IODP Proceedings    Volume contents     Search
iodp logo

doi:10.2204/iodp.proc.308.103.2006

Operations

Site U1319

The summary of operations at Site U1319 can be found in Tables T2 and T3. The vessel arrived at Site U1319 in the early afternoon of 6 June 2005 and deployed a beacon at 1350 h. The APC/XCB bottom-hole assembly (BHA) was made of a 9⅞ inch polycrystalline diamond (PDC) bit, bit sub, seal bore drill collar, landing sub, top sub, head sub, nonmagnetic drill collar, four controlled-length drill collars, a tapered drill collar, two stands of 5½ inch drill pipe, and a crossover sub (total length = 127.1 m). The usual routine of measuring and rabbiting the tubulars was carried out, and the bit was suspended at a depth of 1393 meters below rig floor (mbrf) by 1945 h. Preparations were then made for a test deployment of the T2P via the coring line colleted delivery system (CDS). Pressure and temperature were measured continuously as the tool was deployed from the surface to the bit, which was suspended ~40 m above the mudline. The core winch operator made planned 2 min stops at 500 and 1000 mbrf for pressure calibration. The probe remained in the bit for 5 min.

After the T2P was recovered, the bit was lowered and tagged the seafloor at 1439.0 mbrf, as observed using the underwater vibration-isolated television (VIT) camera that was deployed to ensure that there were no obstructions, pipeline, or cables on the seafloor prior to spudding. The drill picked up 5 m from seafloor tagging depth in preparation for spudding the hole. At this point, electrical control problems associated with the mud pumps delayed operations for 45 min while the problem was resolved.

Hole U1319A

Hole U1319A was spudded at 0130 h on 7 June 2005. Recovery in the first core established the seafloor depth at 1440.0 mbrf or 6.4 m shallower than the corrected precision depth recorder (PDR) depth. Piston coring advanced to 80.5 mbsf, when coring was halted for a second deployment of the T2P probe. The T2P was deployed in the hole for the first time at a depth of 80.5 mbsf for 30 min. Because the formation was stiffer than anticipated, the tip of the probe bent and the data quality was questionable.

After the probe was recovered, piston coring resumed to a depth of 114.6 mbsf (Core 13H). After the last four cores partially stroked and were advanced by recovery, coring continued with the XCB. The APC cored 114.6 m with a biogenic gas–augmented average recovery of 104.3%. The cores were oriented starting with Core 4H, and one APCT measurement was attempted at 42.5 mbsf (Core 5H). Fluorescent microspheres were deployed in the core catchers of Cores 1H–10H and 12H. All piston coring was conducted with nonmagnetic APC hardware.

The hole was then deepened to 157.5 mbsf with the XCB, where coring terminated short of the original depth objective of 230 mbsf because all scientific objectives for the site were fulfilled. The XCB system cored 42.9 m with an average recovery of 83.5%. The total cored interval was 157.5 m with a recovery of 155.29 m (average recovery = 98.6%). The bit was pulled clear of the hole at 2120 h on 7 June and raised to 240 m above the seafloor.

Hole U1319B

Hole U1319B was positioned 20 m north of Hole U1319A. A beacon was dropped on site at 0005 h on 12 June 2005, and the hole was spudded at 0915 h on 12 June as the driller observed the bit contacting the seafloor at a depth of 1447.0 mbrf. MWD drilling advanced without incident to the depth objective of 180.0 mbsf at an average rate of penetration of 30.0 m/h by 2100 h on 13 June. After the bit cleared the seafloor at 2200 h, preparations were made to begin the short offset to an approved alternate site.