The décollement zone for NBR-9A was estimated at 424 mbsf. We attempted to drill at 35 m/hr down to 5487 m (459 mbsf) where high torque and pump pressures were encountered. The drill string was pulled back to 362 mbsf with a maximum drag of 50,000 lb. The hole was washed and reamed for 3 hr in the zone from 362 to 459 mbsf. All drilling parameters returned to normal and drilling resumed at 459 mbsf. No further difficulties were experienced, and the hole was drilled at about 35 m/hr to a total depth of 5860 m (832 mbsf) where basement was encountered and the drilling rate slowed to 6 m/hr. Hole 1046A was terminated at 5860 mbrf (832 mbsf) having successfully achieved the depth objective. Average LWD drilling parameters during Hole 1046A were 0-15 K weight on bit (WOB), 40-55 rpm, 300-550 psi, 100-200 Amps torque, and 35 m/hr rate of penetration (ROP).
The drill string was raised to 400 mbsf, and the hole was displaced with 130 bbl of heavy (11.0 lb/gal) mud. The trip continued to the surface where the nuclear sources were removed, the LWD data were retrieved, and the LWD collars were laid out. The bit cleared the rotary table at 1530 hr 03 January ending Hole 1046A.
To 171A Site 1047
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