CN104662251A - Diamond cutting elements for drill bits seeded with HCP crystalline material - Google Patents

Abstract

Polycrystalline diamond composites (PDCs) attached or bonded to a substrate to form cutters for drill bits comprise sintered polycrystalline diamond with seed material dispersed in it having a hexagonal close-packed (HCP) crystal structure. One or more regions of the sintered polycrystalline diamond structure, adjacent to the working surface in which HCP seed material was seeded prior to sintering, are leached to remove catalyst. Selective seeding of portions or regions of the sintered polycrystalline diamond structure allows for different leaching rates to form leaching zones with varying distances or depths and geometries.

Description

Diamond cut components for drill bits seeded with HCP crystalline material

technical field

The present invention relates generally to cutting elements for drill bits for land drilling.

Background technique

When drilling oil and gas wells, there are two basic types of bits used to drill through subterranean formations: the drag bit and the roller cone bit.

Drag bits have no moving parts. As a drag bit is rotated, typically by rotating the drill string to which it is attached, discrete cutting elements ("cutters") attached to the bit face scrape across the bottom of the hole, scraping or shearing the formation. Each cutter of a rotary drag bit is positioned and oriented on a face of the drag bit such that a portion of the face, which will be referred to as its wear surface, engages the formation as the bit rotates. The cutters are spaced in a fixed predetermined pattern on the cutting outer surface or face of the bit body. The cutters are usually arranged along each of several blades, which are raised ridges generally radially from the center of the bit to the periphery of the face, usually in a sweep (rather than a straight line) extend. Cutters along each blade provide a predetermined cutting profile to the formation, shearing the formation as the bit rotates. Drilling fluid is pumped down the drill string into a central channel formed in the center of the drill bit and exits through outlets formed in the face of the drill bit, which fluid both cools the cutters and assists in removing and transporting cuttings between the blades.

A roller cone bit includes two or three conical cutters that rotate about an axis that is at a 35 degree angle to the bit's axis of rotation. As the bit rotates, the cone rolls across the bottom of the hole. As rock passes between the cone and the formation, cutting elements—also called knives—on the face of the cone crush the rock.

In order to improve the performance of the drill bit, one or more of the wear surfaces or working surfaces of the cutting elements are made of polycrystalline diamond (“PCD”) in the form of a polycrystalline diamond compact (“PDC”) attached to a substrate. ) layer made. One common substrate is cemented tungsten carbide. The PDC is bonded to a substrate after fabrication, and the PDC bonded substrate contains the cutter. Drag bits with such PDC cutting elements are sometimes referred to as "PDC bits". Although PDC is very hard and has high abrasion or abrasion resistance, it tends to be relatively brittle. The substrate, while not as hard as PDC, is more ductile than PDC and thus has higher impact resistance. The substrate is usually made long enough to act as a mounting stud, a portion of which just fits into a pocket or recess formed in the bit body, or for a roller cone bit into a pocket formed in the roller ( packet). However, in some drag bits, the PDC and substrate structure are attached to metal mounting studs, which are then embedded in grooves or other recesses.

Polycrystalline diamond compacts are produced by mixing polycrystalline diamond in powder form with one or more powdered metal catalysts and other materials, forming the mixture into compacts, and subsequently using high heat and pressure or microwave Heat to sinter it. Although cobalt or alloys of cobalt are the most common catalysts, other Group VIII metals such as nickel, iron and their alloys can also be used as catalysts. For cutting knives, the PDC is typically formed by stacking polycrystalline diamond grains (called "diamond grit") without metal catalysts adjacent to a cemented tungsten carbide substrate and subsequently sintering the two together. During sintering, the metallic binder in the substrate—cobalt in the case of cobalt-cemented tungsten carbide—sweeps or infiltrates the compact, acting as a catalyst to cause diamond cracking between adjacent diamond grains. - Formation of diamond compacts. The result is a clump of bonded diamond crystals, described as a continuous or unitary diamond matrix or even a "lattice", the interstices between the diamonds being at least partially filled with the metal catalyst.

The substrate supporting the PDC layer is at least partially made of cemented metal carbide, most commonly tungsten carbide. A cemented metal carbide substrate is formed by sintering powdered metal carbide powder and a metal alloy binder. The composite of PDC and substrate can be fabricated in many different ways. For example, it may also include transition layers where metal carbides and diamonds are mixed with other components to improve bonding and reduce stress between the PDC and the substrate. Reference herein to a substrate includes such substrates.

PDCs exhibit thermal instability due to the presence of metal catalysts. Cobalt has a different coefficient of expansion than diamond. Its expansion rate is greater and thus tends to weaken the diamond structure at higher temperatures. In addition, cobalt has a lower melting point than diamond, which can lead to cobalt causing the diamond crystals within the PDC to begin graphitizing when temperatures reach or exceed the melting point of cobalt, also weakening the PDC. To make the PDC at least more thermally stable, a substantial percentage—usually over 50%; frequently 70% to 85%; and possibly higher—of the catalyst is removed from at least one adjacent one or more temperature in the area of the work surface to remove. The catalyst is removed by a leaching process that involves placing the PDC in hot strong acids, examples of which include nitric acid, hydrofluoric acid, hydrochloric acid, or perchloric acid, and combinations thereof. In some cases, the acid mixture can be heated and/or shaken to speed up the leaching process.

However, the removal of cobalt is believed to reduce the toughness of PDC and thus reduce its impact resistance. In addition, leaching of the PDC may result in the removal of some of the cobalt that cements or bonds the substrate, thereby affecting the strength or integrity of the substrate and/or the substrate-diamond interface. Because of these concerns, leaching of cutters is currently "partial," meaning that the catalyst is only removed from one area of the PDC, typically by leaching from one or more working surfaces of the PDC, including the tops of the cutters, bevels, Defined by depth or distance measured from cut edge or side.

There are technical limits to the depth to which PCD can be leached without damaging the substrate or the bond between the substrate and PCD. This technical limitation involves masks and seals that protect the substrate from the acid bath in which the cutter is placed for leaching. The seal is made of a material that tends to break down over time when exposed to the acids used to leach the PCD, thereby limiting the duration of leaching and thus the depth. Furthermore, the diamond structure in PCD becomes much denser as the diamond particle size is reduced, in some cases down to nanoparticle size (less than 100 nm), and thus leached to any useful depth (e.g., greater than 100 nm). Micron leach depth) becomes impractical. At the very least, these denser structures are much more difficult to leach and require much longer leaching times.

Contents of the invention

The present invention relates to an improved cutting element for a land drilling bit, a method of manufacturing the cutting element, and a drill bit using the cutting element.

In one example of an improved cutting component, a polycrystalline diamond compact (PDC) comprising sintered polycrystalline diamond interspersed with seed material having a hexagonal close packed (HCP) crystal structure is attached to or Bonded to a substrate to form a cutter for a drill.

In another example of an improved PDC cutting component, a region of the sintered polycrystalline diamond structure near one or more of its working surfaces that had been seeded with HCP seed material prior to sintering was leached to remove catalyst. Regions with HCP seed material leach faster than regions of sintered polycrystalline diamond structures that do not contain HCP seed material, allowing deeper than otherwise possible due to technical limitations of PCD made without using any seed material leach. Rapid leaching is of particular advantage for polycrystalline diamond feeds comprising particles less than 30 microns in size. Selective seeding of portions or regions of the sintered polycrystalline diamond structure also allows the use of different leaching rates to form leached regions with different distances or depths and geometries.

Description of drawings

Figure 1 is a perspective view of a PDC drag bit.

2A, 2B, and 2C are perspective, side, and top views, respectively, of a representative PDC cutter suitable for use with the drag bit of FIG. 1 .

3A, 3B, and 3C are cross-sections of four different examples of the PDC cutters of FIGS. 2A-2C that have been seeded with HCP material in discrete regions within their diamond structure and subsequently leached to The catalyst is partially or completely removed from at least the inoculation zone.

4 is a cross-section of one embodiment of the PDC cutter of FIGS. 2A-2C with HCP seed material dispersed throughout the diamond layer.

Detailed ways

In the following description, the same numerals refer to the same components.

One example 100 of a PDC drag bit is shown in FIG. 1 . However, it is intended as a representative example of drag bit, and bits used in drilling oil and gas wells in general. The drag bit is designed to rotate about its central axis 102 . The drag bit comprises a bit body 104 connected to a shank 106 having a tapered threaded coupling 108 connecting the bit to the drill string, and a "bit handle" for engaging a wrench to tighten and loosen the coupling to the drill string. device" surface 111. The outer surface of the body which is intended to face generally in the direction of drilling is called the bit face. The bit face generally lies on a plane perpendicular to the central axis 102 of the bit. The body is not limited to any particular material. For example, it can be made of steel or a matrix material such as powdered tungsten carbide cemented with a metal binder.

A plurality of protruding "blades", each designated 110, are arranged on the face of the bit, protruding from the face of the bit. Each blade extends generally in a radial direction outwardly to the periphery of the cutting face. In this example, there are 6 blades spaced substantially equidistantly about the central axis, and each blade in this embodiment sweeps or bends back in the direction of rotation indicated by arrow 115 .

Mounted to each blade are a plurality of discrete cutting elements, or "cutters" 112 . Each discrete cutting member is disposed within a recess or groove. In a drag bit, the cutters are placed along the advancing (intended direction of rotation) side of the blades, with their working surfaces generally facing the advancing direction for shearing the formation as the bit rotates about its central axis. In this example, the cutters are aligned along the blades to form a structure that cuts or gouges the formation, and the resulting debris is then pushed into the drilling fluid, which exits the drill bit through nozzles 117 . The drilling fluid in turn transports debris or cuttings up the borehole to the surface.

In this drag bit example, all cutters 112 are PDC cutters. However, in other embodiments, not all cutters need to be PDC cutters. The PDC cutter in this example has a working surface mainly made of superhard polycrystalline diamond or similar, and is supported by a substrate forming mounting bolts for seating in grooves formed in the blade Inside. Each PDC cutter is manufactured discretely and then mounted by brazing, press-fitting or other methods into a groove formed on the drill bit. However, PDC layers and substrates are usually used in the form of cylinders in which they are made. Examples of the drill include gauge pads 114 . In certain applications, the gauge liner of a drill bit such as drill bit 100 may include an insert of thermally stable, sintered polycrystalline diamond (TSP).

An example of a PDC cutter 200 is shown in FIGS. 2A-2C . The PDC cutter includes a substrate 202 attached to a layer 204 of sintered polycrystalline diamond (PCD). This layer is also sometimes referred to as the diamond pedestal. It should be noted that the cutters are not drawn to scale and are intended to represent a typical cutter having a polycrystalline diamond structure attached to a substrate, particularly the one or more PDC cutters 112 on the drill bit 100 of FIG. 1 . Although generally cylindrical, PDC cutters are generally not limited to a particular shape, size or geometry, or to a single layer of PCD. In this example, the edge between top surface 206 and side surface 208 of diamond layer 204 is chamfered to form chamfered edge 210 . In this example, the top surface and the chamfered surface are each working surfaces for contacting and cutting through the formation. A portion of the side surfaces, especially near the top, may also be in contact with formations or debris. Not all cutters on a drill have to be the same size, configuration or shape. In addition to being sintered in different sizes and shapes, PDC cutters can be cut, ground or milled to change their shape. Additionally, the cutter may have multiple discrete PCD structures. Examples of other possible cutter shapes could be pre-flatted gauge cutters, pointed or scribe cutters, chisel-shaped cutters and arched inserts thing (dome insert).

Referring now to FIGS. 3A-3C and 4 in addition to FIGS. 2A-2C , the diamond structure comprising diamond layer 204 has at least one discrete region or region in which particles of crystalline seed material are interspersed. One example of the crystal seed is a material with a hexagonal close packed (HCP) structure. Examples of the HCP crystal seed material include materials having a wurtzite crystal structure, including, for example, wurtzite boron nitride (BNw), wurtzite silicon carbide, and hexagonal carbon (hexagonal diamond).

The diamond structure is formed by mixing small or fine particles of synthetic or natural diamond, known in the industry as diamond abrasive, with HCP seed material particles (with or without additional materials) in predetermined proportions to obtain desired concentration. The composite sheet is then formed either from the entire mixture, or alternatively, the composite sheet is formed in such a way that a discrete region or volume of the mixture within the composite sheet contains the mixture while the rest of the composite sheet (or composite sheet At least one additional region of ) contains PCD particles (with any additional material) but does not contain HCP seed material. The formed compact is then sintered at high pressure and temperature in the presence of a catalyst such as cobalt, a cobalt alloy, or any Group VIII metal or alloy. The catalyst can be infiltrated into the compact by forming the compact on a tungsten carbide substrate cemented with the catalyst and then sintering the compact. The result is a sintered PCD structure having at least one region comprising HCP seed material dispersed throughout the region in the same proportion as the mixture.

The HCP seed material may have a particle size between 0 and 60 microns in one embodiment, between 0 and 30 microns, and in another embodiment between 0 and 10 microns. The PCD particles in the mixture can range from 0 to 40 microns and can be as small as nanometers in size. In one embodiment, the proportion or concentration of HCP seed material within the mixture - and thus within the region seeded with HCP seed material - is 5% by volume or less. In another embodiment, the ratio or concentration is in the range of 0.05% to 2% by volume, and in a further embodiment, the ratio or concentration is in the range of 0.05% to 0.5% by volume.

PCD can be layered within the composite sheet according to particle size. For example, layers closer to the working layer will contain finer particles (ie, particles smaller than a predetermined size), while layers further away (perhaps the base layer closer to the substrate) have particles larger than the predetermined size. The HCP seed material may be mixed with only the finer particles of diamond hybrid abrasive to form a first region or layer near the working surface, or with multiple layers of diamond composite abrasive.

Alternatively, mixtures of HCP seed material with different concentrations or ratios within the diamond layer can form multiple distinct regions or layers in the diamond structure, with or without HCP seed material in the remaining structure of the PCD layer. kind of material.

In another alternative example, the HCP material is replaced with a crystalline seed material (not diamond) having a zinc blend crystal structure, which is a face centered cubic (FCC) structure. Examples of such materials include cubic boron nitride.

It is believed that seeding PCD with HCP crystalline seed material, particularly BNw as described above, results in sintered polycrystalline diamond structures with faster leaching times. It is further believed that a PDC cutter having a diamond layer formed according to the method described above with HCP seed material, and in particular BNw as a seed material, is identical to having a diamond structure formed without HCP seed material Compared to PDC cutters, it performs better due to improved fracture toughness and wear resistance.

In the various embodiments of the PDC cutter 200 shown in FIGS. 3A-3C , the regions or portions of the sintered PCD diamond layer or structure 204 in which the HCP seed material is interspersed (“seed regions”) are generally marked with stippling, whereas The depth to which the diamond layer is partially leached is indicated by dashed line 300 . In each example, the inoculation area is adjacent to the top surface 206 and the chamfered perimeter edge surface 210, which are both working surfaces.

In the embodiment of FIG. 3A , the inoculated region 302 spans the entire top surface of the diamond layer 204 and extends down a portion of its sides. The inoculated region extends down from the top surface 206 to a uniform depth 304 measured from the top surface and less than the thickness of the PCD layer. As indicated by dashed line 300, the diamond layer is leached to depth 304, which removes a substantial percentage of the metal catalyst remaining in the diamond layer after sintering compared to the unleached region.

The seeded region 306 in the embodiment of FIG. 3B also extends across the entire face of the diamond layer 204 as in the embodiment of FIG. 3A . The region extends down the side surface 208 a distance 308 that is approximately the same as the distance shown as depth 304 from the top surface of the inoculation region 302 in the embodiment of FIG. 3A . However, unlike the embodiment of FIG. 3A , the seeded region extends from the top surface to a depth of approximately a distance 308 , which is much less than depth 304 in FIG. 3A . Since the leaching rate in the inoculated region 306 of the diamond layer is relatively faster than in the non-inoculated region, the leaching pattern indicated by line 300 may substantially coincide with the inoculated region boundary.

The embodiment of FIG. 3C has an inoculated region 310 in the shape of a ring that extends inwardly from the perimeter of top surface 206 a distance 312 (which is less than the radius of the top surface) to a distance 312, as measured from top surface 206, as shown at 208 in FIG. 3C. Depth 314. This embodiment is leached to a depth indicated by dashed line 300 . Due to the faster leaching rate of the inoculated region 310 , the leach depth 314 of the inoculated region 310 is greater below the portion of the top surface 206 than the leach depth 316 in the non-inoculated region, as shown by region 318 .

In the embodiment of Figure 4, the entire diamond layer 204 is seeded with HCP crystalline material. For diamond mixtures of 0 to 10 microns, especially at very high compaction pressures, the resulting PCD tends to be very dense. The increased density results in a significant increase in leaching time. It is believed that this is due to the relatively small lattice spacing of the PCD microstructure, which inhibits the access of leaching acids to the Group VIII metal catalyst. For example, if the PCD layer contains diamond abrasives with a particle size of 0 to 10 microns, pressed at high pressure, the practical limit for leaching depth will be about 250 microns. This is due to degradation of the sealing material used to prevent the acid from contacting the substrate. If nanoparticles are used in the diamond abrasive, this actual leaching depth will decrease further as the diamond density rises further, rendering the benefit of leaching negligible. The addition of HCP seed material may allow leaching of fine-grained diamond feed PCD having a particle size of less than 20 microns to depths well in excess of 500 microns, and in certain embodiments to depths in excess of 1200 microns.

What has been described above is an exemplary and preferred embodiment. The invention, as defined by the appended claims, is not limited to the described embodiments. Alterations and modifications may be made to the disclosed embodiments without departing from the invention. Unless expressly stated otherwise, the meanings of the terms used in this specification are intended to have conventional and customary meanings and are not intended to be limited to the structures or implementations shown or described.

Claims (29)

1. manufacture a method for the polycrystalline diamond structure being used for land drill bit, described method comprises:

HCP seed crystal material particle is mixed to form mixture with diamond compound abrasive particle;

Form composite sheet for sintering, described composite sheet contain throughout diamond compound abrasive, the mixture at least partially containing HCP seed crystal material and diamond compound abrasive of described composite sheet; With

Sinter described composite sheet in the presence of a catalyst thus form diamond lattic structure, described structure comprises the integrated agglomerate showing the polycrystalline diamond (PCD) that diamond-diamond combines, metallic catalyst occupies wherein space, and described composite sheet is scattered with described HCP seed crystal material at least in part.

2. the process of claim 1 wherein that described catalyzer comprises metal.

3. the process of claim 1 wherein that described HCP seed crystal material has wurtzite crystal structure.

4. the process of claim 1 wherein that described HCP seed crystal material is selected from the group be substantially made up of buergerite boron nitride, buergerite carborundum and lonsdaleite.

5. the process of claim 1 wherein that described HCP seed crystal material comprises buergerite boron nitride.

6. the method for any one of claim 1 to 5, the particle diameter of wherein said HCP seed crystal material is 0 to 40 micron.

7. the method for any one of claim 1 to 5, in wherein said mixture, the particle diameter of polycrystalline diamond is less than 40 microns.

8. the method for claim 7, in wherein said mixture, the particle diameter of polycrystalline diamond is less than 30 microns.

9. the method for claim 7, in wherein said mixture, the particle diameter of polycrystalline diamond is less than 100 nanometers at least one dimension.

10. the method for any one of claim 1 to 5, what wherein said HCP seed crystal material formed described mixture is less than 5 volume %.

The method of 11. claims 10, what wherein said HCP seed crystal material formed described mixture is less than 1 volume %.

The method of 12. claims 10, in wherein said mixture, the amount of HCP seed crystal material forms the amount between 0.05 volume % to 0.5 volume % of described mixture.

13. the process of claim 1 wherein that described composite sheet has multiple surface, and wherein at least one surface is working surface; With wherein said composite sheet, there is at least one contiguous described working surface, zone of dispersion containing described mixture, and at least one is containing the region of described mixture.

14. the process of claim 1 wherein that described mixture is arranged at least one zone of dispersion of described composite sheet, and wherein said composite sheet has at least, and another has the region of the PCD without HCP seed crystal material.

The method of 15. claims 1, wherein said mixture has HCP seed crystal material and the PCD of the first ratio, wherein said method comprises further and being mixed with the second ratio being different from described first ratio with HCP seed crystal material particle by diamond compound abrasive particle, and formed and comprise at least one and have the HCP seed crystal material of the first ratio and the mixture zone of dispersion of PCD, and at least one has the composite sheet of the HCP seed crystal material of the second ratio and the mixture zone of dispersion of PCD.

16. the process of claim 1 wherein that described composite sheet is formed by multiple surface, and one of them surface is working surface and one of them surface is basal surface; And the described composite sheet wherein formed has at least two-layer PCD: be close to described working surface, there is the first floor of the PCD particle of the first particle diameter or particle size range, with closer to described basal surface, the second layer with the PCD particle being greater than described first particle diameter or particle size range.

The method of 17. any one of claim 1 to 16, it to comprise from described diamond lattic structure leaching metals catalyzer further to desired depth.

The method of 18. any one of claim 1 to 10, wherein,

Described composite sheet has multiple surface, and one of them surface is working surface;

Described composite sheet has at least one contiguous described working surface, zone of dispersion containing described mixture, and at least one is containing the region of described mixture; With

Described method comprise further from described diamond lattic structure, from described at least one contain leaching catalyzer the zone of dispersion of described mixture.

The method of 19. any one of claim 1 to 10, wherein,

Described composite sheet has multiple surface, and one of them surface is working surface;

Described composite sheet has at least one contiguous described working surface, zone of dispersion containing described mixture, and not containing the region of described mixture; With

Described method comprise further from described diamond lattic structure, described at least one contain described mixture zone of dispersion and not containing described mixture both areas at least partially in leaching metals catalyzer.

20. drill bits comprising the main body with cut surface, described cut surface has the multiple cutting knifes be configured on it, each of described multiple cutting knife comprises the composite polycrystal-diamond be combined with substrate, and wherein said composite polycrystal-diamond obtains according to the method for any one of claim 1 to 19.

21. composite polycrystal-diamonds, it obtains according to the method for any one of claim 1 to 19.

22. for the cutting knife of drill bit, and described cutting knife has that be combined with substrate, obtained according to the method for any one of claim 1 to 19 PDC.

23. for the cutting knife of drill bit, described cutting knife comprises the substrate combined with polycrystalline diamond composite sheet (PDC), wherein said PDC comprises the integrated agglomerate showing the polycrystalline diamond that diamond-diamond combines, and described PDC is scattered with HCP seed crystal material at least in part.

The cutting knife of 24. claims 23, a part of wherein said PDC contains metallic catalyst, and a part of described PDC has the metallic catalyst of remarkable less amount.

The cutting knife of 25. claims 23, wherein said HCP seed crystal material intersperses among in PDC at least one zone of dispersion interior of contiguous described cutting knife working surface, and wherein said PDC has the region that at least one does not contain HCP seed crystal material.

The cutting knife of 26. claims 25, wherein metallic catalyst from least one zone of dispersion described in the PDC containing HCP seed crystal material at least partially removal to the desired depth relative to described working surface.

The cutting knife of 27. any one of claim 23 to 26, wherein said HCP seed crystal material has wurtzite crystal structure.

The cutting knife of 28. any one of claim 23 to 26, wherein said HCP seed crystal material is selected from the group be substantially made up of buergerite boron nitride, buergerite carborundum and lonsdaleite.

The cutting knife of 29. any one of claim 23 to 26, wherein said HCP seed crystal material comprises buergerite boron nitride.