Patent Application
20190128073
Embodiments of the present disclosure relate generally to rotatable cutting elements, earth-boring tools including such cutting elements, and related methods.
Wellbores are formed in subterranean formations for various purposes including, for example, extraction of oil and gas from the subterranean formation and extraction of geothermal heat from the subterranean formation. Wellbores may be formed in a subterranean formation using a drill bit, such as an earth-boring rotary drill bit. Different types of earth-boring rotary drill bits are known in the art, including fixed-cutter bits (which are often referred to in the art as “drag” bits), rolling-cutter bits (which are often referred to in the art as “rock” bits), diamond-impregnated bits, and hybrid bits (which may include, for example, both fixed cutters and rolling cutters). The drill bit is rotated and advanced into the subterranean formation. As the drill bit rotates, the cutters or abrasive structures thereof cut, crush, shear, and/or abrade away the formation material to form the wellbore. A diameter of the wellbore drilled by the drill bit may be defined by the cutting structures disposed at the largest outer diameter of the drill bit.
The drill bit is coupled, either directly or indirectly, to an end of what is referred to in the art as a “drill string,” which comprises a series of elongated tubular segments connected end-to-end that extends into the wellbore from the surface of earth above the subterranean formations being drilled. Various tools and components, including the drill bit, may be coupled together at the distal end of the drill string at the bottom of the wellbore being drilled. This assembly of tools and components is referred to in the art as a “bottom hole assembly” (BHA).
The drill bit may be rotated within the wellbore by rotating the drill string from the surface of the formation, or the drill bit may be rotated by coupling the drill bit to a downhole motor, which is also coupled to the drill string and disposed proximate the bottom of the wellbore. The downhole motor may include, for example, a hydraulic Moineau-type motor having a shaft, to which the drill bit is mounted, that may be caused to rotate by pumping fluid (e.g., drilling mud or fluid) from the surface of the formation down through the center of the drill string, through the hydraulic motor, out from nozzles in the drill bit, and back up to the surface of the formation through the annular space between the outer surface of the drill string and the exposed surface of the formation within the wellbore. The downhole motor may be operated with or without drill string rotation.
A drill string may include a number of components in addition to a downhole motor and drill bit including, without limitation, drill pipe, drill collars, stabilizers, measuring while drilling (MWD) equipment, logging while drilling (LWD) equipment, downhole communication modules, and other components.
Cutting elements used in earth boring tools often include polycrystalline diamond compact (often referred to as “PDC”) cutting elements, which are cutting elements that include so-called “tables” of a polycrystalline diamond material mounted to supporting substrates and presenting a cutting face for engaging a subterranean formation. Polycrystalline diamond (often referred to as “PCD”) material is material that includes inter-bonded grains or crystals of diamond material. In other words, PCD material includes direct, intergranular bonds between the grains or crystals of diamond material.
Cutting elements are typically mounted on the body of a drill bit by brazing. The drill bit body is formed with recesses therein, commonly termed “pockets,” for receiving a substantial portion of each cutting element in a manner which presents the PCD layer at an appropriate back rake and side rake angle, facing in the direction of intended bit rotation, for cutting in accordance with the drill bit design. In such cases, a brazing compound is applied between the surface of the substrate of the cutting element and the surface of the recess on the bit body in which the cutting element is received. The cutting elements are installed in their respective recesses in the bit body, and heat is applied to each cutting clement to raise the temperature to a point high enough to braze the cutting elements to the bit body in a fixed position but not so high as to damage the PCD layer.
Unfortunately, securing a PDC cutting element to a drill bit restricts the useful life of such cutting element, as the cutting edge of the diamond table wears down as does the substrate, creating a so-called “wear flat” and necessitating increased weight on bit to maintain a given rate of penetration of the drill bit into the formation due to the increased surface area presented. In addition, unless the cutting element is heated to remove it from the bit and then rebrazed with an unworn portion of the cutting edge presented for engaging a formation, more than half of the cutting element is never used.
Rotatable cutting elements mounted for rotation about a longitudinal axis of the cutting element can be made to rotate by mounting them at an angle in the plane in which the cutting elements are rotating (side rake angle). This will allow them to wear more evenly than fixed cutting elements, having a more uniform distribution of heat across and heat dissipation from the surface of the PDC table and exhibit a significantly longer useful life without removal from the drill bit. That is, as a cutting element rotates in a bit body, different parts of the cutting edges or surfaces of the PDC table may be exposed at different times, such that more of the cutting element is used. Thus, rotatable cutting elements may have a longer life than fixed cutting elements.
Additionally, rotatable cutting elements may mitigate the problem of “bit balling,” which is the buildup of debris adjacent to the edge of the cutting face of the PDC table. As the PDC table rotates, the debris built up at the edge of the PDC table in contact with a subterranean formation may be forced away as the PDC table rotates.
In one embodiment of the disclosure, a cutting element assembly includes a support structure and a pin having a cylindrical exterior bearing surface. Retention elements may couple opposing ends of the pin to the support structure. The cutting element assembly also includes a rotatable cutting element including a table of polycrystalline hard material having an end cutting surface and a supporting substrate. The rotatable cutting element may have an interior sidewall defining a longitudinally extending through hole. The pin may be positioned within the through hole of the rotatable cutting element and may be supported on the opposing ends thereof by the support structure.
In another embodiment of the disclosure, an earth-boring tool includes a body and a cutting element assembly. The cutting element assembly includes a support structure and a pin having a cylindrical exterior bearing surface. Retention elements may couple opposing ends of the pin to the support structure. The cutting element assembly also includes a rotatable cutting element including a table of polycrystalline hard material having an end cutting surface and a supporting substrate. The rotatable cutting element may have an interior sidewall defining a longitudinally extending through hole. The pin may be positioned within the through hole of the rotatable cutting element and may be supported on the opposing ends thereof by the support structure.
In a further embodiment of the disclosure, a method of drilling a subterranean formation includes applying weight-on-bit to an earth-boring tool disposed within a wellbore substantially along a longitudinal axis thereof and rotating the earth-boring tool. The method also includes engaging a formation with rotatable cutting elements located on blades of the earth-boring tool. The rotatable cutting elements may be rotatably secured within pockets of the blades with pins extending through a through hole of each of the rotatable cutting elements. Each of the pins may be coupled on opposing ends thereof to a support structure located within a respective pocket of the blades. The method may also include absorbing compressive forces imposed on the rotatable cutting elements with the support structure.
The illustrations presented herein are not actual views of any particular tool or drill string, but are merely idealized representations that are employed to describe example embodiments of the present disclosure. The following description provides specific details of embodiments of the present disclosure in order to provide a thorough description thereof. However, a person of ordinary skill in the art will understand that the embodiments of the disclosure may be practiced without employing many such specific details. Indeed, the embodiments of the disclosure may be practiced in conjunction with conventional techniques employed in the industry. In addition, the description provided below does not include all elements to form a complete structure or assembly. Only those process acts and structures necessary to understand the embodiments of the disclosure are described in detail below. Additional conventional acts and structures may be used. Also note, any drawings accompanying the application are for illustrative purposes only, and are thus not drawn to scale. Additionally, elements common between figures may retain the same numerical designation.
As used herein, the terms “comprising,” “including,” “containing,” “characterized by,” and grammatical equivalents thereof are inclusive or open-ended terms that do not exclude additional, unrecited elements or method steps, but also include the more restrictive terms “consisting of” and “consisting essentially of” and grammatical equivalents thereof.
As used herein, the term “may” with respect to a material, structure, feature or method act indicates that such is contemplated for use in implementation of an embodiment of the disclosure, and such term is used in preference to the more restrictive term “is” so as to avoid any implication that other, compatible materials, structures, features and methods usable in combination therewith should or must be excluded.
As used herein, the term “configured” refers to a size, shape, material composition, and arrangement of one or more of at least one structure and at least one apparatus facilitating operation of one or more of the structure and the apparatus in a predetermined way.
As used herein, the singular forms following “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.
As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
As used herein, spatially relative terms, such as “beneath,” “below,” “lower,” “bottom,” “above,” “upper,” “top,” “front,” “rear,” “left,” “right,” and the like, may be used for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Unless otherwise specified, the spatially relative terms are intended to encompass different orientations of the materials in addition to the orientation depicted in the figures.
As used herein, the term “substantially” in reference to a given parameter, property, or condition means and includes to a degree that one of ordinary skill in the art would understand that the given parameter, property, or condition is met with a degree of variance, such as within acceptable manufacturing tolerances. By way of example, depending on the particular parameter, property, or condition that is substantially met, the parameter, property, or condition may be at least 90.0% met, at least 95.0% met, at least 99.0% met, or even at least 99.9% met.
As used herein, the term “about” used in reference to a given parameter is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the given parameter).
As used herein, the term “hard material” means and includes any material having a Knoop hardness value of about 1,000 Kgf/mm2 (9,807 MPa) or more. Hard materials include, for example, diamond, cubic boron nitride, boron carbide, tungsten carbide, etc.
As used herein, the term “intergranular bond” means and includes any direct atomic bond (e.g., covalent, metallic, etc.) between atoms in adjacent grains of material.
As used herein, the term “polycrystalline hard material” means and includes any material comprising a plurality of grains or crystals of the material that are bonded directly together by intergranular bonds. The crystal structures of the individual grains of polycrystalline hard material may be randomly oriented in space within the polycrystalline hard material.
As used herein, the term “earth-boring tool” means and includes any type of bit or tool used for drilling during the formation or enlargement of a wellbore and includes, for example, rotary drill bits, percussion bits, core bits, eccentric bits, bi-center bits, reamers, mills, drag bits, roller-cone bits, hybrid bits, and other drilling bits and tools known in the art.
The bit body 202 may include internal fluid passageways that extend between the face 203 of the bit body 202 and a longitudinal bore, extending through the shank 204, the extension 208, and partially through the bit body 202. Nozzle inserts 214 also may be provided at the face 203 of the bit body 202 within the internal fluid passageways. The bit body 202 may further include a plurality of blades 216 that are separated by junk slots 218. In some embodiments, the bit body 202 may include gage wear plugs 222 and wear knots 228. A plurality of cutting element assemblies 210 may be mounted on the face 203 of the bit body 202 in cutting element pockets 212 that are located along each of the blades 216. The cutting element assemblies 210 may include PDC cutting elements, or may include other cutting elements. For example, some or all of the cutting element assemblies 210 may include rotatable cutters, as described below and shown in
The cutting element assembly 210 also includes a support structure 320 for retaining the rotatable cutting element 302. The support structure 320 may be brazed or fastened within a respective cutting element pocket 212 of the blades 216 of the bit body 202 (
The support structure 320 may also include side support structures attached to or integrally formed with the base 321. For example, a side support structure 326 may be located on a proximal end of the base 321 and a side support structure 328 may be located on a distal end of the base 321, each of the side support structures 326, 328 extending generally transverse to the base 321. The side support structures 326, 328 may include an opening (e.g., blind bore or through hole) being sized and positioned to receive an end of a pin 318, as discussed in greater detail below. In some embodiments, the side support structures 326, 328 may be substantially planar, having a substantially uniform thickness. In other embodiments, at least a portion of the side support structures 326, 328 may be tapered and/or inclined inward toward the interior of the support structure 320, as shown in
Materials of the support structure 320 may include a metal carbide or steel material (e.g., high-strength steel alloy). For example, the support structure 320, including the base 321 and the side support structures 326, 328, may include materials such as tungsten carbide, tantalum carbide, or titanium carbide. Additionally, various binding metals may be included in the support structure 320, such as cobalt, nickel, iron, metal alloys, or mixtures thereof, such that metal carbide grains may be supported within the metallic binder. In some embodiments, the support structure 320 may be formed of the same material as the cutting element pockets 212, while in other embodiments, the support structure 320 may be formed of a different material than that of the cutting element pockets 212. In some embodiments, an outer surface of the side support structure 328 (i.e., proximate an engaged formation) may include a hard material (e.g., polycrystalline hard material) similar to that of the end cutting surface 306 of the table 304 of the rotatable cutting element 302.
The pin 318 may be a cylindrical-shaped bearing pin sized and shaped to conform with the interior sidewall 316 defining the through hole 310 of the rotatable cutting element 302. The pin 318 may be configured to reduce frictional forces and/or binding as the rotatable cutting element 302 rotates about a longitudinal axis thereof relative to the pin 318. In some embodiments, the pin 318 may include a friction-reducing surface, such as a bearing. For example, the pin 318 may function as a journal bearing, a roller bearing (e.g., needle bearings) or the like. In some embodiments, the pin 318 may include a journal bearing between the rotatable cutting element 302 and the support structure 320. In other embodiments, the pin 318 may include an elongated cylindrical body having a hard and smooth finished exterior surface such that when the rotatable cutting element 302 rotates about the pin 318, the interior sidewall 316 of the rotatable cutting element 302 is in sliding contact with bearing surfaces of the pin 318. Materials of the pin 318 may include, for example, a metal carbide (e.g., tungsten carbide), aluminum, or steel material (e.g., steel alloy). In addition, the pin 318 and/or the interior sidewall 316 may include a diamond-like coating or other low-friction material to provide such bearing surfaces between the pin 318 and the rotatable cutting element 302.
In operation, the pin 318 is located in the through hole 310 of the rotatable cutting element 302 and the pin 318 is secured to the support structure 320. The pin 318 may be fixedly coupled to and simply supported on opposing ends by each of the side support structures 326, 328 and the rotatable cutting element 302 is free to rotate about the pin 318. For example, the rotatable cutting element 302 may be retained within the support structure 320 in an orientation such that the proximal end 312 of the through hole 310 at the bearing surface 309 of the substrate 308 may be located proximate the side support structure 326, while the distal end 314 of the through hole 310 at the end cutting surface 306 of the table 304 may be located proximate the side support structure 328. Thus, the rotatable cutting element 302 may be rotatably secured to the support structure 320 utilizing the pin 318.
The ends of the pin 318 may be permanently or removably coupled to the support structure 320. Opposing ends of the pin 318 may be attached (e.g., fastened) to the side support structures 326, 328 using retention elements. For example, a proximal end of the pin 318 may be coupled to the side support structure 326 using a retention element 322, while a distal end of the pin 318 may be coupled to the side support structure 328 using a retention element 324. In some embodiments, the retention elements 322, 324 may include braze material, for example, to permanently and/or removably couple the pin 318 to the support structure 320 and to restrict relative movement therebetween. In other embodiments, the retention elements 322, 324 may include threaded fasteners having complementary threaded surfaces on each of the pin 318 and the side support structures 326, 328. Such threaded fasteners may also include locking devices (e.g., nuts or washers) located thereon to prevent such threaded fasteners from becoming loosened. In yet other embodiments, the retention elements 322, 324 may include weld material, adhesive, locking mechanisms, such as interference fit (e.g., shrink-fitting or press-fitting), mechanical fasteners (e.g., snap rings) or the like to facilitate removable attachment between the pin 318 and the side support structures 326, 328. In some embodiments, the support structure 320 including the retention elements 322, 324 may be located only within (i.e., without extending beyond) the cutting element pocket 212 (
In some embodiments, an outer side surface of the base 321 of the support structure 320 may not extend beyond an outer side surface of the rotatable cutting element 302 on the first side 330 of the support structure 320 as viewed from the top view of
As shown in
Once the rotatable cutting element 302 is coupled to the support structure 320, the support structure 320 may be coupled to the bit body 202 (
In embodiments of the present disclosure, the cutting element assemblies 210 including the rotatable cutting element 302 may include selective placement relative to the number and placement of fixed cutting elements. In other words, it is contemplated that the rotatable cutting elements 302 may be selectively positioned relative to one another on the blades 216 (
Interior surfaces of the substrate 308 of the rotatable cutting element 302 may generally define the through hole 310 (e.g., longitudinally extending) having the proximal end 312 at the bearing surface 309 of the substrate 308 and having the distal end 314 at the end cutting surface 306 of the table 304. In other words, the through hole 310 may extend through the entire rotatable cutting element 302 from the bearing surface 309 of the substrate 308 to the end cutting surface 306 of the table 304. The through hole 310 may be defined by the interior sidewall 316 of the rotatable cutting element 302 and may be generally centered along the longitudinal axis L of the rotatable cutting element 302. The through hole 310 may impart an annular cross-sectional shape to the rotatable cutting element 302. The pin 318 mates with the corresponding through hole 310 such that when the rotatable cutting element 302 rotates about the pin 318, the interior sidewall 316 may substantially conform to exterior surfaces of the pin 318, as discussed in greater detail in connection with
The difference of the embodiment of
In the embodiment of
Rotatable cutting element assemblies as disclosed herein may have certain advantages over conventional rotatable cutting elements and over conventional fixed cutting elements. For example, support structures (i.e., auxiliary housings) may be installed into a bit body (e.g., by brazing) or integrally formed with the bit body or a blade thereof before the rotatable cutting elements are installed onto the support structures. Thus, the rotatable cutting elements, and particularly the PDC tables, need not be exposed to the high temperatures typical of brazing. Thus, installing rotatable cutting elements onto support structures already secured to a bit body may avoid thermal damage caused by brazing. In addition, because the edge of the cutting element contacting the formation changes as the rotatable cutting element rotates, the cutting edge remains sharp, avoiding the generation of a local wear flat. The sharp cutting edge may increase the rate of penetration while drilling formation, thereby increasing the efficiency of the drilling operation.
Furthermore, rotatable cutting elements and/or support structures as disclosed herein may be removed and replaced more easily, such as when the cutting elements are worn or damaged. Separation of rotatable cutting element from a support structure secured by retention elements (e.g., braze material) may be trivial in comparison to removal of cutting elements brazed directly into a bit body. For example, rotatable cutting elements may be removed, for example, by applying heat to the retention elements securing the cutting elements to the support structures. Alternatively, support structures may be removed by applying heat to the retention elements securing the support structures to the bit body. Similarly, insertion of a new cutting element may be effected rapidly and without damage to the drill bit. Thus, drill bits may be repaired more quickly than drill bits having conventional cutting elements.
Additional non-limiting example embodiments of the disclosure are described below.
Embodiment 1: A cutting element assembly, comprising: a support structure; a pin having a cylindrical exterior bearing surface; retention elements coupling opposing ends of the pin to the support structure; and a rotatable cutting element comprising a table of polycrystalline hard material having an end cutting surface and a supporting substrate, the rotatable cutting element having an interior sidewall defining a longitudinally extending through hole, wherein the pin is positioned within the through hole of the rotatable cutting element and is supported on the opposing ends thereof by the support structure.
Embodiment 2: The cutting element assembly of Embodiment 1, wherein the support structure comprises two opposing side support structures having a base therebetween, each of the two opposing side support structures extending generally transverse to the base.
Embodiment 3: The cutting element assembly of Embodiment 2, wherein at least a portion of the table of the rotatable cutting element is covered by one of the two opposing side support structures.
Embodiment 4: The cutting element assembly of Embodiment 2 or Embodiment 3, wherein a surface of the base adjacent the rotatable cutting element has a concave shape.
Embodiment 5: The cutting element assembly of any of Embodiments 2 through 4, wherein the base of the support structure is asymmetric with respect to a longitudinal axis of the rotatable cutting element.
Embodiment 6: The cutting element assembly of any of Embodiments 1 through 5, wherein the pin functions as at least one of a journal bearing or a roller bearing between the rotatable cutting element and the support structure.
Embodiment 7: The cutting element assembly of any of Embodiments 1 through 6, wherein the pin is fixed relative to the support structure and the rotatable cutting element is configured to rotate about a longitudinal axis thereof relative to the pin and the support structure.
Embodiment 8: The cutting element assembly of any of Embodiments 1 through 7, wherein the retention elements comprise at least one of a braze material, a threaded elements, a weld material, adhesive, or a snap ring.
Embodiment 9: An earth-boring tool, comprising: a body; and at least one cutting element assembly, comprising: a support structure; a pin having a cylindrical exterior bearing surface; retention elements coupling opposing ends of the pin to the support structure; and a rotatable cutting element comprising a table of polycrystalline hard material having an end cutting surface and a supporting substrate, the rotatable cutting element having an interior sidewall defining a longitudinally extending through hole, wherein the pin is positioned within the through hole of the rotatable cutting element and is supported on the opposing ends thereof by the support structure.
Embodiment 10: The earth-boring tool of Embodiment 9, wherein the body further comprises at least one cutting element pocket, the at least one cutting element assembly being located within the at least one cutting element pocket.
Embodiment 11: The earth-boring tool of Embodiment 9 or Embodiment 10, wherein the through hole of the rotatable cutting element extends entirely through the rotatable cutting element from a bearing surface of the supporting substrate to the end cutting surface of the table.
Embodiment 12: The earth-boring tool of Embodiment 11, wherein: a first end of the pin is supported by a first side support structure proximate the bearing surface of the supporting substrate; and a second end of the pin is supported by a second side support structure proximate the end cutting surface of the table.
Embodiment 13: The earth-boring tool of Embodiment 12, further comprising a first retention element and a second retention element, the second retention element being different than the first retention element, the first end of the pin being coupled to the first side support structure by the first retention element, and the second end of the pin being coupled to the second side support structure by the second retention element.
Embodiment 14: The earth-boring tool of Embodiment 13, wherein the at least one cutting element assembly further comprises a spring and a port, the spring being located between a protruding portion on the first end of the pin and an interior surface of a respective cutting element pocket, and the port is located in the second side support structure such that at least a portion of the second end of the pin is retained within the second side support structure.
Embodiment 15: The earth-boring tool of any of Embodiments 9 through 14, wherein the earth-boring tool comprises an earth-boring rotary drill bit, wherein the body comprises a bit body having a face including a cone region, a nose region, a shoulder region, and a gage region, and wherein the at least one cutting element assembly is located in the shoulder region or the gage region of the bit body.
Embodiment 16: A method of drilling a subterranean formation, comprising: applying weight-on-bit to an earth-boring tool disposed within a wellbore substantially along a longitudinal axis thereof and rotating the earth-boring tool; engaging a formation with a plurality of rotatable cutting elements located on blades of the earth-boring tool, wherein the plurality of rotatable cutting elements are rotatably secured within pockets of the blades with pins extending through a through hole of each of the plurality of rotatable cutting elements, each of the pins being coupled on opposing ends thereof to a support structure located within a respective pocket of the blades; and absorbing compressive forces imposed on the plurality of rotatable cutting elements with the support structure.
Embodiment 17: The method of Embodiment 16, wherein engaging the formation with the plurality of rotatable cutting elements further comprises utilizing each of the pins as a journal bearing between a respective rotatable cutting element and the support structure.
Embodiment 18: The method of Embodiment 16 or Embodiment 17, wherein engaging the formation with the plurality of rotatable cutting elements comprises rotating at least some of the plurality of rotatable cutting elements about an axis of rotation thereof responsive to frictional forces acting between the plurality of rotatable cutting elements and the formation when the earth-boring tool moves relative to the formation.
Embodiment 19: The method of any of Embodiments 16 through 18, further comprising engaging the formation with the plurality of rotatable cutting elements and a plurality of fixed cutting elements, each of the plurality of rotatable cutting elements and the plurality of fixed cutting elements comprising a table of polycrystalline hard material having an end cutting surface and a supporting substrate.
Embodiment 20: The method of Embodiment 19, wherein engaging the formation with the plurality of rotatable cutting elements comprises covering at least a portion of the table of polycrystalline hard material with a portion of the support structure.
While the present invention has been described herein with respect to certain illustrated embodiments, those of ordinary skill in the art will recognize and appreciate that it is not so limited. Rather, many additions, deletions, and modifications to the illustrated embodiments may be made without departing from the scope of the invention as hereinafter claimed, including legal equivalents thereof In addition, features from one embodiment may be combined with features of another embodiment while still being encompassed within the scope of the invention as contemplated by the inventors. Further, embodiments of the disclosure have utility with different and various types and configurations of earth-boring tools.
