IODP NanTroSEIZE Stage 1:
Expedition 314: NanTroSEIZE LWD Transect
Weekly Report #4
Date 19/Oct/2007
After finishing the diagnosis, correction, and final evaluation of the Dynamic Positioning and Acoustic Positioning Reference System (APRS), the ship moved to a low current area (14 nm northwest) in order to avoid shock and vibration from the Kuroshio current while picking up and running in with the LWD assembly and drill collars on 13 October. Drifting back to Site C0002, and Hole C0002A was spudded in at 00:45 of 14 October. The top 70.5 m was jetted in, and then rotary drilling began. Up to the depth of 562.5 meter below seafloor (mbsf), real time results showed good hole condition, little deviation from vertical, and measurement quality was also good. A short wiper trip was carried out at 709.5 mbsf for 8 stands, including a re-log of a short missed interval. Drilling continued without excessive torque or downhole pressure all the way to the planned Total Depth of 1400 m below the sea floor, reaching TD (1401.5 mbsf) at 11:15 on 17 October.
While pulling out of the hole, seismic data tool check-shot points were taken at every pipe connection to double the number of seismic tie depths. Data from all LWD tools were successfully dumped and pre-processing by field engineers is now ongoing. The seismic data had a battery failure before retrieval of the tool, and the data had to be sent to land base for pre-processing. As the assembly was rigged down, the ROV was deployed to pick up four beacons, then the ship was moved to next site (NT2-01) and four beacons were deployed at the new location.
This week processing and interpretation of the LWD data taken from Site C0001C and C0001D was the main activity. The scientific party reviewed and discussed the results at a first site summary meeting on October 12. A second, final meeting was held on 15 October, to confirm results from each group as they prepared the site report. Report drafts are under review by Co-Chief Scientists since October 17.
Meanwhile, real time monitoring of data from Site C0002A was being carried out in the lab area. In a first for IODP, LWD engineers and scientists continuously updated the drilled depth on the seismic data, plotting the bit position on seismic depth sections in near-real time. The real time gamma, resistivity, and other logs indicated that the bit passed from the Kumano Basin sediments into the underlying Accretionary prism and remained in this interval until the TD at 1400 meter.
Special technical seminars were held for LWD tools shocks and vibrations by an LWD engineer on October 16, and VSP surveying and data processing on 17 October.
Co-Chief Scientist and several scientists were interviewed by telephone or email for media in their home countries. Weekly safety drill (oil spill and abandon ship) was held on October 14 and bi-weekly safety management system meeting was held on October 15.
