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| MHI's
high-tech derrick facilitates drilling
on a moving sea. |
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A
key technological difference between the Chikyu
and earlier scientific drillships is the riser
system using large-diameter outer pipes, called
"risers," connecting the ship to
the seabed and serving as conductors for mud
fluid. Previous drillships, without riser
systems, have been unable to reach much beyond
two kilometers (2,000 meters) beneath the
seabed. The advanced drilling techniques enabled
by the riser system enhance the ability of
scientists on the Chikyu to reach
as far as seven kilometers into the earth's
crust, revealing many more of its secrets.
To protect the ship,
persons on board and the surrounding marine
environment from blow-out gas, oil and other
formation substances the drill may encounter,
the hole is sealed by a structure called a
"blowout preventer."
The riser system with mud circulation,
which controls and keeps the bore hole condition
stable, makes it possible to retrieve the
deep core samples. Additionally, for technical
reasons, the borehole made possible by the
riser operation is much larger than one made
by riserless drilling. This makes it easy
for researchers to lower instruments into
the hole to capture images of rock formations,
and take various other measurements. We are
waiting for the day the earth's mysteries
are revealed by Chikyu with MHI's
technology.
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