Abstract:
Method of manufacturing and remanufacturing wellbore drill bits and wellbore drill bit manufactured or remanufactured by the methods are disclosed. The manufacturing method comprises providing a drill bit having at least one blade, providing at least one cutter pocket in each blade, providing a registration device in each cutter pocket, and positioning a cutting surface within each cutter pocket and in engagement with each the registration device therein.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    The invention is directed to methods and devices for manufacturing and refurbishing drill bits. Specifically, the invention is directed to methods and devices for inserting and replacing polycrystalline diamond compacts (PDCs) in drill bits. 
         [0003]    2. Background of the Invention 
         [0004]    Wellbore drilling is the process of drilling one or more holes into the ground for the extraction of water, brine, natural gas, petroleum, or other natural resources. One of the main components for wellbore drilling is the drill bit. Drill bits typically comprise a solid metal or composite matrix-type metal body having a lower cutting face region and an upper shank region for connection to the bottom hole assembly of a drill string formed of jointed tubular members which are then rotated as a single unit by a rotary table or top drive drilling rig, or by a downhole motor selectively in combination with the surface equipment. Alternatively, rotary drill bits may be attached to a bottom hole assembly, including a downhole motor assembly, which is, in turn, connected to a drill string wherein the downhole motor assembly rotates the drill bit. The bit body may have one or more internal passages for introducing drilling fluid, or mud, to the cutting face of the drill bit to cool cutters provided thereon and to facilitate formation chip and formation fines removal. The sides of the drill bit typically may include a plurality of radially or laterally extending blades that have an outermost surface of a substantially constant diameter and generally parallel to the central longitudinal axis of the drill bit, commonly known as gage pads. The gage pads generally contact the wall of the borehole being drilled in order to support and provide guidance to the drill bit as it advances along a desired cutting path or trajectory. 
         [0005]    Fixed cutter drill bits have no moving parts. Instead, drilling occurs due to percussion or rotation of the drill string. Fixed cutter bits can be polycrystalline diamond compact (PDC), grit hotpressed inserts (GHI), or other hard materials. PDCs are aggregate tiny, inexpensive, manmade diamonds into relatively large, intergrown masses of randomly oriented crystals that can be formed into useful shapes called diamond tables. Diamond tables are the part of a cutter that contacts a formation. Besides their hardness, PDC diamond tables efficiently bond with tungsten carbide materials that can be brazed (attached) to bit bodies. Diamonds, by themselves, will not bond together, nor can they be attached by brazing. Under the high temperature, high stress, high impact, and/or corrosive conditions that the PDCs are subjected to, the PDCs often chip, crack, become loose, or otherwise degrade. While the PDCs may become less effective, the drill bit body may still be useable. Therefore, a process to remanufacture (or repair) drill bits has been developed over the years. The process involves removing broken or problematic PDCs and replacing them with new PDCs. However, during initial fabrication and replacement, the PDCs may not be properly centered or positioned. Therefore, there is a desire for a method and system to properly position PDCs in drill bits. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention overcomes the problems and disadvantages associated with current strategies and designs and provides new tools and methods of manufacturing and remanufacturing drill bits. 
         [0007]    One embodiment of the invention is directed to a method of manufacturing a wellbore drill bit. The method comprises providing a drill bit having at least one blade, providing at least one cutter pocket in each blade, providing a registration device in each cutter pocket, and positioning a cutting surface within each cutter pocket and in engagement with each the registration device therein. 
         [0008]    Preferably, each cutting surface is a polycrystalline diamond compact (PDC). In a preferred embodiment, a registration device is milled into each cutter pocket. Preferably, the registration device aligns the cutting surface within the cutter pocket. The alignment preferably comprises coaxially aligning the cutting surface with the cutter pocket. Preferably, the alignment occurs automatically. In a preferred embodiment, each cutting surface is positioned within the associated cutter pocket with a constant peripheral brazed joint of between 0.004″ and 0.006″ between the cutting surface and the cutter pocket. Preferably, the cutting surface is brazed into the cutter pocket. 
         [0009]    Another embodiment of the invention is directed to a method of remanufacturing a wellbore drill bit. The method comprises, providing a drill bit having at least one blade, providing at least one cutter pocket in each blade, providing a registration device in each cutter pocket, positioning a cutting surface within each cutter pocket and in engagement with each the registration device therein, distributing the drill bit for use, receiving the drill bit after use, assessing each cutting surface, removing damaged cutting surfaces, and replacing the damaged cutting surfaces with new cutting surfaces within each cutter pocket and in engagement with each the registration device therein. 
         [0010]    Preferably each cutting surface is a polycrystalline diamond compact (PDC). In a preferred embodiment, a registration device is milled into each cutter pocket. Preferably, the registration device aligns the cutting surface within the cutter pocket. The alignment preferably comprises coaxially aligning the cutting surface with the cutter pocket. Preferably, the alignment occurs automatically. In a preferred embodiment, each cutting surface is positioned within the associated cutter pocket with a constant peripheral brazed joint of between 0.004″ and 0.006″ between the cutting surface and the cutter pocket. Preferably, the new cutting surfaces have the same tolerances as the replaced cutting surfaces. Preferably, the step of removing damaged cutting surfaces occurs without damaging the registration devices. The use is preferably drilling a wellbore. 
         [0011]    Another embodiment of the invention is directed to wellbore drill bits manufactured by the methods disclosed herein. 
         [0012]    Other embodiments and advantages of the invention are set forth in part in the description, which follows, and in part, may be obvious from this description, or may be learned from the practice of the invention. 
     
    
     
       DESCRIPTION OF THE DRAWING 
         [0013]    The invention is described in greater detail by way of example only and with reference to the attached drawing, in which: 
           [0014]      FIG. 1  is a schematic depicting the existing process of inserting PDCs into a drill bit. 
           [0015]      FIG. 2  is a schematic depicting the inventive method of inserting PDCs into a drill bit. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0016]    As embodied and broadly described herein, the disclosures herein provide detailed embodiments of the invention. However, the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. Therefore, there is no intent that specific structural and functional details should be limiting, but rather the intention is that they provide a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention 
         [0017]      FIG. 1  depicts the current method of installing and replacing polycrystalline diamond compacts (PDCs) in drill bits. While the invention is described with reference to PDCs and drill bits, the cutting surfaces can be grit hotpressed inserts (GHIs), aluminum oxide, silicon carbide, cubic boron nitride or another material with a high 
         [0018]    Young&#39;s Modulus and the housing can be a router or another drilling, grinding, or cutting device. 
         [0019]    As can be seen in  FIG. 1 , in order for a PDC  110  to fit within a cutter pocket  105  (or cavity in the drill bit for the PDC  110 ), the cutter pocket&#39;s interior dimensions must be larger than the PDC&#39;s exterior dimensions. Ideally, there is between a 0.004″ and 0.006″ gap  115  between the outer surface of the PDC  110  and the inner surface of the cutter pocket. This gap  115  allows for the brazing material (e.g. molten silver solder) to be inserted between the PDC  110  and cutter pocket  105  to couple the PDC  110  to the drill bit  120 . However, in practice, the gap  115  can range between, for example, no gap at all (as shown in dashed lines  125 ) and a 0.012″ gap (as shown in dotted lines  130 ). 
         [0020]    The variation in the size  135  of the gap  115  can cause the PDC  110  to be seated improperly. Such variations can cause the PDC  110  not to extend the proper distance proud of the drill bit  120  body, be off center, or improperly angled. 
         [0021]    During the remanufacturing process, the drill bit is heated to at or above 375° C. so that the damaged PDCs are easily removable. Once the PDCs are removed, the cutter pocket is conditioned by removing any excess material and sized to receive a new PDC. 
         [0022]    The new PDC is then placed in the cutter pocket and brazed to affix the PDC to the drill bit. During this process, the cutter pocket can become irregularly shaped, enlarged, or otherwise degraded. 
         [0023]      FIG. 2  depicts a schematic of an embodiment of the inventive method of positioning a PDC  210  in a cutter pocket  205 . As can be seen in the figure, a registration device  240  is added to the cutter pocket  205  prior to insertion of the PDC  210 . The registration device  240  preferably aligns or properly positions the PDC  210  relative to the cutter pocket  205 . Preferably, the registration device  240  is machined directly into base material (for example the registration device can be milled, ground, or molded into the cutter pocket  205 ). The registration device  240  can be a rod, ball, hemisphere, triangular, a prism, or another shape. However, the registration device  240  may be affixed to the interior surface of the cutter pocket  205 . For example, recesses can be machined to receive a registration device  240  or one or more registration devices  240  to be affixed to the interior surface of the cutter pocket  205  during manufacturing of the drill bit  220 . For example, three, four, or five registration devices  240  can be affixed to the interior surface of the cutter pocket  205 . The registration device(s)  240  can be steel, bronze, a PDC, or another material. The registration device(s)  240  can be affixed with adhesive, solder, brazing, a mechanical coupling, friction, or another fixation method. 
         [0024]    The PDC  210  is then placed into the cutter pocket  205  and into engagement with the registration device  240 . Preferably, the registration device  240  automatically aligns the PDC  210  within the cutter pocket  205  such that the center of the PDC  210  is coaxial with the center of the cutter pocket  205  and the PDC  210  extends proud of the drill bit  220  the desired distance without the need for grinding the full diameter PDCs (gage). Preferably the registration device  240  allows the brazer to exert pressure on the PDC  210  without dislocating the PDC  210  from its ideal position. Furthermore, the registration device  240  preferably provides a constant peripheral brazed joint of between 0.004″ and 0.006″ between the PDC  210  and the cutter pocket  205 . 
         [0025]    After the drill bit returns from the oil fields or other use, any damaged PDCs  210  can be removed, preferably without damaging the registration device  240  and new PDCs  210  can preferably be inserted into the cutter pocket  205  and into engagement with the registration device  240  in the same manner as the original PDCs  210 . Preferably, the new PDCs  210  have the same tolerances as the original PDCs  210 . 
         [0026]    Other embodiments and uses of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. All references cited herein, including all publications, U.S. and foreign patents and patent applications, are specifically and entirely incorporated by reference. It is intended that the specification and examples be considered exemplary only with the true scope and spirit of the invention indicated by the following claims. Furthermore, the term “comprising of” includes the terms “consisting of” and “consisting essentially of.”