Site 1144 (Proposed Site SCS-1)

The beacon was dropped on GPS coordinates for proposed site SCS-1 at 1745 hr on 13 March. The corrected PDR depth referenced to the DES was 2051.4 m.

Hole 1144A

Hole 1144A was spudded with the APC at 2245 hr on 13 March. The seafloor depth was inferred to be 2047.0 m from the recovery of the first core. Piston coring advanced to 234.9 mbsf with an excellent average recovery of 104.4%. The high recovery percentage was in part a result of the gas expansion of many of the cores. APC refusal was encountered when the core barrel for Core 25H could not be pulled free of the sediment with an overpull of 120,000 lb. The core barrel had to be drilled over to free it from the sediment. The cores were oriented starting with Core 3H. During piston coring, heat-flow measurements were obtained at 26, 64, 102, and 149 mbsf. A low temperature gradient of 24°C/km was calculated from these data. The hole was deepened with the XCB to the target depth of 452.6 mbsf. The XCB average recovery was 102.6%; the average recovery for this hole was an exceptional 103.6%. Only moderate amounts of biogenic methane were measured in the cores.

After the hole was flushed with a 30-bbl mud treatment, the bore was displaced with an additional 115 bbl of sepiolite. During the pipe trip to the logging depth of 87 mbsf, the driller did not observe any increased weight resulting from restriction in the size of the hole. Logging began at 1200 hr on 15 March. Three successful wireline logging runs were completed with all three tool suites (triple combo, FMS-sonic, and GHMT) covering the open hole from 452 to 87 mbsf. Hole conditions, were good with some washouts detected in the lower portion. No problems with the swelling clays were encountered at Site 1144. At 0615 hr on 16 March, the logging equipment was disassembled and the drill string pulled back. The bit cleared the seafloor at 0655 hr on 16 March.

Hole 1144B

The vessel was offset 20 m east of Hole 1144A. Hole 1144B was spudded with the APC at 0800 hr on 16 March. The seafloor depth inferred from recovery was 2049.8 m. Piston coring advanced to 199.6 mbsf with an average recovery of 98.3%. The cores were oriented starting with Core 3H. Time saved at the previous hole and wireline logging permitted us to deepen Hole 1144B with the XCB to provide a stratigraphic overlap with Hole 1144A. The hole was deepened to 452.0 mbsf by 1930 hr on 17 March. Once again, the XCB did well with an average recovery of 100.0%. The recovery for the entire hole was 98.6%. After the hole was abandoned with 30 bbl of heavy mud, the bit was pulled clear of the seafloor at 2115 hr on 17 March.

Hole 1144C

Hole 1144C was spudded with the APC at 2230 hr on 17 March and advanced to a depth of 198.7 mbsf, which was considered the target depth for this hole. The average recovery for the hole was 99.9%; all cores were oriented starting with Core 3H. The interval from 37.2 to 42.2 mbsf was washed ahead without coring to obtain a proper stratigraphic overlap with Hole 1144B.

The total recovery for Site 1144 was 1113.3 m, 100.9% of the cored interval. After the bit cleared the seafloor at 1245 hr on 18 March, the drilling crew temporarily interrupted the pipe trip to perform the routine maintenance of slipping and cutting 115 ft of drilling line. The bit was at the rotary table by 1630 hr. Both primary and backup beacons were recovered. The drilling equipment, hydrophones, and thrusters were secured for the short voyage to the next site. The vessel was under way at 1645 hr on 18 March.

Operations-Site 1145

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