They drill with water, or “muds”. The bit on the end is larger than the drill rods themselves, creating an annulus for water to pass through. This film of water prevents hole drag by keeping the rods from grabbing the rock.
As far as pushing goes, after about 400 meters, the drill is no longer pushing, the weight of the rods is what’s pushing the bit into the ground. After around 800 meter, the drill is being used to hold the weight of the rods back a little bit, creating tension on the rod string which helps keep them straight.
Latest Answers