I am no expert, but was fortunate many decades ago to know some one in management of a coal mine in Newcastle, and was given a one on one tour of mine.
He told me, we were under a lake at that moment of time in the tour. Interesting Tour.
With coal they remove all the material, hence a tunnel that I was in was 2m high 5m wide approx going by memory.
They had bigger "room" near bottom of shaft entrance for workshop were thy assemble and disassemble their "mole" and other machinery,to fit in shaft for delivery and removal.
Fracking from what I read is just a drill hole then cracking the formation to remove gases.
A bit like pin hole surgery to open surgery I would assume, not as invasive.
