I’m not an expert, but I believe drilling, at least horizontal drilling, is not accomplished by rotating the whole pipe.
There’s a bit on the end that does the actual boring and it’s hydraulic. The pipe is pressurized to drive the boring bit and flush the material out. Since only the “end” is doing the boring, I believe this is how they can steer it.
From what I’ve heard, they actually communicate with the bit using some sort of pressure pulse signaling through the working fluid.
I’m sure others with more experience can elaborate. I may not understand it properly.
Wow. Excellent explanation. Thank you so much. More like the Big Dig.