Down boring

In this system, the pilot hole is drilled downwards until it connects to a lower access level. The drill string (all drill rods, stabilizers and cutting bits) is retrieved and then a reamer is pushed downwards. The cuttings flow down the previously drilled pilot hole. This method uses drill string in compression and usually stabilizers must be installed to eliminate the potential of the drill string buckling.

In mines, it used in large fill-holes between 0.6 and 1.8 m in diameter.

Applications

★Mining sector: Directional Drilling enables a straight shaft to be drilled in many different applications, such as hoisting shafts in mining. This can be used as an alternative to blind sinking with explosives, as well drilling of batch plant holes when delivering material to underground operations. A straight hole and installation of pipes allows for less wear of the pipe.

★Energy sector: It is commonly used in hydro-electrical projects to ensure straight excavations. Predominantly one gets verticality systems, rotary steerable stabilizers and the more traditional down-the-hole motors.