Drilling with mixed tooth types

Abstract

A rotary-cutter Earth-penetrating bit in which a given track of bottom hole is attacked by inserts of two different types, e.g. chisel-shaped and pointed, wider and narrower, higher and shorter, and/or of different materials. The different types of inserts can both be included within a single row of a cone.

1 - 21 . (canceled)  
   
   
       22 . A rotary-cutter rock-penetrating drill bit, comprising: 
 a plurality of rotatable elements, each bearing thereon first and second pluralities of inserted cutting elements which incrementally remove rock rock as the drill bit is rotated and advanced;    wherein at least some of said first and second cutting elements remove rock from a shared location, and    wherein said first and second inserted cutting elements have different material compositions.    
   
   
       23 . The bit of  claim 22 , wherein at least one single row of inserts on at least one rotatable element includes ones of said first and ones of said second cutting elements.  
   
   
       24 . The bit of  claim 22 , wherein said cutting elements comprise diamond-loaded cermets.  
   
   
       25 . The bit of  claim 22 , wherein said cutting elements are inserted into said rotatable element.  
   
   
       26 . The bit of  claim 22 , wherein said rotatable elements are attached through a rotary joint to arms which are affixed to a body having an API thread.  
   
   
       27 . The bit of  claim 22 , comprising only three of said rotatable elements.  
   
   
       28 - 32 . (canceled)  
   
   
       33 . A method for rotary drilling, comprising the actions of: 
 (a.) applying torque and axial force to a bit according to  claim 22 , while    (b.) pumping drilling fluid through a drill string to which said bit is connected.    
   
   
       34 . A rotary drilling system, comprising: 
 a bit according to  claim 22;     a drill string which is connected to conduct drilling fluid to said bit from a surface location; and    a rotary drive which rotates at least part of said drill string together with said bit.    
   
   
       35 . A rotary drilling system, comprising: 
 a bit according to  claim 22;     a drill string which is connected to conduct drilling fluid to said bit from a surface location; and    a rotary drive which rotates at least part of said drill string together with said bit.    
   
   
       36 . A rotary drilling system, comprising: 
 a bit according to  claim 22;     a drill string which is connected to conduct drilling fluid to said bit from a surface location; and    a rotary drive which rotates at least part of said drill string together with said bit.    
   
   
       37 . A rotary drilling system, comprising: 
 a bit according to  claim 22;     a drill string which is connected to conduct drilling fluid to said bit from a surface location; and    a rotary drive which rotates at least part of said drill string together with said bit.    
   
   
       38 - 45 . (canceled)  
   
   
       46 . A cutter for a roller-cone-type rock-penetrating drill bit, comprising: 
 a tapered cutter body bearing a gage row, and at least one other row of cutting elements;    wherein said other row includes first and second different types of said cutting elements, wherein said first type and said second type have different cermet compositions.    
   
   
       47 . The cutter of  claim 46 , wherein said body is steel, and said cutting elements are cermet inserts.