Cutting element arrangement for single roller cone bit

Abstract

A cutting element arrangement for a single roller cone bit includes both at least one substantially non-planar cutting element and at least one substantially planar cutting element. The substantially non-planar cutting element is disposed on an inner row of the single roller cone and the substantially planar cutting element is disposed on an outer row of the single roller cone. With such an arrangement, the substantially non-planar inner row cutting elements effectively penetrate formations while the substantially planar outer row cutting elements maintain bore hole gage.

1 . A roller cone drill bit, comprising: 
 a bit body adapted to be coupled to a drill string;    a bearing journal depending from the bit body; and    a single roller cone rotatably attached to the bearing journal, the single roller cone having at least one substantially planar cutting element and at least one substantially non-planar cutting element.    
   
   
       2 . The roller cone drill bit of  claim 1 , wherein the at least one substantially non-planar cutting element is any one of a conical cutting element and a chisel cutting element.  
   
   
       3 . The roller cone drill bit of  claim 1 , wherein the at least one substantially planar cutting element is a flat crested cutting element.  
   
   
       4 . The roller cone drill bit of  claim 1 , wherein any one of the at least one substantially planar cutting element and the at least one substantially non-planar cutting element is formed of tungsten carbide.  
   
   
       5 . The roller cone drill bit of  claim 1 , wherein the single roller cone is substantially hemispherical in shape.  
   
   
       6 . The roller cone drill bit of  claim 1 , wherein an angular position of any cutting element is defined as the sum of (1) a journal angle from a horizontal plane and (2) an angle between an axis of the single roller cone and an axis of the cutting element.  
   
   
       7 . The roller cone drill bit of  claim 6 , wherein the at least one substantially non-planar cutting element is disposed at an angle substantially between 0 degrees and 120 degrees.  
   
   
       8 . The roller cone drill bit of  claim 6 , wherein the at least one substantially planar cutting element is disposed at an angle substantially between 120 degrees and 175 degrees.  
   
   
       9 . The roller cone drill bit of  claim 6 , wherein the at least one substantially planar cutting element is disposed at an angle substantially between 125 degrees and 165 degrees.  
   
   
       10 . The roller cone drill bit of  claim 6 , wherein the at least one substantially planar cutting element is disposed at an angle substantially between 135 degrees and 155 degrees.  
   
   
       11 . The roller cone drill bit of  claim 6 , wherein the at least one substantially planar cutting element is disposed at an angle substantially between 140 degrees and 150 degrees.  
   
   
       12 . The roller cone drill bit of  claim 6 , wherein the at least one substantially planar cutting element is disposed at an angle substantially between 120 degrees and 175 degrees, and wherein the at least one substantially non-planar cutting element is disposed at an angle substantially between 0 and 120 degrees.  
   
   
       13 . The roller cone drill bit of  claim 1 , wherein the at least one substantially non-planar cutting element has a tip radius to extension ratio substantially equal to 0.3.  
   
   
       14 . The roller cone drill bit of  claim 1 , wherein the at least one substantially planar cutting element has a tip radius to extension ratio substantially between 0.2 and 0.5.  
   
   
       15 . The roller cone drill bit of  claim 1 , wherein any one of the at least one substantially planar cutting element and the at least one substantially non-planar cutting element extends less than or equal to 0.6 inches from a surface of the single roller cone.  
   
   
       16 . The roller cone drill bit of  claim 1 , wherein any one of the at least one substantially planar cutting element and the at least one substantially non-planar cutting element extends greater than or equal to {fraction (7/16)} inches from a surface of the single roller cone.  
   
   
       17 . The roller cone drill bit of  claim 1 , wherein any one of the at least one substantially planar cutting element and the at least one substantially non-planar cutting element extends greater than or equal to 0.5 inches from a surface of the single roller cone.  
   
   
       18 . The roller cone drill bit of  claim 1 , wherein any one of the at least one substantially planar cutting element and the at least one substantially non-planar cutting element extends greater than or equal to 0.55 inches from a surface of the single roller cone.  
   
   
       19 . The roller cone drill bit of  claim 1 , wherein the at least one substantially non-planar cutting element is formed having a core harder than an exterior such that the substantially non-planar cutting element is self-sharpening.  
   
   
       20 . A roller cone drill bit, comprising: 
 a bit body adapted to be coupled to a drill string;    a bearing journal depending from the bit body; and    a single roller cone rotatably attached to the bearing journal, the single roller cone having a plurality of cutting elements disposed at positions selected such that a majority of cutting elements adapted to engage a bottom of a bore hole are substantially non-planar cutting elements and a majority of cutting elements adapted to engage a wall of the bore hole are substantially planar cutting elements.    
   
   
       21 . The roller cone drill bit of  claim 20 , wherein the at least one substantially non-planar cutting element is any one of a conical cutting element and a chisel cutting element.  
   
   
       22 . The roller cone drill bit of  claim 20 , wherein the at least one substantially non-planar cutting element is formed having a core harder than an exterior such that the substantially non-planar cutting element is self-sharpening.  
   
   
       23 . The roller cone drill bit of  claim 20 , wherein the at least one substantially planar cutting element is a flat crested cutting element.  
   
   
       24 . The roller cone drill bit of  claim 20 , wherein any one of the at least one substantially planar cutting element and the at least one substantially non-planar cutting element is formed of tungsten carbide.  
   
   
       25 . The roller cone drill bit of  claim 20 , wherein the single roller cone is substantially hemispherical in shape.  
   
   
       26 . The roller cone drill bit of  claim 20 , wherein an angular position of any cutting element is defined as the sum of (1) a journal angle from a horizontal plane and (2) an angle between an axis of the single roller cone and an axis of the cutting element.  
   
   
       27 . The roller cone drill bit of  claim 26 , wherein the at least one substantially non-planar cutting element is disposed at an angle substantially between 0 degrees and 120 degrees.  
   
   
       28 . The roller cone drill bit of  claim 26 , wherein the at least one substantially planar cutting element is disposed at an angle substantially between 120 degrees and 175 degrees.  
   
   
       29 . The roller cone drill bit of  claim 26 , wherein the at least one substantially planar cutting element is disposed at an angle substantially between 125 degrees and 165 degrees.  
   
   
       30 . The roller cone drill bit of  claim 26 , wherein the at least one substantially planar cutting element is disposed at an angle substantially between 135 degrees and 155 degrees.  
   
   
       31 . The roller cone drill bit of  claim 26 , wherein the at least one substantially planar cutting element is disposed at an angle substantially between 140 degrees and 150 degrees.  
   
   
       32 . The roller cone drill bit of  claim 26 , wherein the at least one substantially planar cutting element is disposed at an angle substantially between 120 degrees and 175 degrees, and wherein the at least one substantially non-planar cutting element is disposed at an angle substantially between 0 and 120 degrees.  
   
   
       33 . The roller cone drill bit of  claim 20 , wherein the at least one substantially non-planar cutting element has a tip radius to extension ratio substantially equal to 0.3.  
   
   
       34 . The roller cone drill bit of  claim 20 , wherein the at least one substantially planar cutting element has a tip radius to extension ratio substantially between 0.2 and 0.5.  
   
   
       35 . The roller cone drill bit of  claim 20 , wherein any one of the at least one substantially planar cutting element and the at least one substantially non-planar cutting element extends less than or equal to 0.6 inches from a surface of the single roller cone.  
   
   
       36 . The roller cone drill bit of  claim 20 , wherein any one of the at least one substantially planar cutting element and the at least one substantially non-planar cutting element extends greater than or equal to {fraction (7/16)} inches from a surface of the single roller cone.  
   
   
       37 . The roller cone drill bit of  claim 20 , wherein any one of the at least one substantially planar cutting element and the at least one substantially non-planar cutting element extends greater than or equal to 0.5 inches from a surface of the single roller cone.  
   
   
       38 . The roller cone drill bit of  claim 20 , wherein any one of the at least one substantially planar cutting element and the at least one substantially non-planar cutting element extends greater than or equal to 0.55 inches from a surface of the single roller cone.  
   
   
       39 . A roller cone drill bit, comprising: 
 a bit body adapted to be coupled to a drill string;    a bearing journal depending from the bit body; and    a single roller cone rotatably attached to the bearing journal, the single roller cone having at least one inner row of cutting elements comprising at least one substantially non-planar cutting element and at least one outer row of cutting elements comprising at least one substantially planar cutting element.    
   
   
       40 . The roller cone drill bit of  claim 39 , wherein the at least one substantially non-planar cutting element is any one of a conical cutting element and a chisel cutting element.  
   
   
       41 . The roller cone drill bit of  claim 39 , wherein the at least one substantially planar cutting element is a flat crested cutting element.  
   
   
       42 . The roller cone drill bit of  claim 39 , wherein any one of the at least one substantially planar cutting element and the at least one substantially non-planar cutting element is formed of tungsten carbide.  
   
   
       43 . The roller cone drill bit of  claim 39 , wherein the single roller cone is substantially hemispherical in shape.  
   
   
       44 . The roller cone drill bit of  claim 39 , wherein an angular position of any cutting element is defined as the sum of (1) a journal angle from a horizontal plane and (2) an angle between an axis of the single roller cone and an axis of the cutting element.  
   
   
       45 . The roller cone drill bit of  claim 44 , wherein the at least one substantially non-planar cutting element is disposed at an angle substantially between 0 degrees and 120 degrees.  
   
   
       46 . The roller cone drill bit of  claim 44 , wherein the at least one substantially planar cutting element is disposed at an angle substantially between 120 degrees and 175 degrees.  
   
   
       47 . The roller cone drill bit of  claim 44 , wherein the at least one substantially planar cutting element is disposed at an angle substantially between 125 degrees and 165 degrees.  
   
   
       48 . The roller cone drill bit of  claim 44 , wherein the at least one substantially planar cutting element is disposed at an angle substantially between 135 degrees and 155 degrees.  
   
   
       49 . The roller cone drill bit of  claim 44 , wherein the at least one substantially planar cutting element is disposed at an angle substantially between 140 degrees and 150 degrees.  
   
   
       50 . The roller cone drill bit of  claim 44 , wherein the at least one substantially planar cutting element is disposed at an angle substantially between 120 degrees and 175 degrees, and wherein the at least one substantially non-planar cutting element is disposed at an angle substantially between 0 and 120 degrees.  
   
   
       51 . The roller cone drill bit of  claim 39 , wherein the at least one substantially non-planar cutting element has a tip radius to extension ratio substantially equal to 0.3.  
   
   
       52 . The roller cone drill bit of  claim 39 , wherein the at least one substantially planar cutting element has a tip radius to extension ratio substantially between 0.2 and 0.5.  
   
   
       53 . The roller cone drill bit of  claim 39 , wherein any one of the at least one substantially planar cutting element and the at least one substantially non-planar cutting element extends less than or equal to 0.6 inches from a surface of the single roller cone.  
   
   
       54 . The roller cone drill bit of  claim 39 , wherein any one of the at least one substantially planar cutting element and the at least one substantially non-planar cutting element extends greater than or equal to {fraction (7/16)} inches from a surface of the single roller cone.  
   
   
       55 . The roller cone drill bit of  claim 39 , wherein any one of the at least one substantially planar cutting element and the at least one substantially non-planar cutting element extends greater than or equal to 0.5 inches from a surface of the single roller cone.  
   
   
       56 . The roller cone drill bit of  claim 39 , wherein any one of the at least one substantially planar cutting element and the at least one substantially non-planar cutting element extends greater than or equal to 0.55 inches from a surface of the single roller cone.  
   
   
       57 . The roller cone drill bit of  claim 39 , wherein the at least one substantially non-planar cutting element is formed having a core harder than an exterior such that the substantially non-planar cutting element is self-sharpening.