US Patent 7814991 Process and apparatus for subterranean drilling

A method and apparatus for drilling a subterranean formation or material utilizing a drilling apparatus which includes a drill string having a leading end and a trailing end and having a bottom hole assembly connected with the leading end. The bottom hole assembly includes a drill bit and an externally threaded screw section. In operation, the drill bit is rotated, forming material cuttings and an opening in the subterranean formation, and the threaded screw section is rotated within the opening, forming a helical groove in the subterranean formation.