Fixed cutter drill bits and methods of making same

Abstract

A method for manufacturing a fixed cutter drill bit for drilling an earthen formation includes (a) providing a mold including a rigid body and a cavity extending from an upper end of the rigid body. The cavity includes a bit body recess, a plurality of circumferentially-spaced blade recesses extending from the bit body recess, and a tool cutting structure recess extending from each blade recess. In addition, the method includes (b) placing a first binder in each tool cutting structure recess. Further, the method includes (c) filling each blade recess and the bit body recess with a powdered matrix material comprising tungsten carbide after (b). Still further, the method includes (d) placing a second binder on top of the powdered matrix material after (c). The method also includes (e) heating the mold, the first binder and the second binder after (d) to melt the first binder and the second binder. Moreover, the method includes (f) infiltrating the powdered matrix material with the melted second binder during (e). Additionally, the method also includes (g) cooling the mold, the melted first binder, and the melted second binder to solidify the melted first binder and the melted second binder after (f) to form a bit body, a plurality of blades, and a tool cutting structure.

What is claimed is: 
     
         1 . A method for manufacturing a fixed cutter drill bit for drilling an earthen formation, the drill bit having a central axis and including a bit body, a plurality of circumferentially-spaced blades extending from the bit body, a plurality of cutter elements mounted to a cutter supporting surface of each blade and defining a formation cutting structure, and a tool cutting structure extending from the cutting supporting surface of each blade, wherein the formation cutting structure is configured to cut a subterranean earthen formation and the tool cutting structure is configured to drill a downhole tool, the method comprising:
 (a) providing a mold including a rigid body and a cavity extending from an upper end of the rigid body, wherein the cavity includes a bit body recess, a plurality of circumferentially-spaced blade recesses extending from the bit body recess, and a tool cutting structure recess extending from each blade recess;   (b) placing a first binder in each tool cutting structure recess;   (c) filling each blade recess and the bit body recess with a powdered matrix material comprising tungsten carbide after (b);   (d) placing a second binder on top of the powdered matrix material after (c);   (e) heating the mold, the first binder and the second binder after (d) to melt the first binder and the second binder;   (f) infiltrating the powdered matrix material with the melted second binder during (e); and   (g) cooling the mold, the melted first binder, and the melted second binder to solidify the melted first binder and the melted second binder after (f) to form the bit body, the plurality of blades, and the tool cutting structure.   
     
     
         2 . The method of  claim 1 , further comprising securing the plurality of cutter elements to the cutter-supporting surface of each blade to form the formation cutting structure after (g). 
     
     
         3 . The method of  claim 1 , further comprising placing a plurality of pieces of hard metal in each tool cutting structure recess before (b), wherein the hard metal has a melting temperature greater than a temperature to which the mold is heated in (e); and
 infiltrating the plurality of pieces of hard metal with the melted first binder during (e).   
     
     
         4 . The method of  claim 3 , wherein the pieces of hard metal comprise tungsten carbide, tungsten, steel, iron, or combinations thereof. 
     
     
         5 . The method of  claim 3 , wherein the pieces of hard metal comprise cemented tungsten carbide cobalt having a cobalt concentration ranging from 5.0 to 20.0 wt %. 
     
     
         6 . The method of  claim 1 , further comprising placing a powdered hard metal or metal alloy in each tool cutting structure recess before (b), wherein the hard metal or metal alloy has a melting temperature greater than a temperature to which the mold is heated in (e); and
 infiltrating the powdered hard metal or metal alloy with the melted first binder during (e).   
     
     
         7 . The method of  claim 1 , wherein the first binder and the second binder comprise copper, brass, or a copper alloy. 
     
     
         8 . The method of  claim 1 , further comprising placing a layer of a non-infiltrating material in a bottom of each tool cutting structure recess before (b). 
     
     
         9 . The method of  claim 8 , wherein the non-infiltrating material comprises sand, graphite, glass or zircon. 
     
     
         10 . The method of  claim 1 , wherein the blades of the fixed cutter bit include a cone region extending radially from the central axis, a shoulder region radially adjacent the cone region, and a gage regions radially adjacent the shoulder region, wherein the shoulder regions is radially positioned between the cone region and the gage region;
 wherein the tool cutting structure extends from each blade in the cone region or the shoulder region.   
     
     
         11 . A method for manufacturing a fixed cutter drill bit for drilling an earthen formation, the method comprising:
 (a) providing a mold including a rigid body and a cavity extending from an upper end of the rigid body, wherein the cavity includes a bit body recess, a plurality of circumferentially-spaced blade recesses extending from the bit body recess, and tool cutting structure recess extending from each blade recess; wherein the bit body recess is configured to form a bit body of the drill bit, the blade recesses are configured to form a plurality of blades of the drill bit, and wherein the tool cutting structure recesses are configured to form a tool cutting structure of the drill bit for drilling through a downhole tool;   (b) placing a plurality of pieces or particles of hard metal or a metal alloy in each tool cutting structure recess;   (c) filling each tool cutting structure recess with a first binder after (b);   (d) filling each blade recess and the bit body recess with a powdered matrix material comprising tungsten carbide after (c);   (e) placing a second binder on top of the powdered matrix material after (d);   (f) heating the mold, the first binder, and the second binder after (e) to melt each binder and convert each binder to a liquid, wherein the hard metal or metal alloy has a melting temperature greater than a temperature to which the mold is heated in (f);   (g) infiltrating the powdered matrix material with the second binder during (f);   (h) infiltrating the plurality of pieces or particles of hard metal or metal alloy with the melted first binder during (f); and   (i) cooling the mold, the first binder, and the second powdered binder after (g) and (h) to convert each binder to a solid; wherein the solidified second binder and the matrix material form the bit body and the blades of the drill bit, and wherein the solidified first binder and the plurality of pieces or particles of hard metal or metal alloy form the tool cutting structure of the drill bit.   
     
     
         12 . The method of  claim 11 , further comprising securing the plurality of cutter elements to the cutter-supporting surface of each blade after (g) to form a formation cutting structure of the drill bit configured to drill the earthen formation. 
     
     
         13 . The method of  claim 11 , wherein the plurality of pieces or particles of hard metal or metal alloy comprise tungsten carbide, tungsten, steel, iron, or combinations thereof. 
     
     
         14 . The method of  claim 11 , wherein the plurality of pieces or particles of hard metal or metal alloy comprise cemented tungsten carbide cobalt having a cobalt concentration ranging from 5.0 to 20.0 wt %. 
     
     
         15 . The method of  claim 11 , wherein the first binder and the second binder comprise copper, brass, or a copper alloy. 
     
     
         16 . The method of  claim 11 , further comprising placing a layer of a non-infiltrating material in a bottom of each tool cutting structure recess before (b). 
     
     
         17 . The method of  claim 16 , wherein the non-infiltrating material comprises sand, graphite, glass or zircon. 
     
     
         18 . The method of  claim 11 , wherein the blades of the fixed cutter bit include a cone region extending radially from a central axis of the drill bit about which the drill bit is configured to rotate in a cutting direction, a shoulder region radially adjacent the cone region, and a gage regions radially adjacent the shoulder region, wherein the shoulder regions is radially positioned between the cone region and the gage region;
 wherein the tool cutting structure is disposed along each blade in the cone region or the shoulder region.