Bi-Axial Drill Bits and Bit Adaptors

Abstract

Drill bits comprise a body having an uphole end and a downhole end. The uphole end is adapted for connection to a tool assembly for rotating the drill bit. The tool assembly has an axis of rotation. The downhole end has one or more cutting members adapted for removing material in contact with the downhole end when the drill bit is rotated. The body has an uphole major axis and a downhole major axis. The uphole axis and the downhole axis are offset from each other. The uphole axis is central to the uphole end and is aligned with the tool assembly axis of rotation. The uphole axis defines an axis of rotation for the drill bit. The downhole axis is central to the downhole end.

1 . (canceled) 
     
     
         2 . (cancelled) 
     
     
         3 . (canceled) 
     
     
         4 . An adaptor for a drill bit, said adaptor comprising:
 (a) a body having an uphole end and a downhole end;   (b) said uphole end being adapted for releasable connection to a tool assembly for rotating a drill bit, said tool assembly having an axis of rotation;   (c) said downhole end being adapted for releasable connection to a drill bit, said drill bit having an axis of rotation;   (d) said body being adapted to transfer rotation of said tool assembly to said drill bit in both directions and having an uphole major axis and a downhole major axis,   (e) said uphole axis being adapted for alignment with said tool assembly axis of rotation;   (f) said downhole axis being adapted for alignment with said drill bit axis of rotation;   (g) wherein said uphole axis and said downhole axis are offset from each other.   
     
     
         5 . The adaptor of  claim 4 , wherein said uphole axis and said downhole axis are substantially parallel to each other. 
     
     
         6 . The adaptor of  claim 4 , wherein said body defines a central passage extending laterally through said body. 
     
     
         7 . The adaptor of  claim 5 , wherein said body defines a central passage extending laterally through said body. 
     
     
         8 . The adaptor of  claim 6 , wherein said body defines a circulation port extending from said central passage to the exterior of said body, said port adapted to divert a portion of fluid from said central passage to the exterior of said adaptor above said drill bit. 
     
     
         9 . The adaptor of  claim 7 , wherein said body defines a circulation port extending from said central passage to the exterior of said body, said port adapted to divert a portion of fluid from said central passage to the exterior of said adaptor above said drill bit. 
     
     
         10 . The adaptor of  claim 8 , wherein said circulation port is directed downhole. 
     
     
         11 . The adaptor of  claim 8 , wherein said circulation port is directed uphole. 
     
     
         12 . A drilling tool assembly, said assembly comprising a drill bit and an adaptor of  claim 4 . 
     
     
         13 . A drilling tool assembly, said assembly comprising a drill bit and an adaptor of  claim 6 . 
     
     
         14 . A drilling tool assembly, said assembly comprising a chill bit and an adaptor of  claim 8 . 
     
     
         15 . The assembly of  claim 10 , wherein said drill bit is a rotary cone or fixed head drill bit. 
     
     
         16 . A method of performing an operation to drill out obstructions in a well tubular, said method comprising:
 (a) running a tool assembly into said tubular, said tool assembly having an axis of rotation and comprising a drill bit having one or more cutting members at its downhole end adapted for removing material from said obstruction, said downhole end of said tool bit having a central axis offset from said tool assembly axis of rotation;   (b) rotating said tool assembly to cause said drill bit to drill out said obstruction.   
     
     
         17 . The method of  claim 16 , wherein said tool assembly comprises an adaptor having a first axis aligned with said tool assembly axis of rotation and a second axis aligned with said tool bit central axis. 
     
     
         18 . The method of  claim 17 , wherein said method comprises circulating fluid through a central passage extending laterally through said adaptor and a port extending from said central passage to the exterior of said adaptor above said tool bit. 
     
     
         19 . The method of  claim 16 , wherein said drill bit is a rotary cone or fixed head drill bit. 
     
     
         20 . The method of  claim 17 , wherein said drill bit is a rotary cone or fixed head drill bit.