Tuesday, September 28, 2010

Faster drilling in Chile

Someone recently told me that after you had been retired a while, you wondered how you ever found time for work. Given that this is the week of my Retirement celebration (a little after the event) I am likely going to be somewhat pre-occupied for most of it, so my apologies if posts appear a bit slower than usual and are shorter.

They are not going quite that slow in Chile, where the miners are now waiting as the three drills now work to enlarge the passages down to the rescue chamber. One of them achieved a rate of advance of 150 ft on Monday this week, and may have gone 243 ft on Tuesday. So that the reamed hole is now 984 ft long. But there are problems with pushing the drills too hard – not the least of this is that you can generate enough torque in the pipe that any sudden release can spin up the head with enough energy that it snaps the pipe. So it is better to be a little slower and make sure that things go according to plan. There is currently also about 15 days of work to be done on the surface, to put all the equipment in place that will be needed, to get all the miners out.

After the holes have been completed, over their full length, the rescuers will line the passage with a steel mesh, and then they will be able to lower the cage, that has now arrived at the site. Before that can be done the cage has to be mounted to a frame, and attached to cables, in such a way as to allow it be raised and lowered safely. That construction is apparently what is going to take the 15 days.

There is a considerable difference in the progress of the three tools, the first one to start turns out to be the slowest, and has not reached the miners with the first hole yet. The second used a pre-existing borehole to give it a start (the T-130) while the oilwell drill is drilling the full sized hole in one pass.
The government said the Strata 950 "Plan A" drill reached 1,667 feet (508 meters) Tuesday morning. Once it breaks through to 2,306 feet (703 meters), this drill will need to start over again, widening the hole to its final diameter of 28 inches (70 centimeters) so that the metal sleeve and escape capsule can pass through.

The other two drills are already carving out holes this wide, and making quick progress: the T-130 "Plan B" drill reached nearly halfway to its 2,047-foot (620-meter) goal Tuesday evening, Sougarret said. The "Plan C" Rig 421 oil well drill has carved out 361 feet (110 meters) of its 1,959-foot (597 meter) goal

The intention once the holes are lined, and the cage able to move up and down it, is first to send down a medic and a trained rescue specialist, who will check on the men’s condition and then help get them to the surface. With the food (about 2,200 calories) that the men are getting they have regained some body mass after the initial starvation. The cages are being called Phoenix, and come with an oxygen supply to help over what could be up to an hour of transit time to the surface.

It is encouraging that progress continues to be ahead of schedule, so that there is a hope that the rescue could be completed some time in October.

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