Patent Grant
9464486
Drill bits used to drill wellbores through earth formations generally are made within one of two broad categories of bit structures. Depending on the application/formation to be drilled, the appropriate type of drill bit may be selected based on the cutting action type for the bit and its appropriateness for use in the particular formation. Drill bits in the first category are generally known as “roller cone” bits, which include a bit body having one or more roller cones rotatably mounted to the bit body. The bit body may be formed from steel or another high strength material. The roller cones may also be formed from steel or other high strength material and include a plurality of cutting elements disposed at selected positions about the cones. The cutting elements may be formed from the same base material as is the cone. These bits may be referred to as “milled tooth” bits. Other roller cone bits include “insert” cutting elements that are press (interference) fit into holes formed and/or machined into the roller cones. The inserts may be formed from, for example, tungsten carbide, natural or synthetic diamond, boron nitride, or any one or combination of hard or superhard materials.
Drill bits of the second category may be referred to as “fixed cutter” or “drag” bits. Drag bits, include bits that have cutting elements attached to the bit body, which may be a steel bit body or a matrix bit body formed from a matrix material such as tungsten carbide surrounded by a binder material. Drag bits may generally be defined as bits that have no moving parts. However, there are different types and methods of forming drag bits that are known in the art. For example, drag bits having abrasive material, such as diamond, impregnated into the surface of the material which forms the bit body are commonly referred to as “impreg” bits. Drag bits having cutting elements made of an ultra hard cutting surface layer or “table” (such as made of polycrystalline diamond material or polycrystalline boron nitride material) deposited onto or otherwise bonded to a substrate are known in the art as polycrystalline diamond compact (“PDC”) bits.
PDC bits drill soft formations easily, but they are frequently used to drill moderately hard or abrasive formations. They cut rock formations with a shearing action using small cutters that do not penetrate deeply into the formation. Because the penetration depth is shallow, high rates of penetration are achieved through relatively high bit rotational velocities.
PDC cutters have been used in industrial applications including rock drilling and metal machining for many years. In PDC bits, PDC cutters are received within cutter pockets, which are formed within blades extending from a bit body, and may be bonded to the blades by brazing to the inner surfaces of the cutter pockets. The PDC cutters are positioned along the leading edges of the bit body blades so that as the bit body is rotated, the PDC cutters engage and drill the earth formation. In use, high forces may be exerted on the PDC cutters, particularly in the forward-to-rear direction. Additionally, the bit and the PDC cutters may be subjected to substantial abrasive forces. In some instances, impact, vibration, and erosive forces have caused drill bit failure due to loss of one or more cutters, or due to breakage of the blades.
In a typical PDC cutter, a compact of polycrystalline diamond (“PCD”) (or other superhard material, such as polycrystalline cubic boron nitride) is bonded to a substrate material, which may be a sintered metal-carbide to form a cutting structure. PCD comprises a polycrystalline mass of diamond grains or crystals that are bonded together to form an integral, tough, high-strength mass or lattice. The resulting PCD structure produces enhanced properties of wear resistance and hardness, making PCD materials extremely useful in aggressive wear and cutting applications where high levels of wear resistance and hardness are desired.
An example of a PDC bit having a plurality of cutters with ultra hard working surfaces is shown in
A plurality of orifices 116 is positioned on the bit body 110 in the areas between the blades 120, which may be referred to as “gaps” or “fluid courses.” The orifices 116 are commonly adapted to accept nozzles. The orifices 116 allow drilling fluid to be discharged through the bit in selected directions and at selected rates of flow between the cutting blades 120 for lubricating and cooling the drill bit 100, the blades 120 and the cutters 150. The drilling fluid also cleans and removes the cuttings as the drill bit 100 rotates and penetrates the geological formation. The fluid courses are positioned to provide additional flow channels for drilling fluid and to provide a passage for formation cuttings to travel past the drill bit 10 toward the surface of a wellbore (not shown).
A factor in determining the longevity of PDC cutters is the exposure of the cutter to heat. Exposure to heat can cause thermal damage to the diamond table and eventually result in the formation of cracks (due to differences in thermal expansion coefficients) which can lead to spalling of the polycrystalline diamond layer, delamination between the polycrystalline diamond and substrate, and conversion of the diamond back into graphite causing rapid abrasive wear. The thermal operating range of conventional PDC cutters is about 700-750° C. or less.
As mentioned, conventional polycrystalline diamond is stable at temperatures of up to 700-750° C. in air, above which observed increases in temperature may result in permanent damage to and structural failure of polycrystalline diamond. This deterioration in polycrystalline diamond is due to the large difference in the coefficient of thermal expansion of the binder material, cobalt, as compared to diamond. Upon heating of polycrystalline diamond, the cobalt and the diamond lattice will expand at different rates, which may cause cracks to form in the diamond lattice structure and result in deterioration of the polycrystalline diamond. Damage may also be due to graphite formation at diamond-diamond necks leading to loss of microstructural integrity and strength loss, at extremely high temperatures.
In convention drag bits, PDC cutters are fixed onto the surface of the bit such that a common cutting surface contacts the formation during drilling. Over time and/or when drilling certain hard but not necessarily highly abrasive rock formations, the edge of the working surface on a cutting element that constantly contacts the formation begins to wear down, forming a local wear flat, or an area worn disproportionately to the remainder of the cutting element. Local wear flats may result in longer drilling times due to a reduced ability of the drill bit to effectively penetrate the work material and a loss of rate of penetration caused by dulling of edge of the cutting element. That is, the worn PDC cutter acts as a friction bearing surface that generates heat, which accelerates the wear of the PDC cutter and slows the penetration rate of the drill. Such flat surfaces effectively stop or severely reduce the rate of formation cutting because the conventional PDC cutters are not able to adequately engage and efficiently remove the formation material from the area of contact. Additionally, the cutters may be under constant thermal and mechanical load. As a result, heat builds up along the cutting surface, and results in cutting element fracture. When a cutting element breaks, the drilling operation may sustain a loss of rate of penetration, and additional damage to other cutting elements, should the broken cutting element contact a second cutting element.
Additionally, the generation of heat at the cutter contact point, specifically at the exposed part of the PDC layer caused by friction between the PCD and the work material, causes thermal damage to the PCD in the form of cracks which lead to spalling of the polycrystalline diamond layer, delamination between the polycrystalline diamond and substrate, and back conversion of the diamond to graphite causing rapid abrasive wear. The thermal operating range of conventional PDC cutters is about 750° C. or less.
This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
In one aspect, embodiments disclosed herein relate to a cutting element assembly that includes a sleeve, a lining extending a distance axially from an end of the sleeve, and an inner cutter. The inner cutter has a cutting end extending a depth from a cutting face, a side surface, and a body at least partially disposed within the sleeve, wherein the side surface of the cutting end interfaces with an interfacing surface of the lining.
In another aspect, embodiments disclosed herein relate to a cutting element assembly that includes a support structure and an inner cutter partially disposed within the support structure. The support structure has a sleeve portion and a lining portion extending a distance axially from the sleeve portion, wherein the support structure has a non-uniform wall thickness. The inner cutter has a cutting end extending a depth from a cutting face, a side surface and a body.
In yet another aspect, embodiments disclosed herein relate to a drill bit that includes a bit body having a plurality of blades extending radially therefrom and at least one cutting element disposed in a cutter pocket formed on the plurality of blades. The cutting element may include a sleeve, a lining extending a distance axially from an end of the sleeve and an inner cutter that has a cutting end extending a depth from a cutting face, a side surface, and a body at least partially disposed within the sleeve, wherein the side surface of the cutting end interfaces with an interfacing surface of the lining.
Other aspects and advantages of the claimed subject matter will be apparent from the following description and the appended claims.
In one aspect, embodiments disclosed herein relate to drill bits or other cutting tools having rotating cutting elements disposed thereon and methods for retaining the rotating cutting elements on cutting tools. Such rotating cutting elements may be used as the sole cutting structure on a bit or cutting tool or may be used with conventional cutting structures such as fixed blades (with cutters).
Referring now to
As shown in
Referring now to
A lining may be formed of the same or different material than the sleeve. For example, in embodiments having an integrally formed sleeve and lining, the sleeve and lining may be formed of the same material, and in embodiments having a separately formed sleeve and lining, the sleeve and lining may be formed of the same or different material. The lining and/or the sleeve may be formed of a wear resistant material such as at least one of a boride, nitride, carbide, such as tungsten carbide, silicon carbide, tantalum carbide, or titanium carbide, and polycrystalline diamond, or combinations thereof. Additionally, various binding metals may be included in the wear resistant material, such as cobalt, nickel, iron, metal alloys, or mixtures thereof. In a carbide wear resistant material, metal carbide grains are supported within a metallic binder, such as cobalt. An example carbide wear resistant material may include tungsten carbide particles dispersed in a cobalt binder, such as cemented tungsten carbide and cobalt (WC/Co). Such wear resistant materials include a hard particle phase and a metal binder phase, wherein the tungsten carbide particles form the hard particle phase and the cobalt forms the binder phase. Tungsten carbide may have, for example, a grain size ranging from about 6 microns or less (fine grain) in some embodiments, or greater than 6 microns (coarse grain) in other embodiments, and a binder content ranging from a lower limit selected from 6%, 8% and 10% by weight to an upper limit selected from 10%, 12%, 14% and 16% by weight.
Further, an inner cutter may have a diamond or other ultrahard material table bonded to a substrate, wherein the ultrahard material table forms the cutting face of the inner cutter, and wherein the substrate forms the body of the inner cutter. For example, as shown in
According to embodiments of the present disclosure, an inner cutter may be axially retained within a sleeve using a retention mechanism disposed between the sleeve and the body of the inner cutter. Retention mechanisms used to axially retain the inner cutter within the sleeve may allow the inner cutter to rotate as it contacts the formation to be drilled, while at the same time retaining the inner cutter within the sleeve and on the cutting tool. According to other embodiments, a retention mechanism may retain the inner cutter within the sleeve, but limit or prevent rotation of the inner cutter within the sleeve.
Referring again to
According to some embodiments of the present disclosure, a retention mechanism may include at least one corresponding groove and protrusion formed in an inner surface of the sleeve and a side surface of the inner cutter. In such embodiments, the sleeve may be formed by joining two or more pieces together around the inner cutter. For example, an inner cutter may have a groove and/or a protrusion formed around its circumference. A sleeve (which may or may not have a lining formed thereto) having a mating protrusion and/or groove formed around the inner surface of the sleeve may be split along the length of the sleeve into at least two pieces. The at least two pieces may be assembled around the inner cutter such that the mating groove(s) and protrusion(s) are aligned, and the at least two pieces may be bonded together.
In some embodiments, a retention mechanism may include a retaining ring. In such embodiments, the retaining ring may be disposed between the inner cutter and a sleeve, in a circumferential groove formed around the body of the inner cutter, wherein the retaining ring protrudes from the circumferential groove to a diameter greater than an inner diameter of the sleeve to retain the inner cutter axially in the sleeve. For example,
Further, the third inner diameter Y3 is shown as having the same size as the first inner diameter Y1. However, according to some embodiments, the second inner diameter may be greater than both the first and third inner diameters, and the third inner diameter may be greater than or less than the first inner diameter. According to other embodiments, a sleeve may have a second inner diameter (larger than the first inner diameter) extend from the first inner diameter to a third inner diameter, wherein the third inner diameter is larger than the second inner diameter. In yet other embodiments, a sleeve may have two inner diameters, a first inner diameter smaller than a second inner diameter. In such embodiments, a retaining ring may protrude from a circumferential groove formed around the body of an inner cutter to a diameter greater than the first inner diameter.
A retaining ring may be planar or non-planar, or a combination of one or more planar rings may be used with one or more non-planar rings. For example,
The retaining ring 1140 may be positioned within the circumferential groove 1137 such that the slits 1145 extend radially outward from the outer surface of the inner cutter 1130 and axially towards the cutting face 1134.
The slits 1145 formed in the retaining ring 1140 may provide the retaining ring 1140 with spring action. Particularly, by providing slits 1145 axially (or substantially axially, such as extending spirally along an angle less than about 45 degrees from a line parallel with the longitudinal axis of the retaining ring) along a partial height h of the retaining ring 1140, the retaining ring 1140 may act as a spring, which may be radially compressed and spring radially outward along the partial height h of the slits 1145. Advantageously, by extending radially outward to contact the larger inner diameter Y2 of the sleeve 1110, the retaining ring 1140 may axially maintain the inner cutter 1130 tight against the sleeve 1110, which may reduce or prevent debris from entering between the inner cutter 1130 and the sleeve 1110, while also radially maintaining the inner cutter 1130 within the center of the sleeve 1110. A lining (not shown) may further be attached to the sleeve 1110, as described herein, such that an interfacing surface of the lining interfaces with the side surface 1138 of the cutting end 1132 of the inner cutter 1130.
Referring now to
According to embodiments of the present disclosure, a sleeve and a lining may be integrally formed together to form a support structure with a non-uniform wall thickness. For example,
According to embodiments of the present disclosure, the wall thickness of a support structure is measured between an inner surface and an outer surface. The wall thickness may vary between the sleeve portion and the lining portion, and/or the wall thickness may vary within each portion. For example, the wall thickness of the sleeve portion (i.e., the sleeve thickness) and/or the wall thickness of the lining portion (i.e., the lining thickness) may have different thicknesses.
As shown in
Further, the sleeve portion 610 of the support structure 600 has a sleeve thickness 615 measured between an inner surface 614 and an outer surface 616. The inner surface 614 of the sleeve portion 610 may have a substantially cylindrical shape to correspond with an inner cutter (not shown) to be inserted therein. The outer surface 616 of the sleeve portion 610 may have at least one non-planar surface and/or at least one planar surface that do not correspond with the inner surface 614, such that the sleeve thickness 615 varies around the circumference of the sleeve portion 610. As shown, a portion of the outer surface 616 substantially corresponds with the shape of the inner surface 614, while another portion of the outer surface 616 includes planar and non-planar surfaces that do not correspond with the shape of the inner surface. Further, a portion of the outer surface 616 smoothly transitions into the base surface 626 of the lining portion 620. However, according to other embodiments, the transition from the outer surface of the sleeve portion to the base surface of the lining portion may be abrupt or include non-planar surfaces. An inner cutter (not shown) may be inserted into the sleeve 610 and lining 620 assembly such that a portion of the inner cutter body is retained within the sleeve portion 610, and the cutting end of the inner cutter interfaces with the interfacing surface 624 of the lining portion 620.
According to embodiments of the present disclosure, a lining formed as a piece separate from a sleeve may overlap the sleeve or may not overlap the sleeve. For example, referring now to
The lining 1320 extends a distance 1322 axially from the sleeve first end 1312 wherein the lining second end 1329 may be aligned or non-aligned with the sleeve first end 1312. For example, the lining second end 1329 may be axially aligned with the sleeve first end 1312, or, as shown, the lining second end 1329 may extend axially from a distance apart from the sleeve first end 1312 such that the lining 1320 and the sleeve 1310 are not overlapping. In other words, the second end 1329 of the lining 1320 may be positioned at a point located an axial distance 1370 away from the first end 1312 of the sleeve 1310, wherein the lining 1320 extends from the point in a direction away from the first end 1312 of the sleeve 1310. According to embodiments of the present disclosure, an axial distance 1370 between the second end 1329 of a lining 1320 and a first end 1312 of a sleeve 1310 may range from greater than 0 to 0.1 inches. In some embodiments, the axial distance 1370 between the lining and sleeve may range from greater than 0 to 0.08 inches. In some embodiments, the axial distance 1370 may be at least 0.02 inches. Further, other distances may be selected based on the relative location of the diamond table/substrate interface. Specifically, in one or more embodiments, the axial distance may be selected so that the second end 1329 of the lining 1320 falls on either side of (but not in line with) the diamond/substrate interface. The lining 1320 may be attached within an inset formed in a cutter pocket (not shown) by brazing or other means known in the art.
For example,
Referring now to
The lining 1920 has a length measured between a first end 1927 and a second end 1929 and a thickness measured between an interfacing surface 1924 and a base surface 1926. The lining 1920 may be attached within an inset 1966 formed in the side wall of the cutter pocket 1965. Upon assembly of the sleeve 1910, the lining 1920 and the inner cutter 1930 within the cutter pocket 1965, the interfacing surface 1924 of the lining 1920 may interface the side surface 1938 of the cutting end 1932 of the inner cutter 1930. The lining 1920 extends a distance 1922 axially from the sleeve first end 1912 wherein the lining second end 1929 may be aligned or non-aligned with the sleeve first end 1912. The interfacing surface 1924 of the lining 1920 is assembled to interface a portion of the inner cutter 1930 such that the lining 1920 extends an arc length around the side surface 1938 of the inner cutter 1930.
Further, the lining 1920 may be aligned or non-aligned radially with the sleeve 1910. For example,
A lining may be offset from the cutter pocket side wall such that the interface surface of the lining (i.e., the surface of the lining that is positioned to interface with the inner cutter) extends a distance above the cutter pocket side wall. For example, as shown in
According to one or more embodiments of the present disclosure, a lining may be a preformed piece. For example, as shown in
Linings of the present disclosure may be used to support the cutting end of a cutting element. For example, as rolling cutters contact and rotate against a formation, a cutting load may be applied in an axial and radial direction against the cutting element, which may cause bending to occur in the shaft region of the cutting element. According to embodiments of the present disclosure, a lining may be used to support portions of the cutting element subjected to the cutting load, such as the cutting end of the cutting element, and thus, may inhibit cutting element failure due to bending.
Further, a lining may or may not be disposed in an inset formed in a cutter pocket. For example, as shown in
Cutting elements of the present disclosure may be attached within cylindrical or non-cylindrical cutter pockets formed in cutting tools, such that the cutter pockets have negative space corresponding with the shape of the lining and sleeve assembled together (or the shape of the support structure in embodiments having the lining and sleeve integrally formed together). For example, where a conventionally formed cutter pocket used to receive a cylindrical cutting element would have a corresponding partial cylindrical cut-out formed in the cutting tool (i.e., have a semi-circular cross-section cut-out), cutter pockets of the present disclosure may have a cut-out corresponding to a portion of the sleeve and the lining, which may have a cross-sectional cut-out in the shape of a partial circle, a partial ellipse, a combination of curved and planar sides, a partial reuleaux polygon, or other non-circular shape.
Cutting elements of the present disclosure may be attached within cutter pockets formed in cutting tools, such as a drill bit, reamer, or other tool used to cut an earthen formation. For example, a drill bit may have a bit body with a plurality of blades extending radially therefrom. At least one cutting element according to embodiments of the present disclosure may be disposed in a cutter pocket formed on the plurality of blades. The at least one cutting element assembly may include a sleeve, a lining extending a distance axially from an end of the sleeve and an inner cutter, wherein the inner cutter has a cutting end extending a depth from a cutting face, a side surface, and a body. The body of the inner cutter is at least partially disposed within the sleeve, and the side surface of the cutting end interfaces with an interfacing surface of the lining. As described above, the lining may be integral with the sleeve, or the lining may be separate from the sleeve and attached adjacent to an outer surface of the sleeve, such that the interfacing surface of the lining interfaces the side surface of the inner cutter and the outer surface of the sleeve. The lining and sleeve may be brazed or attached by other methods known in the art to a cutter pocket formed on one of the plurality of blades. Further, the lining, sleeve, or combination of the lining and sleeve may be replaced, for example, if a component in the cutting element assembly has failed and needs replacement. For example, in embodiments having separate lining and sleeve components assembled together, the lining may be removed from the cutting element assembly and replaced with a new lining.
Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims.
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| Number | Date | Country | |
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| 20140174834 A1 | Jun 2014 | US |
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| 61789317 | Mar 2013 | US | |
| 61746064 | Dec 2012 | US |
