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doi:10.2204/iodp.proc.307.104.2006

Operations

The vessel was moved 0.5 nmi in dynamic positioning (DP) mode with the drill string in the water from Site U1316 to Site U1317. A positioning beacon was deployed at 1837 h on 2 May 2005. The vessel moved in DP mode to position over the site coordinates.

Hole U1317A

There was some difficulty obtaining an accurate reading from the PDR because of the steep bathymetric slopes of the carbonate mound. The PDR tended to give readings shallower, by as much as 40 m, than the actual water depth at the position of the rig floor. Because of the tight restrictions concerning the allowed locations for drilling the mound, this mismatch caused several hours delay while we established our exact location. After the drill string was spaced out, Hole U1317A was spudded with the advanced piston corer (APC) at 2335 h on 2 May 2005, and a seafloor depth of 832.5 mbrf was established.

Sixteen APC cores advanced to 130.8 mbsf (956.8 mbrf) (recovery = 105%). Perfluorocarbon tracer (PFT) and microsphere tracers were run on all cores. APC temperature tool measurements were taken at 25.5, 63.5, and 110.0 mbsf, and the Tensor orientation tool took measurements from 25.5 to 63.5 mbsf. Overpulls were required on all temperature runs (70 klb at 110.0 mbsf). The coring assembly was switched to extended core barrel (XCB), and two XCB cores advanced an additional 8.0 m to a total depth (TD) in Hole U1317A of 138.8 mbsf (964.8 mbrf; recovery = 63%). The drill string was pulled clear of the seafloor at 1815 h on 3 May, officially ending operations in Hole U1317A.

Hole U1317B

The vessel was offset 25 m southeast of Hole U1317A. After the drill string was spaced out, Hole U1317B was spudded at 1920 h on 3 May 2005, and a seafloor depth of 809.0 mbrf was established.

Sixteen APC cores advanced to 145.2 mbsf (954.2 mbrf; recovery = 101%). No tracer material was run in Hole U1317B, and the Tensor orientation tool took measurements from 24.5 to 110.0 mbsf. Overpulls were required on six cores, with 80 klb needed for two of them. At 110.5 mbsf, the core barrel had to be drilled over. The coring assembly was switched to XCB for one core, which advanced only 3 m, for a TD in Hole U1317B of 148.2 mbsf (957.2 mbrf). The drill string was pulled clear of the seafloor at 0815 h on 4 May, officially ending operations in Hole U1317B.

Hole U1317C

The vessel was offset 25 m southeast of Hole U1317B. After the drill string was spaced out, Hole U1317C was spudded at 1000 h on 4 May 2005, and seafloor depth was established at 802.7 mbrf.

Seventeen APC cores advanced to 150.8 mbsf (953.5 mbrf; recovery = 103%). No tracer material was run in Hole U1317C, and the Tensor orientation tool took measurements from 19.8 to 95.8 mbsf. Overpulls were required on four cores. The coring assembly was switched to XCB for one core, which advanced only 2.2 m, for a TD in Hole U1317C of 153.0 mbsf (955.7 mbrf). The drill string was pulled clear of the seafloor at 2130 h on 4 May. The drill string was tripped back to the surface, and the bit cleared the rotary at 2330 h on 4 May, officially ending operations in Hole U1317C. The bit, seal bore drill collar, and nonmagnetic drill collar were laid out.

Hole U1317D

The vessel was offset 15 m south of Hole U1317B. A rotary core barrel (RCB) bottom-hole assembly with an mechanical bit release (MBR) and three stands of drill collars was made up. Hole U1317D was spudded at 0400 h on 5 May 2005, and seafloor was established at 805.0 mbrf. The RCB was initially run with a center bit, and the hole was drilled ahead to 110.0 mbsf (915.0 mbrf). The center bit was retrieved, and 18 RCB cores advanced an additional 160 m to a TD of 270.0 mbsf (1075.0 mbrf) at 0420 h on 6 May (recovery = 64%). PFT and microsphere tracers were run on all cores.

Hole U1317D was prepared for logging. A wiper trip was run from bottom to 30 mbsf and back to bottom. During the wiper trip up, overpulls of 70 klb at 242 mbsf and 30 klb at 185 mbsf were experienced. On the wiper trip down, the bit took weight at 222 mbsf. A core barrel was dropped, and the hole was reamed and washed down to TD (270 mbsf). Fill (2 m) was circulated out, and hole-cleaning sweep with 30 bbl of sepiolite mud was pumped around. The RCB bit was released and dropped to the bottom. The hole was displaced with 84 bbl of sepiolite mud, and the drill pipe was tripped to the logging depth of 88 mbsf.

The Schlumberger wireline logging sheaves were rigged up, and the triple combination (triple combo) tool string was assembled. The logging string was run in the hole and took weight at 246 mbsf. The attempt to work the tools down was not successful, and the hole was logged up from that depth. After the single pass the tools were pulled out of the hole and laid out at 0600 h on 6 May 2005.

The second logging run was with the Well Seismic Tool (WST). Preparation for this run required following the Marine Mammal Policy for seismic sources. The watch for marine mammals began an hour before the air gun was put through a soft start. The soft start required ramping up the firing pressure to operational levels over a 30 min period. No mammals were sighted. The WST tool string was assembled and run into the hole to 246 mbsf. Check shots were taken at 13 stations on the way up. The signals were good and the WST string was pulled out of the hole and laid out at 2000 h on 6 May.

The third logging run was with the Formation MicroScanner (FMS)-sonic tool string, which was assembled and run to 246 mbsf. Two logging passes were made from 246 to 88 mbsf. With the logging complete, the string was pulled out of the hole and laid out at 0100 h on 7 May. The Schlumberger wireline logging sheaves were rigged down, ending the logging operation at 0230 h on 7 May.

The drill pipe was tripped to surface, and the beacon was released at 0326 h and recovered. The MBR cleared the rotary at 0430 h on 7 May, ending operations in Hole U1317D.

Hole U1317E

Note: Hole U1317E was drilled out of sequence because it was a late add-on that required approvals from both the Integrated Ocean Drilling Program (IODP) safety panel and the Irish government.

The transit from Site U1318 to Site U1317 occurred on 11 May 2005 and took 1.5 h. As the vessel came on site, the thrusters were lowered and the vessel was positioned over the site coordinates. The positioning beacon was dropped at 1138 h on 11 May. The vessel was offset 50 m south-southeast of Hole U1317D, and the drill string was spaced out for spudding. Hole U1317E was spudded at 1430 h on 11 May, and a seafloor depth was established at 792.2 mbrf.

Eighteen APC cores advanced to 158.6 mbsf (950.8 mbrf; recovery = 103%). No tracer material was run, and the Tensor orientation tool took measurements from 25.7 to 139.7 mbsf. Overpulls were required on nine cores with 80 klb needed for Core 307-U1317E-17H. Cores 17H and 18H had incomplete stroke, and Core 17H had to be drilled over. The core catcher of Core 17H held the prize of the hole, the boundary interval where coral growth initiated.

The drill pipe was tripped out of the hole, pulling clear of seafloor at 0100 h and continuing to the surface. The beacon was released and recovered at 0111 h on 12 May. The collars were laid out and the rig was secured for transit. The ship was under way to Ponta Delgada, Azores (Portugal), at 0429 h on 12 May, ending operations at Site U1317 (Table T1).

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