TRANSIT TO SITE 1118 (ACE-1C)

During the ~11.5 nmi transit from Site 1117, an RCB BHA with drilling jars and a MBR was put together and run down to the seafloor.

After the positioning beacon was deployed (1830 hr on 28 July), Hole 1118 was spudded at 2030 hr on 28 July. A seafloor depth of 2303.6 mbsl was determined by reduction in drill string weight. This was 3.0 m shallower than the 3.5-kHz PDR depth. With a center bit in place, we drilled without coring to 205.0 mbsf with an average ROP of 51.3 m/hr.

Once the center bit was retrieved and the hole circulated with a 20-bbl gel mud sweep, RCB coring began at 0330 hr on 29 July. Cores 1R-73R were taken from 205.0 to 897.5 mbsf. When the driller raised the bit off bottom to recover Core 73R, he observed 30,000 lb overpull, high torque, high pump pressure, and 3.0 m of fill in the bottom of the hole. Core 74R also had similar overpull and fill. Coring was stopped after reaching 926.6 mbsf (Core 76R) to allow enough time for a wiper trip, hole conditioning, and a full wireline logging program. Overall ROP for the cored portion of the hole was 15.3 m/hr. Total recovery for the hole was 466.21 m (65%).

After circulating the hole clean with a 40-bbl pill of bentonite gel mud, a wiper trip was conducted up to 98.6 mbsf. When the bit was lowered back down, 36.0 m of fill was encountered in the bottom of the hole. We decided not to take the time to clean out the fill and released the bit at 892.6 mbsf. In preparation for logging, the hole was displaced with 300 bbl of sepiolite mud and the drill string raised up to 98.6 mbsf. Overpulls of 20,000–30,000 lb were required to pull the pipe from 491.6 to 434.6 mbsf; therefore, an additional 20-bbl pill of 10.5 ppg mud was spotted in the pipe before continuing up to logging depth.

We began rigging up for logging at 1030 hr on 3 August 1998. The first logging was with the triple combo tool and was able to reach 887.6 mbsf, which was 5.0 m above where the bit was released. The loggers requested that the pipe be raised 20 m to log more of the shallow section, but this was rejected because the pipe was experiencing up to 30,000 lb overpull. A second pass was made with the triple combo to get more detailed temperature data, and the tool was stopped for 10 min each at 410.0 mbsf, 620.0 mbsf, and 830.0 mbsf.

After the triple combo run was finished, the FMS-sonic tool string was run and also reached 887.6 mbsf. The lowermost 50.0 m of the hole was logged twice, and the logs were collected up to the pipe depth (98.6 mbsf). Caliper data from the FMS tool indicated some tight spots (4–5 in diameter) down as far as 298.6 mbsf. During the FMS-sonic run, the drill string began taking weight (10–20,000 lb) and overpull of 10–20,000 lb. After the FMS-sonic run was finished and it was in the pipe being retrieved, the pipe was raised slightly but could only be lowered back down to within 6 in of the dual-elevator stool, even with slow circulation (higher circulation could not be used with the logging tool inside the drill pipe). We decided to pull back up about 1.0 m with the pipe hung off the elevator bales and retrieve the FMS-sonic tool string by pulling it through the blocks. Once the tools were laid down, the top drive was picked up and the pipe lowered back down to 309.6 mbsf; however, no resistance was encountered and the pipe was pulled back to 107.6 mbsf in preparation for the VSP logging with the WST. The WST was run in the hole but could not pass 691.6 mbsf (due to its light weight). A total of 20 stations occupied between 691.6 and 107.6 mbsf. The WST was retrieved and logging was completed at 1845 hr on 4 August.

While we were logging, PNG customs and immigration officials came aboard to clear the ship and personnel out of PNG territorial waters. One of the two PNG observers departed the ship on the helicopter with the PNG officials.

The drill string was lowered to 395.6 mbsf and the hole was displaced with 144 bbl of 10.5 ppg mud. After the drill pipe was retrieved and the BHA taken apart and secured, the positioning beacon was recovered at 0337 hr on 5 August. At 0430 hr on 5 August the vessel began the transit to Sydney, Australia.

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