Retrieving the CORK

Hole 395A was first drilled in 1975, and on Friday, we successfully retrieved the CORK observatory that was installed in 1997 on ODP Leg 174B (14 years ago). Here’s a look at part of that process.

First, the drill floor guys picked up the CORK pulling tool and started preparing to lower it to the seafloor. They then picked up some drill collars (very thick-walled, heavy, orange pipe)—these make lots of noise as they pull them up from where they are stored on the main deck to the rig floor. The heavy drill collars at the bottom of the drill string will keep it in tension (it is weak in compression = bad!).

Once the CORK pulling tool and drill collars were lowered through the moonpool, we started adding stands of drill pipe (a stand is 3 joints of drill pipe and is 30 m long). The first time we pick up the stands of drill pipe, it takes a bit longer than normal—they have to “strap and rabbit” the drill pipe [“strap” = measure the length of every piece of pipe; “rabbit” = pass a tool through the inside of each piece of pipe to make sure there’s nothing blocking it]. The stands are added one after another until the pipe reaches the ocean floor, which is at about 4490m. Since each stand is 30m long, that’s about 150 stands of pipe that have to be screwed together! Watch the video below to see the guys fitting the stands together…a process we call “Tripping Pipe.”


A single question

Wow, the Tripping Pipe video was very cool! I only have one question:
Do the workers on board sometimes confuse the various instruments for readying the drill pipe?

sometimes, but rarely

Hi Luke, I asked Adam, our Expedition Project Manager, and here's what he said: Sometimes people get confused, but only rarely. The work on the drill floor is not only super important, but it's REALLY dangerous. When we are coring in deep water (like this expedition), the driller is raising and lowering up to 550,000 lbs of drill pipe with workers all around. If they get something wrong, someone can get very hurt. They also check the “pipe tally” very carefully (that’s the number and length of each piece of drill pipe they have in the drill string); it's an important part of their job.


My name is Kay Benitez and I'm a biology / astronomy / environmantal science teacher at the North Hollywood Zoo Magnet for biological / zoological studies. What an incredible process! How far down can the pipe extend? Have you ever broken it? How can you detect how far down the ocean floor is? Thanks for posting this!

great questions, kay!

How far down can the pipe extend? The deepest water depth the JR has drilled in was 5,980 m (19,614 ft, 3.72 miles) in the Pacific Ocean in 1989. The maximum water depth the JR is capable of drilling in is 8,230m (27,000 ft, 5.11 mi).

Have you ever broken it?
From Adam (our Expedition Project Manager): Oh yes. My first expedition as a staff scientist was Leg 149 off Iberia (Spain/Portugal). When retrieving the drill string, the pipe failed (broke off) at the rig floor with the bit about 3600 m below the rig floor. We lost 3600 m of drill pipe (about $500,000 in 1993 = a lot more today).

How can you detect how far down the ocean floor is?
We use sonar to bounce sound off the seafloor and listen for the returned sound—this gives us the time for traveling down and back. The speed of sound in water is 1500 m/s. From this info, you can get the depth. We also use the drill string. We measure each piece of drill pipe and lower it down and touch the seafloor—we can also use the camera system to see this.