CN101614107B - Matrix drill bits and method of manufacture - Google Patents

Abstract

The invention discloses a matrix drill bit and a method for manufacturing a matrix drill bit body from a matrix material compound. Composite matrix bit bodies may be formed using two or more matrix materials. The first matrix material may be selected to provide optimum fracture resistance (toughness) to the matrix bit body such as the tool socket, cutting structure, cutter body, flute and other portions associated with engaging and removing formation material. ), and the best corrosion resistance, abrasion resistance and wear resistance. The second carcass material can be selected to provide the required infiltration of the hot liquid binder material with the first carcass material to form a strong bonded composite carcass bit body.

Description

Matrix drill bit and manufacturing method

The patent application of the present invention is a divisional application of the patent application for invention with the filing date being April 13, 2006, the application number being 200610073633.0, and the title of the invention being "matrix drill bit and manufacturing method".

related application

This application claims priority to U.S. Provisional Patent Application Serial No. 60/671,272, filed April 14, 2005, and entitled "MATRIX DRILL BITS AND METHOD OF MANUFACTURE," (matrix drill bit and method of manufacture).

technical field

The present invention relates to rotary drill bits, and more particularly, to matrix drill bits having a matrix drill bit body composed in part of at least a first matrix material and a second matrix material. Two carcass materials are formed.

Background technique

Rotary drill bits are often used to drill oil and gas wells, geothermal wells, and water wells. Rotary drills can generally be divided into rotary cone or roller cone drills, and fixed cutter drilling equipment or cutting drills. Fixed cutter bits or cutting bits are often formed using a matrix bit body with cutting elements or inserts disposed at selected locations on the exterior of the matrix bit body. Typically, fluid flow channels are formed in the matrix bit body to enable the transfer of drilling fluid from the associated surface drilling equipment through a drill string or drill pipe mounted on the matrix bit body. Such fixed cutter bits or cutting bits may sometimes be referred to as "matrix bits".

Typically, a carcass drill is formed by placing loose carcass material (sometimes called "carcass powder") into a mold and infiltrating the carcass material with a binder such as a copper alloy. The mold can be defined by milling a block of material such as graphite to define a cavity with features that generally correspond to the desired external features of the resulting matrix bit. By shaping the mold cavity and/or by disposing a temporary displacement material inside the mold cavity, various features of the resulting matrix drill bit, such as blades, cutter pockets, and/or fluid flow channels, can be provided. . A prefabricated steel shank or bit blank may be placed into the mold cavity to reinforce the matrix bit body and allow the connection of the finished matrix bit to the drill string.

A quantity of carcass material, typically in powder form, is then placed into the mold cavity. The matrix material may be infiltrated with a molten metal alloy or a binder, and after the binder solidifies, forms the matrix bit body together with the matrix material. Tungsten carbide powder is often used to form the body of a conventional matrix bit.

Contents of the invention

In accordance with the teachings of the present disclosure, the first and second carcass materials are mated to eliminate or substantially reduce the problems encountered in forming a dense carcass bit free of internal defects. One aspect of the present disclosure may include loading a first carcass material into a mold to form the body, sipe, junk slots and other exterior portions of the associated carcass bit. A metal blank or casting core may be mounted in the mold above the first carcass material. A second carcass material can then be added to the mold. The second carcass material may be selected so as to allow the liquid binder material to infiltrate rapidly into, or flow rapidly throughout, the first carcass material. Thereby, alloy segregation of the binder material and the first carcass material in the portion that solidifies last can be substantially reduced or eliminated. The first matrix material may also provide desirable enhancements in transverse rupture strength, impact strength, corrosion, abrasion and wear properties for an associated composite matrix bit.

The cooperation between the second carcass material and the binder substantially reduces and/or eliminates quality problems associated with unsatisfactory infiltration of the binder material through the first carcass material. By adding the second carcass material, porosity, shrinkage, cracking, segregation, and/or non-bonding of the binder material from the first carcass material can be reduced or eliminated. The first matrix material may be cemented carbide of tungsten, titanium, tantalum, niobium, chromium, vanadium, molybdenum, hafnium alone, or combinations thereof and/or spherical carbides. The second carcass material may be coarse crystalline tungsten carbide and/or tungsten cast carbide. However, the present disclosure is not limited to sintered tungsten carbide, spherical carbide, coarse crystalline tungsten carbide and/or cast tungsten carbide or mixtures thereof. Also, the teachings of the present disclosure may be used to manufacture or cast relatively large composite matrix bit bodies as well as relatively small, complex composite matrix bit bodies.

Technical effects of the present disclosure include, but are not limited to, eliminating or substantially reducing quality problems associated with incomplete infiltration of matrix bits or bonding with hard particulate matter. Examples of such quality problems include, but are not limited to, reduction of alloy segregation, formation of undesired intermetallic compounds, formation of porosity and/or undesired pores or voids in the associated matrix bit body.

An aspect of the present disclosure includes forming a matrix drill bit having a first portion or region formed in part from cemented carbide and/or spherical carbide, along with improved wear resistance properties, corrosion resistance and wear resistance together, providing increased toughness, the drill bit also has a second portion or second region, the second portion or second region is partially composed of coarse crystalline tungsten carbide and/or Cast carbide formation, the second portion or region enhances the infiltration of hot, liquid binder material throughout the cemented carbide and/or spherical carbide.

Description of drawings

A more complete and adequate understanding of the present embodiments and their advantages may be obtained by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numerals indicate like features, in which:

1 is a schematic diagram representing an isometric view of a fixed cutter bit having a matrix bit body formed in accordance with the teachings of the present disclosure;

2 is a schematic, partially broken-away cross-sectional view illustrating an example of a mold assembly with first and second carcass materials suitable for forming a carcass drill bit according to the teachings of the present disclosure;

FIG. 3 is a partially cutaway schematic cross-sectional view showing the carcass bit body removed from the mold shown in FIG. 2 after the binder material has infiltrated the first and second carcass materials; and

4 is a schematic, partially broken-away cross-sectional view of one example of a mold suitable for use in forming a carcass bit body in accordance with the teachings of the present disclosure.

Detailed ways

Preferred embodiments of the present disclosure and advantages thereof are best understood by referring to FIGS. 1-4 , wherein like numerals indicate like and like parts throughout FIGS. 1-4 .

In this application, the terms "casing bit" and "matrix bits" are used to mean "rotary cutter bit", "cutting bit", "fixed cutter bit", or any other tool embodying the teachings of this disclosure. Other drill bits. Such a drill bit may be used to form a borehole or drill a hole in an earth formation.

A matrix bit embodying the teachings of the present disclosure may include a matrix bit body formed in part from at least a first matrix material and a second matrix material. Such a matrix bit may be described as having a composite matrix bit body because the bit body may be formed from two different matrix materials having at least different operating characteristics. As will be described in detail below, more than two matrix materials may be utilized to form a matrix bit body according to the teachings of the present disclosure.

For certain applications, the first carcass material may have enhanced toughness or high fracture resistance and provide desirable corrosion, wear and abrasion resistance. Preferably, the second carcass material has only a limited, if any, amount of alloy material or other contamination. The first carcass material may include, but is not limited to, cemented carbide or spherical carbide. The second carcass material may include, but is not limited to, coarse crystalline tungsten carbide and/or cast carbide.

Various types of binder materials may be utilized to infiltrate the matrix material to form the matrix bit body. Binder materials may include, but are not limited to, copper (Cu), nickel (Ni), cobalt (Co), iron (Fe), molybdenum (Mo) alone or alloys based on these metals. Alloying elements may include, but are not limited to, one or more of the following elements: manganese (Mn), nickel (Ni), tin (Sn), zinc (Zn), silicon (Si), molybdenum (Mo), tungsten (W) , boron (B) and phosphorus (P). The matrix bit body can be mounted to a metal shank. A tool joint may be mounted to the metal shank, the tool joint having a threaded connection that operably connects the associated matrix bit body to the drill string, drill pipe, bottom hole assembly or drilling motor. Engage releasably.

The terms "tungsten carbide" and "a variety of cemented carbides" used in the application of the present invention include solid solutions of WC, MoC, TiC, TaC, NbC, Cr ₃ C ₂ , VC and mixed carbides, for example, in metal WC-TiC, WC-TiC-TaC, WC-TiC(Ta,Nb)C in the binder (matrix) phase. Typically, Co, Ni, Fe, Mo, and/or other alloys can be utilized to form the metal binder. Cemented carbides are also sometimes referred to as "composite" carbides or cemented carbides. Some cemented carbides are also called spherical carbides. However, cemented carbide can have many structures and shapes other than spherical.

Cemented carbides are generally described as powdered refractory metal carbides bonded together by pressure and heat using binder materials such as cobalt, iron, nickel, molybdenum and/or their alloys. Cemented carbide can also be sintered, crushed, sieved and/or subjected to further suitable treatments. Carbide pellets may be used to form the matrix bit body. The binder material provides ductility and toughness which generally result in larger cemented carbide grains, balls or other structures compared to cast carbides, coarse crystalline tungsten carbides and/or formulations thereof. Crack resistance (toughness).

In this application, the binder material used to form cemented carbide is sometimes referred to as "bonding material" to help distinguish the binder material used to form cemented carbide from the bond used to form the matrix bit agent material.

As will be described in detail later, the metal elements and/or their alloys in the cemented carbide-related bonding materials, when the molten infiltrant passes through the cemented carbide, before solidification to form the desired matrix , has the potential to "contaminate" hot liquid (molten) infiltrants such as copper-based alloys, and other types of binder materials associated with forming the matrix bit. This "contamination" of the melt infiltrant (enrichment of the infiltrant by the binder material from the cemented carbide) alters the infiltration as it travels through the cemented carbide under the influence of capillary action The solidus line of the agent (below this temperature, the infiltration agent is all solid) and the liquidus line (above this temperature, the infiltration agent is all liquid). This phenomenon, which has an adverse effect on the wettability of the cemented carbide, can lead to a lack of satisfactory infiltration of the cemented carbide before solidification to form the desired matrix.

Cast carbides can generally be described as having two phases, tungsten carbide and ditungsten carbide. Cast carbides often have properties different from cemented carbide or spherical carbides, such as hardness, wettability, and response to contaminated hot liquid binders.

Coarse crystalline tungsten carbide can generally be described as relatively small particles (powder) of single crystals of monotungsten carbide in which carbonyl compounds with cast carbides, Ni, Fe, and Fe and Ni etc. . Both cemented carbide and coarse crystalline tungsten carbide are generally described as hard materials with high resistance to wear, corrosion and wear. Coarse crystalline tungsten carbide may also have properties different from cemented carbide or spherical carbides, such as hardness, wettability, and response to contaminating hot liquid binders.

The term "binder" or "binder material" as used in this application includes: copper, cobalt, nickel, iron, any alloy of these elements, or any material suitable for forming a matrix bit. other materials. This binder generally provides the required ductility, toughness, and thermal conductivity for the associated matrix bit. Other materials, such as, but not limited to, tungsten carbide, have previously been used as a binder material to provide wear resistance, corrosion resistance, and wear resistance to matrix bits. The binder material can be combined with two or more different types of carcass materials selected in accordance with the teachings of the present disclosure to form a composite carcass bit body that is more compact than many conventional carcass bits. The body bit body has increased toughness and wear resistance.

FIG. 1 is a schematic diagram illustrating one example of a matrix bit or fixed cutter bit formed using a composite matrix bit body according to the teachings of the present disclosure. For the embodiment shown in FIG. 1 , the matrix bit 20 may include a metal shank 30 onto which the composite matrix bit body 50 is securely mounted. Metal handle 30 may be described as having a generally hollow cylindrical structure partially defined by fluid flow channel 32 in FIG. 3 . On the metal shank 30, on the opposite side of the composite matrix bit body 50, various types of threaded connections, such as American Petroleum Institute (API) fittings or threaded pins 34, may be formed.

For certain applications, a generally cylindrical metal blank or cast 36 (see FIGS. 2 and 3 ) may be mounted to the generally hollow cylindrical metal shank 30 using various techniques. Between the blank 36 and an adjacent portion of the shank 30, for example, an annular weld groove 38 may be formed (see FIG. 3). A weld 39 may be formed in the groove 38 between the blank 36 and the shank 30 . See Figure 1. A fluid flow channel or longitudinal bore 32 preferably extends through the metal shank 30 and the metal blank 36 . Metal blank 36 and metal shank 30 may be formed from various steel alloys or other metal alloys relevant to the manufacture of rotary drill bits.

A matrix bit may include a plurality of cutting elements, inserts, sipes, blades, cutting structures, flutes, and/or fluid flow passages formed or mounted on the exterior of an associated bit body. For the embodiment shown in FIGS. 1 , 2 and 3 , a plurality of blades 52 may be formed on the exterior of the composite matrix bit body 50 . The blades 52 may be spaced apart from each other on the composite matrix bit body 50 to form fluid flow channels or flutes therebetween.

A plurality of nozzle openings 54 may be formed on the composite matrix bit body 50 . Individual nozzles 56 may be disposed within each nozzle opening 54 . For some applications, nozzle 56 may be described as an "interchangeable" nozzle. Various drilling fluids may be drawn from surface drilling equipment (not expressly shown) through a drill string (not expressly shown) mounted using nipple 34 and fluid flow passage 32, from one or more nozzles 56 discharge. Cuttings, drilling cuttings, formation fluid and/or drilling fluid may be returned to the Well noodles.

A plurality of slots or grooves 58 may be formed in selected locations on the blade body 52 . See Figure 3. A respective cutting element or insert 60 may be securely mounted to each slot 58 to engage and remove an adjacent portion of the downhole formation. During rotation of matrix bit 20 by an attached drill string, cutting elements 60 may scrape and plan formation material from the bottom and sides of the wellbore. For some applications, as insert 60, polycrystalline diamond compact (PDC) cutters may be satisfactorily used. A matrix drill with such a PDC cutter is sometimes referred to as a "PDC drill".

U.S. Patent 6,296,069 entitled "Bladed Drill Bit with Centrally Distributed Diamond Cutters" ("Bladed Drill Bit with Centrally Distributed Diamond Cutters"), and U.S. Patent 6,296,069 entitled "Drag-Bit Drilling with Multiaxial Tooth Inserts" (with U.S. Patent 6,302,224 to U.S. Patent 6,302,224 gives examples of various blades and/or cutting elements that can be combined with a composite matrix embodying the teachings of this disclosure Use with a drill. It will be apparent to those of ordinary skill in the art that a wide variety of fixed cutter drills, cutting drills, and other drills can be satisfactorily formed using composite matrix drills embodying the teachings in accordance with the present disclosure. The present disclosure is not limited to the carcass bit 20 shown in FIGS. 1-4 or to any particular components.

A wide variety of molds may be satisfactorily used to form composite carcass bit bodies and related carcass bits according to the teachings of the present disclosure. The mold assembly 100 shown in FIGS. 2 and 4 represents only one example of a mold assembly suitable for use in forming a composite matrix bit body according to the present disclosure. U.S. Patent 5,373,907 entitled "Method And Apparatus For Manufacturing And Inspecting The Quality Of A Matrix Body Drill Bit" ("Method and Apparatus for Manufacturing Matrix Body Drill Bit and Inspection of the Quality Of A Matrix Body Drill Bit"), gives Supplementary details pertaining to mold components and conventional matrix bit bodies.

The mold assembly 100 shown in FIGS. 2 and 4 may include several components such as a mold 102 , a ring gauge or connector ring 110 and a funnel 120 . Mold 102, ring gauge 110 and gate 120 may be made of graphite or other suitable materials. Various techniques can be employed including, but not limited to, machining a graphite blank to produce a mold 102 with a cavity 104 having the desired exterior features for the formed fixed cutter bit. Negative contour or inverse contour. For example, the cavity 104 may have a negative profile corresponding to the outer profile or configuration of the blade body 52 and flutes or fluid flow passages formed therebetween shown in FIG. 1 .

As shown in FIG. 4 , a plurality of mold inserts 106 may be placed into the mold cavity 104 to form individual slots 58 in the blade body 52 . The position of the mold insert 106 within the mold cavity 104 corresponds to the position required to mount the cutting element 60 into the associated blade body 52 . Mold insert 106 may be made from various types of materials such as, but not limited to, consolidated sand and graphite. Various techniques, such as brazing, may be utilized for mounting the cutting elements 60 into the respective slots 58 .

Various types of temporary replacement material may be satisfactorily installed within the mold cavity 104 depending on the desired configuration of the formed matrix bit. Additional mold inserts (not expressly shown) formed of various materials such as consolidated sand and/or graphite may be disposed within mold cavity 104 . A variety of resins can be used to form consolidated sands. Such mold inserts may have configurations corresponding to the desired exterior components of the composite matrix bit body 50 , such as the fluid flow channels formed between adjacent blades 52 . As will be described in detail later, a first matrix material having increased toughness or fracture resistance may be loaded into the mold cavity 104 to form a portion of an associated composite matrix bit body, the portion of the bit body Engages and removes downhole formation material during the drilling of the wellbore.

The composite matrix bit body 50 may include a relatively large fluid cavity or chamber 32 with a plurality of fluid flow channels 42 and 44 extending therefrom. See Figure 3. As shown in FIG. 2, a replacement material, such as consolidated sand, may be installed at desired locations within mold assembly 100 to form cavity 32 and fluid flow channels 42 and 44 extending therefrom. Such replacement materials can have various structures. The orientation and configuration of consolidation sand legs 142 and 144 can be selected to correspond to the desired location and configuration of associated fluid flow channels 42 and 44 that lead from chamber 32 to the respective Nozzle discharge port 54 . Fluid flow passages 42 and 44 may receive threaded sockets (not expressly shown) for retaining respective nozzles therein.

A relatively large, generally cylindrical core of consolidated sand 150 may be placed on legs 142 and 144 . Core 150 and legs 142 and 144 may sometimes be described as having a "crow'sfoot" shape. Core 150 may also be referred to as a "stalk." The number of legs extending from the core 150 is based on the desired number of nozzle openings on the resulting composite bit body. Legs 142 and 144 and core 150 may also be formed from graphite or other suitable materials.

After the required replacement material, including the core 150 and legs 142 and 144, has been installed in the mold assembly 100, it will have optimum fracture resistance (toughness) and optimum corrosion, wear and abrasion resistance. The first carcass material 131 with wear resistance and wear resistance is put into the mold assembly 100 . The first matrix material 131 will preferably form a first region or layer that will generally correspond to the outer portion of the composite matrix bit body 50, which during drilling of the wellbore will interact with the first region or layer. contact with the formation material and remove it. Addition of the first carcass material 131 to the mold assembly 120 is preferably limited such that the carcass material 131 does not contact the end 152 of the core 150 . The present disclosure allows for the formation of either fixed cutter bits or cutting type bits using a matrix material with optimal toughness and wear resistance characteristics.

A generally hollow cylindrical metal blank 36 may then be placed into the mold assembly 100 . Metal blank 36 preferably includes an inner diameter 37 that is larger than the outer diameter of sand core 150 . Various clamps (not expressly shown) may be utilized to position metal blank 36 at a desired location within mold assembly 100 spaced from first carcass material 131 .

A second carcass material 132 may then be loaded into the mold assembly 100 to fill the void or annulus formed between the outer diameter 154 of the sand core 150 and the inner diameter 37 of the metal blank 36 . Preferably, the second carcass material 132 covers the first carcass material 131 , including the portion of the first carcass material 131 adjacent to and spaced from the end 152 of the core 150 .

For some applications, it is preferred that the second carcass material 132 be loaded in a manner that eliminates, or minimizes, the portion of the second carcass material 132 exposed to the exterior of the composite carcass bit body 50. . The first matrix material 131 is primarily used to form the outer portion of the composite matrix bit body 50 in connection with cutting, planing, and scraping downhole formation material during rotation of the matrix bit 20 to form a wellbore. The second matrix material 132 is primarily used to form the inner and outer portions of the composite matrix bit body 50 that are not normally associated with cutting, planing, and scraping downhole formation materials. See Figures 2 and 3.

For some applications, a third carcass material 133 , such as tungsten powder, may then be placed into the mold assembly 100 between the outer diameter 40 of the metal blank 36 and the inner diameter 122 of the funnel 120 . The third carcass material 133 can be a relatively soft powder that forms the transition between the carcass bit body 50 and the metal shank 36 which can then be machined to provide the desired outer structure and carcass. The third carcass material 133 is sometimes described as "infiltrated machinable powder". The third carcass material 133 is loaded so as to cover all or substantially all of the second carcass material 132 adjacent the exterior of the composite carcass bit body 50 . See Figures 2 and 3.

During the loading of the carcass materials 131, 132 and 133, care must be taken to prevent unwanted mixing between the first carcass material 131 and the second carcass material 132, and between the second carcass material 132 and the third carcass material. Undesirable mixing between bulk materials 133. Slight mixing at the interface to avoid sharp demarcations between different carcass materials provides a smooth transition for bonding between adjacent layers. When cemented carbide and spherical carbide are configured in the more complex mold assemblies associated with the matrix bit body used to hold the cutter bit, previous experience and testing have shown that it is not as effective as using hot, liquid binders. Various problems associated with material infiltration of cemented carbide and spherical carbides. Similar problems have been noted when attempting to utilize cemented carbide and/or spherical carbides to form other types of complex downhole tools used in connection with drilling and constructing oil and gas wells.

The manufacturing problems associated with utilizing cemented carbide and/or spherical carbide as the matrix material, as well as resulting quality issues, are generally related to insufficient infiltration, porosity, shrinkage, torsion, etc. Cracking and segregation of binder material components. The relatively intricate design and large size of many fixed cutter bits present difficult challenges to the manufacturability of bit bodies having cemented carbide and/or spherical carbide as matrix material. The same quality problems occur in the manufacture of other downhole tools, such as reamers, reamers, and combined reamer/drill bits, formed at least in part with a matrix of cemented carbide and spherical carbide. An example of such a combined downhole tool is given in U.S. Patent 5,678,644 entitled "Bi-center And Bit Method For Enhanced Stability."

Previous trials and experiments by pre-mixing cemented carbide and/or spherical carbide and coarse crystalline tungsten carbide and/or cast carbide powders have often failed to produce reliable, high quality matrix drill bits. Increasing the immersion time of the binder material in such mixtures of cemented carbide and/or spherical carbides with coarse crystalline tungsten carbide and/or cast carbide powders does not significantly eliminate the effects of shrinkage, alloy segregation, insufficient infiltration, porosity problems related to infiltration, and other problems associated with insufficient infiltration of cemented carbide and/or spherical carbides. Furthermore, increasing the temperature of the hot liquid binder material used for infiltration of such mixtures does not significantly reduce the associated quality problems. It has been confirmed that the high alloy segregation of the last solidified portion of the liquid binder material in various mixtures of cemented carbide and/or spherical carbides with crystalline carbides and/or cast carbides, is in such mixtures A cause of insufficient adhesion, unwanted shrinkage, porosity, and other quality issues.

Utilizing the first carcass material 131 to form a first layer or region, combined with utilizing the second carcass material 132 to form a second layer or region adjacent to the first carcass material 131, can substantially reduce or eliminate heat, Segregation of the liquid binder material and the alloy of the last solidified portion of the first carcass material 131 . Adding the second carcass material 132 within the annular portion formed between the outer diameter 154 of the core 150 and the inner diameter 37 of the metal blank 36, and covering the first carcass material 131 as shown in FIG. Problems related to insufficient infiltration, porosity, shrinkage, cracking, and/or segregation of the binder component within the first carcass material 131 . One reason for these improvements may be that the hot liquid binder material can readily infiltrate coarse crystalline tungsten carbide and/or cast carbide powders.

As previously noted, the hot liquid binder material can leach or remove small amounts of alloy and/or other contaminants from the bonding material used to form the cemented carbide. Alloys and/or other contaminants that are leached may have higher melting points than typical binder materials associated with the manufacture of carcass bits. Thus, leached alloy and/or other contaminants can solidify in the small gaps or pores between adjacent cemented carbide pellets, balls or shapes and prevent the hot liquid binder material Further infiltration between the alloy shapes.

"Contaminated" infiltrants, or hot liquid binder materials, may have different solidus and liquidus temperatures than "pure" binder materials. During the setting of the binder material, "enrichment" of the infiltration agent with the contaminants may occur as a result of repelling solute contaminants into the hot liquid ahead of the solidification front. Any lack of directional solidification, in addition to segregation of contaminants (solutes) at later stages of solidification, causes potential problems including, but not limited to, shrinkage, porosity and/or thermal cracking.

Coarsely crystalline tungsten carbide and cast carbide powders may be substantially free of alloying or other contaminants associated with binder materials used to form cemented carbides. The second carcass material may be selected to have less than five percent (5%) alloys or other potential contaminants. Thus, infiltration of the hot liquid binder material through the second carcass material selected in accordance with the teachings of the present disclosure does not substantially leach large quantities of alloys or other potential contaminants.

As mentioned above, the first carcass material 131 may be cemented carbide and/or spherical carbide. Alloys of cobalt, iron and/or nickel may be used to form cemented carbides and/or spherical carbides. For some matrix bit designs, an alloy concentration of about six percent in the first matrix material provides the best results. Alloy concentrations between three and six percent, and between about six and fifteen percent, may also be satisfactory for some matrix bit designs . However, alloy concentrations greater than about fifteen percent and less than about three percent alloy concentrations result in less than optimal properties of the resulting matrix bit body.

The second carcass material 132 may be coarse crystalline tungsten carbide or cast carbide powder. Examples of such powders include P-90 and P-100, commercially available from Kennametal, Inc. of Fallon, Nevada. U.S. Patent 4,834,963, entitled "Macrocrystalline Tungsten Monocarbide Powder and Process for Producing" (macrocrystalline tungsten carbide powder and its production process), assigned to Kennametal, describes techniques that can be used to produce macrocrystalline tungsten carbide. The third matrix material 133 may be tungsten powder, such as M-70, which is commercially available from H.C. Starck, Osram Sylvania and Kennametal. Typical alloy concentrations in the second carcass material 132 may be between about one percent and two percent. A second matrix material having an alloy concentration of about five percent or greater may result in unsatisfactory operating characteristics for the associated matrix bit body.

A typical infiltration process for a cast composite matrix bit body 50 may begin by forming the mold assembly 100 . Ring gauge 110 may be screwed onto the top of mold 102 . The sprue 120 may be screwed onto the top of the ring gauge 110 to extend the mold assembly 100 to the desired height for holding the previously described carcass material and binder material. Then, replacement material, such as, but not limited to, mold insert 106 , legs 142 and 144 , and core 150 , if not previously placed into mold cavity 104 , may be loaded into mold assembly 100 . Carcass material 131 , 132 , 133 and metal blank 36 may be loaded into mold assembly 100 as previously described.

With mold assembly 100 filled with carcass material, a series of vibratory cycles may be induced within mold assembly 100 to help pack each layer or region of carcass material 131 , 132 and 133 . This vibration can help ensure a consistent density of each layer of the carcass material 131 , 132 and 133 over various ranges to achieve the desired properties of the composite carcass bit body 50 . Undesirable mixing of the carcass materials 131 , 132 and 133 should be avoided.

Adhesive material 160 may be placed on top of layers 132 and 133 , metal blank 36 and core 150 . Adhesive material 160 may be covered with a flux layer (not explicitly shown). A shroud or cover (not explicitly shown) may be placed over mold assembly 100 . The mold assembly 100 and the materials disposed therein may be preheated and then placed in a furnace (not expressly shown). When the temperature of the heating furnace reaches the melting point of the adhesive material 160 , the liquid adhesive material 160 may infiltrate the carcass materials 131 , 132 , and 133 . As has been noted before, the second carcass material 132 allows the hot liquid adhesive material 160 to infiltrate the first carcass material 131 more uniformly, so as to avoid a gap between the liquid adhesive material 160 and the first carcass material. Undesirable segregation in the final solidified portion of 131.

The upper portion of the mold assembly 100 , such as the gate 120 , may have enhanced thermal insulation properties (not expressly shown) compared to the mold 102 . Thus, the liquid binder material in the lower portion of the mold assembly 100 begins to solidify with the first carcass material 131 before the hot liquid binder material solidifies with the second carcass material 132 . This difference in solidification potentially allows the hot liquid binder material to "float" or transport alloys and other potential contaminants leached from the first carcass material 131 into the second carcass material 132 . Since the hot liquid carcass material infiltrates through the second carcass material 132 before infiltrating the first carcass material 131, the alloys and other contaminants transported from the first carcass material 131 have a negative effect on the finished product. The quality of the matrix bit body 50 is not affected as much as alloys and other contaminants remain in the first matrix material 131 . Also, preferably, the second carcass material contains less than four percent (4%) of such alloys or contaminants.

Proper infiltration and solidification of the adhesive material 160 with the first carcass material 131 is particularly important near features such as nozzle openings 54 and grooves 58 . Thinner blades 52 can be designed through the improved quality control obtained by increased infiltration of binder material 160 into the portion of first carcass material 131 forming each blade 52 . It is also possible to orient the blades 52 at a more aggressive cutting angle, with a greater fluid flow area created between adjacent blades 52 .

Compared to the same design of a fixed cutter bit having a matrix bit body formed using only coarse crystalline tungsten carbide and/or cast carbide powders or formulations thereof that are commercially available, for certain drill bits formed in accordance with the teachings of the present disclosure Fifty percent (50 percent) improvements in wear resistance and one hundred percent (100 percent) improvements in corrosion resistance are possible for designs of fixed cutter drill bits with a composite bit body of a first matrix material and a second matrix material. %), fifty percent (50%) improvement in transverse rupture strength, and sometimes more than one hundred percent (100%) improvement in impact resistance.

The mold assembly 100 may then be removed from the furnace and cooled at a controlled rate. Once cooled, the mold assembly 100 may be stripped, exposing the composite matrix bit body 50, as shown in FIG. Subsequent processing may be employed in order to manufacture the matrix bit 20 according to known techniques.

Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the following claims.

Claims (13)

1. drill bit with composite casing bit body comprises:

A plurality of cutting elements, said a plurality of cutting elements are configured on the selected position of exterior section of bit body;

Composite casing bit body, this composite casing bit body have the first area at least and the second area at least of the configuration of being adjacent to each other; Said first area forms the exterior section of composite casing bit body, and said second area forms the interior section of composite casing bit body,

Said first area is formed by first carcass material that comprises hard particle and at least a adhesive material at least in part; Said hard particle comprises carbide alloy, and said adhesive material is by selecting the group of forming from following material: cobalt, nickel, iron or the alloy that is the basis with these elements;

Said second area is formed by second carcass material that comprises hard particle at least in part, and the hard particle of said second carcass material is selected from the group of being made up of macrocrystalline tungsten carbide and cast carbide; And

Second area has the adhesive material identical with the first area;

Wherein, With can be compared by alloy and other potential pollutant of liquid adhesive agent material leaching from first carcass material of heat, that said second carcass material has a remarkable decrease or do not have basically can be by alloy and other potential pollutant of the liquid adhesive agent material leaching of heat.

2. drill bit as claimed in claim 1 is characterized in that, said second carcass material cooperates with adhesive material, so that reduce fully or the flaw of elimination in the interior section of composite casing bit body.

3. drill bit as claimed in claim 1 is characterized in that, the alloy material that said second carcass material comprises and the content of other pollutant are less than 4 percent.

4. drill bit as claimed in claim 1 is characterized in that, the first area comprises the hard particle that has less than 6 percent alloy concentrations.

5. drill bit as claimed in claim 1 is characterized in that, the first area comprises the hard particle of the alloy concentrations that has between 3 percent to 6 percent.

6. drill bit as claimed in claim 1 is characterized in that, said first carcass material has the cobalt of concentration between 20 6 percent to percent.

7. drill bit as claimed in claim 1 is characterized in that, in the time of in being exposed to hot liquid adhesive agent material, compares with the wettability of said first carcass material, and said second carcass material has the wettability of increase.

8. method of making matrix drill bits comprises:

At least the first floor of first carcass material is put in the matrix drill bits mould, and wherein, said first carcass material is selected from the group of carbide alloy and spherical carbide composition;

The hollow metal blank is put into mould;

At least the second layer of second carcass material is put in the mould, and wherein, said second carcass material is selected the group from macrocrystalline tungsten carbide and cast carbide composition;

Adhesive material is put into mould, and said adhesive material is near the second layer and the hollow metal blank of second carcass material;

In heating furnace, said mould and the material that is configured in the said mould are heated to chosen temperature, so that allow the adhesive material fusing, and with hot liquid adhesive agent material infiltration second carcass material and first carcass material;

Before second carcass material solidifies, will with can be compared not alloy and other potential pollutant of leaching from first carcass material remarkable decrease or basic by alloy and other potential pollutant of liquid adhesive agent material leaching from first carcass material of heat and not be transported in second carcass material;

Before the liquid adhesive agent material of heat and second carcass material solidify, the solidifying of the liquid adhesive agent material of beginning heat and first carcass material; And

Cool off said mould and be configured in the material in the said mould, so that form the coherent composite casing bit body that combines securely with the hollow metal blank.

9. method as claimed in claim 8 further comprises:

To have partly and put in the mould by the core of the substantial cylindrical structure of external diameter qualification;

The hollow metal blank is placed on the core, so that form a ring part, said ring part is partly limited the internal diameter of hollow metal blank and the external diameter of core; And

Fill the said ring part between core and the hollow metal blank with second carcass material.

10. method as claimed in claim 8 further comprises:

Core is installed in the mould, the first floor of the end of core and first carcass material is spaced apart; And

The part of second carcass material is put between the adjacent part of first floor of a said end and said first carcass material of core.

11. method as claimed in claim 8 further comprises: the interior section that forms the composite casing bit body with second carcass material.

12. method as claimed in claim 8 further comprises: form the exterior section of composite casing bit body with first carcass material, said exterior section and remove with the engagement of down-hole formation material and with said down-hole formation material is associated.

13. method as claimed in claim 8 further comprises: before putting into mould to adhesive material, the 3rd layer of the 3rd carcass material is placed on the second layer of second carcass material.

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