Center for Deep Earth Exploration
CHIKYU Q&A Archive
Q.11 How fast does CHIKYU drill and pull up pipes?
Mr. Noritaka Taniguchi
Operations Department
The derrick (Drill tower) on CHIKYU is used to hang drill pipe, and is the mount for the top drive to power drilling.
Drilling speed (Rate of Penetration, or ROP) for ocean drilling around Japan, is about 300m/day (15m/hr) at shallow depths (from 0 to 1,000m below the seafloor), about 150m/day (8m/hr) at intermediate depths (from 1,000 to 2,000m below the seafloor), and about 70m/day (3m/hr) at depths greater than 2,000m below the seafloor.
Pulling up all drill pipes assuming a drilling depth of 4,000m and changing a worn drill bit takes about 6 hours, giving an estimate for pulling pipe of about 600m/hr.

*Do you want to know how drilling and corking works? Go to CHIKYU IMAGES to see a movie that graphically outlines deep sea drilling and coring procedure.

>Drill the deep Earth
Q.10 When and where will the 1st CHIKYU test drilling operation take place?
Mr. Noritaka Taniguchi
Operations Department
D/V CHIKYU will be delivered at the end of July 2005, and will be tested over a period of about 2 years. In 2005, a piston coring test will be scheduled in an east of the Shimokita Peninsula, offshore between Hokkaido and Tohoku, Japan.

During this test and training operation, D/V CHIKYU will penetrate to a depth of about 50m below the seafloor. Tests and training for riser drilling and coring operations required for deep drilling and/or drilling in areas with overpressured fluids is scheduled for the following summer in the same area.

Q.9 Why was D/V CHIKYU built by Japan?
Mr. Yoshi Kawamura
Science Planning Dept.

First of all, scientific deep sea drilling started in 1959. At the beginning, the purpose of the deep sea drilling was to take a sample of the earth’s mantle, however, up to the present, this dream was not achieved due to technical difficulties. Moreover, almost all major international science programs (for instance, Space Station Project) have been initiated by the United States. To show emergence of Japan as a premier maritime nation in the world, and to advance technological development as a technological founding state, Japan started the construction of D/V CHIKYU which can drill into the earth’s mantle for the first time. It is strongly thought that Japan plays a leading role in the international scene and contributes in the future of human beings by operating D/V CHIKYU .

D/V CHIKYU was introduced to the representatives who participated in the international conference.
The CDEX staffs report the activities of D/V CHIKYU and CDEX in the international conferences.
Q.8 To whom will the mantle samples that will be collected by D/V CHIKYU belong?
Mr. Yoshi Kawamura
Science Planning Dept.
The mantle that is collected by D/V CHIKYU will belong to JAMSTEC, the owner and operator of the vessel.However, so far no one has collected samples of the earth’s mantle, and such samples, if successfully obtained by drilling, will be extremely important scientific treasures similar to the first samples from the moon.

To get the best scientific results and to encourage comprehensive scientific collaboration, JAMSTEC will distribute the mantle to as many researchers as possible in a fair and equitable manner. We are thinking of the best ways to utilize the precious mantle samples to make maximum contribution for the future.

D/V CHIKYU Core repository : Kochi Core Center
Q.7 What amount of drill pipe can D/V CHIKYU carry at one time?
Mr. Yoshi Kawamura
Science Planning Dept.


Instead of busy Mr. Kosuge from procurement group, Yoshi, who is a CDEX super substitute from the PR group, will answer your questions.

There are three types of pipe carried on board D/V CHIKYU .

First is RISER PIPE, which connects the vessel to the sea floor installation (the Blow Out Preventer, or BOP). It is essential for operation of the riser drilling system, which gives us the ability to drill deep boreholes and to drill in areas where there are overpressured fluids in the crust.

Second is DRILL PIPE, which is use for drilling operations and has a drill bit mounted at the bottom end of the pipe. The rotation of the bit and the pipe grind the rocks and cut into the earth, forming the borehole. (see CHIKYU IMAGES for more information.)

Third is CASING PIPE, which prevents drilled boreholes from collapsing. See the detail process in the CG animation for more information and a graphical explanation. D/V CHIKYU usually carries 90 pieces of riser pipe for a total length of 2,500m.

D/V CHIKYU can drill a deep hole in water depths of up to 2,500m. This limitation is dictated by the strength of these pipes and the physics of the drilling setup. Current engineering research and development is aimed at increasing this maximum water depth for riser drilling. D/V CHIKYU carries more than 1,000 pieces of drill pipe. The length of a single piece of drill pipe is 9.5m, so D/V CHIKYU could theoretically reach 10,000m in total depth from the bottom of the ship to the bottom of the drill hole. For instance, if the water depth is 2,500m, D/V CHIKYU can drill to 7,500m depth below the sea floor.

When D/V CHIKYU drills very deep hole, she needs several sizes of CASING PIPE to protect the hole. She carries casing pipes sufficient to make a 7,000m deep hole. If needed, resupply by ship to D/V CHIKYU can deliver more piping or casing.

In conclusion, D/V CHIKYU can carry all necessary pipe to drill a 7,000m hole water depths of up to 2,500m.
The diameter of the riser pipe is quite large!
Q.6 What is a seismic survey?
Mr. Hideki Tanaka
Operations Dept.

When you climb a mountain and shout hi-de-ho, an echo comes back. That is because the mountains in the distance have reflected the sound waves back to you.

If you shout toward the ground, though, you don't hear any echo. Why not, since the ground must be reflecting back the sound waves? The answer is that you are too close: the sound waves are reflected back at almost the same instant as when you shout, so you don't hear the reflected ones separately.

It's not just the surface of the earth reflecting back echoes. The ground on which you stand is composed of layers, called strata. Each stratum reflects back an echo. Echoes from thin strata and dense rocks are fast. Echoes from thicker strata and less dense rocks are slower. But innumerable echoes are reflected back.

Why don't we hear these echoes? As your voice (the sound) penetrates the earth it becomes weaker and weaker. The echoes reflected back are too weak for you to hear them. It's the same principle that allows you to hear people standing close to you while not being able to hear people at a distance.

If you could shout loud enough and your ears were sensitive enough, you could theoretically hear the echoes from deeper strata. Practically speaking, human voices aren't loud enough and human ears are not sensitive enough to accomplish this. Let's try it, however, with a really loud noise, for example, the sound of dynamite exploding.

In this case, weak echoes return from all the different strata. If we place a sensitive sensor on the earth, it can capture these echoes. Analyzing the sound waves that make up the echoes to determine the shape of the strata in the earth is what we do in a seismic survey.

But how does a seismic survey actually work?
Let's look at the example of a seismic survey under the sea. In the diagram below, we see an air gun in the water below the ship. When the air gun shoots compressed air into the water, sound waves are generated. It used to be that sound waves were generated by using dynamite or other explosives, but this killed fish and damaged the environment. The air gun is more environment-friendly.

The sound waves generated by the air gun are reflected back from the bottom of the sea and the strata in the earth beneath it. They are picked up by the streamer cable towed behind the ship (a cable to which multiple sensors are attached).
How can sound waves reflected from strata in the earth help us to understand the shape of underground strata? Sound waves from thin and dense strata are reflected more quickly than those from thicker or less dense strata. As shown in the next diagram, the sound waves generated by the research ship's air gun return at different speeds.

As the research ship goes forward, emitting sound waves and capturing echoes, it captures data used to map the sea bottom and the strata beneath it. The next diagram shows how this is done. In this way, we can understand how deep the strata are and the angles at which they lie, without ever seeing them.

Finally, the last diagram shows an actual example of data collected through seismological investigation. As indicated on the left, the color changes with the strength of the echoes. Can you see the fault (the offset of what should be continuous lines) on the right side? This is how we investigate the structure of the earth hidden beneath the surface.

Q.5 I'd like to tour the CHIKYU . How can I see the ship?
Ms. Ayumi Yoshimatsu
Administration Group
Since the CHIKYU is still under construction, for safety reasons, I'm sorry that tours are not permitted at this moment.

JAMSTEC is, however, planning a series of open houses and tours around the Tokyo area this September. This will take place during the test cruise after the vessel has been handed over to us. Please keep checking our website for details.

Q.4 I've heard the word "J-CORES." What does it mean?
Dr. Kyoma Takahashi
Science Planning Dept.
"J-CORES" is the name of CHIKYU on-board database system. This system stores and distributes all of the data measured automatically by CHIKYU instruments and descriptions by the scientists who work on the CHIKYU .

For details please see J-CORES website.

After a moratorium period during which time only shipboard scientists will have access to drilling and core data, all data will be disclosed to the world through the internet.

Q.3 Where is the registration port of CHIKYU and what is her ship class? Where is her home port?
Dr. Yasushi Ishioka
Operations Dept.
Port of Registration
All ships are required by law to have a port of registration. For CHIKYU , the port of registration is Yokosuka, Japan.

Home Port
In contrast to the port of registration, the home port is where a ship is based and is not legally determined. The owners or crew are free to choose whatever home port they prefer. The CHIKYU , however, is designed for long voyages with crew replaced and fuel and other supplies replenished while the ship remains at sea. It will only rarely return to port, and when it does that port could be anywhere in the world. It thus has no particular home port.

Ships, like automobiles, are required to have regular inspections. A ship is inspected and legally certified as safe by the Bureau of Shipping where it is registered. The ship's "classification" is the abbreviation of the official name of the Bureau of Shipping. For CHIKYU , it is Nippon Kaiji Kyokai, known as NK.

Other famous classifications are Lloyd (UK), DNV (Norway) and ABS (US).

Q.2 Can drilling pipes be reused?
Mr. Yoshinori Kosuge
Technology Dept.
Both the drill pipe, which drills under the seafloor, and the riser pipe, which connects the vessel with the seafloor, can be reused repeatedly.

The casing pipe, which is inserted into the borehole to keep the walls from collapsing onto the drill string, can only be used once,. Cement is used to fill gaps between the casing pipe and the strata. Pipes are fixed and left in place after the drilling operation.

The drilling pipe and riser pipe are both marked with serial numbers. Once a year the pipes are inspected and may be replaced if necessary.
Q.1 Can CHIKYU continue to drill during typhoons or storms?
Mr. Jun Tomomoto
Operations Dept.
CHIKYU is, of course, designed to withstand a certain degree of wind and wave activity. There are, however, limits beyond which it cannot continue to drill.

It goes without saying that the safety of CHIKYU and those who work on her are our No. 1 priority. CHIKYU constantly monitors weather forecasts. If a warning of a typhoon or other powerful storm is received, safety measurement is taken. Then, the borehole can be closed with the Blow-Out Preventer (BOP).

Once the hole has been sealed,the Lower Marine Riser Package (LMRP: the upper part of the BOP) is detached from the riser and the riser is pulled back to the vessel, allowing CHIKYU to leave for safer seas.
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