Logging in Hole 1077A
Hole 1077A was logged with a limited suite of sensors to identify and locate the presence of gas hydrate in the sediments and to provide data for core-log integration. After a "go-devil" was pumped down the pipe to ensure the proper operation of the lockable float valve, the drill pipe was tripped to 63.5 mbsf, the top drive was picked up, and the bit was placed at 79.0 mbsf. The logging tool included the spectral gamma ray (NGT), long-spacing sonic (LSS), phasor dual induction (DITE-SFR), and the TLT sondes and was deployed at 0725 hr on 30 August. The tool logged Hole 1077A at 400 m/hr from 202 to 79 mbsf. By 1115 hr on 30 August, the logging equipment was rigged down, and the top drive was set back as the drill string was pulled to the surface. The bit cleared the seafloor at 1130 hr on 30 August, ending operations at Hole 1077A.
The vessel was offset 20 m to the west, and Hole 1077B was spudded at 1235 hr on 30 August. The seafloor depth was established at 2392.9 mbrf by DPM. APC Cores 175-1077B-1H through 22H were taken from 0 to 205.1 mbsf, with 205.1 m cored and 212.7 m recovered (103.6% recovery). The drill string was pulled back with the bit clearing the seafloor at 0455 hr on 31 August, ending operations at Hole 1077B.
The vessel was offset 20 m to the west, and Hole 1077C was spudded with the APC at 0550 hr on 31 August. The seafloor depth was estimated from recovery to be at 2396.7 mbrf. Three APC cores were taken to a depth of 22.8 mbsf when on-site operating time expired. Core recovery was only 72.2% of the cored interval because of the loss of watery sediments during the core retrieval process. The drill string was pulled out of the hole and cleared the seafloor at 0720 hr on 31 August, ending operations at Site 1077. By 1206 hr on 31 August, the drilling equipment was secured and the vessel was underway to Lobito, Angola, for a scheduled arrival at 0700 hr on 2 September to take the Angolan scientific observers on board.
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