SITE 1166Hole 1166A
The reentry showed that the seafloor was 6.7 m higher than identified by the driller's blind tag with the bit at the start of the hole. Observations with the television camera showed a seafloor depth of 480.0 m. Continuous RCB coring resumed and continued to a depth of 381.3 mbsf. Overall recovery for the hole was 18.6%.
In preparation for logging the bit was released, the hole was displaced with sepiolite logging mud, and the drill string was tripped to the logging depth of 41.2 mbsf. The hole was logged with a full suite of sensors (seismostratigraphic suite, lithoporosity suite, FMS suite, and the geological high-sensitivity magnetic tool) from 41.2 to 377.3 mbsf. All logging runs were successful. By 0745 hr on 21 February, the logging sheaves had been rigged down and the wireline logging program was completed.
The hole was abandoned with a 21.5-bbl plug of cement, and the drill pipe was pulled clear of the seafloor and tripped back to the ship. At 1600 hr on 21 February, the rotary table was clear, ending Hole 1166A.
Hole 1166B was planned as a test of the measurement- and logging-while-drilling (M/LWD) tools. This included the transmission of data in real time by using a downhole turbine-driven mud pulsing unit.
The drill string was tripped to bottom, and Hole 1166B was spudded at 0020 hr on 22 February. The seafloor depth was determined to be 480.0 mbsf, and the first hard layer was contacted at 485 mbsf. Drilling proceeded very slowly for the first 25 m. Very little weight could be put on the drill string until at least the M/LWD tools were buried beneath the seafloor. The hole was terminated at a depth of 42.5 m because the objectives of the test had been met and the ability to pulse back data in real time was confirmed.
The hole was displaced with heavy mud, and the drill pipe was pulled clear of the seafloor by 1020 hr. The beacon was released and recovered aboard at 1050 hr. The pipe was back aboard ship and the M/LWD tools rigged down by 1330 hr on 22 February, and the JOIDES Resolution was under way for the final site of Leg 188.
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