Deep sea drilling vessel CHIKYU has resumed Integrated Ocean Drilling Program drilling operations in the off the coast of Japan. The scientific drilling expedition’s first target is located in water depths of 6,800 feet. Following sea floor surveys, the crew began fitting riser pipe and a blow-out prevention (BOP) system into an upper section of the first borehole to be drilled. The riser pipe and BOP successfully was connected to the wellhead. After testing the circulation of the drilling fluid, the first riser-drilling operations for CHIKYU in the history of scientific ocean drilling began on June 25. The British Broadcasting Corporation (BBC) chronicled the lead-in to this historic activity, the first media organization outside Japan to broadcast live from CHIKYU.
The target drilling depth at the first borehole is 1 mile below the seafloor.
Following drilling operations, vertical seismic profiling (VSP) is expected to
begin as part of geophysical logging.
Riser drilling involves a large marine riser pipe that connects the CHIKYU and
the seafloor. The riser pipe guides the drill pipe as it reenters the well.
Drilling fluid is pumped up and down between the riser pipe and the drill pipe.
Fluid circulation and use of the blow-out preventer (BOP) help maintain
pressure balance within the borehole and prevent it from collapsing, enabling
safer and deeper drilling. CHIKYU is the world’s first scientific drilling
vessel capable of riser drilling deep beneath the ocean floor and in
seismogenic (earthquake-producing) zones that have never been reached before.
Earthquake Zone Research
August 5, 2009