OPERATIONS

Expedition 309

The JOIDES Resolution arrived at Puerto Cristobal, Panama, and dropped anchor at 0752 h on 8 July 2005. The ship was advised that the berth at PIMPSA terminal in Balboa was not available, and the port call activities were moved to San Cristobal. The vessel was moved to Pier 7A, and Expedition 309 began with first line ashore at 1420 h on 8 July. Port call was concluded with last line released at 1620 h on 12 July.

The last line away from Berth 7A, Cristobal, Panama, was cast at 1620 h on 12 July 2005, and the vessel was under way through the Panama Canal, exiting the Miraflores Locks (iodp.tamu.edu/publicinfo/gallery/exp309/Panama_canal). The ship passed under the Bridge of the Americas on 13 July and began the transit to Site 1256. The transit was relatively benign, with the ship rolling/pitching moderately while averaging 10.1 kt over the 822 nmi distance. The vessel arrived at Site 1256 and thrusters were lowered at 1030 h on 16 July. The vessel was placed in dynamic positioning mode by 1100 h (Table T4).

Predrilling Logging Operations

A BHA consisting of a logging bit and 10 drill collars was assembled, marking the beginning of operations for Expedition 309. The drill string was assembled to a depth of 2467 meters below rig floor (mbrf), and the vibration isolated television (VIT) camera was launched to monitor reentry. Hole 1256D was located, the ship was offset 50 m northwest, and the positioning beacon was dropped at 1930 h on 17 July 2005. Hole 1256D was reentered at 1945 h (Movie ExpSum-C-1), and the drill string was lowered to a depth of 4370 mbrf, at which point it began taking weight, indicating ~27 m of fill.

The drill string was raised to a depth of ~4368 mbrf, and the top drive was picked up. The WSTP was lowered into the drill string to obtain a water sample and temperature measurement at 724.6 mbsf (4369.6 mbrf). The water sample was found to be murky, and low salinity (26‰) indicated the filters had become clogged with silt before the sampler was completely purged of nanopure water. The WSTP temperature measurement gave a flat-line temperature of 60°C because of a software failure in the tool. It was decided to run the WSTP again to get a better water sample. While the WSTP was cleaned for its second run, the APCT tool was deployed to obtain accurate temperature readings above 60°C. Temperature at 712.6 mbsf was 64.5°C and at 724.6 mbsf was 65.8°C. The second run of the WSTP, taken at 4357.6 mbrf, returned a good water sample.

The bit was raised to 3907 mbrf, and preparations were made for logging. Hole 1256D was logged using the triple combo and the FMS-sonic tool strings to determine hole condition and gauge prior to beginning coring operations. The Schlumberger logging tools were lowered into the drill string at 0030 h on 18 July. The hole was logged from 724.4 mbsf to casing depth. The tools were removed from the drill string at 0530 h on 19 July. The logging BHA was then retrieved, and an RCB coring assembly was prepared.

At 2325 h, Hole 1256D was reentered with an RCB assembly. The drill string was lowered to a depth of 4370 mbrf, and a center bit was dropped. The hole was then washed and reamed to a depth of 4395 mbrf, when the bit began taking weight. The center bit was pulled, and the first core barrel was dropped. A 50 bbl mud sweep was circulated, and coring operations began (Table T4). The hole was cored without incident to a depth of 4466.5 mbrf (821.1 mbsf). The bit accumulated a total of 51.7 rotating hours and was in relatively good condition. To minimize the risk of downhole bit failure and to ensure that the hole diameter was in gauge, it was decided that subsequent bits would be changed approximately every 50 h (Table T5).

The drill string was redeployed and reentered Hole 1256D at 1911 h on 22 July 2005 with a new CC-9 bit. The bit was lowered to bottom, and coring was resumed at 2330 h that day. Core 309-1256D-86R was recovered with 3.65 m recovery, but all the core catcher dogs were missing and it appeared that some of the core had fallen out of the core barrel. The next core barrel was dropped, and high pump pressures were noted. The barrel was pulled, and a deplugger was deployed twice to clear any obstructions. A core barrel was dropped again, and pressures had returned to a normal range. Coring was resumed at 1045 h on 23 July. The bit was pulled after Core 309-1256D-96R with 52.1 rotating hours.

After the drill string was recovered, a new bit was deployed and the drill string reentered Hole 1256D at 1610 h on 26 July. The drill string began taking weight at 4525 mbrf. The top drive was picked up, and the hole was washed and reamed to bottom. The hole was cored without incident from 4543.2 to 4604.2 mbrf (897.8–958.8 mbsf). Penetration rates and recovery dropped through this cored interval. The bit was pulled after 52.8 rotating hours.

The drill string was recovered and a new bit deployed. The bit was lowered to a depth of 3640 mbrf, and the WSTP was deployed to obtain a bottom seafloor water sample and temperature measurement. The WSTP was then recovered, and Hole 1256D was reentered at 1015 h on 30 July. The bit was lowered to a depth of 4514 mbrf. The top drive was picked up, and the hole was reamed to bottom. Coring resumed at 4604.2 mbrf (964.8 mbsf). Coring continued without incident to a depth of 4619.8 mbrf (Core 309-1256D-110R). After retrieving this core and dropping the next core barrel, the driller noticed a pressure drop of 200–250 psi. The core barrel was pulled and depluggers were dropped twice in attempts to clear the bit throat. Pressures were still lower than normal.

While retrieving Core 309-1256D-111R, the driller again noticed pressure drops of 200–250 psi when lifting the BHA off bottom. The pressure increased when weight was applied to the bit, indicating that there was a crack in the BHA, and the drill string was retrieved. Major damage was clear to the 8.5 inch bit sub assembly ~15 inches from the bit (Fig. F67). A straight horizontal gash had opened for ~150° (11 inches) of the circumference of the propagating a further ~75° around the pipe from each end of the clean fracture. When in tension with the drill bit hanging from the sub, the fracture opened up to 1 cm and the bit was held on by only ~4.25 inches of the bit sub wall. Such a failure of the bit sub assembly had not been witnessed before in the shipboard memory of scientific ocean drilling, and the rapid diagnosis and response of the Transocean operations team certainly averted a time-consuming major equipment loss in Hole 1256D. Bit number 4 was pulled after only 17.8 rotating hours and had cored 20.4 m.

The drill string was recovered and a new bit was deployed. Hole 1256D was reentered on 1 August. The bit was lowered to a depth of 4514 mbrf. The top drive was picked up, and the hole was reamed to bottom. Coring resumed at 4624.6 mbrf (979.2 mbsf). Mud sweeps were increased to 50 bbl to ensure cutting removal. Bit number 5 was pulled on 4 August with 50.1 rotating hours.

Hole 1256D was reentered for the seventh time on 5 August. The bit was lowered to a depth of 4657 mbrf. The top drive was picked up, and the hole was reamed to bottom. Coring resumed at 1430 h on 5 August at 4696.7 mbrf (1051.3 mbsf). Bit number 6 was pulled on 8 August with 50.8 rotating hours.

The drill string was recovered and a new bit was deployed. Hole 1256D was reentered at 0148 h on 9 August. The bit was lowered to a depth of 4715 mbrf (1069.6 mbsf). The top drive was picked up, and the hole was reamed to bottom. Coring resumed at 0800 h on 8 August at 4754.3 mbrf (1108.9 mbsf). While cutting Core 309-1256D-146R, the driller noticed a 100 psi pressure drop. The drill string was pulled off bottom, and a 350 psi drop in pressure was noted. Core 309-1256D-146R was recovered at 1330 h on 11 August after a 3.0 m advance and a recovery of 3.5 m. After dropping another core barrel, the pressures remained 350 psi lower than normal. It was suspected that there was another crack in the BHA. The decision was made to pull the drill string and inspect the BHA for cracks. When the bit cleared the reentry cone, the vessel was repositioned ~50 m from the cone.

The BHA was on deck at 2300 h on 11 August. All drill collars and subs were inspected for cracks. Bit number 7 was pulled after 42.5 rotating hours. With no cracks in the BHA found, a new bit was made up to the drill string and the drill string was again lowered. One stand of 5 inch transition pipe was laid out, as well as the tapered drill collar and crossover sub because of excessive wear at the connections.

A core barrel was dropped into the BHA while running in with bit number 8. The drill string was filled with seawater every 25 stands, and the pressure was checked. Pump pressure increases were noted at 25 and 50 stands, but there was no further pressure increases with 75 and 100 stands deployed, indicating there might be a crack in the drill string above the BHA. The VIT camera was lowered when 100 stands were below the rotary table. A pill of high-viscosity mud was pumped as a tracer as the camera was lowered. The camera passed through very cloudy water just above the BHA, indicating that mud had exited the drill pipe somewhere and drifted down. The camera was pulled up above the BHA, and another mud pill was circulated. As the VIT camera was again lowered toward the BHA, a vigorous jet of drilling mud was observed streaming from the 5 inch pipe (Movie ExpSum-C-2) about two stands above the 5 inch transition pipe. The drill string was pulled back up to the rig floor, the crack was found in the 5 inch pipe, and the bottom two stands of 5 inch drill pipe were replaced (Fig. F68).

The drill string was again lowered below the rotary table. Hole 1256D was reentered for the ninth time at 0230 h on 13 August (Movie ExpSum-C-3). A core barrel was dropped, and coring resumed at 0730 on 13 August. Bit number 8 was pulled on 16 August after 57.8 h of coring.

The drill string was recovered and a new bit deployed. Hole 1256D was reentered at 0304 h on 17 August, a core barrel was dropped, and coring resumed. The ninth and final RCB coring bit of Expedition 309 was pulled on 20 August. A mud sweep was pumped before the final core barrel was retrieved at 1100 h on 20 August. The bit was pulled to the casing shoe and lowered back to bottom. No fill was encountered. A mud sweep was pumped around, and the drill string was pulled out of the hole. Bit number 9 was pulled after 53.1 rotating hours.

A logging BHA was made up, and the hole was reentered at ~0800 h on 21 August. The bit was set at 3905.5 mbrf (260.1 mbsf), ~9 m above the casing shoe, and preparations were made for logging Hole 1256D.

The first logging run with the triple combo tool string started taking weight ~29 m above bottom, at 4871 mbrf (1225.6 mbsf). The logging run started at this depth and continued to 4200 mbrf (554.6 mbsf). This allowed for full coverage of the section drilled during Expedition 309 and approximately the bottom 200 m of the original hole from Leg 206. The FMS-sonic tool string was rigged up and lowered into the hole. The FMS was unable to pass 4868 mbrf (1222.6 mbsf). The tool logged up to 4300 mbrf (654.6 mbsf). Attempts to close the arms and lower the tool to log the entire length of the hole failed. The FMS was pulled out of the hole, encountering ~700 lb overpull while entering the drill pipe. When the tool exited the drill pipe, the arms were in the open position. The arms were manually closed, and the tool was laid out.

The third logging run utilized the UBI. The UBI was deployed with a sinker bar to enhance deployment speed. The UBI encountered fill at 4865 mbrf (1219.6 mbsf) and logged up to 4745 mbrf. The fourth logging run was to be a VSP utilizing the three-component WST and the generator-injector air gun. The tool was lowered into the drill pipe at 0400 h on 23 August. The tool began taking weight at 3920 mbrf (274.6 mbsf) and was worked down to 4020 mbrf (374.6 mbsf) but could not be lowered any further. The tool was pulled out of the hole, taking 800 lb of overpull to enter the drill pipe. When the tool reached the surface, several kinks were noted in the Schlumberger wireline cable. A total of 60 m of wireline cable was cut, and the cable was reheaded. The back-up FMS tool was rigged up, function tested, and lowered into the hole for a log of the complete hole. The tool was unable to pass 4861 mbrf (1215.6 mbsf). The tool logged up to 3950 mbrf (304.6 mbsf). Following the completion of the FMS-sonic log, the wireline heave compensator was tested to evaluate the performance of the new drum compensator and compare it to the performance of the older LDEO wireline compensator. The tools were pulled out of the drill string and were laid out.

The ship was secured for transit and was under way at 1300 h on 24 August 2005. The transit was relatively benign, with the ship rolling/pitching moderately while averaging 10.1 kt over the 822 nmi distance. The JOIDES Resolution arrived at Balboa, Panama, at 0000 h on 28 August. The ship was at anchorage by 0029 h.

Port Call

Expedition 312 began when the first line was placed ashore at Odgen Docks in Victoria, British Columbia (Canada), at 1225 h on 28 October 2005. The routine port call was accomplished in 3.8 days. The plan to conduct remedial cementing operations at two circulation obviation observatory kit (CORK) observatories installed at Site 1301 during Expedition 301 was cancelled at the last minute because of heavy seas at the location. The 13 educators participating in the School of Rock Expedition boarded the ship on the morning of 31 Oct. The last line was released at 0800 h on 1 November, as the vessel began the 2638 nmi transit to Acapulco to pick up the Expedition 312 scientific party.

During the transit, the educators applied what they learned about scientific ocean drilling through ship tours and interaction with U.S. Implementing Organization and Transocean personnel into developing a curriculum based on their shipboard experiences. The finished product will be tested in various classrooms and delivered at upcoming teacher workshops. During the transit, the teachers answered many e-mails from their students asking questions about ocean drilling. The educators departed the vessel on 12 November at 0730 h and continued their workshop on shore before the pilot program concluded on the evening of 13 November.

The vessel completed the 2598 nmi transit to Acapulco, Mexico, at an average speed of 10.9 kt. The first line was secured to Berth 2, Fiscal Wharf, at 1135 h on 11 November. During the 22.5 h port call, the School of Rock Expedition participants were discharged and the Expedition 312 scientific party embarked. The last line was released at 0958 h on 12 November from Fiscal Wharf, and the vessel began the journey to Hole 1256D. In accordance with routine, the new arrivals were given a safety briefing shortly after leaving port. A presite meeting to discuss the general strategy of the expedition was held on 14 November. The 3 day journey to Hole 1256D was without incident.

The vessel completed the 763 nmi transit from Acapulco, Mexico, to Hole 1256D at an average speed of 11.1 kt and the 3361 nmi trek from Victoria, British Columbia, to Acapulco, Mexico, to Site 1256 was accomplished at an average speed of 10.9 kt. The first piece of coring equipment was placed in the water at 0730 h on 15 November, shortly after positioning on site using Global Positioning System data.

The bit entered the reentry cone for the first time at 2030 h on 15 November 2005 (Table T6). The drill string advanced effortlessly until it contacted resistance at 927 mbsf. This was an indication of hole trouble that required extensive washing and reaming. Coring was finally initiated at 0715 h on 21 November and proceeded without incident as the hole was deepened from 1255.1 to 1372.8 mbsf with generally good drilling conditions. At this depth, the fifth coring bit of the expedition failed and all three cones and most of the fourth cone were left in the hole (Fig. F69). Before coring could resume, it was necessary to clean out the metal debris from the bottom of the hole. This effort required four fishing round trips (two with a fishing magnet and two with a mill) before coring could be confidently resumed.

Hole 1256D was reentered with the sixth rotary bit of the expedition at 0754 h on 8 December, and coring resumed at 1300 h. There were no further hardware failures or major hole problems, and rotary coring deepened the hole to a final depth of 1507.1 mbsf by 0300 h on 19 December. A historic event was recorded when Core 312-1256D-213R arrived on deck at 0800 h on 13 December 2005 containing the first in situ dike/gabbro contact ever drilled from an intact section of oceanic crust.

The hole was deepened by 252.0 m to a total depth of 1507.1 mbsf and abandoned without hardware in the bottom of the hole. A total of 9.5 operating days were lost to hole maintenance activities: 5.2 days were expended cleaning out the hole at the beginning of the expedition and another 4.3 days were consumed with fishing and milling the cones from the bottom of the hole after the bit failure. These 9.5 days are exclusive of the additional time that was spent washing down to the bottom of the hole after all reentries subsequent to each coring bit trip.

The average ROP during Expedition 312 was 0.8 m/h for all bits. The average recovery for the cored interval was 18.5%, which is less than the two previous cruises to this hole (Leg 206 = 47.8%; Expedition 309 = 36.3%). To put this into perspective, the average recovery for the last ODP cruise (Leg 148) to Hole 504B was 8.6%.

A logging BHA was made up and reentered Hole 1256D at 2318 h on 19 December 2005. The bit was placed in the open hole at ~20 m below the 16 inch casing shoe at a depth of 289 mbsf. The hole was successfully logged with five different tool strings:

The triple combo tool string made two passes, from 1440 to 343 mbsf and from 1438 to 1080 mbsf. A check shot experiment using the VSI was conducted at 58 stations ~22 m apart from a maximum depth of 1383 mbsf. The UBI tool string with the GPIT, SGT, and DSI logged from 1430 to 1099 mbsf, followed by a repeat pass covering the interval from 1433 to 1089 mbsf. The FMS was combined with the SGT and logged the hole from 1437 to 1098 mbsf and from 1436 to 1089 mbsf. A last logging suite made up of the TAP, DLL, and SGT logged the hole from 325 to 1431 mbsf. The drill string was pulled out of the hole, clearing the seafloor by 1345 h on 23 December. The vessel was secured for sea and left for Balboa, Panama, at 2200 h on 23 December. The total time at Hole 1256D was 926.5 h (38.6 days).