Fixed cutter drill bit heel and back-ream cutter protections for abrasive applications

Abstract

A method of manufacturing a fixed cutter drill bit may include loading a first matrix material of controlled thickness to at least a portion of a mold cavity corresponding to a heel surface of at least one blade; loading a second matrix material into the remaining portions of the mold cavity; heating the mold contents to form a matrix body of the fixed cutter drill bit; and disposing at least one back reaming element in at least one back reaming cutter pocket.

What is claimed is: 
     
         1 . A method of manufacturing a fixed cutter drill bit, comprising:
 loading a first matrix material of controlled thickness into at least a portion of a mold cavity corresponding to a heel surface of at least one blade;   loading a second matrix material into the remaining portions of the mold cavity;   heating the mold contents to form a matrix body of the fixed cutter drill bit; and   disposing at least one back reaming element in at least one back reaming cutter pocket.   
     
     
         2 . The method of  claim 1 , further comprising infiltrating the mold contents with an infiltrating binder. 
     
     
         3 . The method of  claim 1 , wherein the loading the first matrix material into the portion of the mold corresponding to the heel surface comprises placing a moldable material in the mold. 
     
     
         4 . The method of  claim 1 , wherein the first matrix material is harder than the second matrix material. 
     
     
         5 . The method of  claim 1 , wherein the first matrix material has a controlled thickness ranging between 0.2 inches and 0.3 inches below the at least one back reaming element. 
     
     
         6 . The method of  claim 1 , wherein the first matrix material comprises diamond impregnated matrix material. 
     
     
         7 . The method of  claim 1 , further comprising disposing at least one wear resistant element on the heel surface. 
     
     
         8 . The method of  claim 7 , wherein the at least one wear resistant element comprises thermally stable polycrystalline diamond. 
     
     
         9 . The method of  claim 1 , wherein the first matrix material has a viscosity of at least about 250,000 cP. 
     
     
         10 . A drill bit, comprising:
 a bit body having a longitudinal axis and a cutting face;   a plurality of blades spaced azimuthally about the cutting face and extending at least laterally through a gage region and terminating at a heel surface;   a plurality of cutters disposed along the blades; and   at least one back reaming element disposed on the heel surface of at least one blade;   wherein the at least one blade comprises a first matrix material extending from the heel surface to a distance below the at least one back reaming element and a second matrix material adjacent to the first matrix material.   
     
     
         11 . The drill bit of  claim 10 , wherein the distance ranges between 0.2 and 0.3 inches. 
     
     
         12 . The drill bit of  claim 10 , wherein the first matrix material is harder than the second matrix material. 
     
     
         13 . The drill bit of  claim 12 , wherein the first matrix material comprises diamond impregnated matrix material. 
     
     
         14 . The drill bit of  claim 10 , wherein an infiltration binder is dispersed within the first and second matrix material. 
     
     
         15 . The drill bit of  claim 10 , wherein the first matrix material is a moldable matrix material. 
     
     
         16 . The drill bit of  claim 10 , wherein the drill bit further comprises at least one wear resistant element disposed on the heel surface of at least one blade. 
     
     
         17 . The drill bit of  claim 16 , wherein the at least one wear resistant comprises thermally stable polycrystalline diamond. 
     
     
         18 . The drill bit of  claim 10 , wherein the first matrix material comprises at least 30 weight percent of the hard particle phase being cast tungsten carbide. 
     
     
         19 . The drill bit of  claim 10 , wherein the first matrix material comprises at least 8 weight percent of the hard particle phase being larger in size than 120 mesh. 
     
     
         20 . The drill bit of  claim 19 , wherein the first matrix material comprises at least about 50 weight percent of hard particle phase being larger is size than 120 mesh. 
     
     
         21 . A fixed cutter drill bit, comprising:
 a bit body having a longitudinal axis and a cutting face;   a plurality of blades spaced azimuthally about the cutting face and extending at least laterally through a gage region and terminating at a heel surface;   a plurality of cutters disposed along the blades; and   at least one back reaming element disposed on a heel surface of at least one blade.   
     
     
         22 . The fixed cutter drill bit of  claim 21 , wherein a plurality of back reaming elements are disposed on the heel surface of the plurality of blades to provide diamond coverage of greater than 300 mm 2  along each of the heel surfaces. 
     
     
         23 . The fixed cutter drill bit of  claim 21 , wherein the at least one back reaming element is selected from at least one of a PCD compact, a PCBN compact, a diamond impregnated insert, a natural diamond element, and a TSP element. 
     
     
         24 . The fixed cutter drill bit of  claim 23 , further comprising a hardfacing material disposed on the heel surface. 
     
     
         25 . The fixed cutter drill bit of  claim 23 , wherein the heel surface is impregnated with diamond particles. 
     
     
         26 . The fixed cutter drill bit of  claim 21 , wherein the at least one back reaming element has a substrate longer than a substrate of the plurality of cutters. 
     
     
         27 . The fixed cutter drill bit of  claim 21 , wherein each heel surface comprises two back reaming elements thereon. 
     
     
         28 . The fixed cutter drill bit of  claim 21 , further comprising at least one gage pad disposed along the gage region of the bit, the at least one gage pad comprises a plurality of wear resistant elements at least partially embedded in the gage pad, wherein each of the plurality of wear resistant elements includes a rounded surface and is formed of a material more wear resistant than matrix material forming a portion of the gage pad. 
     
     
         29 . The fixed cutter drill bit of  claim 28 , wherein the at least one gage pad has a leading edge extending along at least a portion of the length of the gage pad; and wherein the rounded surfaces of the plurality of wear resistant elements are aligned to form a substantially continuously rounded wear-resistant leading edge on the gage pad.