TRANSIT TO ESCANABA TROUGH


The 447 nmi transit to Escanaba Trough required 40.75 hr at an average speed of 10.6kt. The ship was slowed to 6 kt, the new 6-channel seismic streamer was deployed to check the signal, and a 6-nmi survey was completed in 1.75 hr. A Datasonics 354M 211dB beacon was dropped at 2300 hr on 24 September on Prospectus Site ET-7 at 40°57.30'N, 127° 30.90'W. The standard APC/XCB BHA was run.

SITE 1037 (PROPOSED SITE ET-7)


Hole 1037A

Hole 1037A was spudded at 0800 hr on 25 September. The seafloor was estimated at 3314.0 mbrf based on recovery. APC Core 169-1037A-1H was taken from 0 to 9.5 m (3323.5 mbrf). The recovery was a full core liner (9.79 m) for 103.1% recovery; therefore, the seafloor core and measurement were questionable and the hole was spudded again.

Hole 1037B

Hole 1037B was spudded at 0840 hr on 25 September. The seafloor was estimated at 3311.9 mbrf based on recovery. APC Cores 169-1037B-1H to 19H were taken from 0 to 177.6 mbsf (3489.5 mbrf) with 99.4% recovery. No orientation was done, but Adara temperature measurements were taken on Cores 169-1037B-3H, 5H, 7H, and 9H. A WSTP temperature run was cancelled because the formation became too hard. Twelve of the last 13 cores were partial strokes. XCB Cores 169-1037B-20X to 55X were taken from 177.6-501.2 mbsf (to 3813.1 mbrf) with 73.1% recovery. Core 169-1037B-53X was pulled after coring 5.5 m in 75 min. and wearing out a soft formation XCB shoe. Core 169-1037B-54X cored 4.1 m in 105 min. and the shoe was jammed. Core 169-1037B-55X was pulled after coring 1.5 m in 50 min. and the hard formation shoe was completely destroyed and grooved in a manner that could indicate a loose bit cone. In addition, the torque was erratic and recovery dropped from near 100% to 22.5% in the last three cores; therefore, the bit was pulled because the rock was too hard for the XCB shoes and there was a reasonable chance that a cone was loose and could be lost in the hole.

A FFF was dropped and checked with the VIT-TV, showing the FFF top at the seafloor. The APC/XCB bit was worn but in good shape. An RCB BHA with an RBI CC-4 bit (for drilling the sediment section) and an MBR was run. The hole was reentered at 0545 hr on 30 September, and the bit was washed to bottom with 7 m of soft fill. RCB Cores 169-1037B-56R to 62R were taken from 501.2 to 546.0 mbsf (3857.9 mbrf) with 27.2% recovery. Basalt was encountered in Core 169-1037B-57R (top at 507.8 m), and the overall rate of penetration on the last 4 cores in solid basalt was 1.5 m/hr. The last 4 cores were partial cores that jammed in the liner support sleeve or liner with 43% recovery. Overall recovery for Hole 1037B was 77.9%. The hole was conditioned for logging with a short trip. The bit was pulled to 247 m when heavy flow back and an apparent loss of 20K lb string weight was noted.

Suspecting a BHA loss, a core barrel was run, but the bit was tagged twice at the correct depth. The circulating pressure indicated the core barrel was not seating, but the string weight with the top drive looked correct; therefore, it is assumed that a piece of core had fallen out of the core barrel and opened the float valve. The apparent loss of weight may have been a reduction in drag in the enlarged hole and 10 stands of drillpipe that had been pulled. The bit was run back to bottom, 30 m of fill was washed and reamed out to bottom, and the bit was dropped. The pump pressure indicated the hole was packing off, so the bit was pulled up 1 stand to close the sleeve and circulate sepiolite mud.


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