Enhanced cutter profile for fixed cutter drill bits

Abstract

In one aspect, a cutting structure for a drill bit includes cutters arranged to form a cutter profile. Substantially all of the cutters in a shoulder section of the cutter profile are positioned at a profile angle of at most 65°. In another aspect, substantially all of the shoulder cutters are arranged so that the longitudinal force exerted by each shoulder cutter onto an earthen formation is at least 25 percent of the normal force exerted by the shoulder cutter onto the earthen formation.

1 . A cutting structure for a fixed cutter drill bit, comprising:
 cutters arranged to form a cutter profile on part of a bit body; and   wherein substantially all of the cutters in a shoulder section of the cutter profile are positioned at a profile angle of at most 65 degrees.   
     
     
         2 . The cutting structure of  claim 1  wherein substantially all of the cutters in the shoulder section are positioned at a profile angle of at most 45 degrees. 
     
     
         3 . The cutting structure of  claim 1  wherein substantially all of the cutters in the shoulder section are positioned at a profile angle of at most 30 degrees. 
     
     
         4 . A cutting structure for a fixed cutter drill bit, comprising:
 cutters arranged on part of a bit body to form a cutter profile; and   wherein substantially all of the cutters in a shoulder section of the cutter profile are positioned such that a longitudinal force exerted on an earthen formation by each cutter is at least 25 percent of a normal force exerted by that cutter on the earthen formation.   
     
     
         5 . The cutting structure of  claim 4  wherein each cutter in the shoulder section is positioned such that the longitudinal force exerted on the earthen formation by that cutter is at least 50 percent of the normal force exerted by that cutter on the earthen formation. 
     
     
         6 . The cutting structure of  claim 4  wherein each cutter in the shoulder section is positioned such that the longitudinal force exerted on the earthen formation by that cutter is at least 75 percent of the normal force exerted by that cutter on the earthen formation. 
     
     
         7 . A fixed cutter drill bit comprising:
 a bit body having a plurality of blades extending laterally away from a longitudinal center of the bit body;   a plurality of cutters affixed to at least one of the plurality of blades and defining a cutter profile having a shoulder section; and   wherein substantially all of the cutters in the shoulder section of the cutter profile are positioned to at least one of (a) having a profile angle of at most 65 degrees and (b) such that a longitudinal force exerted on an earthen formation by each cutter is at least 25 percent of a normal force exerted by such cutter on the earthen formation.   
     
     
         8 . The bit of  claim 7  wherein substantially all of the cutters in the shoulder section are positioned to at least one of (a) having a profile angle of at most 45 degrees and (b) such that the longitudinal force exerted on an earthen formation by each cutter is at least 50 percent of the normal force exerted by such cutter on the earthen formation. 
     
     
         9 . The bit of  claim 7  wherein substantially all of the cutters in the shoulder section are positioned to at least one of (a) having a profile angle of at most 30 degrees and (b) such that the longitudinal force exerted on an earthen formation by each cutter is at least 75 percent of the normal force exerted by such cutter on the earthen formation. 
     
     
         10 . The bit of  claim 7  wherein the cutters comprise polycrystalline diamond compacts. 
     
     
         11 . The bit of  claim 8  wherein the cutters comprise polycrystalline diamond compacts. 
     
     
         12 . The bit of  claim 9  wherein the cutters comprise polycrystalline diamond compacts.