The ship arrived in the survey area at 0630 hr on 1 November 1996. The course was changed to allow a survey across both Sites 1040 (CR-2) and 1039. Vessel speed was reduced and the seismic gear was deployed 45 min before reaching the desired survey point. Both 200 in3 and 80 in3 water guns were deployed, however, a hose failed on the 80 in3 gun 20 min into the survey. The technicians managed to repair the gun and get it back in the water before reaching Site 1039, but it was decided to continue using the 200 in3 gun for consistency. Once the survey was completed, the ship returned to Site 1039 and prepared for drilling operations. A positioning beacon was dropped at 0930 hr on 1 November 1996, initiating operations at Site 1039.
Due to the loss of the drill string at Leg 169, we used refurbished 5" drill pipe at Site 1038 and all new drill collars were picked up. In addition, a new seal bore drill collar for APC coring was picked up. All drill collars were rabbited and all reconditioned drill pipe was rabbited and strapped while running in the hole (RIH). When the drill collars were being made up, the iron roughneck developed a leak that necessitated using the rig tongs while it was repaired. One joint of reconditioned 5" drill pipe had to be set aside during the trip because the box tool joint was too short for make-up.
Hole 1039A was spudded at 0015 hr on 2 November 1996. The mudline core recovered 9.0 m, placing the drill pipe measured seafloor at 4362.5 m or 5.9 m above the corrected precision depth recorder (PDR) mudline depth of 4368.4 m. The plan was to only recover three piston cores from this hole. Coring was terminated after core 170-1039A-3H at a total depth of 28.0 mbsf. The drill string was pulled above the mudline and the vessel was immediately offset 10 m to the north in preparation for spudding Hole 1039B.
Hole 1039B was spudded at 0430 hr on 2 November. The first core recovered 2.02 m, established a seafloor depth of 4364.5 m or 3.9 m above the corrected PDR mudline for this site. APC coring continued with electronic core orientation (Tensor) beginning on Core 170-1039B-5H at a depth of 40.0 mbsf. Oriented APC coring was terminated with Core 170-1039B-11H at a depth of 97.0 mbsf after Cores 170-1039B-10H and 11H failed to fully stroke. A maximum overpull of 50 kips was experienced on Core 170-1039B-8H.
Coring continued using the XCB system to approximately 378 mbsf, where a drilling break was noted. The formation turned hard and drilling torque increased. Core 170-1039B-41X was pulled early after an 8.0 m advance. One meter of fill was detected on bottom prior to cutting Core 170 1039B-42X. The hole was advanced an additional 3.5 m to a total depth of 384.3 mbsf. Core 170 1039B-42X recovered gabbroic rock fragments.
Immediately after recovering the mudline core a Water Sampler Temperature and Pressure Probe (WSTP) was deployed with an Adara temperature measurement sub attached. The bit was positioned 10 m above the seafloor for taking a bottom-water sample and temperature reading. During recovery, the tool hung up at +45 m above the seafloor. The tool came free after jarring it. It is assumed an errant APC shear pin stub wedged the barrel. The bottom-water sample had a salinity of 31.5, indicating surface-water contamination caused by the circulation used to pump the tools to bottom. Additional bottom-water deployments were done without circulation by running the wireline winch at slower speeds.
After taking three more piston cores, another WSTP fluid sample was taken after Core 170 1039B-4H at a depth of 30.5 mbsf. Apparently the wrong sub was installed for this run and the tool only sampled drill pipe circulating fluid. Another WSTP fluid sample was attempted after Core 170-1039B-7H at a depth of 59.0 mbsf. This time the tool hung up at +1800 m below the ship during deployment. After 20 min of working the wireline jars, the overshot shear pin sheared and the barrel dropped to bottom. An attempt was made to collect data, but the temperature data indicated that the tool never penetrated the formation. It appears that the core line operator ran the tool in too fast, causing the barrel to float. When the line went slack on the XCB latch it allowed the latch dogs to come out enough to wedge the barrel. The WSTP system was not deployed for the remainder of the hole.
A total of 10 temperature measurements were taken, four with the Adara tool during APC coring and six with the DVTP during XCB coring. One Adara measurement was bad due to battery failure. One DVTP measurement was bad.
There were no significant hydrocarbon shows identified while drilling this hole. Methane ranged from 3 to 36 ppm and there was no ethane or propane identified with the exception of Core 170 1039B-10X at 84 mbsf where 110 ppm methane and 6 ppm ethane were recorded.
No mud sweeps were required during coring. Once coring had ceased, the hole was filled with 10.5 pound per gallon (lb/gal) mud and the drill string was tripped out of the hole. While pulling pipe, an overpull of 50 kips was taken at a depth of 4600 m. The drill string cleared the seafloor at 2400 hr, ending Hole 1039B.
Operations at Site 1040 (CR-2)
Before drilling deeper at Site 1039 using the RCB system, operations began at Site 1040 with the APC and XCB to save a pipe trip. See Site 1040 section for operations report.
The ship was moved 30 m south of Hole 1039A to spud Hole 1039C. An RCB bottom hole assembly (BHA) was made-up, and the RCB core barrel space-out was checked. The BHA was tripped in the hole and the top drive picked up placing the bit at a depth of 4313.0 m. The rig floor corrected PDR water-depth reading for this site was 4366.4 m. This was very close to the drill pipe measured depth of 4362.5 m for Hole 1039B. Due to the proximity of the two holes, the water depth for Hole 1039A was used for Hole 1039C.
After collecting a bottom-water fluid sample, a center bit was deployed, the pipe was tripped the remaining distance to bottom, and Hole 1039C was spudded at 0030 hr 9 November 1996. Drilling ahead with a center bit continued to a depth of 363.1 mbsf. A Sepiolite mud sweep was pumped at 344.0 mbsf to flush any remnant cuttings from the hole before RCB coring began with Core 170-1039C-1R. Coring continued through Core 170-1039C-7R where a gabbro intrusion was contacted at a drillers's depth of 4789.7 m (427.2 mbsf). This is ~46 m deeper than where gabbro was contacted at Hole 1039B. Coring continued through apparent sills and occasional thin (1.0 to 3.0 m thick) softer material, presumed to be sediments, with dramatically different drilling rates. However, no sediments were recovered from these intervals. Coring continued through Core 170-1039C-11R to a total depth of 4811.2 m (448.7 mbsf). Coring was terminated due to slow rate of penetration (0.5 to 1.0 m per hr) through the massive gabbroic units and an inability to recover the softer interlayered sediments.
No drilling mud was circulated during the coring operation. However, the hole was displaced with 10.5 lb/gal mud before pulling out. Overpulls of 20-30 kips were required while pulling out of the hole from 340.9 to 167.8 mbsf. The bit cleared the seafloor at 0115 hr, ending hole 1039C.
No temperature measurements were made in this hole and no WSTP fluid samples were taken except for a bottom-water sample collected prior to spudding the hole at approximately 50 m above the seabed. No significant hydrocarbon shows were identified while drilling this hole. Methane ranged from 3 to 4 ppm and neither ethane nor propane were identified.
Operations at Site 1040 (CR-2)
After completion of Hole 1039C, the ship returned to Site 1040 to drill the RCB Hole 1040C. During the transit back from Site 1039, the drill string was recovered and preparations for logging while-drilling were made.
The ship was already positioned on the drilling location for Hole 1039D before the drill string and BHA were fully recovered aboard ship. Hole 1039D was to be spudded 50 m south of Hole 1039A.
Prior to making up the LWD tools the drill line was slipped and cut. It required 2.5 hr to make-up the LWD tools (CDR and CDN), load the nuclear sources, and make-up the cross-over sub between the Schlumberger Anadrill LWD drill collars and the modified connection on the ODP 8 1/4" drill collars. The remaining BHA was then made up and tripped to the seafloor with the drill string.
LWD Hole 1039D was spudded at 2330 hr on 18 November 1996. Drilling proceeded slowly at first until the BHA was fully buried. Overall, the rate of penetration (ROP) averaged 23.3 m/hr, which was very close to the maximum desired rate of 25 m/hr. A 3.5-m-thick hard layer was contacted at a depth of 395.0 mbsf. A reduced ROP of ~2.5 m/hr continued until breaking out at a depth of 398.5 mbsf. The original drilling rate resumed until severe torquing began approximately 5 m later. The bit became stuck on bottom during drilling, which required 40 kips overpull to free it. The driller immediately pumped a 30 bbls Sepiolite mud sweep and pulled above the hard layer. We reamed back through this area without incident until the bit was again on bottom, where torque increased dramatically and the bit became stuck on bottom again. The bit was freed with 40 kips overpull and the decision was made to terminate the LWD hole at a depth of 4769.5 m or 407.0 mbsf. The stabilizer on the LWD tool was suspected of causing the problem as it entered the hard layer. We felt that continued reaming of the area coupled with the use of generous mud sweeps would probably have corrected the problem. However, the co-chiefs felt that the main objectives were achieved, and the decision was made to pull out of the hole. The hole was subsequently filled with 10.5 lb/gal mud and the drill string was pulled clear of the seafloor by 0100 hr on 20 November 1996. The pipe trip continued to the surface where the nuclear sources were removed, and the LWD collars were laid out. The positioning beacon for this site was released/recovered and the bit cleared the rotary table at 0915 hr ending Hole 1039D and operations at Site 1039.
To 170 Operations - Site 1040
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