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doi:10.2204/iodp.proc.307.103.2006

Operations

The 302 nmi transit from Dublin, Ireland, to Site U1316 was accomplished at an average speed of 9.7 kt in just under 32 h. During the transit, drilling and coring equipment was prepared.

Hole U1316A

Once on site, the thrusters were lowered and the vessel was placed in dynamic positioning mode. The hydrophones were lowered and the positioning beacon was deployed at 0410 h on 30 April 2005, officially marking the beginning of on-site operations. The precision depth recorder provided a seafloor depth of 956.4 m, corrected to the rig floor dual elevator stool. The drill string deployment for Hole U1316A was initiated by picking up drill collars and strapping (measuring) and drifting (verifying minimum internal bore diameter) all tubular components. A two-stand advanced piston corer (APC)/​extended core barrel (XCB) bottom-hole assembly (BHA) was used for coring. After tripping the drill string to bottom, the top drive was picked up and the drill string was spaced out for spudding. Hole U1316A was spudded with the APC at 1120 h on 30 April, and a seafloor depth of 959.2 meters below rig floor (mbrf) was established.

Eight APC cores advanced to 66.3 meters below seafloor (mbsf) (1025.5 mbrf; recovery = 95%). APC temperature measurements were taken at 26.3 and 54.8 mbsf, and the Tensor orientation tool took measurements from 26.3 to 64.3 mbsf. Core 8H short-stroked and became stuck at 66.3 mbsf, and a maximum of 80 klb overpull was not able to free it. The core barrel was released after overdrilling 1.5 m. The coring assembly was switched to XCB, and 13 XCB cores advanced an additional 67.7 m to a total depth (TD) of 134.0 mbsf (1093.2 mbrf; recovery = 80%). XCB coring times were long and recovery erratic. The XCB coring shoe on Core 18X failed in torsion but remained on the core barrel, and heat checking was evident on other coring shoes. The average penetration rate was <3 m/h. Coring was suspended at 2015 h on 1 May because of the slow penetration rate.

Hole U1316A was prepared for logging. A wiper trip was run from bottom up to 30 mbsf and back to bottom using the top drive, fill (1 m) was circulated out, and the hole was displaced with 45 bbl of sepiolite mud. The bit was then pulled up to logging depth of 30 mbsf.

The Schlumberger wireline logging sheaves were rigged up, and the triple combination (triple combo) tool string was assembled and deployed. On the way into the open hole it encountered an obstruction at 45 mbsf, which left 5 m of the logging string still inside the drill pipe. The logging string was picked up and run back down but would not pass beyond 30 mbsf, which was coincident with the lockable float valve. It was speculated that vessel heave and the shallow engagement of the drill pipe in the hole (30 m) allowed the pipe to “walk around” and wallow out the top of the hole. The logging program was suspended and the tools recovered. The Schlumberger logging sheaves were rigged down and the drill string was pulled clear of the seafloor at 0640 h on 2 May, officially ending operations in Hole U1316A.

Hole U1316B

The drillship was offset 20 m north of Hole U1316A, and the drill string was spaced out for spudding. Hole U1316B was spudded with the APC at 0830 h on 2 May 2005, and a seafloor depth of 959.0 mbrf was established.

Eight APC cores advanced to a TD of 59.5 mbsf (1018.5 mbrf; recovery = 103%). Perfluorocarbon tracer (PFT) and microsphere tracers were run on all cores, and the Tensor orientation tool took measurements from 24.5 to 59.5 mbsf. The drill string was pulled clear of the seafloor at 1500 h on 2 May, officially ending operations in Hole U1316B.

Hole U1316C

Note: Hole U1316C was drilled out of sequence to take advantage of the logistics of APC/XCB coring at nearby Site U1317. After completing Hole U1316B, the ship moved to Site U1317, where we cored three APC/XCB holes and changed out the BHA from APC/XCB to rotary core barrel (RCB) to core Hole U1317D.

The ship moved back to Site U1316 from Site U1317 on 7 May 2005. The location coordinates for Hole 1316C were 20 m south-southeast of Hole U1316A. The RCB BHA was made up with a mechanical bit release (MBR) and three stands of drill collars. Hole U1316C was spudded at 0800 h on 7 May, and seafloor was established at 959.0 mbrf. The RCB was initially run with a center bit and the hole was drilled ahead to 40.0 mbsf (999.0 mbrf). The center bit was retrieved and 11 RCB cores advanced an additional 103.1 m to a TD of 143.1 mbsf (1102.1 mbrf) at 0010 h on 8 May (recovery = 68%). PFT and microsphere tracers were run on all cores.

Hole U1316C was prepared for logging. A wiper trip was run from bottom up to 58 mbsf and back to bottom. There was no fill. The RCB bit was released by a wireline releasing tool and dropped to the bottom. The hole was displaced with 44 bbl of sepiolite mud, and the drill pipe was tripped to the logging depth of 59 mbsf.

The Schlumberger wireline logging sheaves were rigged up, and the triple combo tool string was assembled. The logging string was run in the hole to TD at 143 mbsf and logged uphole. After a single pass, the tools were pulled out of the hole and laid out at 0715 h on 8 May.

The second logging run was with the Formation MicroScanner (FMS)-sonic tool string. The FMS-sonic tool string was assembled and run to bottom. Two logging passes were made from bottom to 59 mbsf. With logging complete, the string was pulled out of the hole and laid out at 1135 h on 8 May. The Schlumberger wireline logging sheaves were rigged down, ending the logging operation at 1330 h on 8 May.

The drill pipe was tripped to the surface, the beacon was released at 1350 h and recovered, and the MBR cleared the rotary at 1515 h on 8 May, ending operations at Site U1316 (Table T1).