How deep drilling(oil, etc) avoids drill twisting on its axis? Wouldn’t kilometers long steel drills be akin to licorice?
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They don’t. The pipe absolutely does twist on its axis. On a very long pipe you might put 10 or more rotations into the top before the bit starts to turn at the bottom. But that’s OK. As long as the bit is turning and you don’t yield (overstress) the pipe it’s fine.
There is a *huge* weight at the bottom, right behind the bit, made of thick wall pipe called “drill collars”. These make sure the pipe is all in tension so it doesn’t want to buckle. One of the major jobs of the driller is to make sure the weight-on-bit is right so that the pipe *doesn’t* buckle. You always want the drill string to be “hanging” from the rig. The weight in the bit should only be from the drill collars.
All these rotations are part of why you need such tight joints…if the bit sticks the pipe will temporarily wind up. When the bit releases all that twist unwinds, quickly, and can overshoot and actually unscrew a connector if you didn’t have the joint torques correct in the first place.
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