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doi:10.2204/iodp.proc.308.106.2006

Summary of operations

Hole U1322A

A summary of operations for Hole U1322A can be found in Table T2. Hole U1322A was spudded at 0130 h on 15 June 2005 when the driller tagged the seafloor at 1330.0 meters below rig floor (mbrf) (precision depth recorder [PDR] = 1336.4 mbrf). The bit was jetted to 3.8 mbsf and the vibration-isolated television (VIT) camera was recovered. The hole was then drilled with an MWD/LWD string from 3.8 to 200.0 mbsf at an average rate of penetration (ROP) of 30 m/h. To ensure that we did not exceed our target depth, the interval from 200 to 238.0 mbsf was drilled at an ROP of 20 m/h. There was no indication of pressurized sands throughout the drilled interval. Resistivity and gamma ray data indicated that the main lithology was mud. After the hole was displaced with 70 bbl of 8.9 ppg sepiolite mud, the drill string was pulled out of the hole, clearing the seafloor at 1525 h on 15 June. When the bit was placed at 1040 mbrf, or ~222 m above seafloor, the dynamic positioning (DP) operator began to offset the vessel to Site U1323. The vessel departed location at 1600 h, leaving behind the beacon because of the planned return to this site subsequent to coring operations at Site U1324. A more detailed description of MWD/LWD operations in Hole U1322A can be found in “Downhole measurements.”

Hole U1322B

A summary of operations for Hole U1322B can be found in Table T3. The vessel was offset 6.2 nmi from Site U1324 on a heading of 079° and an average speed of 1.0 kt and arrived at the location of Site U1322 at 0915 h on 28 June 2005. After observing the seafloor with the VIT camera, Hole U1322B was spudded with the APC at 1145 h. The water depth calculated based on recovery of the first core was 1330.5 mbrf (PDR = 1336.4 mbrf). Piston coring advanced to 61.0 mbsf, when operations were interrupted because a control transformer in the variable field supply of the core winch failed. This required 3.75 h to troubleshoot and repair. Piston coring resumed at 2345 h on 28 June and continued to 0730 h on 30 June, when the total depth of 234.5 mbsf was reached. The average recovery for the hole was 101.0%. Cores were oriented starting with Core 4H. Fluorescent microspheres were deployed in the core catchers of Cores 1H–11H and then on every even-numbered core barrel. The Fugro cutting shoe was used on even-numbered barrels, except when the APC temperature (APCT) tool was deployed. The uppermost 10 cores and Core 15H fully stroked, and all the other cores partially stroked and were advanced by recovery. The nonmagnetic core barrel was used for all cores.

The T2P probe was deployed three times in this hole. The first measurement in the hole was made at 42.0 mbsf for 60 min following Core 5H. The second attempt was subsequent to Core 15H at 134.3 mbsf and lasted 30 min. On this occasion, the hole was displaced with 10.5 ppg mud. The last deployment lasted 60 min at 157.8 mbsf. This deployment was made after recovering Core 18H and with the hole displaced with 55 bbl of 10.5 ppg mud. The DVTPP was deployed once at 166.7 mbsf, following Core 19H. The hole was displaced with 55 bbl of 10.5 ppg mud prior to this 90 min DVTPP deployment. The bit was pulled free of Hole U1322B at 1010 h on 30 June.

Hole U1322C

A summary of operations for Hole U1322C can be found in Table T4. Hole U1322C was dedicated to temperature and pressure measurements. Mechanical and electronic problems with the probes during earlier deployments compromised many measurements, and further deployments were required to complete the data set and resolve reliability issues. Following a DP offset 20 m west of Hole U1322A, the VIT camera was deployed. Visual examination of the seafloor confirmed a clear area under the bit. Hole U1322C was spudded with the APC at 1125 h on 30 June 2005. The recovery of the first and only core in this hole established the seafloor depth at 1330.0 mbsf. The hole was then drilled in six intervals to a final depth of 231.5 mbsf. The T2P probe was deployed at 50, 75, 150, and 200 mbsf. On each occasion the probe stayed at the bottom of the hole for 60 min without rotation or circulation. After the first measurement, the hole was stabilized by displacing it with 10.5 ppg mud. The DVTPP was deployed at 100 mbsf (90 min), 220 mbsf (60 min), and 238 mbsf (90 min). Additionally, the hole was displaced with heavy mud prior to each deployment with no circulation or rotation of the drill bit. The hole was displaced with an additional 75 bbl of 10.5 ppg mud prior to abandonment. The bit cleared the seafloor at 1824 h on 1 July and was observed with the VIT camera to ensure that no flow was visible.

While operating in Hole U1322C, the work boat Emily G made the third and final visit to the JOIDES Resolution. The Emily G was on our location and standing by at 0400 h on 30 June. She came alongside and was secured to the port side by 0555 h and offloaded to our vessel catering supplies and freight originally destined for Panama. We also loaded 35.5 short tons (710 sacks) of Florigel (Attupulgite) from the Emily G. The work boat departed for Port Fourchon, Louisiana, at 0930 h, transporting the Mud Engineer George Stokes and two other personnel (Integrated Ocean Drilling Program [IODP] Marine Laboratory Specialist Karen Johnson and Transocean DP Operator John Powell) to shore.

For various technical reasons, many deployments of the probes in Hole U1322C did not yield accurate results, with the exception of the DVTPP deployment at 236 mbsf and a T2P deployment at 150 mbsf. Based on these results (or lack thereof), we decided to spend the remaining 36 h of operation time drilling an additional hole devoted to pressure and temperature measurements at Site U1322. This decision was also motivated by the fact that our revised authorized depth of penetration at Site U1323 (174 mbsf) meant that the interval of major scientific interest could not be penetrated. The purpose of Hole U1322D was to deploy the pressure and temperature probes and spot core after each deployment.

Hole U1322D

A summary of operations for Hole U1322D can be found in Table T5. The vessel was offset 20 m north of Hole U1322A, where Hole U1322D was spudded with the APC at 1925 h on 1 July 2005. This followed a seafloor survey with the VIT camera. The first core established the seafloor depth at 1330.0 mbrf. The hole was drilled and cored in five steps to a total depth of 175.0 mbsf. Three piston cores were obtained from the seafloor to 9.5, 70.0–79.5, and 100.0–107.8 mbsf. The average recovery of the cored interval of 26.8 m was 101.5%. The T2P probe was deployed four times: at 40.0 mbsf (60 min), 70.0 mbsf (45 min), 100 mbsf (45 min), and 134 mbsf (45 min). The DVTPP was deployed at 175.0 mbsf for 60 min. With the exception of the first T2P run, the holes were displaced with heavy mud prior to deployment and all downhole measurements were attempted with no circulation or rotation.

All operations concluded by 1600 h on 2 July to allow sufficient time to recover the drill string, beacons, and disassemble and store the bottom-hole assembly (BHA) components. The VIT camera was deployed prior to withdrawal of the drill string from the hole, and a short inspection of the top of Hole U1322D confirmed the absence of flow. After the drilling equipment was secured, the vessel began the voyage to Panama at 0030 h on 3 July.

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