SITE 1050
(Proposed Site BN-2Alt)

Hole 1050C
After the 16.5-nmi transit to return to Site 1050, we deployed a beacon at 1930 hr on 8 February. We wanted to reoccupy Site 1050 to core the deep objectives that were not attained earlier in the leg at Hole 1050A because the XCB coring system could not penetrate to the desired depth of at least 500 mbsf. We decided to use the RCB coring system to core deeper than Hole 1050A penetrated until operational time remaining for the leg expired.

Hole 1050C was spudded at 0045 hr on 9 February at a depth of 2308.0 m. We used an RCB BHA with a mechanical bit release and new bit (RBI C-3). We drilled without coring to 317.5 mbsf and then started RCB coring at 1545 hr on 9 February. Rotary coring advanced without incident to a depth of 606.0 mbsf, coring 288.5 m and recovering 200.19 m of core (69.4%). Operations were terminated at 2130 hr on 11 February after operational time for this leg expired. The average rate of penetration for the cored segment of this hole was 11.2 m/hr.

After a 20 bbl high viscosity mud flush was circulated, a wiper trip (105-606 mbsf) was conducted to prepare the hole for logging. The region from 586 to 606 mbsf had to be washed and reamed. The bit was then released at the bottom of the hole with the wireline and the hole displaced with 155 bbls of sepiolite mud. The end of the drill string was pulled up to the logging depth of 105 mbsf.

At 0245 hr on 12 February, the Schlumberger equipment was rigged up and the first logging tool (Triple Combo, DITE-HLD-APS-HNGS) was run in the hole. All data collected was of high quality. No problems were experienced during the run. The hole appeared to be in very good condition with an average diameter of 10 in. By 0900 hr on 21 February, the Triple Combo was retrieved, rigged down, and the second log prepared.

At 0910 hr, the second logging string (FMS/SDT(Array)/NGT) was run in the hole. All data collected were of high quality. No problems were experienced on the run with the exception of some noise on the analog sonic curves; however, the digital data appear to be good. FMS calipers indicated that the hole was slightly oval and washed out to 14 in near just below the bottom of the drill pipe. Maximum hole deviation was 1.5°. Two full passes were planned, but the second logging pass was canceled. When the tool reached the oval sections approaching drill pipe, it became apparent that the "track" in the borehole left behind by the caliper of the tool used on the first logging run could be seen in the image of the second run, so the second pass was shortened.

At 1500 hr, the second log was rigged down and the third and final logging suite made up. At 1515 hr, the third log, magnetic susceptibility (GHMT/NGT), was run in the hole. All data collected were of high quality. All three logging tools reached the bottom of the hole. Only the upper 40 m of the hole (105 to 145 mbsf) suffered significant washout. The hole was successfully logged between 103 and 606 mbsf. Sea conditions were mild with less than 1.5-m swells.

After the logging equipment was rigged down, the hole was displaced with 35 bbls of 10.5 ppg mud. The pipe was pulled out of the hole and the BHA was disassembled into individual drill collars and laid down. The main and a backup beacon were retrieved and the drilling equipment secured by 0600 hr on 13 February.

Transit from Hole 1050C to Charleston, South Carolina
After the drilling equipment was secured and the coring winch prepared for repair during port call, we began the transit to Charleston, South Carolina, at 0600 hr on 13 February. We arrived at the pilot station at 0530 and sailed the last 15 nmi in heavy fog. The first line was ashore at 0830 hr on 14 February.

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