(Site 672)

The last line was cast off from Pier 18 at Balboa, Panama, at 0300 hr 20 December and the vessel commenced its sea voyage through the Panama Canal. Due to heavy traffic, the vessel waited at anchor for 13 hrs in Gatum Lake until clearance was received to pass through the Gatum Locks. After exiting the Panama Canal, moderate seas (8-12 ft) and winds (25-30 kt) held the vessel speed to under 8 kt for two days. Improved weather and sea states allowed for better progress toward the end of the transit to Proposed Site NBR-11A. The vessel arrived at Site NBR-11A at 2100 hr on 26 December after a transit of 1371 nmi with an average speed of 9.1 kt.

HOLE 1044A
(Site 672; Proposed Site NBR-11A)

Logging while drilling (LWD) Hole 1044A was located at global positioning system (GPS) coordinates 15°32.3965'N and 58°38.4793'W. This location is at a range of 35 m and a bearing of 259° from ODP Site 672. The location of Hole 1044A was based on 3-D seismic reflection survey, dGPS navigation data, and the final site position for Site 672 (Leg 110), which was produced by averaging transit satellite fixes. JOIDES Resolution GPS navigation data were automatically corrected to the moonpool using the ship's heading (gyro compass) and the known offset of the GPS antenna from the moonpool. Upon arrival at the desired drill site GPS coordinates, a beacon was deployed. After the beacon had settled to the seafloor and while we were tripping pipe to the seafloor, the ship was stabilized over the beacon using the ship's dynamic positioning system. The GPS data collected during the pipe trip to the seafloor were averaged, and we offset from the beacon location prior to spudding the hole to ensure we were in the desired location with respect to the 3-D seismic data. After we spudded into the seafloor, GPS data collected while we were drilling were averaged over approximately a 48-hr period to calculate the final site position.

The LWD bottom-hole assembly (BHA) consisted of a used 9-7/8 in Smith FDGH (3x14) bit, LWD Bit Sub, LWD Compensated Dual Resistivity (CDR) tool, double pin LWD crossover, LWD Compensated Density Neutron (CDN) tool, LWD crossover sub, 8 each 8-1/4 in drill collars, crossover, Bowen down jars, Bowen up jars, crossover, 2 each 8-1/4 in drill collars, Tapered Drill Collar (TDC), and 6 joints of 5-1/2 in drill pipe.

Hole 1044A was spudded at 1400 hr 27 December 1996. Drilling was initiated at 25 m/hr at a water depth of 4991.4 mbrf based on the precision depth recorder (PDR) reading. It was not possible to determine the mudline with the drill pipe in the soft hemipelagic sediments. Therefore, the PDR reading of 4991.4 mbrf was used for the water depth and the actual water depth will be corrected after analyzing the LWD data. Drilling continued at 25 m/hr down to 5291 mbrf (300 mbsf) where a precautionary wiper trip was made. The proto-décollement was estimated at 200 mbsf and the wiper trip was made from 300 mbsf back to 160 mbsf to allow the top of the BHA to clear the seafloor and also ream the hole in the location of the décollement. No drag or hole problems were encountered during the wiper trip. A 30-bbl sweep of sepiolite mud was used to clean out 9 m of fill that had accumulated at the bottom of the hole and drilling resumed at 25 m/hr. The rate of penetration was increased to 35 m/hr at 5379 mbrf (388 mbsf) to finish the hole more quickly. The drilling rate slowed down dramatically to 4 m/hr at a depth of 5663 mbrf, indicating we had reached basement. Hole 1044A was terminated at 5666 mbrf (675 mbsf) having successfully achieved the depth objective.

The drill string was raised to 5126 m (135 mbsf) and the hole was displaced with 45 bbl of heavy (10.5 lb/gal) mud. The LWD tools were raised to the drill floor where the nuclear sources were removed and the LWD collars were laid out. The beacon was recovered and the bit cleared the rotary table at 0200 hr 30 December ending Hole 1044A.

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