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IODP Expedition 335:
Superfast Spreading Rate Crust 4
Week 3 Report (25 April - 1 May 2011)
PDF file is available for download.
On 24-25 April, the drilling assembly was run in the hole to
test the result of the cementing operation. The bit tagged the bridge at 922.0
mbsf, indicting that the 5 barrels of cement deployed earlier were not
sufficient to fill the void above the obstruction. The driller's effort to wash
and ream past the ledge met with high erratic torque and was given up after an
hour. The drill string was tripped to the surface with the bit clearing the
rotary table at 0615 h on 25 April.
The cementing assembly was deployed for the second time with
the bit entering the reentry cone for the fifth time at 1445 h on 25 April. The
bit was placed at 922 mbsf and this time 50 barrels of 15 ppg cement was pumped
into the hole. The bit was recovered at 0345 h on 26 April. The drilling
assembly with the Atlas bit was redeployed and entered the cone with the sixth
reentry at 1520 h on 26 April. The top of the cement plug was found at 882
mbsf. The 40 m cement plug was drilled out at an average rate of penetration of
At 2230 h on 26 April, washing and reaming the hole at ~920
mbsf resumed and continued until 0600 h on 28 April with no apparent progress.
The driller worked stuck pipe for one hour during this interval. The drill
string was recovered to change the bit, which had accumulated 33.3 hours. The
used bit was found to be in gauge and exhibited little wear on the cones and
bit body. The two junk baskets were emptied and contained basaltic cuttings
ranging from fine angular sand to small pebbles. Rare small (up to cm-scale)
chunks of cement were also recovered. The quantity of material was noticeably
less than that from the previous junk basket deployment.
A new hard formation Smith Q7JS (IADC code 735) bit was made
up and deployed with the drilling assembly. The nozzles were reduced to 14/32"
from the usual 16/32" to increase the downhole hydraulic horsepower. The junk
baskets were not added to the BHA to reduce the risk of downhole hardware
failure. The bit entered the reentry cone for the seventh time of the
expedition at 0135 h on 29 April. Washing and reaming resumed and this time
persistence was finally rewarded when the bit passed through the obstruction at
922 mbsf shortly before midnight on 29 April. The pipe got stuck for 2 hours at
1162 mbsf. The total depth achieved during Expedition 312 (1507.1 mbsf) was
reached at 0915 h on 1 May 2011. Six meters of hard fill was encountered at the
bottom of the hole, which was ground and removed before the bore was flushed
with a 100-barrel high viscosity mud sweep. The wiper trip to 890 mbsf was
without incident. A pill of 60 barrels of heavy mud was spotted across the zone
extending from 920 to 960 mbsf to keep the formation from bridging over the
open hole prior to retrieving the pipe trip to the surface.
We will reenter the hole with the cementing assembly and
attempt to stabilize the problem region by placing a 60-barrel cement plug
across the zone prior to recovering the drill pipe. The next objective will be
to change to an RCB coring assembly, reenter the hole, drill through the
cement, and resume coring in Hole 1256D.
The science party laboratory teams continued to configure
their measurement systems. Major effort has gone into the development of core
and thin section description templates, largely based on the migration of
Expedition 312 data and the rigorous re-description of Expedition 312 gabbro
cores from Hole 1256D (Cores 312-1256D-213R-1 to 234R-1; 1406.1 to 1507.1
mbsf). USIO staff used the specifications to configure the data capture
application DESClogik, to be used for the entry of data from new cores to be recovered
from Hole 1256D. Imaging and other core logging measurements were carried out
as well on the Expedition 312 cores. Further training into report writing
protocols has taken place with science discipline teams submitting draft
methods sections and beginning to write reports on their observations and
measurements of Expedition 312 cores. This will ensure seamless,
self-consistent observations down from the Hole 1256D dike-gabbro boundary. The
science seminar series continued throughout week 3 with daily presentations by
shipboard participants on a range of topics directly or indirectly related to
the Expedition objectives. This has been an excellent opportunity for early
career scientists to showcase their research. The talks
of a consistently high caliber have sparked vigorous discussions that have
often required curtailment to allow feeding.
Education and Outreach
Regular updates about the expedition continue to be posted
to the JR.org blog, Facebook, and Twitter. Numerous members of the science
party helped spread the word to schools and universities around the world
regarding the opportunity to sign up for a live video broadcast with the ship,
and the first video broadcast was scheduled with a high school in Virginia for
Thursday, May 5. In addition, the NSF has again asked Deep Earth Academy to do
a broadcast to NSF for this year's winners of the Presidential Awards for
Excellence in Mathematics & Science Teaching (PAEMST), which is the U.S.'s
highest honor for K-12 teachers of mathematics and science. NSF administers
PAEMST on behalf of the White House Office of Science and Technology Policy.
The PAEMST broadcast from the ship will be on May 18.
Technical Support and HSE Activities
Technical staff continued to support the science party's
reexamination of Expedition 312 cores while drilling operations prepared Hole
1256D for coring.
- Support for the DESCLogik project continued.
- Installation and testing of new pyncometer interface board continued.
- Science pallet storage reorganization project continued with the installation of various storage areas. Work on lighting and power relocation and gas bottle storage started.
- Unable to effect repair of aft VSAT, parts moved from forward installation aft successful.
- Technical cross training continued with the thin section, physical properties, DESClogik, and RigWatch systems.
- ODL staff
completed modification to the Bridge work deck that will allow supplies to be
shifted from the port side to the elevator.
The weekly fire and abandon ship drill was held as
scheduled. No incidents to report.