Air percussion drilling assembly for directional drilling applications

Abstract

An air percussion hammer drill is disclosed for operation in an earthen formation. The air compression hammer mechanism comprises a piston that reciprocates while simultaneously rotating within its housing. A hammer drill bit slidably keyed to the bottom of the piston transfers the impact energy to the formation and rotates during operation independent of an attached drill string. The air percussion hammer assembly is therefore ideally suited to directional drilling activities.

What is claimed is: 
     
       1. An air percussion hammer apparatus for directional drilling operations with means for rotating the hammer bit while it reciprocates in a housing independent of an attached drill string, said bit rotating means comprising: a cylindrical housing forming a first open up-stream end connectable to a drill string component and a second downstream end, said second end containing said hammer bit,   a pneumatic feed tube forming a first open end and second substantially closed end, said first end of the feed tube is concentric with and fixed within said housing and positioned toward said first up-stream end of said housing, the second end of the feed tube forms one or more metered openings between said first and second ends of the feed tube,   a piston body is slidably retained within a first cylindrical sleeve formed by said cylindrical housing, the piston body forms a first open upstream end and a second open downstream end, said first open upstream end is reduced in diameter, inner walls formed by said first open upstream end further concentrically contains said second end of said feed tube, said inner walls of said first open upstream end being slidably engaged with an outside surface formed by said second end of said feed tube, said second downstream end of said piston body engaged with said first cylindrical sleeve forms a hammer striking surface, said piston body further forms at least one axially oriented helical groove in an outside wall formed by said reduced diameter first open upstream end of said piston body and at least a pair of pneumatic communication ports between an outside wall of said piston body positioned between said first open upstream end and said second open downstream end of said piston body and an interior chamber formed by said piston body, one of said ports leads from said interior chamber formed by said piston body to a chamber formed between said outside wall of the first open upstream end of the piston body and said first cylindrical sleeve, the other of said ports leads from an interior chamber formed within the first open upstream end of the piston body through a port formed by said piston body to said first cylindrical sleeve adjacent thereto, one or the other of said ports in said body sequentially registers with said metered openings in said feed tube when said reciprocating piston is moved into alignment therewith during an operating cycle of said apparatus, said second open downstream end of the piston body further forms a longitudinally extended sleeve concentrically therein,   a hammer bit body is slidably contained within a second sleeve formed by said second end of said cylindrical housing, said hammer bit body further forms an upstream shaft end adapted to be axially slidable within said sleeve formed in said second open downstream end of said piston body, said shaft end of said hammer is rotationally keyed to said piston body by an engagement means such that the hammer bit moves in concert with said piston, said bit body forming a second downstream cutter end, and   clutch means contained within said housing, said clutch means being positioned adjacent to and interconnected with said at least one helical groove formed in said first reduced diameter open upstream end of said piston body, the clutch means serves to rotate the piston body and the hammer bit body engaged therewith incrementally and in one direction only, each time the piston body oscillates within the cylindrical housing during operation of the air percussion hammer apparatus.   
     
     
       2. The invention as set forth in claim 1 wherein said engagement means that slidably keys the upstream shaft end of said hammer bit body to said sleeve formed by said second open downstream end of the piston body comprises at least a pair of longitudinally extending, oppositely opposed flats formed by said shaft end, said second open downstream end of the piston body forming complimentary flats to slidably accept said shaft within said sleeve. 
     
     
       3. The invention as set forth in claim 1 wherein said engagement means comprises at least a pair of spherically shaped detents slidably engaged with complimentary shaped, longitudinally extending grooves formed in adjacent surfaces of said upstream shaft end of said hammer and said sleeve formed in said piston. 
     
     
       4. The invention as set forth in claim 3 wherein there are three spherically shaped detents connected to and extending from said upstream end of said shank of said hammer, said detents being positioned about 120 degrees apart, said detents being slidably engaged with complimentary shaped longitudinally extending grooves formed in an inner wall of said sleeve formed by said second open downstream end of the piston body. 
     
     
       5. The invention as set forth in claim 1 wherein said engagement means comprises a multiplicity of longitudinally extending splines formed by said shank of said hammer bit, said splines being slidably interfitted with splines formed by said second open downstream end of the piston body in a wall of said sleeve therein. 
     
     
       6. The invention as set forth in claim 1 wherein said piston body and hammer bit is rotated by said clutch means when said piston body moves toward said second open downstream end of said cylindrical housing. 
     
     
       7. The invention as set forth in claim 1 wherein the rotational speed of the piston and hammer is between 10 and 20 RPM. 
     
     
       8. The invention as set forth in claim 7 wherein the rotational speed is about 20 RPM. 
     
     
       9. The invention as set forth in claim 1 wherein the hammer bit impacts an earthen formation during operation of the air percussion apparatus about 1600 strokes of said reciprocating piston body and hammer bit per minute. 
     
     
       10. The invention as set forth in claim 9 wherein the rotational speed of the piston and hammer results in a rotational displacement of the hammer bit with respect to said cylindrical housing of about 5 degrees per each impact of the bit against the formation. 
     
     
       11. The invention as set forth in claim 1 wherein the clutch means is a sprag clutch. 
     
     
       12. The invention as set forth in claim 11 wherein the sprag clutch allows the piston and hammer to rotate on the downstroke only, the clutch releases on an upward cycle of the piston body when said piston body moves toward said first open upstream end of said cylindrical housing. 
     
     
       13. The invention as sets forth in claim 11 wherein the clutch is engaged with the helical groove formed in said reduced diameter first open upstream end of the piston body by a ball bearing secured to said clutch, said helical groove being circular in cross section to match the circumference of the ball bearing engaged therewith. 
     
     
       14. The invention as set forth in claim 12 wherein there are three helical grooves formed in said first open upstream end of the piston body 120 degrees apart, each of said grooves is engaged with said ball bearing retained within said clutch means. 
     
     
       15. An air percussion hammer apparatus for directional drilling operations comprising: a cylindrical housing having an upstream end connectable to a drill string component and a downstream end including means for mounting a hammer bit;   a piston slidably retained within the housing, a downstream end of the piston including a surface for striking a hammer bit mounted on the end of the housing;   fluid porting in the housing for alternately driving the piston upwardly in the housing and driving the piston downwardly in the housing for striking a hammer bit;   means for rotating the piston during the downward stroke of the piston;   means for preventing rotation of the piston during the upward stroke of the piston; and   keying means for permitting relative longitudinal movement while preventing relative rotation between the hammer bit and the piston.   
     
     
       16. The invention as set forth in claim 15 wherein the hammer bit is mounted for reciprocal movement in the housing and characterized by means for venting fluid from the hammer when the hammer bit is relatively down in the housing and for applying fluid pressure for driving the piston when the hammer bit is relatively up in the housing. 
     
     
       17. The invention as set forth in claim 15 wherein the hammer bit is slidably contained within the downstream end of the cylindrical housing, the hammer bit comprising an upstream shaft end axially slidable within the piston, the shaft end of the hammer being rotationally keyed to the piston by an engagement means such that the hammer bit rotates in concert with the piston. 
     
     
       18. The invention as set forth in claim 17 wherein the clutch means comprises at least a pair of spherically shaped detents for slidably engaging complementary shaped helical grooves in the upstream end of the piston. 
     
     
       19. The invention as set forth in claim 15 wherein the keying means for permitting relative longitudinal movement while preventing relative rotation between the hammer bit and the piston comprises three spherically shaped detents between the upstream end of the shank of the hammer and the inside of the piston, the detents being positioned about 120 degrees apart and slidably engaged with complementary shaped longitudinally extending grooves. 
     
     
       20. The invention as set forth in claim 15 wherein the means for rotating the piston during the downward stroke of the piston comprises a helical groove in the piston with a helix angle and length sufficient for rotating the piston approximately five degrees per cycle of the piston. 
     
     
       21. The invention as set forth in claim 15 wherein the means for rotating the piston during the downward stroke of the piston comprises a helical groove in the piston and a ball bearing engaging the housing and the helical groove. 
     
     
       22. The invention as set forth in claim 21 wherein there are three helical grooves formed in the upstream end of the piston 120 degrees apart, each of the grooves being engaged with a ball bearing retained within the housing. 
     
     
       23. A method of rotating a hammer rock bit of an air percussion hammer bit apparatus for directional drilling operations while it reciprocates in a housing, the rotation of the bit being independent of an attached drill string comprising the steps of; forming a cylindrical housing an open upstream end connectable to a drill string component and a downstream end containing a hammer bit, the hammer bit being free to reciprocate longitudinally in the housing;   mounting a longitudinally moveable annular piston on the housing defining a first chamber having an upstream end and a downstream end having a hammer striking surface, and including a helical groove in an outside wall of the piston;   alternately   passing air from a chamber above the upstream end of the piston to the inside of the piston, and   passing air from the inside of the piston to a chamber outside of the piston adjacent to the downstream end of the piston, for reciprocating the piston in the housing and striking the hammer bit;   engaging the helical groove with a detent for rotating the piston during a downward stroke of the piston;   rotating the hammer bit in concert with the piston; and   preventing rotation of the piston during an upward stroke of the piston. .Iadd.   
     
     
       24.  A component for a bottomhole assembly used for directional drilling in an underground borehole, the assembly having a bend and one or more stabilizers comprising: a housing having an up-stream end associated with a drill string and a downstream end associated with a drill bit;   a reciprocating member slidably mounted within the housing, the reciprocating member being movable upwardly and downwardly within the housing and having an impact surface for striking the drill bit; and   means within the housing for cooperatively rotating the reciprocating member and the drill bit independent of movement of the housing, and independent of movement of the drill string. .Iaddend..Iadd.   
     
     
       25.  A component for a steerable bottomhole assembly, the assembly having a bend and one or more concentric stabilizers comprising: a housing having an upstream end connectable with a drill string and a downstream end;   a reciprocating piston slidably retained and movable upwardly and downwardly within the housing, the piston having an impact surface for striking a drill bit; and   a clutch that permits rotation of the piston independent of rotation of the housing. .Iaddend..Iadd.26. A component for a bottomhole assembly used for directional drilling in an underground borehole, the assembly having a bend and one or more stabilizers comprising:   a housing having an upstream end connectable to a drill string and a downstream end;   a reciprocating piston slidably retained and movable upwardly and downwardly within the housing, the piston having an impact surface for striking a drill bit; and   a clutch that permits rotation of the piston independent of rotation of the drill string. .Iaddend..Iadd.27. A component for a steerable bottomhole assembly for controlled drilling of a borehole, the assembly having an upstream end connected with a drill string, wherein the drill string is rotatable from the surface comprising:   a housing having an up-stream end associated with a drill string and a downstream end associated with a drill bit;   a reciprocating member slidably mounted within the housing and moveable upwardly and downwardly within the housing, the reciprocating member having an impact surface for striking the drill bit; and   means for cooperatively rotating the reciprocating member and drill bit independent of movement of the housing, and independent of movement of the   
     
     
        drill string. .Iaddend..Iadd.28.  A component for a directional drilling assembly, the assembly including a bend and one or more concentric stabilizers and having an upstream end connectable with a drill string comprising: a housing;   a piston slidably retained within the housing;   fluid porting in the housing allowing the piston to be driven upwardly and downwardly in the housing;   means for rotating the piston during the downward stroke of the piston;   means for preventing rotation of the piston during the upward stroke of the piston; and   keying means for permitting relative longitudinal movement while preventing   
     
     
        relative rotation between a hammer bit and the piston. .Iaddend..Iadd.29. A method for directional drilling of a borehole with a bottomhole assembly having an upstream end connected with a drill string, the drill string being rotatable from the surface, wherein the bottomhole assembly further includes a drill bit and a housing containing a reciprocating piston, comprising: associating the piston and drill bit to allow cooperative rotation of the piston and drill bit;   reciprocating the piston in the housing;   rotating the piston in the housing;   rotating the drill bit in concert with the piston; and   restraining rotation of the drill string. .Iaddend..Iadd.30. A method for controlled directional drilling of a borehole utilizing a drilling system, the drilling system including a rotatable drill string and a bottomhole assembly, the bottomhole assembly having an upsteam end connectable to the drill string for cooperative movement therewith, the bottomhole assembly further having a bend and a drilling hammer, the drilling hammer including a rotatable piston capable of impacting a drill bit, the piston and drill bit associated for cooperative rotation independent from rotation of the drill string, comprising:   drilling at an angle by rotating the piston of the drilling hammer and restraining rotation of the drill string; and   drilling in a straight direction by rotating both the piston of the   
     
     
        drilling hammer and the drill string. .Iaddend..Iadd.31.  A method for controlled directional drilling of a borehole utilizing a drilling system, the drilling system including a rotatable drill string and a bottomhole assembly, the bottomhole assembly having an upsteam end connectable to the drill string for cooperative movement therewith, the bottomhole assembly further having a bend and a drilling hammer, the drilling hammer including a rotatable piston capable of impacting a drill bit, the piston and drill bit associated for cooperative rotation independent from rotation of the drill string, comprising: steering the bottomhole assembly by activating the drilling hammer and selectively rotating the drill string. .Iaddend..Iadd.32. A bottomhole assembly for directional drilling, the bottomhole assembly comprising:   a housing having an upstream end connectable to a drill string and a downstream end, the housing being insertable into an underground borehole;   a reciprocating piston slidably retained and movable upwardly and downwardly within the housing, the reciprocating piston having an impact surface for striking a drill bit; and   at least one helical groove allowing rotation of the piston independent of rotation of the housing. .Iaddend..Iadd.33. A bottomhole assembly for directional drilling, the bottomhole assembly comprising:   a housing having an upstream end connectable to a drill string and a downstream end, the housing being insertable into an underground borehole;   a reciprocating piston slidably retained and movable upwardly and downwardly within the housing, the reciprocating piston having a cylindrical outer surface and an impact surface for striking a drill bit; and   at least one helical groove formed on the cylindrical outer surface of the piston and allowing rotation of the piston independent of rotation of the   
     
     
        drill string. .Iaddend..Iadd.34.  A component for a directional drilling assembly, the assembly including a bend, comprising: a housing having an upstream end connectable to a drill string and being insertable into an underground borehole;   a piston slidably mounted within the housing, the piston moveable upwardly and downwardly within the housing and rotatable within the housing;   the piston engaging a shaft;   a key engaging the piston and the shaft and for allowing cooperative rotational movement of the piston and the shaft; and   the key including at least one ball and at least one groove. .Iaddend.