November 22, 2012
The deep-sea drilling vessel Chikyu has been deployed by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC: Asahiko Taira, President) on the Integrated Ocean Drilling Program (*1 IODP) Expedition 338: The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) Stage 3 from October 4, 2012. Plans for FY2012 included drilling from 860 m to 3600 m below the seafloor. Although drilling has progressed to 2000 m below the seafloor, plans for this fiscal year have been revised as sudden changes in sea conditions resulted in damage to parts of the drilling equipment.
1. Circumstances when drilling equipment was damaged
2. Outline of changes in plans
As the ongoing riser operation cannot be conducted without the damaged equipment; these operations will be suspended during FY2012 after securing the borehole. The drilling will be resumed in FY2013. Plans for the remainder of FY2012 will be revised and drilling scheduled for FY2014 as part of the Nankai Experiment at other locations will be conducted including collection of geological samples and well logging.
3. Schedule for Chikyu
*1 The Integrated Ocean Drilling Program (IODP)
IODP is an international marine research-drilling program dedicated to advancing scientific understanding of the Earth by monitoring and sampling subseafloor environments. Through multiple platforms, scientists explore IODP's principal themes: the deep biosphere, environmental change, and solid Earth cycles. IODP has been in operation since October 2003, funded jointly by the Japan Ministry of Education, Culture, Sports, Science and Technology and by the U.S. National Science Foundation. The 18-member European Consortium of Ocean Research Drilling (ECORD), the People's Republic of China, the Republic of Korea, India, Australia and New Zealand (ANZIC), Federative Republic of Brazil provide additional support.
*2 Riser Pipe
Pipe connecting the ship to the blowout preventer equipment. Drilling is conducted by lowering the drill pipe inside the riser pipe.
*3 LMRP(Lower Marine Riser Package)
Upper part of Blowout Preventer, which is for retrieving the riser and for emergency disconnect.
*4 Blowout Preventer
Equipment to prevent the uncontrolled discharge of fluids in the event of infiltration of oil, gas, or other fluids from strata into a borehole by rapidly sealing the borehole and controlling the pressure.
Figure 1 Damaged equipment (left) and cracks inside the equipment (right).