IODP Expedition 349 Preliminary Report

doi:10.14379/iodp.pr.349.2014

Operations

Port call

Expedition 349 began with the first line ashore in Hong Kong at China Merchants Wharf at 0848 h (UTC + 8 h) on 26 January 2014. The science party and technical staff boarded on the day of arrival. The majority of incoming cargo and off-going cargo was loaded and unloaded on 26 January. The following day, the Siem Offshore crew change was completed. All main port call activities, including preparation of the passage plan were completed. Public relation tours were given on all three days of the port call. After taking on 2200 metric tons of marine gas oil, the vessel was secured for sea with the final maintenance checks performed prior to departure.

On the morning of 29 January, two tugs and the harbor pilot arrived at our location. The last line was released from shore at 1238 h, beginning the 463 nmi voyage to Site U1431 (proposed site SCS-3G). The pilot departed the vessel at 1326 h, and the vessel began the sea passage to the first site.

Site U1431

After a 463 nmi transit from Hong Kong averaging 11.0 kt, the vessel arrived at the first expedition site. A prespud meeting was held prior to arrival to review operations at the first site. The vessel stabilized and switched from cruise mode to dynamic positioning over Site U1431 at 0640 h on 31 January 2014. The positioning beacon was then deployed at 0712 h.

The bottom-hole assembly (BHA) was picked up and assembled and then run in the hole with drill pipe to 4165.25 meters below rig floor (mbrf). All drill pipe was measured (strapped) and the internal diameter verified (drifted) during the pipe trip. There were no operational problems running the drill string into the hole. The top drive was picked up, the drill string circulated out, and a pig was pumped to remove any debris that might have accumulated in the string. The calculated precision depth recorder (PDR) depth for the site was 4252.1 mbrf, and after some consideration 4248 mbrf was selected as the shoot depth for the first core. The bit was spaced out to 4248 mbrf and the APC barrel was run in the hole with wireline and landed. Hole U1431A was spudded at 0040 h on 1 February. The mudline core recovered 9.45 m of sediment and the seafloor was calculated to be 4248.1 mbrf (4237.3 meters below sea level [mbsl]). Nonmagnetic core barrels were used for APC coring from Core 349-U1431A-1H through 3H. Hole U1431A was terminated by plan at a final depth of 4276.5 mbrf (28.4 mbsf). At the conclusion of coring, the drill string was pulled from the hole. The seafloor was cleared at 0345 h on 1 February, ending Hole U1431A. Three piston cores were taken over a 28.4 m interval, with a total recovery of 28.39 m of core. Overall core recovery for Hole U1431A was 100.0%. The total time spent on Hole U1431A was 21.0 h.

After the bit cleared the seafloor, the vessel was offset 20 m east of Hole U1431A. As part of the planned microbiological analyses, the PFT pump was turned on and the drill string displaced with contamination testing fluid. The pump remained on for the remainder of coring operations in Hole U1431B. The bit was spaced out to 4245.5 mbrf in an attempt to recover ~7.0 m on the mudline core. The mudline core recovery was 7.5 m. The seafloor depth was calculated to be 4247.5 mbrf (4236.7 mbsl). Hole U1431B was spudded at 0420 h on 1 February. Nonmagnetic core barrels were used for APC coring from Core 349-U1431B-1H through 2H to a final depth of 17.0 mbsf. At the conclusion of coring, the drill string was pulled from the hole. The bit cleared the seafloor at 0620 h, ending Hole U1431B. Two piston cores were taken over a 17.0 m interval in Hole U1431B, with a total recovery of 17.16 m of core (100.9%). The total time spent on Hole U1431B was 2.58 h.

After the bit cleared the seafloor, the vessel was offset 20 m south of Hole U1431B. The bit was spaced out to 4245.5 mbrf. The mudline core recovery was 4.7 m, but the core liner was split. The seafloor depth was calculated to be 4250.3 mbrf (4239.5 mbsl). Hole U1431C was spudded at 0700 h on 1 February. Nonmagnetic core barrels were used for APC coring from Core 349-U1431C-1H through 2H to a final depth of 14.2 mbsf. The PFT pump remained running during coring in Hole U1431C. Hole U1431C was terminated when we determined that the mudline core would not meet sampling requirements. At the conclusion of coring, the drill string was pulled from the hole. The bit cleared the seafloor at 0852 h on 1 February, ending Hole U1431C. A total of two piston cores were taken over a 14.2 m interval in Hole U1431C, with a total recovery of 14.45 m of core (101.8%). The total time spent on Hole U1431C was 2.42 h.

After the bit cleared the seafloor, the vessel was offset 20 m west of Hole U1431C. The bit was spaced out to 4245.0 mbrf. The mudline core recovery was 3.22 m. The seafloor depth was calculated to be 4251.3 mbrf (4240.5 mbsl). Hole U1431D was spudded at 0925 h on 1 February. Nonmagnetic core barrels were used for APC coring from Core 349-U1431D-1H through 19H to a depth of 168.9 mbsf. Temperature measurements were taken with the APCT-3 on Cores 4H, 7H, 10H, and 13H with good results. After six partial strokes of the APC, the coring system was switched over to the XCB. XCB coring continued from Core 20X through 67X at a final depth of 4868.3 mbrf (617.0 mbsf). The PFT pumps remained on through Core 23X. While cutting Core 67X, the rate of penetration dropped severely and the core barrel was retrieved after a 2.7 m advance. While recovering the core barrel at the surface, we discovered that the cutting shoe, core catcher sub assembly, and the break off sub were missing from the XCB coring assembly. With ~1 m of junk metal remaining in the hole, we decided to pull out of the hole, offset, and begin a new hole with the RCB coring system. The top drive was then set back and the bit tripped from the hole, clearing the seafloor at 0355 h on 6 February. The bit was then tripped to the surface and cleared the rig floor at 1415 h, ending Hole U1431D. A total of 19 APC cores were taken over a 168.9 m interval in Hole U1431D, with a total recovery of 165.61 m of core. The XCB was used 48 times over an interval of 448.1 m, recovering 236.50 m of core. Overall core recovery for Hole U1431D was 402.11 m over an interval of 617.0 m (65.2%). The total time spent on Hole U1431D was 125.5 h.

After offsetting the vessel 20 m west of Hole U1431D, an RCB BHA was assembled with a new RCB C-4 bit. The BHA was run in the hole to 4163.22 mbrf, and the rig crew performed a slip and cut of 115 ft of drilling line. The remainder of the drill pipe was then run in the hole, and at 4221.46 mbrf, the top drive was picked up and then spaced out to spud Hole U1431E. A center bit was dropped and pumped to land out in the bit. Hole U1431E was spudded at 0650 h on 7 February. The seafloor depth for the hole was determined to be 4251.3 mbrf, calculated using an offset depth from Hole U1431D. Hole U1431E was advanced by drilling without coring from the seafloor to 507.0 mbsf. The center bit was pulled from the BHA by wireline and a core barrel was dropped to take a spot core (349-U1431E-2R) from 507.0 mbsf. After cutting the core without recovery, the center bit was dropped and drilling continued from 516.7 to 575.0 mbsf. The center bit was then retrieved by wireline, a core barrel dropped, and continuous coring started with Core 349-U1431E-4R from 575.0 mbsf. The next three cores (4R to 6R [575.0–603.3 mbsf]) did not recover any material. Coring continued with good recovery from Core 7R through 36R (603.3–894.3 mbsf). Core 36R was the first to recover basalt, with several small pieces present in the core catcher. Coring then continued into acoustic basement from Core 37R to 47R (894.3–991.4 mbsf). Penetration rates varied from 1.62 to 4.66 m/h over this interval, except for a sediment section in Core 45R that cored more quickly than the basalt. Microspheres were deployed in the RCB core catcher for Cores 12R through 43R.

With torque becoming higher and erratic, we decided to make a wiper trip to allow any debris collecting around the drill collars to fall into the hole. After pumping a sweep from the bottom of the hole, the drill string was pulled back to 862.95 mbsf. The bit was then run back to bottom, tagging fill material at 972.65 mbsf. With 18.75 m of fill in the bottom of the hole, a core barrel was dropped and the bit worked back to bottom with circulation and rotation without difficulty. The core barrel was retrieved with 0.65 m of material that was curated as ghost Core 48G. Another 50 bbl high-viscosity mud sweep was pumped after reaching 991.4 mbsf, and then another core barrel dropped. Coring continued from 991.4 mbsf to the final depth of 1008.8 mbsf (Cores 49R and 50R). Just prior to finishing coring, a 50 bbl high-viscosity mud sweep was pumped to clean and condition the hole for logging. The total depth of Hole U1431E was reached at 0740 h on 14 February. After reaching total depth, the final core was pulled to the surface and laid out. A total of 47 RCB cores were collected in Hole U1431E over a 443.5 m interval, with a total recovery of 242.35 m of core (54.8% recovery, excluding the single 0.65 m long ghost core).

At the completion of coring, the rotary shifting tool (RST) was deployed to activate the mechanical bit release and the bit was dropped in the bottom of the hole. The RST was retrieved, and the other RST run in the hole to shift the sleeve back into the closed position. The end of the drill pipe was then raised to a depth of 4900.08 mbrf (648.78 mbsf) with the top drive in place. The hole was displaced from 648 mbsf to the seafloor with 11.4 ppg high-viscosity mud designed to improve logging conditions. The top drive was set back and the end of the pipe raised to 4400.9 mbrf (149.62 mbsf) for logging operations. After holding a logging safety meeting for rig floor personnel, the triple combo tool string was rigged up and run in the hole, reaching 463.7 m WSF on 15 February. The hole was then logged up, a short repeat pass recorded, and the tool string was then pulled to surface and rigged down. After rigging down the triple combo tool string, the FMS-sonic tool string was rigged up and deployed to 444 m WSF. Two full passes were made with the tool string, and then the tool string was pulled to the surface and rigged down at 1915 h on 15 February. The drill string was then tripped out of the hole from 4900.9 mbrf (149.6 mbsf) and cleared the seafloor at 2010 h. While pulling out of the hole with the drill string, the starboard conveyor on the pipe racker had a hydraulic failure. The hydraulic block in the derrickman’s control booth was repaired, but 1.5 h was recorded as operational downtime. The rest of the trip out of the hole was uneventful and the bit cleared the rig floor at 0555 h. The rig floor was secured for transit at 0600 h on 16 February, ending operations at Site U1431. Total time spent in Hole U1431E was 231.75 h.

Site U1432

The vessel arrived at Site U1432 (proposed Site SCS-6A) at 2337 h on 16 February 2014 after a 181 nmi transit at an average speed of 10.3 kt. An acoustic positioning beacon was deployed at 2352 h.

The primary objectives at this site required deep penetration, so the plan was to install a reentry cone and casing system, with the first step in this process to conduct a jet-in test to determine the length of 20 inch casing that should be attached to the reentry cone. The BHA for the jet-in test was assembled with an 18½ inch tricone bit and run to just above the seafloor. The vessel was offset 20 m south of the original coordinates for Site U1432 when the acoustic beacon landed within 6 m of the coordinates. The subsea camera and frame (VIT) was deployed to observe the bit tag the seafloor (3840.0 mbrf). After picking up the top drive and spacing out the bit, Hole U1432A was spudded at 1525 h on 17 February. The BHA with the 18½ inch tricone bit was jetted into the formation 62.0 m over a 3 h period. The drill string was then pulled clear of the seafloor and the top drive set back. The remainder of the drill string was tripped out of the hole and the bit cleared the rotary table at 0205 h on 18 February, ending Hole U1432A. The total time spent in Hole U1432A was 26.5 h.

Based on the results from the jet-in test, a five-joint, 57.12 m long 20 inch casing string was selected. The 20 inch casing shoe joint was cut off to length and a Texas Pattern casing shoe welded on the end of the shoe joint. The remainder of the reentry cone and base were put together, moved into the moonpool, and positioned underneath the rotary table. The casing was run through the rotary table and the reentry cone in the moonpool. Each casing connection was tack welded to prevent the casing from backing out. The third joint of casing had to be replaced because of a damaged thread on the pin. The casing hanger and casing pup joint were picked up and attached to the top of the casing string. The Dril-Quip CADA (casing) running tool was made up into the casing hanger on the rig floor. The casing was then lowered through the rig floor, into the moonpool, and through the reentry cone. The casing hanger was landed into the landing ring inside the reentry cone and snapped into place inside the cone. The landing joint was lowered to release the weight of the casing. The casing running tool was rotated 3.75 turns to the right and the casing released. A BHA (casing stinger) with an 18½ inch bit, bit sub, and six drill collars was lowered into the reentry cone and casing. The casing running tool was inserted into this BHA and latched into the casing hanger in the reentry cone and secured by rotating the upper BHA 3.75 turns to the left. The moonpool doors were opened and the reentry system with the 20 inch casing was lowered through the moonpool to 3819 mbrf. The top drive was picked up and spaced out to jet-in the 20 inch casing. Hole U1432B was spudded at 0635 h on 19 February. Jetting continued as the casing was slowly lowered. Seven hours later the reentry system landed on the seafloor. The subsea camera was lowered to assist in releasing the casing. After attempting to release the casing for 2.5 h, the casing tool finally released after the vessel was offset from the original position in order to get the casing running tool to rotate. The rotation required to release the tool was observed clearly on the new subsea camera system. The camera was then pulled back to the surface and secured. The drill sting was tripped back to the surface, and the BHA was set back in the derrick. During the trip out of the hole, the rig was secured to slip and cut 115 ft of drilling line as per the slip and cut program.

An HOC underreamer with an 11¾ inch closed diameter was made up to the 18½ inch tricone bit and bit sub. The underreamer was set to open up the 18½ inch hole to 22 inches in diameter. The underreamer and bit were lowered into the moonpool, the top drive picked up, and the underreamer function tested. The top drive was then set back, and the remainder of the BHA assembled and run in the hole to 3828.7 mbrf. During the trip, the subsea camera system was deployed. The bit was spaced out for reentry and the vessel was positioned using the subsea camera system. Hole U1432B was reentered at 2005 h on 20 February. After reentering the hole, the top drive was picked up and the drill string washed down to the casing shoe at 57.1 mbsf. After carefully washing down below the casing shoe so that the underreamer was below the base of the 20 inch casing, the pump rate and speed (rotations per minute [rpm]) were optimized for drilling a 22 inch hole below the 20 inch casing. Drilling continued to 4000.0 mbrf (160.0 mbsf). Drilling was suspended at 0610 h on 21 February when weather conditions worsened and the high heave of the vessel began to severely affect the weight on the bit and underreamer. The bit was tripped back inside the 20 inch casing and the top drive set back. The drill string was then tripped back to the surface, clearing the seafloor at 0835 h on 21 February, and finally clearing the rig floor at 1620 h. The underreamer and bit were inspected and laid out, and the BHA racked back into the derrick. While waiting on the weather to subside, the vessel offset 40 m south to be well away from the reentry cone for Hole U1432B. An APC hole (U1432C) was cored and, after coring to 110.0 mbsf, the weather appeared to have subsided sufficiently for another attempt at drilling out the 22 inch hole for the 16 inch casing.

After pulling out of Hole U1432B, the upper guide horn was picked up from the drill collar rack, lifted to the rig floor, and reinstalled below the rotary table. An APC/XCB BHA was made up while the vessel was offset 40 m south of Hole U1432B. The drill string was then tripped toward the seafloor. After completing the pipe trip to just above the seafloor, the top drive was picked up and spaced out, and Hole U1432C was spudded at 0555 h on 22 February. The first coring attempt with the bit at 3835 mbrf did not recover any core. The bit was then lowered to 3838.5 mbrf and the next coring attempt recovered a mudline core of 7.95 m of sediment. This core length was used to calculate the seafloor depth at 3840.1 mbrf (3829.1 mbsl). Nonmagnetic core barrels were used for the APC from Core 329-U1432C-1H through 12H to a final depth of 110.0 mbsf. PFT fluid was displaced into the drill string prior to spudding the hole and was pumped continuously during Hole U1432C. Temperature measurements were taken with the APCT-3 on Cores 5H, 7H, 9H, and 11H with good results. The hole was terminated when weather conditions improved sufficiently to return to Hole U1432B. The bit was tripped to the surface and cleared the rig floor at 0735 h, ending Hole U1432C. A total of 12 APC cores were taken over a 110.0 m interval in Hole U1432C, recovering 88.74 m of core (80.7% recovery). The total time spent in Hole U1432C was 39.25 h.

After tripping out of Hole U1432C, the BHA was set back in the derrick and the upper guide horn removed and laid out on the drill collar racks. We then returned to Hole U1432B to continue drilling the 22 inch hole for the 16 inch casing. As before, an HOC underreamer with an 11¾ inch closed diameter was made up to the 18½ inch tricone bit and bit sub. The underreamer was set to open up the 18½ inch hole to a 22 inch diameter. The underreamer and bit were lowered into the moonpool, the top drive picked up, and the underreamer function tested. The top drive was set back, and the remainder of the BHA assembled and run in the hole to 3828.7 mbrf. During the trip, the subsea camera system was deployed. The bit was spaced out for reentry and Hole U1432B reentered at 1944 h on 23 February. The subsea camera system was pulled back to surface while the top drive was picked up. The bit and underreamer were run in the hole to 160.0 mbsf and drilling continued from 4000 to 4090.0 mbrf (160.0–250.0 mbsf). The depth of Hole U1432B reached 250 mbsf at 0640 h on 24 February. The hole was conditioned and displaced with 379 bbl of 10.5 ppg mud. The drill string was tripped back to the surface and cleared the rig floor at 2120 h. During the trip out of the hole, the rig was secured to slip and cut 115 ft of drilling line as per the slip and cut program.

The drill floor was rigged up to run 16 inch casing. We assembled 240.85 m of 16 inch casing, including a Dril-Quip casing hanger. The casing was landed on the moonpool doors with the casing running tool, which was then released and pulled back through the rig floor. The 240.77 m casing stinger was made up to the bottom of the casing hanger running tool and lowered through the 16 inch casing in the moonpool. The casing hanger running tool with the casing stinger below was latched into the 16 inch casing hanger, with two control length drill collars and a tapered drill collar above the casing running tool. The entire casing string plus running tools were lowered to 3827.4 mbrf while filling the drill pipe with water every 20 stands. The subsea camera system was installed and lowered to reenter Hole U1432B. After 15 min of maneuvering the vessel, we reentered Hole U1432B at 0500 h on 26 February. The camera system was pulled back to the surface while the top drive was picked up. The casing was lowered into the 22 inch hole and washed down to ~200 mbsf. The subsea camera system was again lowered to assist in releasing the casing running tool from the casing. As the camera system neared the seafloor, the video feed from the subsea camera was lost. The camera system was pulled back to the surface for repair (water had intruded the pan and tilt unit, causing a power overload in the system). The casing was washed in to 240.9 mbsf and landed in the reentry cone. The casing running tool was rotated clockwise 3.75 turns and released from the casing hanger. The BHA, including the internal casing stinger, was pulled back ~11 m and the top drive set back. The cementing assembly was rigged up, the lines were pressure tested, and ~20 bbl of cement mixed to 15 ppg was pumped downhole. The cement was displaced with seawater and positioned to balance at the casing shoe to an estimated height of 17 m above the casing shoe (both inside and outside the casing). The cementing equipment was rigged down and the drill string pulled back to 161.9 mbsf. The circulating head was connected and the drill string flushed with twice the drill string capacity with seawater. The remainder of the drill string was pulled from the hole, clearing the seafloor at 2140 h on 26 February and finally clearing the rig floor at 0400 h on 27 February. The BHA components were secured and the running tool was detorqued.

A new 14¾ inch bit and four stands of drill collars were made up and run in the hole with drill pipe while filling with water at 20-stand intervals. When the bit was at 3823.3 mbrf, the subsea camera system was lowered to allow reentry. Hole U1432B was reentered at 1655 h on 27 February. and the camera pulled back to the surface. After securing the camera system, the drill string was run in the hole until the top of the cement was tagged at 4069.0 mbrf (229 mbsf). The cement was drilled out from 4069.0 to 4083.0 mbrf (229.0–243.0 mbsf). After washing down to total depth (250.0 mbsf), new 14¾ inch hole was drilled from 4090.0 to 4640.0 mbrf (250.0–800.0 mbsf). After reaching 800.0 mbsf, the hole was swept clean with high-viscosity mud. After setting back the top drive, the drill string was pulled back to the surface. The bit cleared the rotary table at 1120 h on 1 March. The 10¾ inch casing stinger components were made up and the underreamer arms were set to 12¾ inches. The top drive was then picked up and the mud motor and underreamer tested. After the test was successfully completed, they were racked back in the derrick. After assembling all the casing stinger components, a slip and cut of the drilling line was completed.

The rig floor was then prepared for running 10¾ inch casing, and 787.06 m of casing with a 10¾ inch casing hanger were made up. The casing was lowered into the moonpool and secured with a casing elevator on the prepared landing platform. The buoyant weight of the casing string was 70,000 lb. The running tool was released from the casing and pulled back to the rig floor. It was then made up to the bottom of a drill collar stand and racked back in the derrick. The casing stinger with the bit, underreamer, and mud motor were then run inside the casing. Also included in the stinger were three stands of drill collars and 24 stands of drill pipe. The bit and underreamer were positioned just below the bottom of the casing after the running tool was landed and made up to the casing. The casing was run to the seafloor with drill pipe and the subsea camera system deployed to assist with the reentry at the seafloor. Hole U1432B was reentered at 0242 h on 3 March. The camera system was pulled back to the surface and set back into the storage position on the moonpool doors. The casing was run in the hole with drill pipe to 223.5 mbsf. The top drive was picked up and the casing lowered to 244.0 mbsf. The casing was washed to the bottom while pumping 530 gpm. At 530 gpm, the mud motor was turning the bit at 80–85 rpm with the underreamer arms extended to clear a 12¾ inch hole in front of the casing. The casing was steadily lowered until it was landed and released at 1745 h on 3 March. The top drive was set back and the drill string tripped from the hole, clearing the seafloor at 2045 h, and then clearing the rotary table at 0915 h on 4 March. The casing stinger components were flushed with freshwater and either laid out or, in the case of the drill collars, racked back in the derrick.

After successfully running the 10¾ inch casing, a cementing stinger was assembled. The stinger consisted of a reentry/cleanout bit, a bit sub, a stand of drill collars, 24 stands of 5 inch drill pipe, F-cup tester, another two drill collars, a tapered drill collar, and two stands of 5½ inch transition drill pipe. The entire assembly was made up and run in the hole with drill pipe to just above the seafloor while stopping every 20 stands to fill the drill pipe with water. The subsea camera system was deployed to just above the seafloor and Hole U1432B reentered at 0344 h on 5 March. The camera system was pulled back to the surface and secured. The bit was run in the hole to 767 mbsf, 20 m above the 10¾ inch casing shoe. The F-cup tester was spaced out so that it was at 42 mbsf, inside the 16 inch casing. The circulating head was made up to the top of the drill string and the mud pumps were brought up to 60 spm to verify circulation up the annulus between the hole and the casing. After establishing circulation, the cement pump was used to pump 10 bbl of freshwater ahead of the cement slurry. Fourteen barrels of 15.5 ppg cement were then mixed and pumped downhole, followed by another 10 bbl of freshwater. This was displaced down the drill string with 263 bbl of saltwater using the mud pumps. After displacing the cement, the circulating head was removed and the driller attempted to pull out of the hole. He immediately noticed a steadily increasing overpull as he tried to pull out of the hole. After pulling up enough to remove two singles of drill pipe, we were unable to raise the drill string any further. It now appears that the formation collapsed around the 10¾ inch casing string, preventing circulation up the open hole annulus and outside the casing. Instead, the circulation path was up through the 10¾ casing, bypassing the cup tester. The elevated temperatures at 700 mbsf (~65°–70°C) accelerated the hardening of the cement. The drill string was worked for the next 9 h using combinations of overpull, torque, and pump pressure in an effort to free the drill string. At that point, we rigged up to sever the drill string. The drill string severing charge was lowered to just above the cup tester, which has a 1.5 inch internal diameter. The charge was detonated at 0430 h on 6 March 2014; however, there was no loss of overpull on the pipe. The wireline was pulled out of the hole and the severing tool cleared the rig floor at 0808 h. The drill pipe was worked with a maximum of 100,000 lb of overpull for ~1 h. The elevators were then lowered back to the elevator stool while the rig was offset 200 m. The top drive was picked up and the drill pipe was picked up slowly while moving the rig back to the original location. The pipe was worked free with a maximum of 400 A of torque and 40,000 lb of overpull. The end of pipe cleared the casing hanger at 1105 h. The top drive was set back and the drill string pulled from the hole. The end of pipe cleared the rotary table at 1830 h. The acoustic positioning beacon was recovered while tripping drill pipe. The upper guide horn was reinstalled, the rig floor secured for transit, and the thrusters raised. The vessel switched to transit mode at 2036 h on 6 March, ending Site U1432. The total time spent on Hole U1432B was 363.25 h (15.1 days).

Site U1433

After a 334 nmi transit lasting 29.9 h, the vessel arrived at Site U1433 (proposed Site SCS-4B) and switched into dynamic positioning mode at 0230 h on 8 March 2014. At 0255 h, an acoustic positioning beacon was deployed. An APC/XCB BHA was assembled and run in the hole to 800.4 mbrf. At 0520 h, a tool joint parted on the twenty-fourth stand of drill pipe, just after picking up the drill string and just prior to unlatching the lower set of elevators. The load cell weight at the time of the incident was recorded at ~200,000 lb. The entire weight of the drill string dropped ~18 inches and landed in the lower set of elevators, which were resting on top of the dual elevator stool. The pin on the top single of drill pipe had parted, leaving one single hanging from the upper set of elevators and two singles sticking up from on top of the lower set of elevators. The stand was then laid out to the V-door. The broken pipe was visually inspected and photographed. As a precaution, the twenty-third stand was also disassembled and laid out. The bottom set of elevators was removed from use and replaced with a reconditioned set of elevators. After clearing the rig floor, the trip in the hole resumed. When the bit was at 1147.8 mbrf, another tool joint failed when the driller was picking up the thirty-sixth stand from the pipe racker. This time, one single fell back into the trough of the pipe racker still attached to the skate, and a double remained connected to the elevators on the bales connected to the main block. After the second tool joint failure, we decided to discontinue using any of the 5 inch drill pipe that had been used in the stuck pipe incident at the previous site. Investigations continue into the root cause of the pipe failure. Documentation of the stuck pipe event was collected for analysis. The failed tool joints were prepared with care for shipment to a laboratory for detailed metallurgical analysis and were shipped from Keelung, Taiwan, at the end of the expedition. The drill string was tripped back to the BHA and all suspect drill pipe was removed from use and stored in the port pipe racker. We picked up 201 joints of new 5 inch drill pipe from the riser hold. The new drill pipe was strapped and drifted as it was assembled and lowered toward the seafloor. After completing assembly of the new pipe, the remaining 37 stands from the starboard 5 inch pipe racker were picked up and run in the hole. The total number of 5 inch pipe stands available was then 104 stands. The remaining 101 stands of suspect drill pipe in the port pipe racker need to be inspected before they can be put back in service.

After running in the hole with 104 stands of 5 inch drill pipe, the 5½ inch drill pipe was picked up until the bit reached 4372.9 mbrf. The trip in the hole was stopped at 3587.0 mbrf to perform a slip and cut of the drilling line. The PDR recorded an estimated depth of 4394.4 mbrf for the seafloor. The top drive was picked up and spaced out to 4390 mbrf. The nonmagnetic core barrels were dressed with liners, the FlexIT core orientation tool was inserted, and a core barrel run down and landed. Hole U1433A was spudded at 1000 h on 9 March. The mudline core recovered 8.9 m of sediment and the seafloor was calculated to be 4390.6 mbrf (4379.4 mbsl). Coring continued without issue through Core 349-U1433A-16H (151.4 mbsf). While running in the hole with a core barrel, the bridge informed the driller that a fishing boat was drifting toward the vessel’s location. At 0540 h on 10 March, the Captain ordered the driller to suspend operations. The core barrel was retrieved, and the driller began tripping out of the hole with the top drive. At 99.1 mbsf, the driller was instructed to standby. After the threat disappeared, the drill string was tripped back to bottom and coring continued to Core 20H (188.3 mbsf). After four consecutive partial strokes of the APC, refusal was called at 188.3 mbsf. Orientation was measured on all APC cores. Temperature measurements were taken with the APCT-3 on Cores 4H, 7H, 10H, and 13H with good results. PFT fluid was used on Cores 18H through 20H. The bit was tripped to the surface and cleared the rig floor at 0325 h on 11 March, ending Hole U1433A. A total of 20 APC cores were taken over a 188.3 m interval in Hole U1433A, recovering 168.79 m of core (89.6%). The total time spent on Hole U1433A was 73.0 h.

After offsetting the vessel 20 m east of Hole U1433A, an RCB BHA was assembled with a new RCB C-4 bit. Three additional drill collars had to be picked up from the drill collar racks to replace the ones lost in Hole U1432B. The core barrels were spaced out at the surface and the 172.07 m BHA assembled and run in the hole to 4350.3 mbrf. The top drive was then picked up and spaced out to spud Hole U1433B. A center bit was dropped and pumped to land out in the bit. Hole U1433B was spudded at 1515 h on 11 March. The seafloor depth for the hole was 4390.6 mbrf (4379.4 mbsl), determined by using an offset depth from Hole U1433A. Hole U1433B was advanced by drilling without coring from the seafloor to 186.1 mbsf. The center bit was pulled from the BHA by wireline and a core barrel dropped to start continuous RCB coring from Core 349-U1433B-2R through 75R to a total depth of 5249.1 mbrf (858.5 mbsf). The PFT pumps were turned on during the drilldown period, and PFT fluid was pumped through Core 26R (426.9 mbsf). Microspheres were added to the RCB core catcher for Cores 56R to 75R. Core 65R encountered basalt at 786.3 mbsf. Coring continued into acoustic basement from Core 65R to Core 75R (858.5 mbsf), with half-cores collected from Core 67R to the total depth in an attempt to improve recovery. Penetration rates varied from 0.9 to 3.9 m/h over the basement interval. The total depth of Hole U1433B was reached at 2100 h on 17 March and the final core was pulled to the surface and laid out. At the completion of coring Hole U1433B, 74 RCB cores had been cut over a 672.4 m interval, recovering 443.04 m of core (65.9%).

After pumping a 50 bbl high-viscosity mud sweep, a short wiper trip was made from total depth to just above the basement contact (786.3 mbsf) with the top drive installed. While tripping back to bottom, the hole had to be reamed from 847.4 to 858.5 mbsf. We then pumped another 50 bbl mud sweep to further clean the hole. The RST was then picked up and run into the hole with a coring line to release the bit for logging. An attempt was made to engage the sleeve in the mechanical bit release. After being unable to engage the shifting sleeve, the RST was pulled back to surface. Examination at the surface revealed the RST did not come back with the core line sinker bars. An overshot (fishing tool) was made up and run in the hole to fish for the RST. After securing the RST, the mechanical bit release sleeve was engaged and the bit was dropped from the drill string. The RST also dropped off the fishing tool on release, leaving the RST in the bottom of the hole. The core line was pulled back to surface and the RST to shift the sleeve back into the original position was deployed. With the bit released, the drill string was raised to 5196.3 mbrf (805.7 mbsf) with the top drive. The top drive was then set back and the drill string raised to 5079.7 mbrf (689.1 mbsf). The circulating head was picked up and the hole displaced from 689.1 mbsf to the seafloor with 10.5 ppg high-viscosity mud designed to improve logging conditions. The drill string was then raised up and spaced out so that the end of the pipe was at 4490.7 mbrf (100.1 mbsf) for logging operations.

After holding a logging safety meeting for rig floor personnel, the triple combo tool string was rigged up and deployed. The tool string reached a total depth of 845.4 m WSF on 18 March. The hole was then logged up and the tool string pulled to surface and rigged down. After rigging down the triple combo tool string, the FMS-sonic tool string was rigged up and deployed to a depth of 842.4 m WSF. The basement section of the hole was logged five times with three passes with the calipers open. On the last pass, the tool become stuck but was eventually worked free. The rest of the open hole was logged up to the end of the drill pipe and the tool string was then pulled to the surface and rigged down. All logging equipment was rigged down by 1300 h on 19 March. The drill string was pulled from the hole and the BHA set back and secured for transit at 2300 h on 19 March, ending Site U1433. Total time spent in Hole U1433B was 211.5 h.

Site U1434

After an 18 nmi transit lasting 2 h, the vessel arrived at Site U1434 (proposed Site SCS-4E) and switched into dynamic positioning mode at 0048 h on 20 March 2014. At 0110 h, an acoustic positioning beacon was deployed. An RCB BHA was assembled with a new RCB C-7 bit. The core barrels were spaced out at the surface and the 172.07 m BHA assembled. The BHA was lowered to 4000.9 mbrf and the top drive picked up and spaced out to 4020.0 mbrf to spud Hole U1434A. A center bit was dropped and pumped down the drill string to land out in the bit. Hole U1434A was spudded at 1215 h on 20 March. The estimated depth of the seafloor was determined to be 4020.4 mbrf using the PDR. The final seafloor depth for the hole was 4020.4 mbrf (4009.0 mbsl), which was determined by tagging the seafloor with the drill bit. Hole U1434A was advanced by drilling without coring from the seafloor to 4217.4 mbrf (197.0 mbsf) over a 10 h period. The center bit was pulled and a core barrel dropped to start continuous RCB coring from Core 349-U1434A-2R. Coring continued through Core 15R to a depth of 4332.9 mbrf (312.5 mbsf). Microspheres were deployed in each RCB core catcher for the duration of RCB coring. We encountered the sediment/basement interface in Core 10R, with the formation change at ~280 mbsf. Coring continued into acoustic basement from Core 10R through 15R to a total depth of 4332.9 mbrf (312.5 mbsf). Half cores were started with Core 12R and continued to total depth. Penetration rates varied from 1.57 to 5.76 m/h over the basement interval. Coring was finally halted because of poor core recovery coupled with high torque and poor coring conditions. The total depth of Hole U1434A was reached at 0925 h on 22 March. After reaching total depth, the final core was pulled to the surface and laid out. At the completion of coring Hole U1434A, 14 RCB cores had been cut over a 115.5 m interval, recovering 26.43 m of core (22.9%).

After retrieving the final core, we attempted to pull the drill string from the hole; however, the high torque and high overpull made this impossible. After 1.5 h of working the pipe with a combination of high torque (900 A), overpull, and constant pumping action, the drill string came free and was pulled out of the hole with the top drive to 4117.4 mbrf (97.0 mbsf). The top drive was then set back and the drill string was tripped to the surface. The bit cleared the seafloor at 1500 h, and then cleared the rotary table at 2300 h. After securing the rig floor for transit and pulling the hydrophones and thrusters, the vessel switched to cruise mode and began the transit to Site U1435 at 2348 h on 22 March. Total time spent on Hole U1434A was 71.0 h.

Site U1435

After a 336 nmi transit lasting 39.65 h, the vessel arrived at Site U1435 (proposed Site SCS-6C) and switched into dynamic positioning mode at 1524 h on 24 March 2014. At 2045 h, an acoustic positioning beacon was deployed. An RCB BHA was assembled with a new RCB C-7 bit. The core barrels were spaced out at the surface and the 172.07 m BHA assembled. The BHA was then run in the hole to 3214.9 mbrf and the top drive picked up and spaced out to 3261.6 mbrf to spud Hole U1435A. While lowering the drill pipe, we conducted a sonar survey with the 3.5 kHz array sonar to select a hole location to maximize sediment thickness. Hole U1435A was spudded at 0035 h on 25 March. The estimated depth of the seafloor was 3261.6 mbrf using the PDR. The final seafloor depth for the hole was 3264.0 mbrf (3252.5 mbsl), which was determined by tagging the seafloor with the drill bit. We advanced Hole U1435A by coring from the seafloor to 3564.0 mbrf (300.0 mbsf). Microspheres were deployed in each RCB core catcher from Core 349-U1435A-5R to the total depth of the hole. Coring continued to Core 349-U1435A-32R (300 mbsf), when operational time for the expedition expired. Penetration rates varied from 2.8 to 58.2 m/h over the cored interval. The total depth of Hole U1435A was reached at 0730 h on 27 March. After reaching total depth, the final core was pulled to the surface and laid out. At the completion of coring Hole U1435A, 32 RCB cores had been cut over a 300.0 m interval, recovering 171.37 m of core (57.1%).

After reaching total depth and laying out the last core, the drill string was pulled out of the hole with the top drive to 3535.1 mbrf (271.1 mbsf). The drilling knobbies were laid out, the top drive set back, and the drill string tripped to the surface. The bit cleared the seafloor at 1020 h, and then cleared the rotary table at 1835 h. After securing the rig floor for transit and pulling the hydrophones and thrusters, the vessel switched to cruise mode and began the transit to Keelung, Taiwan, at 1900 h on 27 March. Total time spent on Hole U1435A was 75.5 h. Expedition 349 officially ended with the first line ashore in Keelung at 0710 h on 30 March.

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