Drilling assembly for percussion drilling of deep wells

摘要

A percussion drilling tool assembly is provided which operates under fluid pressure to reciproce a hammer, the hammer is disposed in a barrel assembly and operates to strike an anvil bit shank to cause the bit to thereby penetrate a rock substrate material. A central fluid passage through the drill stem of the assembly and through the reciprocating hammer allows a flushing fluid to be used with the drilling assembly to flush cuttings from the hole up and around the drill stem simultaneously with and separate from the fluid operating system for reciprocating the hammer. The drill stem includes intake and exhaust passages for pressured working fluid as well as a mud passage for the flushing fluid or mud, the drill stem is made up in sections connected to form a string which extends the length of the hole and provide the pressured working fluid and mud to the pneumatic tool connected at the end of the drill stem.