review. Scientists compete to make their cases why drilling in a particular geographical locality can help in solving problems of fundamental or global importance that
cannot be achieved otherwise.
The progress of scientific ocean drilling can be
described in terms of technological advancements in core
sampling and downhole measurements, program management, and scientific achievements.
Ocean drilling history
The history of scientific ocean drilling starts from the
Mohole Project Phase 1 (1958–1966), which eventually
aimed to penetrate the Mohorovičić discontinuity, which
is the seismic velocity discontinuity that separates the
crust and the mantle (Bascom, 1961). The Mohole Project
started from engineering developments, as scientific
ocean drilling from a vessel without anchoring in deep
water had not existed. On April 2, 1961, CUSS I with a
dynamic positioning system to keep its station made its
historic achievement of sampling basalt beneath 183 m
of sediments in 3,658 m of water depth offshore Guadalupe Island. Although this Phase 1 was a success, technical
difficulties and financial constraints prevented the project
to advance to the next phase.
The success of Phase 1 opened the era of scientific
ocean drilling more focused on sediments and shallow
crustal drilling at many geographical locations rather than
aiming for a few deep crustal penetrations. Exploration of
the sediments builds on the success of Kullenberg piston
corers (e.g., Swedish deep-sea expedition Albatross
1947–1948). These led to successful years of scientific
programs: Deep Sea Drilling Project (1968–1983), International Phase of Ocean Drilling (1975–1983), Ocean
Drilling Program (1985–2003), Integrated Ocean Drilling
Program (2003–2013), and International Ocean Discovery Program (2013–2023) (Table 1).
After the retirement of the drilling vessel, Glomar
Challenger for DSDP (Legs 1–96), JOIDES Resolution
(JR) was introduced from ODP (Legs 100–210; a Leg is
typically about 8 weeks long with about 25 scientists on
board) and 32 JR expeditions for IODP (similar to ODP
mode). IODP has been a major upgrade for scientific
ocean drilling as the participating countries had agreed
to operate three uniquely capable drilling platforms to
expand the potential drilling targets to ice-covered, very
shallow (a few tens of meters water depth), or very deep
water drilling (>~5 km) (Figure 2).
The European Consortium for Ocean Research Drilling
(ECORD) introduced chartered drilling vessels for IODP
in 2004. This type of platform is called Mission-Specific
Platform and is aimed to drill in waters where JR is not
the optimal platform. The first MSP was a fleet of vessels
to drill in ice-covered Arctic Sea (Exp. 302). In 2007, a
riser-equipped drilling vessel Chikyu joined the program
as planned for IODP. Chikyu is capable of drilling deeper
because the riser pipes that allow mud circulation to prevent hole collapse are normally used by the oil industry.
Currently, Chikyu can drill in riser mode to 2,500 m water
depth with 10,000 m drill pipes. During IODP, five MSP
expeditions were conducted (Exps. 302, 310, 313, 325,
347, Arctic Sea and shallow waters). Chikyu was mostly
engaged in a multiple-expedition project to drill and study
the plate subduction fault off central Japan capable of generating M8-class earthquakes (ten expeditions). JR holds
the record of penetrating deep in oceanic crust (2,111 m
below seafloor (mbsf) as of 2013) at Hole 504B, and
Chikyu holds the record of deep drilling in thick sedimentary sequence of continental margin (2,466 mbsf as of
2013) at Hole C0020.
The Glomar Challenger (GC) visited 624 sites during
DSDP and cored 97 km total length at 57 % recovery rate.
JR visited 669 sites during ODP and cored 222 km at 69 %
recovery rate.
In a few occasions, JR has drilled in shallow water
depths at <500 m (38 m water depth test (Leg 143) and
other legs such as Leg 194 in 304 m, Exp. 307 in 420 m,
Exp. 317 in 84 m, and Exp. 334 in 137 m). Deepwater
depth drillings have been successfully made in depths well
exceeding the normal ocean basin depths (e.g., Leg 129 in
5,980 m (JR), Exp. 343 in 6,898 m (Chikyu)).
Scientific ocean drilling owes much to the technology
of dynamic positioning and wire line coring. The former
allows the drillship to sail almost anywhere in the world
oceans in deep waters and drill at the desired location
keeping the position. The latter allows continuous coring
without retrieving the drill string. The precision of absolute position on Earth and relative location in a particular
seafloor locale has improved over the years by GPS positioning and seafloor swath bathymetry. The ability to
recover as much as possible from beneath the seafloor
owes much to the drilling technology, i.e., cutting into
Ocean Drilling, Table 1 Ocean drilling platforms
Glomar challenger (DSDP, retired 1983)
Built 1968: 123 m length, 20 m breadth, 10,500 t displacement (LT)
Maximum drilling/coring depth: 8,375 m (reentry depth 7,960 m)
Drilling water depth: >6,000 m
JOIDES Resolution (ODP and IODP (overhauls in 1984 and 2009,
scientists 25))
Built 1978: 143 m length, 21.3 m breadth, 10,282 gross tonnage
Maximum drilling/coring depth: 8,375 m (reentry depth 7,960 m)
Drilling water depth: 75 m to >6,000 m
Wire line coring retrieval rate: ~200 m/min
Chikyu (IODP, scientists and lab staff 50)
Built 2005: 210 m length, 38 m breadth, 56,752 gross tonnage
Maximum drilling/coring depth: 10,000 m
Drilling water depth: 500–2,500 m (riser drilling mode)
Wire line coring retrieval rate: ~150 m/min
Mission-Specific Platforms (IODP; various chartered platforms
outfitted with drill rigs)
Vidar Viking, Oden, and Sovetskiy Soyuz were utilized for drilling
through the Arctic ice (Exp. 302). Other expeditions by DP
(dynamically positioned) Hunter (Exp. 310), L/B Kayd (liftboat,
313), Greatship Maya (325), and Greatship Manisha (347)
544
OCEAN DRILLING
cannot be achieved otherwise.
The progress of scientific ocean drilling can be
described in terms of technological advancements in core
sampling and downhole measurements, program management, and scientific achievements.
Ocean drilling history
The history of scientific ocean drilling starts from the
Mohole Project Phase 1 (1958–1966), which eventually
aimed to penetrate the Mohorovičić discontinuity, which
is the seismic velocity discontinuity that separates the
crust and the mantle (Bascom, 1961). The Mohole Project
started from engineering developments, as scientific
ocean drilling from a vessel without anchoring in deep
water had not existed. On April 2, 1961, CUSS I with a
dynamic positioning system to keep its station made its
historic achievement of sampling basalt beneath 183 m
of sediments in 3,658 m of water depth offshore Guadalupe Island. Although this Phase 1 was a success, technical
difficulties and financial constraints prevented the project
to advance to the next phase.
The success of Phase 1 opened the era of scientific
ocean drilling more focused on sediments and shallow
crustal drilling at many geographical locations rather than
aiming for a few deep crustal penetrations. Exploration of
the sediments builds on the success of Kullenberg piston
corers (e.g., Swedish deep-sea expedition Albatross
1947–1948). These led to successful years of scientific
programs: Deep Sea Drilling Project (1968–1983), International Phase of Ocean Drilling (1975–1983), Ocean
Drilling Program (1985–2003), Integrated Ocean Drilling
Program (2003–2013), and International Ocean Discovery Program (2013–2023) (Table 1).
After the retirement of the drilling vessel, Glomar
Challenger for DSDP (Legs 1–96), JOIDES Resolution
(JR) was introduced from ODP (Legs 100–210; a Leg is
typically about 8 weeks long with about 25 scientists on
board) and 32 JR expeditions for IODP (similar to ODP
mode). IODP has been a major upgrade for scientific
ocean drilling as the participating countries had agreed
to operate three uniquely capable drilling platforms to
expand the potential drilling targets to ice-covered, very
shallow (a few tens of meters water depth), or very deep
water drilling (>~5 km) (Figure 2).
The European Consortium for Ocean Research Drilling
(ECORD) introduced chartered drilling vessels for IODP
in 2004. This type of platform is called Mission-Specific
Platform and is aimed to drill in waters where JR is not
the optimal platform. The first MSP was a fleet of vessels
to drill in ice-covered Arctic Sea (Exp. 302). In 2007, a
riser-equipped drilling vessel Chikyu joined the program
as planned for IODP. Chikyu is capable of drilling deeper
because the riser pipes that allow mud circulation to prevent hole collapse are normally used by the oil industry.
Currently, Chikyu can drill in riser mode to 2,500 m water
depth with 10,000 m drill pipes. During IODP, five MSP
expeditions were conducted (Exps. 302, 310, 313, 325,
347, Arctic Sea and shallow waters). Chikyu was mostly
engaged in a multiple-expedition project to drill and study
the plate subduction fault off central Japan capable of generating M8-class earthquakes (ten expeditions). JR holds
the record of penetrating deep in oceanic crust (2,111 m
below seafloor (mbsf) as of 2013) at Hole 504B, and
Chikyu holds the record of deep drilling in thick sedimentary sequence of continental margin (2,466 mbsf as of
2013) at Hole C0020.
The Glomar Challenger (GC) visited 624 sites during
DSDP and cored 97 km total length at 57 % recovery rate.
JR visited 669 sites during ODP and cored 222 km at 69 %
recovery rate.
In a few occasions, JR has drilled in shallow water
depths at <500 m (38 m water depth test (Leg 143) and
other legs such as Leg 194 in 304 m, Exp. 307 in 420 m,
Exp. 317 in 84 m, and Exp. 334 in 137 m). Deepwater
depth drillings have been successfully made in depths well
exceeding the normal ocean basin depths (e.g., Leg 129 in
5,980 m (JR), Exp. 343 in 6,898 m (Chikyu)).
Scientific ocean drilling owes much to the technology
of dynamic positioning and wire line coring. The former
allows the drillship to sail almost anywhere in the world
oceans in deep waters and drill at the desired location
keeping the position. The latter allows continuous coring
without retrieving the drill string. The precision of absolute position on Earth and relative location in a particular
seafloor locale has improved over the years by GPS positioning and seafloor swath bathymetry. The ability to
recover as much as possible from beneath the seafloor
owes much to the drilling technology, i.e., cutting into
Ocean Drilling, Table 1 Ocean drilling platforms
Glomar challenger (DSDP, retired 1983)
Built 1968: 123 m length, 20 m breadth, 10,500 t displacement (LT)
Maximum drilling/coring depth: 8,375 m (reentry depth 7,960 m)
Drilling water depth: >6,000 m
JOIDES Resolution (ODP and IODP (overhauls in 1984 and 2009,
scientists 25))
Built 1978: 143 m length, 21.3 m breadth, 10,282 gross tonnage
Maximum drilling/coring depth: 8,375 m (reentry depth 7,960 m)
Drilling water depth: 75 m to >6,000 m
Wire line coring retrieval rate: ~200 m/min
Chikyu (IODP, scientists and lab staff 50)
Built 2005: 210 m length, 38 m breadth, 56,752 gross tonnage
Maximum drilling/coring depth: 10,000 m
Drilling water depth: 500–2,500 m (riser drilling mode)
Wire line coring retrieval rate: ~150 m/min
Mission-Specific Platforms (IODP; various chartered platforms
outfitted with drill rigs)
Vidar Viking, Oden, and Sovetskiy Soyuz were utilized for drilling
through the Arctic ice (Exp. 302). Other expeditions by DP
(dynamically positioned) Hunter (Exp. 310), L/B Kayd (liftboat,
313), Greatship Maya (325), and Greatship Manisha (347)
544
OCEAN DRILLING