IODP Expedition 328:
Cascadia A-CORK Observatory
Week 2 Report (12-18 September 2010)
PDF file is available for download.
After jetting in the 16 inch casing and re-entry cone, our
next objective was to drill a 14-3/4 inch hole to accommodate the
10-3/4 inch casing string. A drilling BHA with a 14-3/4 drilling bit
was made up and deployed, reentering Hole U1364A at 0905 hr on 13 September.
The VIT was recovered and then drilling advancing without incident to a final
depth of 336.0 mbsf. High viscosity mud sweeps (20 barrels (bbl) each) were
circulated at 164, 193, 222, 278, 307, and at 336.0 mbsf. A large high
viscosity 50 bbl flush was pumped at the conclusion of drilling. The hole was
then displaced with 250 bbl of 10.5 pounds/gallon (ppg) mud. The drill string
was recovered with the bit clearing the rotary table at 1435 hr on 14
The next operational step was to make up the ACORK assembly.
The construction of the ACORK, which include making connections to the
hardware, strapping and taping the umbilical to the casing, and making the
plumbing connections to the screens and ACORK, began at 1430 hr on 14 September
and continued to 1000 hr on 15 September. The ACORK assembly included a custom
ACORK head, a 10-3/4 inch casing hanger, 20 joints of 10-3/4 inch casing,
2 pup joints of 10-3/4 inch casing, a TAM Freecap 10 inch x 14 inch
dual-element swellable packer, and 4 screen joints of 10-3/4 inch casing
and one shoe joint. The length of the entire assembly was 329.1 m. Because 6.0
m of ACORK head extended above the hang-off point in the reentry cone, the
effective depth of the assembly into the hole was 323.1 m. With a 12.9 m rat
hole, the bottom of the hole was 336.0 mbsf. The next phase of the rigging up
was to make up a reaming BHA, which included a 9-7/8 inch
tricone bit, a 9.5 inch HOC DTU950 under-reamer, a 9.5 inch Ultra XL mud motor,
and the CADA casing running tool. The total length of this BHA was 418.9 m. As
the BHA was being assembled, it was lowered incrementally into the ACORK
suspended in the moon pool until the running tool landed into the ACORK at 1345
hr on 15 September. The ACORK and reaming assembly were then lowered into the
water with the ACORK head ~10 m beneath the surface for 5 minutes to purge any
entrapped air. Once the ACORK head was in the moon pool, the four purge valves
were manually turned to the closed position. The ACORK and reaming BHA were
deployed and Hole U1364A was entered for the second time at 1930 hr.
The ACORK was gradually lowered into the open hole until it was successfully
landed in the reentry cone at 0025 hr on 16 September. No under-reaming was
required, because the hole appeared to have remained open, possibly due to the
presence of the 10.5 ppg mud that was pumped into the hole at the conclusion of
the drilling process.
The ROV platform was tethered to the VIT and deployed at
0400 hr on 16 September. The platform was successfully deployed when the
mechanical release activated upon contacting the CADA top hat at 0515 hr. The
VIT was then recovered.
A Hammer Drill System (HDS) cone, adapted to fit over the 16
inch casing hanger at the top of the ACORK to facilitate re-entry, was made up
and free fall deployed at 0820 hr on 16 September. However, the cone was
dislodged while retrieving the drill string and fell to the seafloor. The
drilling string was tripped back to the rig floor.
The final operation was deployment of a hydraulic packer to
seal the bottom of the 10-3/4 inch casing. The packer assembly was deployed
and Hole U1364A was reentered for the third time at 2320 hr on 16 September.
Although the 16 inch casing hanger presented a smaller target than the HDS
cone, the reentry was made in less than an hour. The packer was positioned at
319 mbsf or 4 m above the casing shoe with a circulating head in place. Prior
to activating the packer, the inside of the casing was displaced with one
volume of seawater while taking care not to exceed 200 psi to insure that the
packer would not inflate prematurely. At 0230 hr the activating steel ball was
dropped into the pipe and seated inside the bridge plug. The pressure was
gradually increased until the packer set at ~ 1300-1400 psi. The packer was
released at 0335 hr when ~2700 psi was applied. The driller pulled back in the hole, circulated seawater while
waiting for the cement to be mixed, and then pumped ~4 bbl of 16 ppg cement
covering the packer with ~14 m of cement. The inside of the casing was then flushed with 3 volumes of seawater. At
0600 hr, the driller began to recover the drill string, which was back onboard
at 1400 hr, ending operations at Site U1364.
The ship was secured for transit, the thrusters raised and
the ship departed for port. The JR arrived at Esquimalt Graving Dock in
Victoria B.C. at 0804 hr on 18 September 2010, concluding Expedition 328.
Outreach and School of Rock
During the second week, the School of Rock participants
continued to observe the ACORK installation process. They learned more about
ACORK technology and demonstrated the physics of the pressure sensors installed
on the tool, got tours of the rig floor, engine room and bridge. Participants
also spent time in the chemistry lab conducting titrations, analyzing
carbonates, and learning how to squeeze core samples for interstitial water
analysis. One day was spent viewing the logging tools then completing
activities based on logging data. Throughout the week, participants
engaged in a wide range of facilitated discussions and group activities aimed
at communicating science and developing their outreach plans and
products. Ship staff and instructors also presented on topics such as
Marine Mammal Observations, Ocean Observatories and NEPTUNE Canada, Site
Surveys, and CORKS. In addition, eight participants, three instructors, and two
science party members participated in a total of seven video
conferences to reach an estimated 530 people. Audiences included museum
staff, K12 students and teachers, undergraduate students, cyber school
students, and attendees of a science fiction convention. Participants
presented summary slides about what they learned, turned in Education Project
Plans and drafts of their projects before departing the ship.
Technical Support and HSE Activities
The weekly fire and boat drill was held as scheduled.
Technical staff provided support for science, education and
engineering projects, including the follow activities.
videoconferences conducted by the School of Rock participants.
- Completed the end of cruise back ups for Expeditions 327 and 328.
- Completed collecting color reflectance and magnetic susceptibility data on select cores from Expedition 327.
- Created new images and installed on all backup PCs and Macs.
- Upgraded Enterasys software to version 3.3.
- Successfully tested the Adobe Connect video conferencing software.
- Assisted scientists and engineers in the assembly and deployment of the ACORK.