Leg 194 began with an early port call in Townsville, Australia, at 2200 hr on 4 January 2001. At 0700 hr on 8 January, 3 days ahead of schedule, the vessel began the transit to Site 1192 (proposed Site CS-13A). The 399-nmi voyage was accomplished at an average speed of 12.0 kt. A beacon was dropped at 1720 hr on 9 January 2001. The precision depth recorder depth referenced to the dual elevator stool (DES) indicated a water depth of 390.4 m.
During the initial fit testing of the HYACE tools in the BHA, it was discovered that the outside diameter of the top 1 m of the H-PCS tool was several thousandths of an in too large to pass through the latch sleeve. It was assumed that this would not cause problems because pump pressure and flow rate between the landing sleeve and the H-PCS would generate sufficient resistance to offset the rotation and torque caused by the rotation of the small bit. Consequently, the latch sleeve was left out of the BHA.
Hole 1192A was spudded with the APC at 0205 hr on 10 January and established the seafloor depth at 385.0 m relative to the top of the DES on the rig floor (water depth of 374.4 m). The HF-VS was deployed three times, and the H-PCS was run twice in this hole. During the H-PCS tests, the LDEO drill string accelerometer was also deployed and provided downhole pressure and accelerations that will be used in a post deployment analysis of the instrument.
The first HF-VS run, designated as Core 4M, cored the interval from 28.5 to 29.5 meters below seafloor (mbsf) (Tables T1, T2). The internal shear pin parted as designed at 525 psi. As the pump pressure was decreased to 250 psi to start the hammer, no clear indication was obtained that the hammer was active, which could be attributed to the soft formation. The tool recovered only 0.19 m (19% of the cored interval). After retrieval, it was noted that the flapper was not completely closed, which prevented recovery of a sample at in situ formation pressure. The Fugro engineers concluded that the speed of bit retraction may have been too fast to allow establishment of a seal.
Piston coring resumed and advanced to 86.5 mbsf, where the HF-VS was deployed a second time (Core 11M; 86.5 to 87.5 mbsf). This time, the HF-VS tool was landed before the bit was placed on bottom. The shear pin parted at 525 psi. The pump pressure was decreased to 250 psi to activate the hammer, which appeared to operate for ~20 s. The bit was lifted off bottom very slowly for the first 3 m before the tool was carefully retrieved by wireline. The tool momentarily stuck in the pipe at 5 m above the landing seat, but came free after several strong pulls on the wireline with tension as high as 9000 lb. After retrieval, the tool was placed horizontally on the pipe racker platform, and it was confirmed that the flapper had closed. The autoclave section was disassembled, and a pressure gauge was connected to the autoclave. The gauge indicated an in situ pressure of 42 bar (609 psi) that roughly corresponded to the expected pressure at 473 m (total drill string length at 87.5 mbsf). The pressure was bled off, and the 0.91-m-long sample (97% recovery) was removed.
Piston coring again resumed to a depth of 192.0 mbsf. The third HF-VS (Core 23M) cored the interval from 192.0 to 193.0 mbsf. The tool was deployed as in the second run. After the shear pin did not appear to part at 600 psi or at the increased pressure of 800 psi, pressure was decreased to 250 psi to see if the hammer would start. Hammering was detected for a few seconds after which the tool was retracted with minimum speed. Once again, the tool became stuck in the drill string during the extraction process but was pulled free by the wireline. When the tool was recovered, it was observed that the latching pawls were jammed, which prevented full retraction of the liner into the inner barrel. In addition, the flapper did not close. The barrel was full, but only 0.77 m (77%) of the sample was recovered because of the difficulties with the polyvinyl chloride liner.
Once again, piston coring resumed and advanced to 231.0 mbsf, where coring was stopped for the initial test of the rotary pressure core sampling test with the H-PCS tool. This tool is designed to operate in more indurated sediments than the HF-VS tool. The first run of the H-PCS (Core 28M) attempted to core the interval from 231.0 to 232.0 mbsf. During this deployment, the expected pressure peaked at ~650 psi, indicating that activation of the positive displacement motor was not observed and that there was not any indication of the end of stroke. After the instrument was recovered, the inner barrel was still retracted in the autoclave and the flapper valve was not properly seated. It is possible that the lack of a latch sleeve in the BHA allowed the upper part of the tool to rotate instead of the lower section.
Piston coring resumed with Core 29H and advanced from 232.0 to 241.5 m. The core barrel had to be drilled over and extracted from the formation with 80 klb of overpull. This interval was considered to be the piston coring refusal depth.
The H-PCS was deployed for the second time (Core 30M) in an attempt to core the interval from 241.5 to 242.5 mbsf. No core was recovered in this attempt. Prior to deployment, the tool was marked with paint on the upper and lower sections in order to ascertain if there was slippage and if the tool was properly seated. After deployment, the marking was reviewed. Abrasions of the paint suggested that the upper section had rotated and that the bottom section had not seated properly. It was decided to recover the drill string and add the latch sleeve. The rig mechanic machined the top 1 m of the tool containing the upper latch body, upper sub, and latch dogs to the same diameter as the tool body.
Twenty-five APC cores were retrieved from Hole 1192A. The cored interval was 237.5 m with 241.59 m recovered (101.7% average recovery). The cores were oriented, starting with Core 3H. The drill string was recovered, and the bit was at the rotary table at 0855 hr.
After the latch sleeve was installed in the BHA and the H-PCS tool was modified, the drill string was deployed again with the vessel offset 10 m from the previous hole. Hole 1192B was spudded at 1145 hr on 11 January. Following a single mudline core that established the seafloor depth at 387.1 m (water depth of 376.5 m), the hole was drilled ahead to 179.9 mbsf (Table T1).
The fourth deployment of the HF-VS (Core 1M) cored the interval from 179.9 to 180.9 mbsf. The results of this test were similar to the Core 23M experiment. There was no positive indication of the parting of the shear pin at 600 psi. The pressure was increased to 800 psi with still no indication of release. The pressure was decreased to 250 psi to see if the hammer would start. Hammering was detected for a few seconds. The tool was retracted with minimum speed. When the tool was recovered, it was observed that the latching pawls were jammed, which prevented full retraction of the liner into the inner barrel. The flapper was not closed. The barrel recovered 0.84 m of sediment (84% recovery).
Immediately following this last HF-VS deployment, the H-PCS tool was run for the third time (Core 2M), attempting to core the interval from 180.9 to 180.9 mbsf. This time, the tool inner barrel did stroke out and rotate, but no sediment sample was obtained.
Coring resumed with hopes of finding more indurated sediment before time on site expired. APC coring advanced to 229.4 mbsf, and XCB boring deepened the hole to 335.2 mbsf. Coring operations were delayed during the retrieval of Cores 18X and 19X (316.0 to 335.2 mbsf) when the core barrels had to be "fished" with the wireline.
The fourth run of the H-PCS, Core 3M, attempted to core the interval from 335.2 to 336.2 mbsf. The tool inner barrel stroked out, rotated, and recovered ~0.27 m of sediment. The formation was too soft for the type of core catcher available, and it was believed that some sediment was lost in the recovery process. The retraction mechanism was not released, so the core was not under pressure.
This run concluded the downhole experiments that preceded the Leg 194 science program as nearly all of the 72 hr allocated for the tests had expired. While the tool was cleaned and dressed, an additional two XCB cores were obtained. In total, six APC cores were retrieved with 43.6 m recovery (87.3%), and 13 XCB cores were retrieved with 60.43 m recovery (48.3%), for a total depth of 355.5 mbsf. Total recovery in Hole 1192B, including test cores, was 105.1 m, representing 59.1% of the cored interval. In addition, a 177.5-m interval was drilled without coring.
Operations at Site 1192 ended at 1440 hr on 12 January, and the vessel proceeded to the first high-priority site of the Leg 194 science program.