Rotary drag bit with increased back rake angle gauge cutter

Abstract

A fixed cutter rotary drill bit having gauge cutting elements at large back rake angles are disclosed. The gauge is located at the outer diameter side wall portion of the bit that extends from the cutting end. The gauge and its cutting components contact the side wall of the bore hole during drilling operations. The gauge cutting elements may be configured at a back rake angle in a range of about 40° to 70°.

1 . A fixed cutter rotary drill bit, comprising:
 a bit body having a bit axis and a cutting profile defined about the bit axis, the cutting profile including a cone extending from the bit axis, a nose adjacent the cone, a shoulder adjacent the nose, and a gauge adjacent the shoulder, the gauge being adapted to engage a side wall of a bore hole during drilling operations; and   a plurality of cutting elements extending from the cone, nose, shoulder and gauge of the cutting profile, and at least one of the cutting elements extending from the gauge has a back rake angle in a range of 40° to 70°.   
   
   
       2 . The fixed cutter rotary drill bit of  claim 1 , wherein the cutting elements are selected from the group consisting of polycrystalline diamond cutters (PDC), and impregnated and natural diamond bit cutting elements. 
   
   
       3 . The fixed cutter rotary drill bit of  claim 1 , wherein at least some of the cutting elements extending from the gauge are ground flat at an outer diameter of the bit body. 
   
   
       4 . The fixed cutter rotary drill bit of  claim 1 , wherein each cutting element has a cylindrical base that is secured in a pocket in the bit body, a cutting element axis, and a cutting face with a beveled edge. 
   
   
       5 . The fixed cutter rotary drill bit of  claim 4 , wherein the cutting face extends in a plane defining a back rake axis and a side rake axis that is perpendicular to the back rake axis, with both the back rake and side rake axes extending through the cutting element axis, and the back rake axis being parallel to a surface of the gauge and the bit axis, such that a positive back rake angle at the gauge inclines the cutting face away from the bit axis. 
   
   
       6 . The fixed cutter rotary drill bit of  claim 5 , wherein the back rake angle is 40°. 
   
   
       7 . The fixed cutter rotary drill bit of  claim 5 , wherein the back rake angle is 65°. 
   
   
       8 . A fixed cutter rotary drill bit, comprising:
 a bit body having a bit axis, a threaded end for connection into a drill string, a cutting end opposite the threaded end, and a cutting profile defined about the bit axis, the cutting profile including a cone extending from the bit axis, a nose adjacent the cone, a shoulder adjacent the nose, and a gauge adjacent the shoulder and on a radially outermost portion of the bit body relative to the bit axis, the gauge being adapted to engage a side wall of a bore hole during drilling operations; and   a plurality of cutting elements extending from the cutting end in the cone, nose, shoulder and gauge of the cutting profile, and at least one of the cutting elements extending from the gauge has a back rake angle in a range of 40° to 70°.   
   
   
       9 . The fixed cutter rotary drill bit of  claim 8 , wherein the cutting elements are selected from the group consisting of polycrystalline diamond cutters (PDC), and impregnated and natural diamond bit cutting elements. 
   
   
       10 . The fixed cutter rotary drill bit of  claim 8 , wherein at least some of the cutting elements extending from the gauge are ground flat at an outer diameter of the bit body. 
   
   
       11 . The fixed cutter rotary drill bit of  claim 8 , wherein each cutting element has a cylindrical base that is secured in a pocket in the cutting end, a cutting element axis, and a cutting face with a beveled edge. 
   
   
       12 . The fixed cutter rotary drill bit of  claim 11 , wherein the cutting face extends in a plane defining a back rake axis and a side rake axis that is perpendicular to the back rake axis, with both the back rake and side rake axes extending through the cutting element axis, and the back rake axis being parallel to a surface of the gauge and the bit axis, such that a positive back rake angle at the gauge inclines the cutting face away from the bit axis. 
   
   
       13 . The fixed cutter rotary drill bit of  claim 12 , wherein the back rake angle is 40°. 
   
   
       14 . The fixed cutter rotary drill bit of  claim 12 , wherein the back rake angle is 65°. 
   
   
       15 . A fixed cutter rotary drill bit, comprising:
 a bit body having a bit axis, a threaded end for connection into a drill string, a cutting end opposite the threaded end, and a cutting profile defined about the bit axis, the cutting profile including a cone extending from the bit axis, a nose adjacent the cone, a shoulder adjacent the nose, and a gauge adjacent the shoulder and on a radially outermost portion of the bit body relative to the bit axis, the gauge being adapted to engage a side wall of a bore hole during drilling operations;   a plurality of cutting elements extending from the cutting end in the cone, nose, shoulder and gauge of the cutting profile, each cutting element having a cylindrical base, a cutting element axis, and a cutting face, wherein the cutting face extends in a plane defining a back rake axis and a side rake axis that is perpendicular to the back rake axis, with both the back rake and side rake axes extending through the cutting element axis, and the back rake axis being parallel to a surface of the gauge and the bit axis, such that a positive back rake angle at the gauge inclines the cutting face away from the bit axis; and   at least one of the cutting elements extending from the gauge has a back rake angle in a range of 40° to 70°.   
   
   
       16 . A fixed cutter rotary drill bit according to  claim 15 , wherein the cutting elements are selected from the group consisting of polycrystalline diamond cutters (PDC), impregnated and natural diamond bit cutting elements. 
   
   
       17 . A fixed cutter rotary drill bit according to  claim 15 , wherein at least some of the cutting elements extending from the gauge are ground flat at an outer diameter of the bit body. 
   
   
       18 . A fixed cutter rotary drill bit according to  claim 15 , wherein the back rake angle is 40°. 
   
   
       19 . A fixed cutter rotary drill bit according to  claim 15 , wherein the back rake angle is 65°.