmagnetic hardware was used to obtain all cores. At 2200 h, 2 December, the coring system was switched to XCB and coring continued to 455.4 mbsf (Cores 19X through 49X), where XCB refusal was reached. Recovery for the XCB interval was 293.5 m (100%).

Hole U1386C

The third hole of Site U1386 was offset 20 m south of Hole U1386B and spudded with the RCB at 0345 h, 5 December. This hole was drilled with a wash barrel to 405 mbsf, except for RCB coring of two intervals that eluded recovery in the two previous XCB holes (Cores 2R and 4R from 165.0–174.6 and 205.0–214.6 mbsf, respectively). Continuous RCB coring started at 405 mbsf at 0545 h, 6 December, and reached the depth objective of 526 mbsf by 0200 h, 7 December. The RCB interval (140 m) recovered 59%. The drilled interval was 386 m. The total cored interval for all holes at this site was 954 m with a recovery of 89% (104 cores).

Downhole logging at Site U1386

Following a wiper trip and hole conditioning, Hole U1386C was displaced with 172 bbl of 10.5 ppg mud to prepare the hole for downhole logging. The open end of the pipe was placed at a logging depth of 102.4 mbsf. During rig up of the wireline cable, the cable jumped from the lower left most sheave wheel in the wireline heave compensator and became jammed between the wheel and the frame. Because of the possibility of damage to the cable, it was cut above the crimped section.

The triple combo tool string descended through the seafloor at 2003 h and was successful in reaching the bottom of the hole (526 mbsf). The tool string was back on deck by 0100 h, 8 December. Subsequently, the FMS-sonic tool suite was run into the hole at 0410 h. The tool suite was blocked from further downhole progress by a bridge at 948 mbrf (375 mbsf), the lowermost of the tight sections observed in the triple combo run. Rig down of the FMS-sonic tool string was completed by 0930 h, 8 December.

The marine mammal watch for conducting the vertical seismic profile (VSP) experiment started at 0800 h, 8 December. The VSI tool started its descent in Hole U1386C at ~1030 h and reached a bridge at 940 mbrf (367 mbsf) at 1105 h. The slightly shallower penetration for this tool run indicated that the hole was closing with time. The seismic source (two-gun cluster; 7 mbsl on the port side) had been ramped up in soft start mode. It was difficult to get a good clamp with the VSI, and consequently noisy waveforms were obtained that were attributed to the rugose borehole and soft formation. Only a fraction of the shots produced clean first arrivals, but there were enough at most stations to stack. The upper part of the hole was especially difficult. The tool was back on deck at 1440 h and rigged down by 1530 h, 8 December. The drill string was recovered and the vessel departed for the next site at 1730 h, 8 December. Total time at Site U1386 was 8.6 days.

Site U1387

The vessel was offset in dynamic position mode 2.2 nmi on a bearing of 128° to Site U1387 (proposed Site GC-09A). During this move, accomplished in 3 h, maintenance was performed on the 480 V switchboard, which required shutting down the regulated power from 1800 to 1845 h. The vessel was positioning on Site U1387 at 2030 h, 8 December 2011.

Three holes were drilled at Site U1387 (Table T1). Hole U1387A was cored using the APC to 47.7 mbsf and then with the XCB to 352.4 mbsf. Hole U1387B was cored with the APC to 46.9 mbsf and then with the XCB to 338.3 mbsf. Hole U1387C was drilled without coring to 290 mbsf and then cored using the RCB to the target depth of 870 mbsf. Downhole logging was carried out in Hole U1387C using the triple combo, FMS-sonic, and VSI tool strings (see “Downhole logging at Site U1387”). Overall recovery at Site U1387 was 97.03 m (102.6% recovery) with the APC, 578.42 m (97% recovery) with the XCB, and 409.5 m (70.6% recovery) with the RCB. The total cored interval at Site U1387 was 1270.7 m, and total recovery was 1084.95 m (85.4%).

Hole U1387A

Prior to spudding Hole U1387A, a 2 h underwater camera survey of the seafloor was made during which many linear furrows on the seabed were observed. These furrows were presumed to be the result of fishing bottom trawls. The vessel had to be offset 10 m from the original position to avoid spudding into what appeared to be man-made debris (a spiral of loose wire or cable). Hole U1387A was spudded with the APC at 0325 h, 9 December. Seafloor depth calculated from the recovery of the first core was established at 570.5 mbrf (559.1 mbsl). APC coring advanced to 47.7 mbsf, where very sticky, firm clay prevented further progress. The APC cored 47.7 m and recovered 48.83 m (102.4% recovery). Cores 339-U1387A-4H through 6H were oriented. The APCT-3 tool was deployed on Core 4H (33.9 mbsf). Nonmagnetic core barrels were used to obtain all piston cores. XCB coring was initiated at 0915 h, 9 December, and deepened Hole U1387A from 47.7 mbsf to a final depth of 352.4 mbsf by 0545 h, 10 December. The XCB system cored 304.7 m with a 98.1% recovery. The total cored interval in Hole U1387A was 352.4 m, with a recovery of 98.7%.

Hole U1387B

The bit was pulled clear of the seafloor at 0715 h, 10 December, and the vessel offset 20 m east of Hole U1387A. The underwater camera was deployed to ensure no man-made debris was present on the seafloor prior to coring. Hole U1387B was spudded with the APC at 1050 h and established a water depth of 569.6 mbrf (558.2 mbsl). Piston coring advanced to 46.9 mbsf (102.8% recovery) before switching to the XCB. Cores 3H through 5H were oriented. All cores were obtained with nonmagnetic core barrels.

XCB coring deepened Hole U1387B to a final depth of 338.3 mbsf. The average recovery for the XCB cored interval of 291.4 m was 95.9%. APC/XCB coring recovered 96.8% of the cored interval in Hole U1387B (338.3 m). Coring was terminated prior to the depth objective of 350 mbsf because the quality of the cores was compromised because of biscuiting disturbance, discovered when the deeper cores in Hole U1387A were examined in the ship’s core laboratory.

Hole U1387C

The drill string was recovered with the bit clearing the rotary table at 1305 h, 11 December. After the nonmagnetic drill collar and seal bore drill collar were laid out along with the APC/XCB polycrystalline diamond bit, a four-stand RCB bottom-hole assembly (BHA) with a new CC-3 Rock Bit International bit was made up and deployed along with the underwater camera. Once the video images provided by the underwater camera confirmed that the seafloor was clear of obstructions, the driller tagged the seabed with the RCB bit at 569.8 mbrf (558.4 mbsl) at 1640 h, 11 December. Following retrieval of the camera, Hole U1387C was spudded with the RCB at 1850 h. The hole was drilled with a wash barrel in place to 290.0 mbsf, where continuous RCB coring was initiated.

Rotary coring proceeded without incident to a final depth of 870 mbsf by 0930 h, 16 December. A total of 580 m was cored in Hole U1387C with an average recovery of 70.6%. The average rate of penetration for the cored interval was 11.6 m/h. The drilled portion of the hole was 290 m and the total penetration (cored plus drilled) was 870 m. While penetrating the cored interval, the drillers pumped eleven 20 bbl and two 30 bbl high-viscosity mud flushes to keep the hole clean of cuttings.

Downhole logging at Site U1387

After a wiper trip and hole conditioning, the bit was dropped at the bottom of Hole U1387C and the hole was displaced with 290 bbl of 10.5 ppg mud. The end of the pipe was positioned at 103.8 mbsf. During the wiper trip, the driller had to pick up the top drive and wash and ream a tight portion of the hole (ledge or bridge) from 649.0 to 653.0 mbsf. There was 28 m of soft fill at the bottom of the hole that was flushed clean with a 50 bbl Hi-Vis sweep.

The triple combo tool string was made up and deployed at 0230 h, 17 December. The tool could not advance past 650 mbsf; therefore, the hole was logged from that point. The triple combo tool string was recovered at 0835 h. The VSI tool was run in the pipe at 1105 h. This tool could not be lowered deeper than 254 mbsf. The Marine Mammal Protocol was observed while conducting the VSP experiment. The VSI tool was recovered at 1420 h. The last log was made with the FMS-sonic tool string, which was deployed at 1610 h and could not go deeper than 334 mbsf. The FMS-sonic tool string was recovered and disassembled by 2300 h. The end of the pipe was pulled clear of the seafloor at 2355 h, and the drill string was recovered. The drilling equipment was secured and the vessel departed for Site U1388 at 0230 h, 18 December. Total time on site was 9.3 days.

Site U1388

The 55 nmi transit from Site U1387 to Site U1388 (proposed Site GC-04D) was accomplished in ~5 h at an average speed of 11 kt. At 0745 h, 18 December 2011, the vessel was positioned on the new location.

The operations plan for Site U1388 called for APC/XCB/RCB coring in three holes and conducting downhole logging operations in Holes U1388B and U1388C. The first two holes were to be cored with the APC to refusal and then with the XCB to ~350 mbsf. The third hole was to be cored with the RCB from 350 to 1300 mbsf. Ultimately, three holes were drilled (Table T1), but the coring objectives were not achieved because of hardware failure caused by a difficult sandy formation. In Hole U1388A, APC Core 339-U1388A-1H advanced only 3.4 m (recovery of 107.6%) because a thick sand layer at the sediment surface prevented the core from penetrating any further. Hole U1388B was cored using the XCB to 225.7 mbsf with recovery of 47.2%. Hole U1388C was drilled without coring to 205 mbsf and then cored using the RCB to 229 mbsf. Overall recovery at Site U1388 was 120.54 m (47.6%): 3.64 m (107.6% recovery) with the APC, 106.54 m (97% recovery) with the XCB, and 10.36 m (43.17% recovery) with the RCB. The site was terminated earlier than planned because of formation instability.

Hole U1388A

An APC/XCB BHA with a 9⅞ inch polycrystalline diamond bit, lockable float valve, seal bore drill collar, and nonmagnetic drill collar was assembled and deployed. Following a 1.3 h underwater camera survey of the seafloor over a 30 m grid pattern, Hole U1388A was spudded with the APC at 1500 h. The calculated seafloor depth from the recovery of the first core was 675.1 mbrf (663.6 mbsl), which was 0.7 m deeper than the corrected depth given by the precision depth recorder. The second attempt at a piston core appeared to be an incomplete stroke. The core winch operator spent ~3 h attempting to recover the stuck core barrel. The Kinley cutter was deployed to cut the coring line above the sinker bars when it was not possible to jar off the core barrel. The only course of action remaining was to recover the drill string and extricate the core barrel on the surface. The drill string was retrieved by 2400 h, 18 December. The reason why the core barrel couldn’t be recovered was obvious. Most of the BHA was full of sand that apparently “U-tubed” when the driller advanced into the formation to position the bit for the next piston core (2H).

Hole U1388B

The BHA was cleared of sand and deployed to 669.9 mbrf. The vessel offset 20 m east of the previous hole. The underwater camera displayed what appeared to be man-made debris on the seafloor and precipitated another 10 m offset to the east. The strategy for the second hole of the site was to core an XCB hole to depth and use the information acquired from that pilot hole to assess if and where the APC could be deployed in subsequent holes. The driller tagged seafloor at 674.4 mbrf (662.9 mbsl) at 0645 h. The camera system was recovered, and the top drive was picked up. Hole U1388B was spudded with the XCB at 0835 h, 19 December, and advanced to 225.7 mbsf by 0745 h, 20 December. While coring this interval, there was extensive cutting shoe damage suggesting that the distribution of fluid flow between the cutting shoe and the polycrystalline diamond bit was not optimum for this formation. Rather than continue coring in this fashion and considering that the objectives of this site were deeper in the formation, XCB coring was terminated at 225.7 mbsf. The average recovery for this hole was 47.2%. The driller pumped a 5 bbl slug of heavy mud prior to making a connection for Cores 1X through 12X (110.9 mbsf) to avoid a reoccurrence of the sand backflowing into the BHA. A 20 bbl sepiolite flush was made at 216.1 mbsf. The drill string was pulled clear of the seafloor at 0925 h and on deck at 1155 h, 20 December.

Hole U1388C

A four-stand RCB BHA with a new CC-4 Rock Bit International bit and mechanical bit release was made up and run in to 668.0 mbrf. After a short underwater camera survey confirmed that the location of the hole was clear of debris, the driller tagged the seafloor at 674.0 mbrf (662.5 mbsl). The underwater camera was recovered, the top drive was picked up, and Hole U1388C was spudded with the RCB at 1915 h, 20 December. The hole was washed to 205.0 mbsf, where rotary coring was initiated. At 119.8 and 167.6 mbsf, 20 bbl Hi-Vis mud sweeps were circulated. Rotary coring advanced from 205.0 to 229.0 mbsf, where the drill sting became firmly stuck in the formation. There was no rotation and limited circulation. It required 1.5 h to free the pipe utilizing overpulls of as much as 120,000 lb and adjusting rotary current limits as high as 1050 A. Once the pipe came free, more mud (both Hi-Vis and 10.5 ppg) was pumped to clear out some of the sand that had collapsed on the BHA. The drill string was pulled free of the seafloor at 1330 h and on deck by 1725 h, 21 December. The formation was considered too unstable to safely core and the decision was made to move on to the next planned site of the expedition. Total time at Site U1388 was 3.2 days, which was 10 days less than the allotted time. The vessel departed for Site U1389) at 1730 h, 21 December.

Site U1389

The vessel departed for Site U1389 (proposed Site GC-11A) at 1730 h, 21 December 2011. The 25 nmi journey from Site U1388 was accomplished in 2.5 h, and the JOIDES Resolution was positioned on the new site by 2000 h, 21 December.

Four holes were drilled at Site U1389 (Table T1). Hole U1389A was cored using the APC to 97.2 mbsf and then with the XCB to 354.9 mbsf. Only one piston core (9.5 m) was taken in Hole U1389B. Hole U1389C was cored with the APC to 95 mbsf and then with the XCB to 350 mbsf. Hole U1389D was cored with the APC to 94 mbsf to provide an additional record of the upper section at the site. Hole U1389E was drilled without coring to 335 mbsf and then cored using the RCB to the depth objective of 990 mbsf. Downhole logging was carried out in Holes U1389A and U1389E using the triple combo and FMS-sonic tool strings (see “Downhole logging at Site U1389”). Overall recovery at Site U1389 was 307.28 m (103.55%) with the APC, 463.93 m (90.49% recovery) with the XCB, and 352.28 m (53.78% recovery) with the RCB. The total cored interval at Site U1389 was 1463.4 m and total recovery was 1123.49 m (76.8%).

Hole U1389A

The APC/XCB BHA was assembled and deployed to 651.7 mbrf. Subsequent to a 1.3 h survey of the seafloor, Hole U1389A was spudded with the APC at 0240 h, 22 December. The water depth calculated from the recovery of the first core established the seafloor at 656.2 mbrf (644.7 mbsl). This was 1.3 m shallower than the corrected precision depth recorder depth.

Piston coring advanced Hole U1389A to the refusal depth of 99 mbsf. The average recovery for this interval was 103%. Core orientation started with Core 339-U1389A-4H. Three APCT-3 measurements were made at 33 (Core 4H), 61 (Core 7H), and 90 (Core 10H) mbsf. Nonmagnetic core barrels were utilized on all cores. XCB coring deepened the hole to a final depth of 357 mbsf by 1415 h, 23 December. The average recovery for the 258 m XCB interval of the hole was 91%. The total average recovery for the entire hole was 94%.

Holes U1389B and U1389C

Hole U1389B was spudded at 2010 h, but the full core barrel could not be used to ascertain the seafloor depth. Hole U1389C was spudded with the APC at 2025 h and established the seafloor depth at 654.5 mbrf (643 mbsl). Piston coring advanced to 95 mbsf. Cores were oriented starting with Core 3H. The APCT-3 was deployed at 19 (Core 2H), 47.5 (Core 5H), and 76 (Core 8H) mbsf. All cores were obtained with nonmagnetic core barrels. Coring continued in Hole U1389C with the XCB, which reached the depth objective of 350 mbsf at 0815 h, 26 December. Recovery for the 255 m XCB interval of the hole was 90%. The total recovery for both coring systems for Hole U1389C was 94%. The bit was pulled free of the seafloor at 1000 h, 26 December, and the vessel offset 20 m south of the previous hole.

Holes U1389D

An additional hole was piston cored to obtain a complete section of the uppermost ~100 m portion of the sedimentary record at Site U1389. Hole U1389D was spudded with the APC at 1120 h, and the water depth was established at 655.5 mbrf (644 mbsl). Piston coring advanced without incident to the depth objective of 94 mbsf by 1845 h. Recovery was 104%. The cores were oriented starting with Core 3H. Three APCT-3 measurements were made at 24.5 (Core 3H), 53 (Core 6H), and 75 (Core 9H) mbsf. All cores were obtained with the nonmagnetic core barrels.

Holes U1389E

The drill string was recovered, and the bit cleared the rotary table at 2220 h, 26 December. The vessel offset 20 m west. A four-stand RCB BHA was made up and deployed. After the driller tagged the seafloor at 655 mbrf (643.5 mbsl), Hole U1389E was spudded with the RCB at 0240 h, 27 December. We drilled without coring to 355 mbsf, where continuous rotary coring was initiated at 1830 h, 27 December. Rotary coring continued until 0845 h, 1 January 2012, when the hole was terminated at the depth objective of 989.9 mbsf. A total of 654.9 m was cored with a recovery of 54%.

Downhole logging at Site U1389

On 23 and 24 December, we carried out downhole logging operations in Hole U1389A. During preparations for logging, the wiper trip found only 1 m of soft fill at the bottom of the hole, and the hole was filled with 112 bbl of 10.5 ppg mud. The open end of the pipe was placed at a logging depth of 85.7 mbsf. The triple combo tool string, composed of the natural gamma radiation, density, and resistivity tools, descended through the seafloor at 2300 h, 23 December, and was run to the bottom of the hole at 1011 mbrf (355 mbsf). A short pass of 75 m was followed by a main pass up to the seabed. Sand-rich layers are apparent by their low gamma radiation signature. The hole was mostly in gauge but had several meter-scale washouts. The tool string was back on deck by 0140 h.

The FMS-sonic reached the bottom of the hole and made two passes, recording resistivity images of the borehole, sonic velocities, and natural gamma radiation data over the entire interval. The tool string was back on deck at 0950 h. The VSI tool was run to conduct the VSP experiment. Marine mammal watch started at ~1100 h, 24 December. The air guns (two-gun cluster, 7 mbsl on the port side) were ramped up in a soft start procedure. The VSI tool started its descent in Hole U1389A at 1145 h and reached the bottom of the hole. Ten out of eleven stations recorded good sonic waveforms. Stations were spaced at ~25 m intervals, and the survey itself lasted from 1300 to 1500 h. The tool string was back on deck at 1630 h, and logging equipment was rigged down by 1715 h. At 1755 h, 24 December, the bit cleared the seafloor and the vessel offset 20 m east of Hole U1389A.

After coring operations had finalized at Hole U1389E, a wiper trip was conducted to condition the hole in preparation for downhole logging. After concluding the wiper trip, the bit was released and the hole displaced with 375 bbl of 10.5 ppg logging mud. The end of pipe was positioned at 102.2 mbsf. The first log was made with the triple combo tool string, which was deployed shortly after 2400 h, 1 January. The tool was not able to pass a bridge or ledge at 567 mbsf. The tool was recovered at 0610 h after logging the hole up from 567 mbsf. The second logging experiment was made with the FMS-sonic tool string, which was also unable to penetrate deeper than 567 mbsf. The FMS-sonic was recovered at 1425 h after logging the upper portion of the hole.

The VSP experiment was canceled. Shortly after arriving at Site U1389, maintenance was carried out in the vessel’s sea chest and bilge spaces. As part of this routine, ultrasonic thickness readings were taken on the steel plating. Evaluation of the readings indicated that some of the sea chest plating had wastage beyond acceptable limits and that several frames on the starboard side required immediate attention. Although repairs were in progress, it was felt that the sound pressure generated by the air gun during seismic profiling could subject the deteriorated sea chest to sufficiently high levels of vibration that would present a potential risk to the vessel. Therefore, VSP measurements planned for the last three sites of the expedition were canceled. The logging equipment was rigged down, the drill string was recovered, and the beacon was recalled. The vessel departed for the sixth site of the expedition at 1930 h, 2 January. Total time at Site U1389 was 12 days.

Site U1390

The vessel departed for Site U1390, the sixth site of the expedition, at 1930 h, 2 January 2012. The 22 nmi transit from Site U1389 was covered in just over 2 h. The vessel was positioned on the new coordinates at 2145 h.

Three holes were drilled at Site U1390 (Table T1). Hole U1390A was cored using the APC to 76.7 mbsf and then with the XCB to 350 mbsf. Hole U1390B was cored with the APC to 194.1 mbsf. Hole U1390C was cored with the APC to 175.4 mbsf. Downhole logging was carried out in Hole U1390A using the triple combo and FMS-sonic tool strings (see “Downhole logging at Site U1390”). Overall recovery at Site U1390 was 437.95 m (98.2%) with the APC and 248.32 m (90.9%) with the XCB. Total cored interval at Site U1390 was 719.5 m and total recovery was 686.27 m (95.4%).

Hole U1390A

The APC/XCB BHA and the drill string were deployed with the underwater camera. A survey of the seafloor was conducted using a 30 m grid pattern. Other than one large rock, no significant obstructions were observed. Hole U1390A was spudded with the APC at 0520 h, 3 January. Seafloor depth was established at 1005.1 mbrf (993.4 mbsl), which was 3.1 m deeper than the corrected precision depth recorder value of 1002 mbrf. Piston coring was only able to advance to 76.7 mbsf. The decision was made to switch to the XCB when the last APC core (339-U1390A-9H) required ~3 h to extract from the core barrel. Recovery for the piston cored interval was 102%. Cores were oriented starting with Core 4H. The APCT-3 was deployed to measure temperature at 32.1 (Core 4H) and 60.6 (Core 7H) mbsf. XCB coring deepened the hole to the depth objective of 350 mbsf by 1700 h, 4 January. Recovery for the 273.3 m XCB interval was 91%. The overall recovery in Hole U1390A was 93%.

Hole U1390B

With the scientific objective of “chasing” a contour line on the seismic record at the site, the vessel was offset 200 m north of Hole U1390A. The underwater camera was deployed and the seafloor monitored during the movement of the vessel. Once the vessel was on position, Hole U1390B was spudded with the APC from 1002 mbrf at 1700 h. The calculated seafloor depth was 1002.4 mbrf (990.7 mbsl). Piston coring advanced to 194.1 mbsf, where Core 21H could not be recovered with the coring line. When the orientation tool was retrieved to the surface using the coring line, it was discovered that the bulkhead lock pin between the male and female sections that connect the nonmagnetic sinker bars to the core barrel had parted in two places (possible metal fatigue). After several fishing attempts failed to grasp the female section that remained downhole with the core barrel, the BHA was recovered and the core barrel extracted at the surface. The bit was at the rotary table at 2120 h, 6 January. Piston coring recovered 189.9 m, which represented 98% of the cored interval. Cores were oriented starting with Core 3H. Temperature measurements were obtained with the APCT-3 at 18.6 (Core 2H), 47.1 (Core 5H), and 75.6 (Core 8H) mbsf. All cores were obtained with nonmagnetic core barrels.

Hole U1390C

The drill string was redeployed for the second time on site and the vessel offset 20 m east of Hole U1390B. Hole U1390C was spudded with the APC at 0240 h, 7 January, and established seafloor depth at 1004.1 mbrf (992.4 mbsl). Piston coring proceeded to the depth objective of 174.5 mbsf by 2200 h, 7 January. Stuck core barrels on Cores 2H through 4H required an extra coring line round trip to pull the orientation tool before it was possible to recover the core barrel. Cores were oriented starting with Core 4H and then followed by Cores 9H through 19H (last core). APCT-3 measurements were obtained at 23.4 (Core 3H), 51.9 (Core 6H), 80.4 (Core 9H), and 108.9 (Core 12H) mbsf. Nonmagnetic core barrels were used to obtain all cores. The bit was pulled free of the seafloor at 2300 h and cleared the rotary table at 0115 h, 8 January, ending operations at Site U1390. The vessel departed for the last site of the expedition at 0230 h that morning. Total time on site was 5.2 days.

Downhole logging at Site U1390

Instead of logging the third hole at the site, it was decided to log Hole U1390A. The hole was subjected to the routine conditioning procedures, including a wiper trip, mud flushes, and displacement with 124 bbl of 10.5 ppg mud before the bit was placed at 96.6 mbsf. The logging program consisted of the triple combo and FMS-sonic tool strings. The triple combo tool string was deployed at 2400 h, 4 January, and recovered at 0330 h. The FMS-sonic tool string was run in at 0600 h and recovered at 1000 h, 5 January. Both tools successfully covered the open hole to 350 mbsf. After the FMS-sonic tool string was rigged down, the bit was pulled clear of the seafloor at 1155 h, 5 January.

Site U1391

The 115 nmi voyage to Site U1391 (proposed Site WI-01B) was made at an average speed of 11.5 kt. The vessel was positioned on the last site of the expedition at 1230 h, 8 January 2012.

Three holes were drilled at Site U1391 (Table T1). Hole U1391A was cored using the APC to 171.1 mbsf and then with the XCB to 353.1 mbsf. Hole U1391B was cored using the APC to 171 mbsf and then with the XCB to 353.5 mbsf. Hole U1391C was drilled without recovery to 340 mbsf and then cored using the RCB to 671.5 mbsf. Downhole logging was carried out in Hole U1391C using the triple combo and FMS-sonic tool strings (see “Downhole logging at Site U1391”). Overall recovery at Site U1391 was 342.1 m (104.7% recovery) with the APC, 230.7 m (90.7% recovery) with the XCB, and 269.02 m (81.15% recovery) with the RCB. The total cored interval at Site U1391 was 1038.1 m and total recovery was 958.57 m (92.3%).

Hole U1391A

The APC/XCB BHA was made up, and a routine survey of the seafloor was conducted using a 30 m grid pattern. No significant obstructions were observed. Hole U1391A was spudded with the APC at 1080.0 mbrf at 2035 h, 8 January. Seafloor depth was established at 1085.4 mbrf (1073.7 mbsl). Piston coring advanced to final depth of 171.1 mbsf with a recovery of 106%. Cores were oriented starting with Core 339-U1391A-4H. Temperature measurements were made at 32.6 (Core 4H), 61.1 (Core 7H), 89.6 (Core 10H), 118.1 (Core 13H), and 146.6 (Core 16H) mbsf. Nonmagnetic core barrels were used to obtain all piston cores. XCB coring deepened the hole to the depth objective of 353.1 mbsf by 0345 h, 10 January. Average recovery for the 182 m XCB interval was 88.8%. Combined recovery in Hole U1391A was 97%. The drill string was pulled out of the hole, clearing the seafloor at 0520 h, 10 January. The vessel was offset 20 m south of Hole U1391A.

Hole U1391B

Hole U1391B was spudded with the APC at1085 mbrf at 0815 h, 10 January. Although the mudline core was 9.65 m, the desired vertical offset (5 m deeper) with the previous hole was maintained and piston coring continued to a final depth of 171 mbsf with a recovery of 104%. Cores were oriented starting with Core 3H. Temperature measurements were made at 19 (Core 2H), 47.5 (Core 5H), 76 (Core 8H), 104.5 (Core 11H), and 133 (Core 14H) mbsf. All cores were obtained with nonmagnetic core barrels. XCB coring deepened the hole to the depth objective of 353.5 mbsf. Average recovery for the XCB interval of 182.5 m was 93%. Combined recovery for Hole U1391B was 98%. The drill string was recovered with the bit clearing the seafloor at 1350 h and the rotary table at 1850 h, 11 January. The trip out of the hole was suspended 1.5 h for the routine maintenance procedure of slipping and cutting the drilling line.

Hole U1391C

A four-stand RCB BHA was made up with a new CC-4 Rock Bit International bit and mechanical bit release and deployed. After the driller tagged the seafloor at 1085 mbrf (1073.3 mbsl), Hole U1391C was spudded with the RCB at 2345 h, 11 January. The hole was drilled with a wash barrel to 340 mbsf by 1400 h, 12 January. The empty wash barrel was recovered and a fresh core barrel dropped at 1430 h when rotary coring was initiated. Rotary coring advanced to a final depth of 671.5 mbsf by 1645 h, 14 January. Recovery for the 331.5 m cored interval in Hole U1391C was 81%. Recovery percentage was adversely affected by the absence of recovery in Cores 26R, 29R, and 35R, which was assumed to be formation related. The average rate of penetration for the 331.5 m cored interval was 14.2 m/h.

Downhole logging at Site U1391

Following the wiper trip, Hole U1391C was flushed with sepiolite mud and the bit was released at the bottom. The hole was displaced with 248 bbl of 10.5 ppg heavy mud, and the end of pipe was placed at the logging depth of 98.9 mbsf. The first log of the hole was made with the triple combo tool string, which was made up of the natural gamma radiation, density, and resistivity tools and deployed at 0330 h, 15 January. The tool string succeeded in reaching 668 mbsf. The tool string was recovered and rigged down by 0815 h. The second and final log was made with the FMS-sonic tool string. The tool string reached 666 mbsf and recorded resistivity images of the borehole, sonic velocities, and natural gamma radiation data. The hole contained many thin washouts. As at previous sites, all the logs have medium-amplitude alternations on the several-meter scale. Sonic velocity, density, and resistivity all show a downhole compaction trend. Logging equipment was rigged down by 1915 h, concluding all science operations of the expedition. We departed Site U1391 at 0200 h, 16 January. Expedition 339 ended at 1342 h, 16 January, with the first line ashore in Lisbon, Portugal.

Top of page   |    Previous   |    Next