SOUTHARD-DRIL

DRILLING APPARATUS, NAMELY, EARTH BORING DEVICES FOR DRILLING BORE HOLES; DRILL BITS USED TO DRILL THROUGH SUBTERRANEAN ZONES INCLUDING HYDROCARBON RESERVOIRS; DRILLING SYSTEMS COMPRISING TUBULAR MEMBERS AND A DRILL BIT; DRILLING SYSTEMS FOR DRILLING SUBTERRANEAN ZONES COMPRISING AN INNER BIT AND AN OUTER BIT