Patent Publication Number: US-2011056751-A1

Title: Ultra-hard matrix reamer elements and methods

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to the copending U.S. patent application Ser. No. 12/313,130, filed Nov. 17, 2008, the U.S. patent application Ser. No. 12/590,429, filed Nov. 6, 2009, the U.S. patent application Ser. No. 12/288,889, filed Oct. 24, 2008, and the U.S. patent application Ser. No. 12/590,561, filed Nov. 10, 2009. Each of the above-referenced applications are incorporated by reference herein, in their entirety. 
    
    
     FIELD 
     Embodiments of the present invention relate, generally, to drill string components formed at least partially from a tungsten carbide matrix material, and more specifically to reamer elements for use with roller reamers and other reamer-type apparatuses usable during drilling operations, methods for forming such components, and methods for performing drilling operations using such components. 
     BACKGROUND 
     Conventional drilling operations utilize a drill bit, secured at the distal end of multiple connected segments of steel drill pipe, termed a drill string, to bore through a formation. Near the distal end of the drill string, above the drill bit, a bottomhole assembly is secured, which includes multiple heavy, thick-walled drill collars to provide weight to the bit to facilitate boring. The bottomhole assembly also includes one or more drilling stabilizers, having ribs or blades protruding therefrom, to contact the borehole wall and minimize undesired deflection of the assembly, both through this contact and due to the thickness and rigidity of the tool. The bottomhole assembly and/or other portions of the drill string can also include one or more reamers, having rollers and/or cutting or abrasive elements disposed thereon to ream the borehole wall to ensure accurate and/or uniform borehole size, and to provide additional drill string stability through contact with the borehole wall. 
     Most drill string components are formed using steel, or an alternative metal, such as monel, when avoidance of magnetic interference with logging while drilling devices is necessary. However, steel and monel components that contact the formation during drilling operations are prone to rapid wear, requiring frequent replacement, especially within hard or abrasive formations. Additionally, steel and monel components must be provided with a significant length to provide sufficient weight to a drill bit to facilitate drilling, which can increase the likelihood of undesirable impact between a bottomhole assembly and the borehole wall due to lateral forces and/or yield in the drill string. Bottomhole assemblies and other portions of the drill string that undesirably contact the borehole wall in such a manner can become stuck, requiring costly and time consuming remedial operations. 
     A need also exists for drill string components, such as roller reamers and similar reamer-type apparatuses, that possess increased wear resistance when compared to conventional components, enabling longer trips, even within hard or abrasive formations, without requiring costly down time, repair, and replacement. 
     A need also exists for reamers that provide increased weight to a drill bit when compared to conventional components, enabling shorter bottomhole assemblies to be used, thereby decreasing the possibility of the bottomhole assembly becoming stuck. 
     A further need exists for reamer-type apparatuses that, in combination with the above, do not magnetically interfere with adjacent logging and/or measurement while drilling devices. 
     A need exists for drill string components that do not yield or permit lateral motion within the bottomhole assembly in the manner common to steel segments of drill pipe, further decreasing the possibility of undesired contact between the bottomhole assembly and the borehole. 
     Embodiments of the present invention meet these needs. 
     SUMMARY 
     Embodiments usable within the scope of the present disclosure include a reamer element for use within a drill string. As known in the art, reamer apparatuses can include roller reamers, as well as fixed reamers of various configurations. Embodied reamer elements can include a body formed from a matrix of tungsten carbide and at least one binding metal, having a longitudinal bore extending therethrough. A tube is disposed in the longitudinal bore, the tube having a bore within for permitting passage of drilling fluid or similar substances. During drilling operations, the body of the reamer element resists compressive forces from the drill string above and the formation and drill bit below, and resists wear caused by contact with the formation, while the tube resists tensile forces. In an embodiment, the ends of the tube can extend beyond the ends of the tungsten carbide matrix body of the reamer element, and can have threaded connections, or another manner of connections, formed thereon for engaging adjacent connectors and/or components. 
     Embodiments usable within the scope of the present disclosure also include methods for reaming a borehole that include securing within the drill string at least one reamer element having a body formed from a matrix of tungsten carbide and at least one binding metal, with at least one reamer member usable to penetrate, cut, or otherwise deform the borehole wall, extending therefrom. As described previously, a tube can be disposed within a longitudinal bore of the body, the tube having a bore extending therethrough. 
     Embodiments usable within the scope of the present disclosure further include a method for forming a reamer element possessing one or more of the characteristics described above. Particles of tungsten carbide can be provided into a mold with a void having the shape of a reamer body. A spacer element can also be provided into the void, which can be placed centrally along the longitudinal axis of the void, to define a bore through the packed tungsten carbide particles. In an embodiment, the spacer element can include a solid metal rod. Alternatively, the spacer element could include a filled metal tube, such as a tube having sand, or a similar material that will not significantly melt, deform, or weaken during the molding process, placed therein. Tubes and/or rods formed from other materials that will not be weakened, destroyed, or significantly deformed by the molding process are also usable within the scope of the present disclosure. 
     One or more binding metals, which can include nickel, copper, a ferrous material, or any other metal or alloy, can be provided in fluid communication with the mold, such as through placement of a funnel or similar containment apparatus adjacent thereto. Heating the one or more binding metals causes the metal to melt, then flow into spaces between the particles of tungsten carbide, such that when the one or more binding metals cool and solidify, a tungsten carbide matrix material is formed. The resulting reamer body can be heat treated after removal from the mold. 
     In an embodiment, the mold can be oriented in a substantially vertical orientation, such that the longitudinal axis of the mold is generally perpendicular with the Earth&#39;s surface. Vertical orientation of the mold facilitates homogenous penetration of the one or more binding metals through the particles of tungsten carbide, while other orientations could cause undesirable accumulation of materials along one side of the mold, resulting in the formation of an unbalanced reamer that would be unsuitable for use. As such, the particles of tungsten carbide and/or the binding metals can be selected to have a size and/or metallurgical properties that facilitate flow of the one or more binding metals from the first end of the mold to the second, to create a generally homogenous tungsten carbide matrix material. 
     In embodiments in which a generally solid spacer element is positioned within the void of the mold, the application of heat to melt the binding metal will not deform, anneal, or significantly weaken the spacer element. Once the reamer body is removed from the mold, a bore can be provided through the spacer element, such as through any manner of drilling and/or machining known in the art. For example, the spacer element can be provided with a small channel and/or counterbore therethrough to facilitate formation of a bore after the molding process. Alternatively, if a filled and/or packed metal tube is provided into the mold, the internal material can be removed to define a bore through the resulting reamer body. 
     In an embodiment, the ends of the spacer element can extend beyond those of the tungsten carbide matrix component body, and threaded connections, or a similar manner of connection for engaging adjacent connectors and/or components, can be provided thereto. 
     The resulting reamer body can have any dimensions, limited only by the size of the furnace or similar heat source usable to melt the one or more binding metals and/or the maximum or minimum size of the mold. 
     While any materials and methods can be used to form a reamer in the manner described above, in an embodiment of the invention, a two-part mold can be used, which can include a shell formed from ceramic and/or graphite, and a core having the void therein provided with a suitable shape for forming the reamer body. In a further embodiment, the shell can be provided with a fusible material, such as foundry sand, a mixture of silica sand and/or binders, a resin, a plasticizer, one or more polymers, or combinations thereof. The fusible material can be heated to form a solid insert, which can then be machined to provide a shape suitable for formation of the reamer. Embodiments of these molding processes are described with particularity in copending application Ser. Nos. 12/288,889 and 12/590,961, which have been incorporated herein by reference. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the detailed description of various embodiments of the present invention presented below, reference is made to the accompanying drawings, in which: 
         FIG. 1  depicts a cross-sectional view of an embodiment of a reamer element usable within the scope of the present disclosure. 
     
    
    
     Embodiments of the present invention are described below with reference to the listed Figures. 
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Before explaining selected embodiments of the present invention in detail, it is to be understood that the present invention is not limited to the particular embodiments described herein and that the present invention can be practiced or carried out in various ways. 
     Referring now to  FIG. 1 , a cross-sectional view of an embodiment of a reamer element ( 10 ) is shown. While the embodiments described herein are usable with and applicable to various types of reamers and other drill string components,  FIG. 1  depicts the reamer element ( 10 ) as a roller usable with a roller reamer or similar apparatus. 
     Specifically, the reamer element ( 10 ) is shown having a body ( 12 ) formed from a matrix of tungsten carbide and one or more metal alloys, providing reduced magnetic interference, improved wear resistance, increased weight, and eliminating yield during drilling operations. While the body ( 12 ) can be provided with any desired shape,  FIG. 1  depicts the body ( 12 ) having a generally tubular shape with beveled edges at each end. The exterior surface of the body ( 12 ) and/or the edges thereof, or any manner of slots, voids, and/or depressions in the body ( 12 ), as known in the art, can be provided with any number and type of abrasive and/or cutting element for reaming a borehole during use. The diameter of the body ( 12 ) can be sized for use within a borehole of a selected size, such that any reaming elements disposed along the body ( 12 ) will contact the borehole wall, thereby reaming the borehole during use. The length of the body ( 12 ) can vary due to manufacturing and/or cost constraints, a desirable quantity of weight to be applied to a drill bit by the reamer ( 10 ), or other similar factors. 
     A tube ( 14 ) is shown disposed centrally along the longitudinal axis ( 16 ) of the body ( 12 ), the tube ( 14 ) having a bore ( 18 ) for accommodating a shaft and/or other types of connections with a reamer apparatus engaged within a drill string. In other embodiments, such as circumstances in which a fixed stabilizer and/or reamer element is used, the bore can be used to accommodate the flow of drilling fluid. The tube ( 14 ) can be formed from any generally rigid material that will not deform during the molding process, such as steel, or other similar metals or alloys. While  FIG. 1  depicts the tube ( 14 ) having a length generally equal to that of the body ( 12 ), in an embodiment, the tube ( 14 ) can have ends extending beyond those of the body ( 12 ), having threaded connections and/or other types of connections formed thereon. For example, the copending U.S. patent application Ser. Nos. 12/313,130 and 12/590,429, incorporated by reference above, describe drill string components having bodies formed from tungsten carbide matrix materials, with interior tubes having threaded connections formed thereon. 
     While conventional reamer elements are typically formed using steel or another machined metal, embodiments of the present invention can be formed through use of a powdered metal infiltration casting process, as described previously. Specific methods of forming reamer elements can include use of a two-part mold, having a shell and a core, such that only the mold core, which can be formed from graphite, ceramic, polymers, composites, or combinations thereof, can potentially be damaged or destroyed while removing the reamer body therefrom, while the mold shell is reusable. In further embodiments, a mold core can be formed by heating, mixing, and/or otherwise fusing a fusible material, such as foundry sand or a similar mixture of silica or another structural component with one or more binders, resins, plasticizers, and/or polymer components. Fusing the fusible material forms a generally solid insert that can be machined to form a mold having the desired features to form a reamer body. Use of a fusible material in the manner described conserves the time and costs required to acquire and machine a mold core formed from graphite or a similar material. Molding apparatuses and processes usable within the scope of the present disclosure are described in detail in copending U.S. patent application Ser. Nos. 12/288,889 and 12/590,561, incorporated by reference above. 
     It should be understood, however, that embodiments usable within the scope of the present disclosure can include use of any type of mold, including single-piece molds formed from graphite or another similar material, two-piece molds, such as those described in U.S. patent application Ser. Nos. 12/288,889 and 12/590,561, or other similar types of molds. 
     Conventionally, powdered metal infiltration casting processes are used exclusively for production of drill bit bodies, the expense of the materials and the process and the characteristics of the metal matrix material being generally regarded as unsuitable for reamer elements and other downhole components. However, drill bit bodies require use of high quality powdered tungsten carbide and metal alloys due to the operational requirements of the drill bit, while reamer elements are relatively simple, tubular components. As a result, embodiments of the present reamer elements can be formed using waste tungsten carbide, such as that produced during grinding or machining of other tungsten carbide components, or similar coarse, waste, and/or otherwise irregular metal matrix materials. 
     Additionally, formation of reamer elements through a molding process as described above enables the components to be provided with a variety of shapes that would normally require a significant quantity of machining and other laborious processes to produce. 
     Furthermore, unlike most conventional reamers, a component formed from a metal matrix material can be repaired without altering the shape or dimensions thereof. While embodiments of reamer elements described herein, once worn or damaged, can be ground or machined to a smaller diameter, it is also possible to provide powdered metal matrix material to a crack or worn area of the component, and one or more metal alloys in fluid communication with the metal matrix material, similar to the molding process by which the component was formed. The metal alloys can then be melted, enabling the molten alloys to flow into the metal matrix material within the crack or worn area. After cooling, the metal alloys harden, thereby repairing the matrix of the reamer body. 
     Embodiments described herein thereby provide reamer elements and related methods that provide increased weight to a drill bit, improved wear resistance, less magnetic interference, and less yield, when compared to conventional components. 
     While various embodiments of the present invention have been described with emphasis, it should be understood that within the scope of the appended claims, the present invention might be practiced other than as specifically described herein.