Patent Application
20080029310
The invention generally relates to particle-matrix composite drill bits and other tools that may be used in drilling subterranean formations, and to abrasive, wear-resistant hardfacing materials that may be used on surfaces of such particle-matrix composite drill bits and tools. The invention also relates to methods for applying abrasive, wear-resistant hardfacing to surfaces of particle-matrix composite drill bits and tools.
A conventional fixed-cutter, or “drag,” rotary drill bit for drilling subterranean formations includes a bit body having a face region thereon carrying cutting elements for cutting into an earth formation. The bit body may be secured to a hardened steel shank having a threaded pin connection, such as an API threaded pin, for attaching the drill bit to a drill string that includes tubular pipe segments coupled end-to-end between the drill bit and other drilling equipment. Equipment such as a rotary table or top drive may be used for rotating the tubular pipe and drill bit. Alternatively, the shank may be coupled to the drive shaft of a down hole motor to rotate the drill bit independently of, or in conjunction with, a rotary table or top drive.
Typically, the bit body of a drill bit is formed from steel or a combination of a steel blank embedded in a particle-matrix composite material that includes hard particulate material, such as tungsten carbide, infiltrated with a molten binder material such as a copper alloy. The hardened steel shank generally is secured to the bit body after the bit body has been formed. Structural features may be provided at selected locations on and in the bit body to facilitate the drilling process. Such structural features may include, for example, radially and longitudinally extending blades, cutting element pockets, ridges, lands, nozzle ports, and drilling fluid courses and passages. The cutting elements generally are secured to cutting element pockets that are machined into blades located on the face region of the bit body, e.g., the leading edges of the radially and longitudinally extending blades. These structural features, such as the cutting element pockets, may also be formed by a mold used to form the bit body when the molten binder material is infiltrated into the hard particulate material. Advantageously, a particle-matrix composite material provides a bit body of higher strength and toughness compared to steel material, but still requires complex and labor-intensive processes for fabrication, as described in U.S. application Ser. No. 11/272,439. Therefore, it would be desirable to provide a method of manufacturing suitable for producing a bit body that includes a particle-matrix composite material that does not require infiltration of hard particulate material with a molten binder material.
Generally, the cutting elements of a conventional fixed-cutter rotary drill bit each include a cutting surface comprising a hard, superabrasive material, such as mutually bound particles of polycrystalline diamond. Such “polycrystalline diamond compact” (PDC) cutters have been employed on fixed-cutter rotary drill bits in the oil and gas well drilling industries for several decades.
A drill bit 10 may be used numerous times to perform successive drilling operations during which the surfaces of the bit body 12 and cutting elements 22 may be subjected to extreme forces and stresses as the cutting elements 22 of the drill bit 10 shear away the underlying earth formation. These extreme forces and stresses cause the cutting elements 22 and the surfaces of the bit body 12 to wear. Eventually, the surfaces of the bit body 12 may wear to an extent at which the drill bit 10 is no longer suitable for use. Therefore, there is a need in the art for enhancing the wear-resistance of the surfaces of the bit body 12. Also, the cutting elements 22 may wear to an extent at which they are no longer suitable for use.
Conventional bonding material 24 is much less resistant to wear than are other portions and surfaces of the drill bit 10 and of cutting elements 22. During use, small vugs, voids and other defects may be formed in exposed surfaces of the bonding material 24 due to wear. Solids-laden drilling fluids and formation debris generated during the drilling process may further erode, abrade and enlarge the small vugs and voids in the bonding material 24. The entire cutting element 22 may separate from the drill bit body 12 during a drilling operation if enough bonding material 24 is removed. Loss of a cutting element 22 during a drilling operation can lead to rapid wear of other cutting elements and catastrophic failure of the entire drill bit 10. Therefore, there is also a need in the art for an effective method for enhancing the wear-resistance of the bonding material to help prevent the loss of cutting elements during drilling operations.
Ideally, the materials of a rotary drill bit must be extremely hard to withstand abrasion and erosion attendant to drilling earth formations without excessive wear. Due to the extreme forces and stresses to which drill bits are subjected during drilling operations, the materials of an ideal drill bit must simultaneously exhibit high fracture toughness. In practicality, however, materials that exhibit extremely high hardness tend to be relatively brittle and do not exhibit high fracture toughness, while materials exhibiting high fracture toughness tend to be relatively soft and do not exhibit high hardness. As a result, a compromise must be made between hardness and fracture toughness when selecting materials for use in drill bits.
In an effort to simultaneously improve both the hardness and fracture toughness of rotary drill bits, composite materials have been applied to the surfaces of drill bits that are subjected to extreme wear. These composite or hard particle materials are often referred to as “hardfacing” materials and typically include at least one phase that exhibits relatively high hardness and another phase that exhibits relatively high fracture toughness.
Tungsten carbide particles 40 used in hardfacing materials may comprise one or more of cast tungsten carbide particles, sintered tungsten carbide particles, and macrocrystalline tungsten carbide particles. The tungsten carbide system includes two stoichiometric compounds, WC and W2C, with a continuous range of mixtures therebetween. Cast tungsten carbide particles generally include a eutectic mixture of the WC and W2C compounds. Sintered tungsten carbide particles include relatively smaller particles of WC bonded together by a matrix material. Cobalt and cobalt alloys are often used as matrix materials in sintered tungsten carbide particles. Sintered tungsten carbide particles can be formed by mixing together a first powder that includes the relatively smaller tungsten carbide particles and a second powder that includes cobalt particles. The powder mixture is formed in a “green” state. The green powder mixture then is sintered at a temperature near the melting temperature of the cobalt particles to form a matrix of cobalt material surrounding the tungsten carbide particles to form particles of sintered tungsten carbide. Finally, macrocrystalline tungsten carbide particles generally consist of single crystals of WC.
Various techniques known in the art may be used to apply a hardfacing material such as that represented in
Arc welding techniques also may be used to apply a hardfacing material to a surface of a drill bit. For example, a plasma transferred arc may be established between an electrode and a region on a surface of a drill bit on which it is desired to apply a hardfacing material. A powder mixture including both particles of tungsten carbide and particles of matrix material then may be directed through or proximate the plasma-transferred arc onto the region of the surface of the drill bit. The heat generated by the arc melts at least the particles of matrix material to form a weld pool on the surface of the drill bit, which subsequently solidifies to form the hardfacing material layer on the surface of the drill bit.
When a hardfacing material is applied to a surface of a drill bit, relatively high temperatures are used to melt at least the matrix material. At these relatively high temperatures, dissolution may occur between the tungsten carbide particles and the matrix material. In other words, after applying the hardfacing material, at least some atoms originally contained in a tungsten carbide particle (tungsten and carbon, for example) may be found in the matrix material surrounding the tungsten carbide particle. In addition, at least some atoms originally contained in the matrix material (iron, for example) may be found in the tungsten carbide particles.
Dissolution between the tungsten carbide particle 40 and the matrix material 46 may embrittle the matrix material 46 in the region 47 surrounding the tungsten carbide particle 40 and reduce the hardness of the tungsten carbide particle 40 in the outer region 41 thereof, reducing the overall effectiveness of the hardfacing material. Dissolution is a process of dissolving a solid, such as the tungsten carbide particle 40, into a liquid, such as the matrix material 46, particularly when at elevated temperatures and when the matrix material 46 is in its liquid phase which transforms the material composition of the matrix material. In one aspect, dissolution is the process where a solid substance enters (generally at elevated temperatures) a molten matrix material which changes the composition of the matrix material. Dissolution occurs more rapidly as the temperature of the matrix material 46 approaches the melting temperature of tungsten carbide particle 40. For example, an iron-based matrix material will have greater dissolution of the tungsten carbide particles 40 than a nickel-based matrix material will, because of the higher temperatures required in order to bring the iron-based matrix material into a molten state during application. Therefore, there is a need in the art for abrasive, wear-resistant hardfacing materials that include a matrix material that allows for dissolution between tungsten carbide particles and the matrix material to be minimized. There is also a need in the art for methods of applying such abrasive wear-resistant hardfacing materials to surfaces of particle-matrix composite drill bits, and for drill bits and drilling tools that include such particle-matrix composite materials.
A rotary drill bit is provided that provides a particle-matrix composite material devoid of a molten binder or infiltrant material as is conventionally employed in so-called “matrix”-type drill bits. Such a drill bit may also be characterized as having a “sintered” particle-matrix composite structure. Further, the rotary drill bit includes an abrasive, wear-resistant material, which may be characterized as a “hardfacing” material, for enhancing the wear-resistance of surfaces of the drill bit.
In embodiments of the invention, a rotary drill bit includes a bit body substantially formed of a particle-matrix composite material and having an exterior surface and an abrasive wear-resistant material disposed on the exterior surface of the bit body being substantially formed of a particle-matrix composite material.
Methods for applying an abrasive wear-resistant material to a surface of a drill bit in accordance with embodiments of the invention are also provided.
Other advantages, features and alternative aspects of the invention will become apparent when viewed in light of the detailed description of the various embodiments of the invention when taken in conjunction with the attached drawings and appended claims.
While the specification concludes with claims particularly pointing out and distinctly claiming that which is regarded as the invention, the advantages of this invention may be more readily ascertained from the following description of the invention when read in conjunction with the accompanying drawings in which:
The illustrations presented herein are, in some instances, not actual views of any particular drill bit, cutting element, hardfacing material or other feature of a drill bit, but are merely idealized representations which are employed to describe the present invention. Additionally, like elements and features among the various drawing figures are identified for convenience with the same or similar reference numerals.
Embodiments of the invention may be used to enhance the wear resistance of rotary drill bits, particularly rotary drill bits having a particle-matrix composite material composition with an abrasive wear-resistant hardfacing material applied to surface portions thereof. A rotary drill bit 140 in accordance with an embodiment of the invention is shown in
As the formation-engaging surfaces of the various regions of the blades 114 slide and scrape against the formation during application of WOB and rotation to drill a formation, the material of the blades 114 at the formation-engaging surfaces thereof has a tendency to wear away. This wearing away of the material of the blades 114 at the formation-engaging surfaces may lead to loss of cutting elements and/or bit instability (e.g., bit whirl), which may further lead to catastrophic failure of the drill bit 140.
In an effort to reduce the wearing away of the material of the blades 114 at the formation-engaging surfaces, various wear-resistant structures and materials have been placed on and/or in these surfaces of the blades 114. For example, inserts such as bricks, studs, and wear knots formed from an abrasive wear-resistant material, such as, for example, tungsten carbide, have been inset in formation-engaging surfaces of blades 114.
As shown in
Abrasive wear-resistant hardfacing material (i.e., hardfacing material) also may be applied at selected locations on the formation-engaging surfaces of the blades 114. For example, a torch for applying an oxygen-acetylene weld (OAW) or an arc welder, for example, may be used to at least partially melt the wear-resistant hardfacing material to facilitate application of the wear-resistant hardfacing material to the surfaces of the blades 114. Application of the wear-resistant hardfacing material, i.e., hardfacing material, to the bit body 112 is described below.
With continued reference to
The manner in which the recesses 142 are formed or otherwise provided in the blades 114 may depend on the material from which the blades 114 have been formed. For example, if the blades 114 comprise cemented carbide or other particle-matrix composite material, as described below, the recesses 142 may be formed in the blades 114 using, for example, a conventional milling machine or other conventional machining tool (including hand-held machining tools). Optionally, the recesses 142 may be provided in the blades 114 during formation of the blades 114. The invention is not limited by the manner in which the recesses 142 are formed in the blades 114 of the bit body 112 of the drill bit 140, however, and any method that can be used to form the recesses 142 in a particular drill bit 140 may be used to provide drill bits that embody teachings of the invention.
As shown in
It is recognized in other embodiments of the invention, hardfacing material may optionally be applied directly to the face 120 of the bit body 112 without creating recesses 142 while still enhancing the wear-resistance of the surfaces of the bit body.
In the embodiment shown in
In additional embodiments, recesses may be provided around cutting elements.
Additionally, in this configuration, the abrasive wear-resistant hardfacing material 160 may cover and protect at least a portion of the bonding material 124 used to secure the cutting element 118 within the pocket 122, which may protect the bonding material 124 from wear during drilling. By protecting the bonding material 124 from wear during drilling, the abrasive wear-resistant hardfacing material 160 may help to prevent separation of the cutting element 118 from the blade 114, damage to the bit body, and catastrophic failure of the drill bit.
The rotary drill bit 140 further includes an abrasive wear-resistant material 160 disposed on a surface of the drill bit 140. Moreover, regions of the abrasive wear-resistant material 160 may be configured to protect exposed surfaces of the bonding material 124.
In this configuration, the continuous portions of the abrasive wear-resistant material 160 may cover and protect at least a portion of the bonding material 124 disposed between the cutting element 118 and the bit body 112 from wear during drilling operations. By protecting the bonding material 124 from wear during drilling operations, the abrasive wear-resistant material 160 helps to prevent separation of the cutting element 118 from the bit body 112 during drilling operations, damage to the bit body 112, and catastrophic failure of the rotary drill bit 140.
The continuous portions of the abrasive wear-resistant material 160 that cover and protect exposed surfaces of the bonding material 124 may be configured as a bead or beads of abrasive wear-resistant material 160 provided along and over the edges of the interfacing surfaces of the bit body 112 and the cutting element 118. The abrasive wear-resistant material 160 provides an effective method for enhancing the wear-resistance of the bonding material 124 to help prevent the loss of cutting elements 118 during drilling operations
The abrasive wear-resistant hardfacing materials described herein may comprise, for example, a ceramic-metal composite material (i.e., a “cermet” material) comprising a plurality of hard ceramic phase regions or particles dispersed throughout a metal matrix material. The hard ceramic phase regions or particles may comprise carbides, nitrides, oxides, and borides (including boron carbide (B4C)). More specifically, the hard ceramic phase regions or particles may comprise carbides and borides made from elements such as W, Ti, Mo, Nb, V, Hf, Ta, Cr, Zr, Al, and Si. By way of example and not limitation, materials that may be used to form hard ceramic phase regions or particles include tungsten carbide, titanium carbide (TiC), tantalum carbide (TaC), titanium diboride (TiB2), chromium carbides, titanium nitride (TiN), aluminium oxide (Al2O3), aluminium nitride (AlN), and silicon carbide (SiC). The metal matrix material of the ceramic-metal composite material may include, for example, cobalt-based, iron-based, nickel-based, iron- and nickel-based, cobalt- and nickel-based, iron- and cobalt-based, aluminum-based, copper-based, magnesium-based, and titanium-based alloys. The matrix material may also be selected from commercially pure elements such as cobalt, aluminum, copper, magnesium, titanium, iron, and nickel.
In embodiments of the invention, the abrasive wear-resistant hardfacing materials may be applied to a bit body or tool body and include materials as described below. As used herein, the term “bit” includes not only conventional drill bits, but also core bits, bicenter bits, eccentric bits and tools employed in drilling of a well bore.
Corners, sharp edges, and angular projections may produce residual stresses, which may cause tungsten carbide material in the regions of the particles proximate the residual stresses to melt at lower temperatures during application of the abrasive wear-resistant material 54 to a surface of a drill bit. Melting or partial melting of the tungsten carbide material during application may facilitate dissolution between the tungsten carbide particles and the surrounding matrix material. As previously discussed herein, dissolution between the matrix material 60 and the sintered tungsten carbide pellets 56 and cast tungsten carbide granules 58 may embrittle the matrix material 60 in regions surrounding the tungsten carbide pellets 56, and cast tungsten carbide granules 58 and may reduce the toughness of the hardfacing material, particularly when the matrix material 60 is iron based. Such dissolution may degrade the overall physical properties of the abrasive wear-resistant material 54. The use of sintered tungsten carbide pellets 56 (and, optionally, cast tungsten carbide pellets 58) instead of conventional tungsten carbide particles that include corners, sharp edges, and angular projections may reduce such dissolution, preserving the physical properties of the matrix material 60 and the sintered tungsten carbide pellets 56 (and, optionally, the cast tungsten carbide pellets 58) during application of the abrasive wear-resistant material 54 to the surfaces of drill bits and other tools.
The matrix material 60 may comprise between about 20% and about 50% by weight of the abrasive wear-resistant material 54. More particularly, the matrix material 60 may comprise between about 35% and about 45% by weight of the abrasive wear-resistant material 54. The plurality of sintered tungsten carbide pellets 56 may comprise between about 30% and about 55% by weight of the abrasive wear-resistant material 54. Furthermore, the plurality of cast tungsten carbide granules 58 may comprise less than about 35% by weight of the abrasive wear-resistant material 54. More particularly, the plurality of cast tungsten carbide granules 58 may comprise between about 10% and about 35% by weight of the abrasive wear-resistant material 54. For example, the matrix material 60 may be about 40% by weight of the abrasive wear-resistant material 54, the plurality of sintered tungsten carbide pellets 56 may be about 48% by weight of the abrasive wear-resistant material 54, and the plurality of cast tungsten carbide granules 58 may be about 12% by weight of the abrasive wear-resistant material 54.
The sintered tungsten carbide pellets 56 may be larger in size than the cast tungsten carbide granules 58. Furthermore, the number of cast tungsten carbide granules 58 per unit volume of the abrasive wear-resistant material 54 may be higher than the number of sintered tungsten carbide pellets 56 per unit volume of the abrasive wear-resistant material 54.
The sintered tungsten carbide pellets 56 may include −10 ASTM (American Society for Testing and Materials) mesh pellets. As used herein, the phrase “−10 ASTM mesh pellets” means pellets that are capable of passing through an ASTM No. 10 U.S.A. standard testing sieve. Such sintered tungsten carbide pellets may have an average diameter of less than about 1680 microns. The average diameter of the sintered tungsten carbide pellets 56 may be between about 0.8 times and about 20 times greater than the average diameter of the cast tungsten carbide granules 58. The cast tungsten carbide granules 58 may include −16 ASTM mesh granules. As used herein, the phrase “−16 ASTM mesh granules” means granules that are capable of passing through an ASTM No. 16 U.S.A. standard testing sieve. More particularly, the cast tungsten carbide granules 58 may include −100 ASTM mesh granules. As used herein, the phrase “−100 ASTM mesh granules” means granules that are capable of passing through an ASTM No. 100 U.S.A. standard testing sieve. Such cast tungsten carbide granules 58 may have an average diameter of less than about 150 microns.
As an example, the sintered tungsten carbide pellets 56 may include −20/+30 ASTM mesh pellets, and the cast tungsten carbide granules 58 may include −100/+270 ASTM mesh granules. As used herein, the phrase “−20/+30 ASTM mesh pellets” means pellets that are capable of passing through an ASTM No. 20 U.S.A. standard testing sieve, but incapable of passing through an ASTM No. 30 U.S.A. standard testing sieve. Such sintered tungsten carbide pellets 56 may have an average diameter of less than about 840 microns and greater than about 590 microns. Furthermore, the phrase “−100/+270 ASTM mesh granules,” as used herein, means granules capable of passing through an ASTM No. 100 U.S.A. standard testing sieve, but incapable of passing through an ASTM No. 270 U.S.A. standard testing sieve. Such cast tungsten carbide granules 58 may have an average diameter in a range from approximately 50 microns to about 150 microns.
As another example, the plurality of sintered tungsten carbide pellets 56 may include a plurality of −60/+80 ASTM mesh sintered tungsten carbide pellets and a plurality of −120/+270 ASTM mesh sintered tungsten carbide pellets. The plurality of −60/+80 ASTM mesh sintered tungsten carbide pellets may comprise between about 30% and about 40% by weight of the abrasive wear-resistant material 54, and the plurality of −120/+270 ASTM mesh sintered tungsten carbide pellets may comprise between about 15% and about 25% by weight of the abrasive wear-resistant material 54. As used herein, the phrase “−120/+270 ASTM mesh pellets” means pellets capable of passing through an ASTM No. 120 U.S.A. standard testing sieve, but incapable of passing through an ASTM No. 270 U.S.A. standard testing sieve. Such sintered tungsten carbide pellets 56 may have an average diameter in a range from approximately 50 microns to about 125 microns.
In one particular embodiment, set forth merely as an example, the abrasive wear-resistant material 54 may include about 40% by weight matrix material 60, about 48% by weight −20/+30 ASTM mesh sintered tungsten carbide pellets 56, and about 12% by weight −140/+325 ASTM mesh cast tungsten carbide granules 58. As used herein, the phrase “−20/+30 ASTM mesh pellets” means pellets that are capable of passing through an ASTM No. 20 U.S.A. standard testing sieve, but incapable of passing through an ASTM No. 30 U.S.A. standard testing sieve. Similarly, the phrase “−140/+325 ASTM mesh pellets” means pellets that are capable of passing through an ASTM No. 140 U.S.A. standard testing sieve, but incapable of passing through an ASTM No. 325 U.S.A. standard testing sieve. The matrix material 60 may include a nickel-based alloy, which may further include one or more additional elements, such as, for example, chromium, boron, and silicon. The matrix material 60 also may have a melting point of less than about 1100° C., and may exhibit a hardness of between about 87 on the Rockwell B Scale and about 60 on the Rockwell C Scale. Hardness values herein are represented of actual or converted hardness microhardness determinations. More particularly, the matrix material 60 may exhibit a hardness of between about <20 and about 55 on the Rockwell C Scale. For example, the matrix material 60 may exhibit a hardness of about 40 on the Rockwell C Scale.
Cast granules and sintered pellets of carbides other than tungsten carbide also may be used to provide abrasive wear-resistant materials that embody teachings of the invention. Such other carbides include, but are not limited to, chromium carbide, molybdenum carbide, niobium carbide, tantalum carbide, titanium carbide, and vanadium carbide.
The matrix material 60 may comprise a metal alloy material having a melting point that is less than about 1460° C. More particularly, the matrix material 60 may comprise a metal alloy material having a melting point that is less than about 1100° C. Furthermore, each sintered tungsten carbide pellet 56 of the plurality of sintered tungsten carbide pellets 56 may comprise a plurality of tungsten carbide particles bonded together with a binder alloy having a melting point that is greater than about 1200° C. For example, the binder alloy may comprise a cobalt-based metal alloy material or a nickel-based alloy material having a melting point that is lower than about 1200° C. In this configuration, the matrix material 60 may be substantially melted during application of the abrasive wear-resistant material 54 to a surface of a drilling tool such as a drill bit without substantially melting the cast tungsten carbide granules 58, or the binder alloy or the tungsten carbide particles of the sintered tungsten carbide pellets 56. This enables the abrasive wear-resistant material 54 to be applied to a surface of a drilling tool at relatively lower temperatures to minimize dissolution between the sintered tungsten carbide pellets 56 and the matrix material 60 and between the cast tungsten carbide granules 58 and the matrix material 60.
As previously discussed herein, minimizing atomic diffusion between the matrix material 60 and the sintered tungsten carbide pellets 56 and cast tungsten carbide granules 58, helps to preserve the chemical composition and the physical properties of the matrix material 60, the sintered tungsten carbide pellets 56, and the cast tungsten carbide granules 58 during application of the abrasive wear-resistant material 54 to the surfaces of drill bits and other tools.
The matrix material 60 also may include relatively small amounts of other elements, such as carbon, chromium, silicon, boron, iron, silver, and nickel. Furthermore, the matrix material 60 also may include a flux material such as silicomanganese, an alloying element such as niobium, and a binder such as a polymer material.
The sintered tungsten carbide pellets 56 may have relatively high fracture toughness relative to the cast tungsten carbide granules 58, while the cast tungsten carbide granules 58 may have relatively high hardness relative to the sintered tungsten carbide pellets 56. By using matrix materials 60 as described herein, the fracture toughness of the sintered tungsten carbide pellets 56 and the hardness of the cast tungsten carbide granules 58 may be preserved in the abrasive wear-resistant material 54 during application of the abrasive wear-resistant material 54 to a drill bit or other drilling tool, providing an abrasive wear-resistant material 54 that is improved relative to abrasive wear-resistant materials known in the art.
Abrasive wear-resistant materials according to embodiments of the invention, such as the abrasive wear-resistant material 54 illustrated in
Certain locations on a surface of a drill bit may require relatively higher hardness, while other locations on the surface of the drill bit may require relatively higher fracture toughness. The relative weight percentages of the matrix material 60, the plurality of sintered tungsten carbide pellets 56, and the plurality of cast tungsten carbide granules 58 may be selectively varied to provide an abrasive wear-resistant material 54 that exhibits physical properties tailored to a particular tool or to a particular area on a surface of a tool. For example, the surfaces of cutting teeth on a rolling-cutter-type drill bit may be subjected to relatively high impact forces in addition to frictional-type abrasive or grinding forces. Therefore, abrasive wear-resistant material 54 applied to the surfaces of the cutting teeth may include a higher weight percentage of sintered tungsten carbide pellets 56 in order to increase the fracture toughness of the abrasive wear-resistant material 54. In contrast, gage surfaces of a drill bit may be subjected to relatively little impact force but relatively high frictional-type abrasive or grinding forces. Therefore, abrasive wear-resistant material 54 applied to the gage surfaces of a drill bit may include a higher weight percentage of cast tungsten carbide granules 58 in order to increase the hardness of the abrasive wear-resistant material 54.
In addition to being applied to selected areas on surfaces of drill bits and drilling tools that are subjected to wear, the abrasive wear-resistant materials according to embodiments of the invention may be used to protect structural features or materials of drill bits and drilling tools that are relatively more prone to wear, including the examples presented above.
The abrasive wear-resistant material 54 may be used to cover and protect interfaces between any two structures or features of a drill bit or other drilling tool. For example, the interface between a bit body and a periphery of wear knots or any type of insert in the bit body may be covered and protected by abrasive wear-resistant material 54. In addition, the abrasive wear-resistant material 54 is not limited to use at interfaces between structures or features and may be used at any location on any surface of a drill bit or drilling tool that is subjected to wear.
Abrasive wear-resistant materials according to embodiments of the invention, such as the abrasive wear-resistant material 54, may be applied to the selected surfaces of a drill bit or drilling tool using variations of techniques known in the art. For example, a pre-application abrasive wear-resistant material according to embodiments of the invention may be provided in the form of a welding rod. The welding rod may comprise a solid, cast or extruded rod consisting of the abrasive wear-resistant material 54. Alternatively, the welding rod may comprise a hollow cylindrical tube formed from the matrix material 60 and filled with a plurality of sintered tungsten carbide pellets 56 and a plurality of cast tungsten carbide granules 58. An OAW torch or any other type of gas fuel torch may be used to heat at least a portion of the welding rod to a temperature above the melting point of the matrix material 60. This may minimize the extent of atomic diffusion occurring between the matrix material 60 and the sintered tungsten carbide pellets 56 and cast tungsten carbide granules 58.
The rate of dissolution occurring between the matrix material 60 and the sintered tungsten carbide pellets 56 and cast tungsten carbide granules 58 is at least partially a function of the temperature at which dissolution occurs. The extent of dissolution, therefore, is at least partially a function of both the temperature at which dissolution occurs and the time for which dissolution is allowed to occur. Therefore, the extent of dissolution occurring between the matrix material 60 and the sintered tungsten carbide pellets 56 and the cast tungsten carbide granules 58 may be controlled by employing good heat management control.
The OAW torch may be capable of heating materials to temperatures in excess of 1200° C. It may be beneficial to slightly melt the surface of a drill bit or drilling tool to which the abrasive wear-resistant material 54 is to be applied just prior to applying the abrasive wear-resistant material 54 to the surface. For example, the OAW torch may be brought in close proximity to a surface of a drill bit or drilling tool and used to heat to the surface to a sufficiently high temperature to slightly melt or “sweat” the surface. The welding rod comprising pre-application wear-resistant material 54 may then be brought in close proximity to the surface, and the distance between the torch and the welding rod may be adjusted to heat at least a portion of the welding rod to a temperature above the melting point of the matrix material 60 to melt the matrix material 60. The molten matrix material 60, at least some of the sintered tungsten carbide pellets 56, and at least some of the cast tungsten carbide granules 58 may be applied to the surface of a drill bit, and the molten matrix material 60 may be solidified by controlled cooling. The rate of cooling may be controlled to control the microstructure and physical properties of the abrasive wear-resistant material 54.
Alternatively, the abrasive wear-resistant material 54 may be applied to a surface of a drill bit or drilling tool using an arc welding technique, such as a plasma-transferred arc welding technique. For example, the matrix material 60 may be provided in the form of a powder (small particles of matrix material 60). A plurality of sintered tungsten carbide pellets 56 and a plurality of cast tungsten carbide granules 58 may be mixed with the powdered matrix material 60 to provide a pre-application wear-resistant material in the form of a powder mixture. A plasma-transferred arc welding machine then may be used to heat at least a portion of the pre-application wear-resistant material to a temperature above the melting point of the matrix material 60 and less than about 1200° C. to melt the matrix material 60.
Other welding techniques, such as metal inert gas (MIG) arc welding techniques, tungsten inert gas (TIG) arc welding techniques, and flame spray welding techniques are known in the art and may be used to apply the abrasive wear-resistant material 54 to a surface of a drill bit or drilling tool.
The abrasive wear-resistant material, i.e., hardfacing, is suitable for application upon a bit body made from particle-matrix composite material or so called “cemented carbide” material. The particle-matrix composite material for a bit body is now presented together with some terminology to facilitate a proper understanding of the invention.
The term “green,” as used herein, means unsintered.
The term “green bit body,” as used herein, means an unsintered structure comprising a plurality of discrete particles held together by a binder material, the structure having a size and shape allowing the formation of a bit body suitable for use in an earth boring drill bit from the structure by subsequent manufacturing processes including, but not limited to, machining and densification.
The term “brown,” as used herein, means partially sintered.
The term “brown bit body,” as used herein, means a partially sintered structure comprising a plurality of particles, at least some of which have partially grown together to provide at least partial bonding between adjacent particles, the structure having a size and shape allowing the formation of a bit body suitable for use in an earth boring drill bit from the structure by subsequent manufacturing processes including, but not limited to, machining and further densification. Brown bit bodies may be formed by, for example, partially sintering a green bit body.
The term “sintering,” as used herein, means densification of a particulate component involving removal of at least a portion of the pores between the starting particles (accompanied by shrinkage) combined with coalescence and bonding between adjacent particles.
As used herein, the term “[metal]-based alloy” (where [metal] is any metal) means commercially pure [metal] in addition to metal alloys wherein the weight percentage of [metal] in the alloy is greater than the weight percentage of any other component of the alloy.
As used herein, the term “material composition” means the chemical composition and microstructure of a material. In other words, materials having the same chemical composition but a different microstructure are considered to have different material compositions.
As used herein, the term “tungsten carbide” means any material composition that contains chemical compounds of tungsten and carbon, such as, for example, WC, W2C, and combinations of WC and W2C. Tungsten carbide includes, for example, cast tungsten carbide, sintered tungsten carbide, and macrocrystalline tungsten carbide.
The rotary drill bit 140, as shown in
The particle-matrix composite material of the bit body 112 may include a plurality of hard particles randomly dispersed throughout a matrix material. The hard particles may comprise diamond or ceramic materials such as carbides, nitrides, oxides, and borides (including boron carbide (B4C)). More specifically, the hard particles may comprise carbides and borides made from elements such as W, Ti, Mo, Nb, V, Hf, Ta, Cr, Zr, Al, and Si. By way of example and not limitation, materials that may be used to form hard particles include tungsten carbide, titanium carbide (TiC), tantalum carbide (TaC), titanium diboride (TiB2), chromium carbides, titanium nitride (TiN), aluminium oxide (Al2O3), aluminium nitride (AlN), and silicon carbide (SiC). Furthermore, combinations of different hard particles may be used to tailor the physical properties and characteristics of the particle-matrix composite material. The hard particles may be formed using techniques known to those of ordinary skill in the art. Most suitable materials for hard particles are commercially available and the formation of the remainder is within the ability of one of ordinary skill in the art.
The matrix material 60 of the particle-matrix composite material may include, for example, cobalt-based, iron-based, nickel-based, iron- and nickel-based, cobalt- and nickel-based, iron- and cobalt-based, aluminum-based, copper-based, magnesium-based, and titanium-based alloys. The matrix material may also be selected from commercially pure elements such as cobalt, aluminum, copper, magnesium, titanium, iron, and nickel. By way of example and not limitation, the matrix material may include carbon steel, alloy steel, stainless steel, tool steel, Hadfield manganese steel, nickel or cobalt superalloy material, and low thermal expansion iron- or nickel-based alloys such as INVAR®. As used herein, the term “superalloy” refers to an iron-, nickel-, and cobalt-based alloys having at least 12% chromium by weight. Additional examples of alloys that may be used as matrix material include austenitic steels, nickel-based superalloys such as INCONEL® 625M or Rene 95, and INVAR®-type alloys having a coefficient of thermal expansion that closely matches that of the hard particles used in the particular particle-matrix composite material. More closely matching the coefficient of thermal expansion of matrix material with that of the hard particles offers advantages such as reducing problems associated with residual stresses and thermal fatigue. Another example of a suitable matrix material is a Hadfield austenitic manganese steel (Fe with approximately 12% Mn by weight and 1.1% C by weight).
In embodiments of the invention, the particle-matrix composite material may include a plurality of −400 ASTM (American Society for Testing and Materials) mesh tungsten carbide particles. As used herein, the phrase “−400 ASTM mesh particles” means particles that pass through an ASTM No. 400 mesh screen as defined in ASTM specification E11 04 entitled Standard Specification for Wire Cloth and Sieves for Testing Purposes. Such tungsten carbide particles may have a diameter of less than about 38 microns. A matrix material may include a metal alloy comprising about 50% cobalt by weight and about 50% nickel by weight. The tungsten carbide particles may comprise between about 60% and about 95% by weight of the particle-matrix composite material, and the matrix material may comprise between about 5% and about 40% by weight of the particle-matrix composite material. More particularly, the tungsten carbide particles may comprise between about 70% and about 80% by weight of the particle-matrix composite material, and the matrix material may comprise between about 20% and about 30% by weight of the particle-matrix composite material.
In another embodiment of the invention, the particle-matrix composite material may include a plurality of −635 ASTM mesh tungsten carbide particles. As used herein, the phrase “−635 ASTM mesh particles” means particles that pass through an ASTM No. 635 mesh screen as defined in ASTM specification E11 04 entitled Standard Specification for Wire Cloth and Sieves for Testing Purposes. Such tungsten carbide particles may have a diameter of less than about 20 microns. A matrix material may include a cobalt-based metal alloy comprising substantially commercially pure cobalt. For example, the matrix material may include greater than about 98% cobalt by weight. The tungsten carbide particles may comprise between about 60% and about 95% by weight of the particle-matrix composite material, and the matrix material may comprise between about 5% and about 40% by weight of the particle-matrix composite material.
Referring to
The container 80 may include a fluid-tight deformable member 82. For example, the fluid tight deformable member 82 may be a substantially cylindrical bag comprising a deformable polymer material. The container 80 may further include a sealing plate 84, which may be substantially rigid. The deformable member 82 may be formed from, for example, an elastomer such as rubber, neoprene, silicone, or polyurethane. The deformable member 82 may be filled with the powder mixture 78 and vibrated to provide a uniform distribution of the powder mixture 78 within the deformable member 82. At least one displacement or insert 86 may be provided within the deformable member 82 for defining features of the bit body, such as, for example, the longitudinal bore 15 (
The container 80 (with the powder mixture 78 and any desired inserts 86 contained therein) may be placed within a pressure chamber 90. A removable cover 91 may be used to provide access to the interior of the pressure chamber 90. A fluid (which may be substantially incompressible) such as, for example, water, oil, or gas (such as, for example, air or nitrogen) is pumped into the pressure chamber 90 through an opening 92 at high pressures using a pump (not shown). The high pressure of the fluid causes the walls of the deformable member 82 to deform. The fluid pressure may be transmitted substantially uniformly to the powder mixture 78. The pressure within the pressure chamber 90 during isostatic pressing may be greater than about 35 megapascals (about 5,000 pounds per square inch). More particularly, the pressure within the pressure chamber 90 during isostatic pressing may be greater than about 138 megapascals (20,000 pounds per square inch). In other methods, a vacuum may be provided within the container 80 and a pressure greater than about 0.1 megapascals (about 15 pounds per square inch) may be applied to the exterior surfaces of the container 80 (by, for example, the atmosphere) to compact the powder mixture 78. Isostatic pressing of the powder mixture 78 may form a green powder component or green bit body 94 shown in
In another method of pressing the powder mixture 78 to form the green bit body 94 shown in
The green bit body 94 shown in
The shaped green bit body 98 shown in
The brown bit body 102 may be substantially machinable due to the remaining porosity therein. Certain structural features may be machined in the brown bit body 102 using conventional machining techniques including, for example, turning techniques, milling techniques, and drilling techniques. Hand-held tools also may be used to manually form or shape features in or on the brown bit body 102. Tools that include superhard coatings or inserts may be used to facilitate machining of the brown bit body 102. Additionally, material coatings may be applied to surfaces of the brown bit body 102 that are to be machined to reduce chipping of the brown bit body 102. Such coatings may include a fixative or other polymer material.
By way of example and not limitation, internal fluid passageways 119, pockets 36, and buttresses (not shown) may be machined or otherwise formed in the brown bit body 102 to form a shaped brown bit body 106 shown in
The shaped brown bit body 106 shown in
During all sintering and partial sintering processes, refractory structures or displacements (not shown) may be used to support at least portions of a bit body during the sintering process to maintain desired shapes and dimensions during the densification process. Such displacements may be used, for example, to maintain consistency in the size and geometry of the pockets 36 and the internal fluid passageways 119 during the sintering process. Such refractory structures may be formed from, for example, graphite, silica, or alumina. The use of alumina displacements instead of graphite displacements may be desirable as alumina may be relatively less reactive than graphite, minimizing atomic diffusion during sintering. Additionally, coatings such as alumina, boron nitride, aluminum nitride, or other commercially available materials may be applied to the refractory structures to prevent carbon or other atoms in the refractory structures from diffusing into the bit body during densification.
In other methods, the green bit body 94 shown in
The sintering processes described herein may include conventional sintering in a vacuum furnace, sintering in a vacuum furnace followed by a conventional hot isostatic pressing process, and sintering immediately followed by isostatic pressing at temperatures near the sintering temperature (often referred to as sinter HIP (hot isostatic pressing)). Furthermore, the sintering processes described herein may include subliquidus phase sintering. In other words, the sintering processes may be conducted at temperatures proximate to, but below the liquidus line of the phase diagram for the matrix material. For example, the sintering processes described herein may be conducted using a number of different methods known to one of ordinary skill in the art such as the Rapid Omnidirectional Compaction (ROC) process, the Ceracon™ process, hot isostatic pressing (HIP), or adaptations of such processes.
Broadly, and by way of example only, sintering a green powder compact using the ROC process involves presintering the green powder compact at a relatively low temperature to only a sufficient degree to develop sufficient strength to permit handling of the powder compact. The resulting brown structure is wrapped in a material such as graphite foil to seal the brown structure. The wrapped brown structure is placed in a container, which is filled with particles of a ceramic, polymer, or glass material having a substantially lower melting point than that of the matrix material in the brown structure. The container is heated to the desired sintering temperature, which is above the melting temperature of the particles of a ceramic, polymer, or glass material, but below the liquidus temperature of the matrix material in the brown structure. The heated container with the molten ceramic, polymer, or glass material (and the brown structure immersed therein) is placed in a mechanical or hydraulic press, such as a forging press, that is used to apply pressure to the molten ceramic or polymer material. Isostatic pressures within the molten ceramic, polymer, or glass material facilitate consolidation and sintering of the brown structure at the elevated temperatures within the container. The molten ceramic, polymer, or glass material acts to transmit the pressure and heat to the brown structure. In this manner, the molten ceramic, polymer, or glass acts as a pressure transmission medium through which pressure is applied to the structure during sintering. Subsequent to the release of pressure and cooling, the sintered structure is then removed from the liquefied ceramic, polymer, or glass material. A more detailed explanation of the ROC process and suitable equipment for the practice thereof is provided by U.S. Pat. Nos. 4,094,709, 4,233,720, 4,341,557, 4,526,748, 4,547,337, 4,562,990, 4,596,694, 4,597,730, 4,656,002 4,744,943 and 5,232,522, the disclosure of each of which patents is incorporated herein by reference.
The Ceracon™ process, which is similar to the aforementioned ROC process, may also be adapted for use in the present invention to fully sinter brown structures to a final density. In the Ceracon™ process, the brown structure is coated with a ceramic coating such as alumina, zirconium oxide, or chrome oxide. Other similar, hard, generally inert, protective, removable coatings may also be used. The coated brown structure is fully consolidated by transmitting at least substantially isostatic pressure to the coated brown structure using ceramic particles instead of a fluid media as in the ROC process. A more detailed explanation of the Ceracon™ process is provided by U.S. Pat. No. 4,499,048, the disclosure of which patent is incorporated herein by reference.
Furthermore, in embodiments of the invention in which tungsten carbide is used in a particle-matrix composite bit body, the sintering processes described herein also may include a carbon control cycle tailored to improve the stoichiometry of the tungsten carbide material. By way of example and not limitation, if the tungsten carbide material includes WC, the sintering processes described herein may include subjecting the tungsten carbide material to a gaseous mixture including hydrogen and methane at elevated temperatures. For example, the tungsten carbide material may be subjected to a flow of gases including hydrogen and methane at a temperature of about 1,000° C. A method for carbon control of carbides is provided by U.S. Pat. No. 4,579,713, the disclosure of which patent is incorporated herein by reference.
The bit body 112 is completed by attaching a shank (not shown), such as an API threaded pin mentioned above, thereto. Several different methods may be used to attach the shank to the bit body 112 and are provided by U.S. application Ser. No. 11/272,439 which is incorporated herein by reference. The bit body 112 with its particle-matrix composite materials and an abrasive wear-resistant hardfacing material attached thereon provides more resistant to the abrasive environment when drilling in subterranean formations.
While the invention has been described herein with respect to certain embodiments, those of ordinary skill in the art will recognize and appreciate that it is not so limited. Rather, many additions, deletions and modifications to the embodiments may be made without departing from the scope of the invention as hereinafter claimed. In addition, features from one embodiment may be combined with features of another embodiment while still being encompassed within the scope of the invention as contemplated by the inventors. Further, the invention has utility in drill bits and core bits having different and various bit profiles as well as cutting element types.
This application claims the benefit of U.S. Application Ser. No. 60/848,154, titled “EARTH-BORING ROTARY DRILL BITS INCLUDING WEAR-RESISTANT HARDFACING MATERIAL DISPOSED IN RECESSES FORMED IN EXTERIOR SURFACES THEREOF,” which was filed Sep. 29, 2006, and is a continuation-in-part of U.S. application Ser. No. 11/513,677, titled “COMPOSITE MATERIALS INCLUDING NICKEL-BASED MATRIX MATERIALS AND HARD PARTICLES, TOOLS INCLUDING SUCH MATERIALS, AND METHODS OF USING SUCH MATERIALS,” which was filed Aug. 30, 2006; U.S. application Ser. No. 11/272,439, titled “EARTH BORING ROTARY DRILL BITS AND METHODS OF MANUFACTURING EARTH BORING ROTARY DRILL BITS HAVING PARTICLE MATRIX COMPOSITE BIT BODIES,” which was filed Nov. 10, 2005; and U.S. application Ser. No. 11/223,215, titled “ABRASIVE WEAR-RESISTANT HARDFACING MATERIALS, DRILL BITS AND DRILLING TOOLS INCLUDING ABRASIVE WEAR-RESISTANT HARDFACING MATERIALS, METHODS FOR APPLYING ABRASIVE WEAR-RESISTANT HARDFACING MATERIALS TO DRILL BITS AND DRILLING TOOLS, AND METHODS FOR SECURING CUTTING ELEMENTS TO A DRILL BIT,” which was filed Sep. 9, 2005, the disclosure of each of which application is incorporated herein in its entirety by this reference.
| Number | Date | Country | |
|---|---|---|---|
| 60848154 | Sep 2006 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11513677 | Aug 2006 | US |
| Child | 11823800 | Jun 2007 | US |
| Parent | 11272439 | Nov 2005 | US |
| Child | 11823800 | Jun 2007 | US |
| Parent | 11223215 | Sep 2005 | US |
| Child | 11823800 | Jun 2007 | US |
