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doi:10.2204/iodp.proc.322.103.2010

Operations

Expedition 322 began at 0000 h on 1 September 2009 during the port call at Yokkaichi, Japan. The science party boarded the D/V Chikyu in the morning hours, and an initial science meeting was held. A prespud meeting with ship crew was held the next day. See Table T1 for a breakdown of general coring operations.

Before the start of Expedition 322, LWD and measurement-while-drilling (MWD) data were collected in Hole C0011A during the contingency days at the end of Expedition 319. As a part of across-expedition collaboration within NanTroSEIZE, data interpretation of the LWD/MWD was carried out mainly during Expedition 322 by its shipboard scientists. Therefore, we start this section with the Expedition 319 LWD/MWD operations.

Hole C0011A (Expedition 319)

Schlumberger engineers and technicians prepared the Schlumberger LWD and MWD tools for assembly prior to drilling Hole C0011A (target depth = as deep as possible or 900 mbsf, water depth = 4049 m). Because the water depth was too great for remotely operated vehicle placement of transponders, the six transponders were dropped from the drillship and all were dropped by 0400 h on 26 August. At 0845 h on 26 August, the 12¼ inch bit LWD/MWD bottom-hole assembly (BHA) (Table T2) was run into the hole, and a calibration check was conducted between the Big Head transducers on the ship and the transponders on the seafloor. At 1900 h on 26 August, a prespud meeting was held to determine target depth (determined as 900 m LWD depth below seafloor [LSF]), jet-in program, and conditions for stopping drilling. Spud-in of Hole C0011A was achieved at 2239 h on 26 August, and the mudline (i.e., water depth) was confirmed to be 4049 m by MWD gamma ray measurement. After jetting in to 41 m drilling depth below seafloor (DSF), drilling the 12¼ inch hole commenced. There were short wiper trips and sweeps to maintain good borehole condition and to prevent the BHA from getting stuck in the hole. Total depth (TD) (952 m LSF) was reached at 2359 h on 29 August, spotted 121 m³ of 1.30 g/cm³ kill mud, and began pulling out of the hole. The BHA reached the surface at 1300 h on 30 August, and the tools were laid down for LWD data recovery. Meanwhile, the Chikyu moved to the rendezvous point for the supply ship, the Kaiko, to load and backload cargo for Expedition 322.

Transit

The Chikyu departed the port of Yokkaichi at 1600 h on 4 September 2009. After ~130 nmi of transit, the Chikyu arrived at drill Site C0011 at 1100 h on 5 September. We carried out underwater television (UWTV) free fall for torsion release and spaced out the inner barrel assembly.

Hole C0011B

We started running into the hole with the 10⅝ inch rotary core barrel (RCB) BHA at 2230 h on 5 September. The center bit was dropped at 1000 h on 6 September, and then we spudded Hole C0011B at 1700 h after the replacement of a leaking wash pipe. UWTV was not used because of bad sea conditions, which created uncertainty in the depth of the mudline. It was decided that removing the guide horn for UWTV deployment was more risky than the lack of UWTV. Water depth at the site was set as 4077 m drilling depth below rig floor (DRF) (4048.7 m DSF), based on the gamma ray log data of Expedition 319 Hole C0011A.

We continued drilling to 4367 m DRF. Rate of penetration (ROP) was controlled at 30 m/h and was 17.6 m/h including the pipe connection. Hi-Vis gel was pumped at every two stands. At 1015 h on 7 September, a leak was found in the wash pipe and it was replaced. At 1700 h, the drain hose of the core line wiper was replaced and drilling operations resumed. We reached 4417 m DRF (340 m DSF) at 1945 h.

The center bit assembly was retrieved at a second attempt at 0030 h on 8 September. RCB core was cut from 4417 m DRF under heave of 1.5 m. Core 322-C0011B-1R was recovered on deck at 0258 h. The core liner was jammed inside the inner barrel and was removed with a high-pressure pump. The hole was swept out with 10 m³ of Hi-Vis gel while removing core liner. The 2.2 m long recovered core was heavily disturbed because of a twisted core liner.

We were unable to continue sinker bar operations because of high winds (>20 m/s). We decided to wait on weather (WOW) as of 0515 h. The drill bit was pulled up to 50 m DSF. Operations resumed at 1300 h once the wind speed decreased to <18 m/s. Before resuming RCB coring, test runs of SET-P and UWTV were carried out. The SET-P tool with colleted delivery system (CDS) was run through the drill pipe and held 30 s without drilling mud circulation at 1000 and 2000 m DRF. The tool was retrieved and the data showed successful results of water pressure measurements. Then, a UWTV test run was carried out from 1645 to 0600 h on 9 September.

RCB coring operations resumed at 0800 h. After running into the hole bottom, Core 322-C0011B-2R was cut from 4426.5 m DRF at 1100 h and recovered on deck at 1315 h. The recovered core was 1.3 m long with 13.7% recovery. Core 322-C0011B-3R was cored by a 6.0 m advance for space-out. The 6.26 m of core was on deck at 1623 h with 104.3% recovery. Core 322-C0011B-4R was recovered on deck after a second attempt at 2337 h. The recovered core was 3.55 m long.

Coring continued smoothly on 10 September. Eight cores were cut and recovered from Core 322-C0011B-5R at 0235 h through 12R at 2324 h. Core recovery averaged 69.7% through the day. Hi-Vis mud was pumped to clean the hole between each coring operation.

Core 322-C0011B-13R was cut from 4527.5 m DRF at 0015 h on 11 September but was not recovered until 0857 h. The core line winch cable was tangled at 160 m DRF, and coring operations were suspended until 0700 h. Core 322-C0011B-14R was on deck at 1148 h and recovery was 5.78 m.

Core 322-C0011B-15R was cut from 4546.5 m DRF at 1247 h, but core jamming was suspected when the ROP decreased at 4553.8 m DRF. Coring was stopped after a 7.3 m advance and retrieval of the inner barrel was attempted. After two unsuccessful latching attempts, the core line was changed from aft to forward. The third attempt was also unsuccessful. The sinker bar was retrieved without the inner barrel, and a shear pin of the retrieving tool was found broken.

Core 322-C0011B-15R was finally retrieved on deck at 1204 h on 12 September. The fourth attempt without a line wiper worked, and the core barrel was successfully caught. The recovered core was 7.36 m long from a 7.3 m advance. After reaming down to the hole bottom and pumping 10 m³ of Hi-Vis gel, the inner barrel was dropped at 1330 h and coring of Core 322-C0011B-16R was started.

Drilling of Core 322-C0011B-16R was stopped after a 2.3 m advance because of a drop in ROP. The core was on deck at 1641 h and 1.98 m of core was recovered. Core 322-C0011B-17R was another short 2.4 m advance. Coring was stopped because of a drilling break. Only a few pieces of mudstone/sandstone were recovered at 2045 h.

On 13 September, seven cores from Core 322-C0011B-18R through 24R were recovered. Core 322-C0011B-18R was no recovery after a full 9.5 m advance. Core 322-C0011B-19R was stopped after a 7.5 m advance because of slow ROP and was on deck at 0545 h with 100% recovery. Core 322-C0011B-20R was on deck at 0930 h after a 3.1 m advance. Coring was stopped because of unsteady pump pressure from 4576 m DRF. The recovered core was 0.58 m long. Cores 322-C0011B-21R and 23R were good recovery (>90%), But Core 322-C0011B-22R recovered only 0.23 m of material in the core catcher. Core 322-C0011B-24R was on deck at 2351 h and 5.21 m of core was recovered.

On 14 September, five cores from Core 322-C0011B-25R through 29R were recovered. Coring of Core 322-C0011B-28R was stopped because of a drop in ROP and abnormal pressure observed at 4649.7 m DRF. Core 322-C0011B-29R was on deck at 1725 h and only 0.3 m of fragments was found in the core catcher.

The center bit assembly was dropped for cleaning inside the pipe and bit. Then, after checking pump pressure of circulation, coring operations resumed at 0100 h on 15 September. Core 322-C0011B-30R was on deck at 0410 h, and 4.01 m of core was recovered from a 6.1 m advance. After reaming from 4625 to 4663 m DRF, Core 322-C0011B-31R was on deck at 0827 h. Relatively good core recovery continued until Core 322-C0011B-39R, except for Core 322-C0011B-34R, which ended up with 0.32 m of material.

On 16 September, SET-P measurement was planned after coring 8.5 m of Core 322-C0011B-40R. This was to deploy the SET-P tool at 680.5 m DSF, targeting an inferred sandy layer identified in the LWD log. Core 322-C0011B-40R, however, hit a hard layer and 4.92 m of core was recovered from a 6.5 m advance. The remaining 2.0 m was cored as Core 322-C0011B-41R in order to determine lithology before planned SET-P measurement.

Core 322-C0011B-41R was on deck at 1730 h, and 0.25 m of calcareous concretion was recovered in the core catcher and several pebbles of hard mudstone were found in the bottom of the core. The lithology was not what we expected around this interval and was obviously not suitable for the SET-P experiment. We attempted another short (4.5 m) core (322-C0011B-42R). Core 322-C0011B-42R was on deck at 2108 h, and 3.64 m of softer mudstone was recovered.

Because we were uncertain in depth determination without good correlation between LWD and multisensor core logger (MSCL) data, it was unclear whether we had overshot the target sand layer or were still above it. We continued to attempt to identify a key bed for SET-P deployment by another short (4 m) core (322-C0011B-43R).

Core 322-C0011B-43R was on deck at 0438 h on 17 September after the fourth attempt to catch the inner barrel. The recovered core was 8.49 m and >200% recovery. At a first sight, the lithology looked like a thick sand layer sandwiched by mudstone in the top 2 m and the bottom. But the bed turned out to be fragmented material such as drill cuttings/debris in the hole bottom.

Having spent more than the 12 h allocated to this experiment in our operations plan, we decided to cancel our SET-P deployment. We canceled a second run planned at ~900 mbsf as well because the deployment would have been more difficult in deeper sections without a clear target.

After this decision, RCB coring operations resumed. Cores 322-C0011B-44R and 45R were good recovery (>8 m), but Core 322-C0011B-46R was a short 3.5 m advance because of low penetration and high torque, and 1.79 m of core was recovered.

RCB coring continued on 18 September but the recovered core was not as good as expected in rough sea conditions under the influence of an approaching typhoon. Core 322-C0011B-48R contained rounded pebble-size mudstone, which was suspected to be caving/cuttings material. Core 322-C0011B-49R was on deck at 1100 h, but the plastic liner was found damaged and jammed in the inner barrel. Recovery of material at the rig floor was finished at 1345 h. The recovered core was 6.68 m long from a 7.9 m advance. Core 322-C0011B-50R was on deck at 1745 h, but core quality was again not good. We decided to clean the bit and the hole and WOW before continuing coring.

After hole and bit cleaning was completed, the drill bit was pulled up to ~50 m DSF for WOW. Advisory status continued until 1800 h on 19 September because of average wind speed >18 m/s. Operations resumed at 2200 h, and Core 322-C0011B-51R was cored from 757 m DSF and was on deck at 1100 h on 20 September. The recovered core was 10.15 m long. Core 322-C0011B-52R was on deck at 1744 h. Another 10.15 m of core was recovered after a second try of catching the inner barrel. Core 322-C0011B-53R was on deck at 2207 h, but a drop in penetration resulted in short 3.7 m advances.

On 21 September, Cores 322-C0011B-54R and 55R were forced to be short 8.8 m and 7.3 m advances, respectively. After Core 322-C0011B-55R, coring was skipped because of the slow penetration and poor quality, and we drilled with the center bit assembly from 4863.3 to 4921 m DRF (57.7 m).

Coring operations resumed at 0000 h on 22 September. Core 322-C0011B-56R was on deck at 0404 h, and 2.53 m of core was recovered from a 2.4 m advance. Core 322-C0011B-57R was on deck at 0937 h, and 6.93 m of core was recovered. Core 322-C0011B-58R was on deck at 1545 h, and 9.89 m of core was recovered in relatively good condition. Core 322-C0011B-59R was on deck at 2146 h, and 3.73 m of core was recovered from an 8.6 m advance.

Core 322-C0011B-60R was on deck at 0215 h on 23 September, and 0.15 m of material was recovered from a short 2.0 m advance because of low ROP. It was decided to wash down several more tens of meters after recovery of the next core. However, Core 322-C0011B-61R was not recovered until 1249 h, even with a 5.0 m advance, and only 5 cm of material was recovered. The Co-Chief Scientists decided to finish operations at this site and move to the next site. Kill mud (100 m³ of 1.3 SG) was spotted, and we started pulling out of the hole at 1730 h. The TD of Hole C0011B was 4958.0 m DRF (881.0 m DSF). Upon retrieval, the drill bit was shown to be heavily damaged with most of its cutting teeth missing.

Retrieval of transponders started in the morning of 24 September and finished before 1830 h. The ship moved to proposed Site NT1-01A and set transponders.

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