Percussive Drill String Assemblies And Systems And Methods Of Using Same

Abstract

A percussive drill string assembly including a drill bit and a drill rod. The drill bit has a body having: a circumferential wall; a crown extending distally from the circumferential wall; and a threaded portion extending proximally from the circumferential wall. The threaded portion has an outer surface that defines at least one thread having a tapered thread profile. The drill rod has a box end portion having an inner surface that defines: a receptacle configured to receive the threaded portion of the bit; and at least one thread having a tapered profile complementary to the tapered thread profile of the threaded portion of the bit.

1 . A single-rod percussive drill string assembly having a longitudinal axis and comprising:
 a drill bit having:
 a body having:
 a circumferential wall; and 
 a crown extending distally from the circumferential wall; and 
 
 a threaded portion extending proximally from the circumferential wall, wherein the threaded portion has an outer surface that defines at least one thread having a tapered thread profile; and 
   a drill rod having:
 a box end portion having an inner surface that defines:
 a receptacle configured to receive the threaded portion of the bit; and 
 at least one thread having a tapered profile complementary to the tapered thread profile of the threaded portion of the bit, 
 
 wherein the drill rod is the only drill rod of the percussive drill string assembly. 
   
     
     
         2 . The percussive drill string assembly of  claim 1 , wherein the box end portion of the drill rod defines a distal end of the drill rod and has an outer surface, wherein at least a portion of the outer surface of the box end portion is inwardly tapered moving proximally from the distal end. 
     
     
         3 . The percussive drill string assembly of  claim 1 , wherein the circumferential wall and the threaded portion of the drill bit cooperate to define an interior space extending along the longitudinal axis of the percussive drill string assembly. 
     
     
         4 . The percussive drill string assembly of  claim 3 , wherein the drill rod comprises a mid-body portion that extends proximally from the box end portion, and wherein the mid-body portion has an inner surface that cooperates with the circumferential wall and the threaded portion of the drill bit to further define the interior space. 
     
     
         5 . The percussive drill string assembly of  claim 3 , wherein the threaded portion of the drill bit defines a proximal end of the drill bit and wherein the body of the drill bit defines a shoulder that is configured to abut a distal end of the drill rod, and wherein the drill bit comprises: a water slot defined by the proximal end of the drill bit and extending radially from the interior space to the outer surface of the threaded portion; and/or a water slot defined by the shoulder and extending radially outwardly to an exterior surface of the drill bit. 
     
     
         6 . The percussive drill string assembly of  claim 3 , wherein the crown of the body of the drill bit is a full-face crown. 
     
     
         7 . The percussive drill string assembly of  claim 6 , wherein the crown of the body of the drill bit defines a plurality of bores in fluid communication with the interior space. 
     
     
         8 . The percussive drill string assembly of  claim 3 , wherein the circumferential wall of the body of the drill bit defines at least one bore in fluid communication with the interior space. 
     
     
         9 . The percussive drill string assembly of  claim 1 , wherein the circumferential wall of the body of the drill bit has an outer surface that defines at least one axial channel. 
     
     
         10 . The percussive drill string assembly of  claim 2 , wherein the outer surface of the box end portion of the drill rod defines a plurality of axial slots. 
     
     
         11 . The percussive drill string assembly of  claim 10 , wherein the circumferential wall of the body of the drill bit has an outer surface that defines at least one axial channel, and wherein at least one axial slot of the plurality of axial slots is axially aligned with a corresponding axial channel of the body of the drill bit. 
     
     
         12 . The percussive drill string assembly of  claim 10 , wherein the axial slots are proximally tapered. 
     
     
         13 . The percussive drill string assembly of  claim 10 , wherein the box end portion of the drill rod has an axial length, and wherein at least one axial slot of the plurality of axial slots has an axial length that is greater than 60% of the axial length of the box end portion. 
     
     
         14 . The percussive drill string assembly of  claim 4 , wherein the mid-body portion of the drill rod is welded to the box end portion of the drill rod. 
     
     
         15 . The percussive drill string assembly of  claim 4 , wherein the mid-body and box end portions of the drill rod are forged as a single piece. 
     
     
         16 . The percussive drill string assembly of  claim 1 , wherein the drill bit has a gauge diameter, wherein the circumferential wall and the crown of the body of the drill bit have a combined axial length, and wherein a ratio between the combined axial length of the crown and the body of the drill bit and the gauge diameter of the drill bit is less than 0.7. 
     
     
         17 . The percussive drill string assembly of  claim 1 , wherein the crown of the body of the drill bit has a staged profile. 
     
     
         18 . The percussive drill string assembly of  claim 10 , wherein the box end portion of the drill rod has an outer diameter that circumscribes a cylinder, and wherein the plurality of axial slots are inwardly recessed from the outer diameter and inwardly tapered moving proximally from the distal end. 
     
     
         19 . The percussive drill string assembly of  claim 1 , wherein the drill rod comprises at least one back face defining a cutting profile. 
     
     
         20 . A drilling system comprising the percussive drill string assembly of  claim 1 , wherein the drilling system is a single-pass system that does not comprise an extension or an additional drill rod. 
     
     
         21 . A drilling method comprising:
 penetrating a formation using a single-rod percussive drill string assembly having a longitudinal axis and comprising:
 a drill bit having:
 a body having:
 a circumferential wall; and 
 a crown extending distally from the circumferential wall; and 
 
 a threaded portion extending proximally from the circumferential wall, wherein the threaded portion has an outer surface that defines at least one thread having a tapered thread profile; and 
 
 a drill rod having:
 a box end portion having an inner surface that defines:
 a receptacle configured to receive the threaded portion of the bit; and 
 at least one thread having a tapered profile complementary to the tapered thread profile of the threaded portion of the bit 
 
 wherein the drill rod is the only drill rod of the percussive drill string assembly.