Because we had left a positioning beacon at Site 1108, we traveled to that site during the transit from Site 1109 to Site 1110 (ACE-10A). Once arriving at Site 1108 we signaled the beacon to release and lowered the thrusters. The beacon was successfully recovered at 0245 hr on 4 July 1998. While the ship moved the final 3.3 nmi (6.1 km) to Site 1110 in dynamic positioning mode, we assembled the advanced hydraulic piston corer/extended core barrel (APC/XCB) coring assembly and began to run the assembly in the hole.
At 0600 hr on 4 July 1998 the positioning beacon for Site 1110 was deployed. The pipe was lowered the remaining distance to the seafloor, and Hole 1110A was spudded at 0945 hr. Core 1H was taken with the bit at 3243.9 meters below sea level (mbsl) and recovered 7.03 m; therefore, the seafloor was calculated to be at 3246.4 mbsl (Tables T1, T2). Core 2H failed to fully stroke and recovered 2.5 m of sand and gravel. We terminated this hole at a total depth of 9.5 mbsf, and Hole 1110A ended at 1100 hr when the pipe was pulled clear of the mudline.
Without offsetting the ship, we spudded Hole 1110B at 1130 hr on 4 July 1998. Core 1H was taken with the bit at 3241.9 mbsl and recovered 5.08 m; therefore, the seafloor was calculated to be at 3246.3 mbsl. We then switched to XCB coring. Core 3X took ~2.5 hr to cut and was recovered with the soft formation XCB cutting structure destroyed. High and erratic torque, slow rate of penetration (ROP), and very low recovery were enough to convince us that the XCB system was not well suited to the formation. Coring was terminated at a total depth of 22.3 mbsf, the drill string was recovered, and Hole 1110B was ended at 2330 hr on 4 July when the bit cleared the rig floor.
After assembling a rotary core barrel (RCB) bottom-hole assembly (BHA), we tripped the pipe back to the seafloor. The ship was offset 30 m on a course of 280º, and we spudded Hole 1110C at 0545 hr on 5 July 1998. A seafloor depth of 3245.8 mbsl was determined by tagging the seafloor with the drilling assembly. Repeated attempts were made to drill ahead with a center bit in place. After 7 hr of high torque, packing off, overpull, fill, and extremely slow penetration, it became painfully clear that a satisfactory hole was not going to be possible at this location. The hole was terminated after penetrating a mere 15.0 meters below seafloor (mbsf) without even one attempt to cut a core. Hole 1110C ended at 1300 hr on 5 July when the bit cleared the mudline.
The center bit was recovered, and a core barrel was deployed. The ship was offset 30 m north and 30 m east prior to spudding Hole 1110D at 1430 hr on 5 July 1998. The seafloor was tagged at 3245.8 mbsl, and drilling (without coring) proceeded to a depth of 22.7 mbsf. A single core was cut to a depth of 28.7 mbsf before this hole was abandoned for the same reason as Hole 1110C. High torque, packing off, overpull, and generally poor hole conditions prevailed once again. The drill pipe was pulled clear of the seafloor at 1845 hr, officially ending Hole 1110D, and the core barrel was retrieved while we waited for the released positioning beacon to surface. Recovery for the 6.0-m interval cored was 0.16 m, or 2.7%.
The positioning beacon was recovered aboard at 1945 hr and with the drill bit positioned three stands above the seafloor we moved the ship ~1 km north to Site 1111 (ACE-11A). A positioning beacon was deployed at 2030 hr on 5 July 1998 at the Site 1111 Global Positioning System (GPS) coordinates.
The drill string was tripped the remaining distance to the seafloor, and at 2230 hr on 5 July 1998 we spudded Hole 1111A (Table T3). The seafloor was determined to be at 3200.8 mbsl. The RCB coring continued through Core 18R to 173.7 mbsf. Drilling rates in the upper part of the hole were 5-10 min per core and recovery, with the exception of two isolated cores at 43%, was very low (1%-7%). A single temperature measurement was taken at 94 mbsf inside the drill pipe using the Davis-Villinger Temperature Probe (DVTP). Two additional measurements were taken using the DVTP with the probe pushed into the formation at 117.2 and 136.5 mbsf. A slow ROP (6.0 m/hr) and concerns over the potential for future instability of the hole led us to abandon the hole at 173.7 mbsf. The hole was displaced with 30 bbl of weighted mud, and the drill string was pulled clear of the mudline at 0335 hr on 7 July 1998. The beacon was released and the pipe trip continued to a depth of 2941 mbsl, where it was secured for the transit to the next site. The beacon was recovered at 0430 hr, ending Hole 1111A. Recovery for the hole was 15.19 m (8.7%).
The ~2.6-nmi transit to Site 1112 (ACE-12A) took 3 hr, and the positioning beacon was deployed at 0730 hr on 7 July 1998.
After picking up the top drive we advanced the pipe the remaining distance to the seafloor. Hole 1112A was spudded at 0900 hr, and the seafloor depth was established to be 3046.7 mbsl (Table T4). The RCB coring continued through Core 11R to a depth of 101.8 mbsf. Although recovery was poor, the hole stability remained reasonably good until this point. At 0745 hr on 8 July, the hole packed off, preventing circulation, and the driller experienced high torque on the pipe. The pipe was pulled up to 39.0 mbsf and then reamed back to bottom. This wiper trip took ~1.25 hr and encountered 5.0 m of fill in the bottom of the hole. After the fill was washed out, the hole was advanced two more cores to 116.4 mbsf. The bit was encountering resistance at 105.0 mbsf; therefore, the pipe was pulled back up to 96.0 mbsf and then reamed back to 116.4 mbsf. At this point we swept the hole with a double sepiolite mud pill (total of 50 bbl) and circulated it out of the hole before recovering the wash barrel. Once again the bit began to take weight at 105.0 mbsf, and 2 hr more were spent pulling the pipe back to 96.0 mbsf then reaming back to 105.0 mbsf, where we circulated another 30-bbl sepiolite mud pill. Because there appeared to be a bad spot in the hole at 105 mbsf, we decided to pull the drill string back up the hole and change the spacing out of the drill string using a 20-ft knobby drilling joint. This was intended to enable us to drill past the trouble spot and make a connection without having to pull the pipe back above the bad spot. The hole packed off again during this process, and we ultimately had to pull the pipe to 77.0 mbsf before circulation could be restored. The bit was reamed down again and reached 116.4 mbsf after 7.0 m of fill was washed out. Another 30-bbl sepiolite mud pill was circulated, and we resumed coring with Core 14R. The hole was advanced to 122.4 mbsf where high pump pressure and top-drive stalling occurred with as little as 10,000 lb weight on bit (WOB). At this point, we decided that this hole was not salvageable; therefore, Core 14R was retrieved and we pulled out of the hole. Because this hole was never advanced beyond the unconsolidated "talus" material it was abandoned using no heavy mud or cement. The seafloor was cleared at 2330 hr on 8 July 1998, and the bit cleared the rig floor at 0430 hr on 9 July, officially ending Hole 1112A. Recovery for the hole was 5.85 m (4.8%).
After the RCB core bit was replaced with a new C-4 bit, the pipe was lowered back to the seafloor and a brief jet-in test was conducted in case a reentry cone was ultimately required at this site. The bit was advanced to a depth of 20 mbsf in ~50 min using up to 100 strokes per minute (spm). The pipe was pulled clear of the mudline in preparation for spudding Hole 1112B.
Hole 1112B was spudded at 1130 hr on 9 July 1998, and the seafloor was determined to be at 3046.7 mbsl. The hole was drilled to 87.0 mbsf with a wash barrel (Core 1W) in place; however, at that depth the driller experienced high torque on the pipe and up to 30,000 lb of overpull. After we worked on the pipe for 30 min, the hole appeared to be cleaned up and Core 1W was retrieved. We then continued drilling with a second wash barrel (Core 2W) to 126.1 mbsf. After Core 2W was recovered, we deployed a bit deplugger to ensure that the throat of the bit was unobstructed before initiating RCB coring. Cores 3R through 5R were then taken from 126.1 to 155.0 mbsf.
After the recovery of Core 5R, the hole again packed off and the top drive began to stall. The pipe was worked up and down the hole for the next 8.25 hr with overpulls of 20,000-40,000 lb. Several 30- to 50-bbl sepiolite pills were circulated and the bit was eventually able to reach back to bottom after 6 m of fill on the bottom was drilled out. Core 6R was then cut to 164.0 mbsf. Once again, the hole packed off and another 5.25 hr was spent fighting hole problems before we abandoned further attempts to deepen the hole. The pipe was pulled clear of the seafloor at 1400 hr on 11 July, ending Hole 1112B. Recovery for the hole was 1.19 m (3.1%).
After raising the drill pipe to 2745 mbsl and recovering the positioning beacon, we began the DP transit to Site 1113 (ACE-13A). The positioning beacon was deployed at the GPS Site 1113 coordinates at 1645 hr on 11 July.
The vessel was positioned over the site as the drill pipe was lowered back to the seafloor. The top drive was picked up, and Hole 1113A was spudded at 2045 hr on 11 July 1998 (Table T5). The seafloor was tagged at a depth of 2915.6 mbsl, and we cut RCB Cores 1R and 2R to 20.2 mbsf. After making the drill pipe connection, but before cutting the next core, we found that 7 m of sediment had filled the bottom of the hole. The fill was washed out, and Core 3R was cut to 25.2 mbsf. We decided to terminate the hole because of the extremely slow ROP (0.8 m/hr) and poor hole conditions at such shallow subseafloor depths. The pipe was pulled clear of the seafloor at 1345 hr on 12 July, and the bit cleared the rig floor ending Hole 1113A at 2000 hr. Recovery for the hole was 0.44 m (1.7%).