So how is the drilling actually conducted? Is there basically a miles-long, rapidly-spinning, articulated shaft with a drill bit at the bottom and a motor at the surface? What sorts of weird and wonderful engineering challenges do you run into with that sort of setup, especially as your giant drill grows larger than 10 miles in length?
Generally, the shaft would rotate with a drill bit at the bottom. But, it seems in the case of Superdeep Borehole, they developed a new mechanism to rotate only the drill bit at the bottom of the shaft[1]. They pumped pressurized "drilling fluid"[2][3] down the shaft to spin the drill bit.
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So how is the drilling actually conducted? Is there basically a miles-long, rapidly-spinning, articulated shaft with a drill bit at the bottom and a motor at the surface? What sorts of weird and wonderful engineering challenges do you run into with that sort of setup, especially as your giant drill grows larger than 10 miles in length?
Generally, the shaft would rotate with a drill bit at the bottom. But, it seems in the case of Superdeep Borehole, they developed a new mechanism to rotate only the drill bit at the bottom of the shaft[1]. They pumped pressurized "drilling fluid"[2][3] down the shaft to spin the drill bit.
[1]http://www.ritchiewiki.com/wiki/index.php/Kola_Superdeep_Bor...
[2]http://www.supertightstuff.com/03/18/featured/kola-superdeep...
[3]http://www.damninteresting.com/the-deepest-hole/