Not applicable.
The disclosure relates generally to drill bits for drilling a borehole in an earthen formation for the ultimate recovery of oil, gas, or minerals. More particularly, the disclosure relates to fixed cutter bits and cutter elements used on such bits.
An earth-boring drill bit is typically mounted on the lower end of a drill string and is rotated by rotating the drill string at the surface or by actuation of downhole motors or turbines, or by both methods. With weight applied to the drill string, the rotating drill bit engages the earthen formation and proceeds to form a borehole along a predetermined path toward a target zone. The borehole thus created will have a diameter generally equal to the diameter or “gage” of the drill bit.
Fixed cutter bits, also known as rotary drag bits, are one type of drill bit commonly used to drill boreholes. Fixed cutter bit designs include a plurality of blades angularly spaced about the bit face. The blades generally project radially outward along the bit body and form flow channels there between. In addition, cutter elements are often grouped and mounted on several blades. The configuration or layout of the cutter elements on the blades may vary widely, depending on a number of factors. One of these factors is the formation itself, as different cutter element layouts engage and cut the various strata with differing results and effectiveness.
The cutter elements disposed on the several blades of a fixed cutter bit are typically formed of extremely hard materials and include a layer of polycrystalline diamond (“PCD”) material. In the typical fixed cutter bit, each cutter element or assembly comprises an elongate and generally cylindrical support member which is received and secured in a pocket formed in the surface of one of the several blades. In addition, each cutter element typically has a hard cutting layer of polycrystalline diamond or other superabrasive material such as cubic boron nitride, thermally stable diamond, polycrystalline cubic boron nitride, or ultrahard tungsten carbide (meaning a tungsten carbide material having a wear-resistance that is greater than the wear-resistance of the material forming the substrate) as well as mixtures or combinations of these materials. The cutting layer is exposed on one end of its support member, which is typically formed of tungsten carbide. For convenience, as used herein, the phrase “polycrystalline diamond cutter” or “PDC” may be used to refer to a fixed cutter bit (“PDC bit”) or cutter element (“PDC cutter element”) employing a hard cutting layer of polycrystalline diamond or other superabrasive material such as cubic boron nitride, thermally stable diamond, polycrystalline cubic boron nitride, or ultrahard tungsten carbide.
While the bit is rotated, drilling fluid is pumped through the drill string and directed out of the face of the drill bit. The fixed cutter bit typically includes nozzles or fixed ports spaced about the bit face that serve to inject drilling fluid into the flow passageways between the several blades. The flowing fluid performs several important functions. The fluid removes formation cuttings from the bit's cutting structure. Otherwise, accumulation of formation materials on the cutting structure may reduce or prevent the penetration of the cutting structure into the formation. In addition, the fluid removes cut formation materials from the bottom of the hole. Failure to remove formation materials from the bottom of the hole may result in subsequent passes by cutting structure to re-cut the same materials, thereby reducing the effective cutting rate and potentially increasing wear on the cutting surfaces. The drilling fluid and cuttings removed from the bit face and from the bottom of the hole are forced from the bottom of the borehole to the surface through the annulus that exists between the drill string and the borehole sidewall. Further, the fluid removes heat, caused by contact with the formation, from the cutter elements in order to prolong cutter element life. Thus, the number and placement of drilling fluid nozzles, and the resulting flow of drilling fluid, may significantly impact the performance of the drill bit.
Without regard to the type of bit, the cost of drilling a borehole for recovery of hydrocarbons may be very high and is proportional to the length of time it takes to drill to the desired depth and location. The time required to drill the well, in turn, is greatly affected by the cutting efficiency and durability of the cutting structure on the drill bit.
Embodiments of cutter elements for drill bits configured to drill boreholes in subterranean formations are disclosed herein. In one embodiment, a cutter element comprises a base portion having a central axis, a first end, a second end, and a radially outer surface extending axially from the first end to the second end. The cutter element also comprises a cutting layer fixably mounted to the first end of the base portion. The cutting layer includes a cutting face distal the base portion and a radially outer surface extending axially from the cutting face to the radially outer surface of the base portion. The cutting face comprises a planar central region centered relative to the central axis and disposed in a plane oriented perpendicular to the central axis. In addition, the cutting face comprises a plurality of circumferentially-spaced cutting regions disposed about the planar central region, wherein each cutting region extends from the planar central region to the radially outer surface of the cutting layer. Each cutting region slopes axially toward the base portion moving radially outward from the planar central region to the radially outer surface of the cutting layer. Further, the cutting face comprises a plurality of circumferentially-spaced relief regions disposed about the planar central region. Each relief region extends from the planar central region to the radially outer surface. Each relief region slopes axially toward the base portion moving radially outward from the planar central region to the radially outer surface of the cutting layer. The plurality of cutting regions and the plurality of relief regions are circumferentially arranged in an alternating manner such that one relief region is circumferentially disposed between two circumferentially adjacent cutting regions of the plurality of cutting regions. Each relief region is defined by a first edge at an intersection of the relief region and one circumferentially adjacent cutting region and a second edge at an intersection of the relief region and another circumferentially adjacent cutting region. The first edge and the second edge of each relief region are angularly spaced apart about the central axis by an angle α that ranges from 45° to 75°.
In another embodiment, a cutter element comprises a base portion having a central axis, a first end, a second end, and a radially outer surface extending axially from the first end to the second end. The cutter element also comprises a cutting layer fixably mounted to the first end of the base portion. The cutting layer includes a cutting face distal the base portion and a radially outer surface extending axially from the cutting face to the radially outer surface of the base portion. The cutting face comprises a planar central region disposed in a plane oriented perpendicular to the central axis. In addition, the cutting face comprises a plurality of circumferentially-spaced cutting ridges disposed about the planar central region. Each cutting ridge comprises a planar surface extending radially outward from the planar central region. The planar surface of each cutting ridge is disposed at an acute angle β measured upward from the planar surface to the plane containing the planar central region. An end of each cutting ridge radially distal the planar central region comprises a cutting edge configured to engage and shear the subterranean formation. Further, the cutting face comprises a plurality of circumferentially-spaced relief regions disposed about the planar central region. Each relief region extends from the planar central region. Each relief region slopes axially toward the base portion moving radially outward from the planar central region. One cutting ridge is circumferentially disposed between a pair of the circumferentially adjacent relief regions. An edge is disposed at an intersection of each relief region and each circumferentially adjacent cutting region. A pair of the edges define a first circumferential end and a second circumferential end of each relief region. The first circumferential end and the second circumferential end of each relief region are angularly spaced apart by an angle α that ranges from 45° to 75°.
Embodiments described herein comprise a combination of features and advantages intended to address various shortcomings associated with certain prior devices, systems, and methods. The foregoing has outlined rather broadly the features and technical advantages of the invention in order that the detailed description of the invention that follows may be better understood. The various characteristics described above, as well as other features, will be readily apparent to those skilled in the art upon reading the following detailed description, and by referring to the accompanying drawings. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.
For a detailed description of the preferred embodiments of the invention, reference will now be made to the accompanying drawings in which:
The following discussion is directed to various exemplary embodiments. However, one skilled in the art will understand that the examples disclosed herein have broad application, and that the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.
Certain terms are used throughout the following description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.
In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices, components, and connections. In addition, as used herein, the terms “axial” and “axially” generally mean along or parallel to a central axis (e.g., central axis of a body or a port), while the terms “radial” and “radially” generally mean perpendicular to the central axis. For instance, an axial distance refers to a distance measured along or parallel to the central axis, and a radial distance means a distance measured perpendicular to the central axis. Any reference to up or down in the description and the claims will be made for purposes of clarity, with “up”, “upper”, “upwardly” or “upstream” meaning toward the surface of the borehole and with “down”, “lower”, “downwardly” or “downstream” meaning toward the terminal end of the borehole, regardless of the borehole orientation.
As previously described, the length of time it takes to drill to the desired depth and location impacts the cost of drilling operations. The shape and positioning of the cutter elements impact bit durability and rate of penetration (ROP) and thus, are important to the success of a particular bit design. Embodiments described herein are directed to cutter elements for fixed cutter drill bits with geometries that offer the potential to improve bit durability and/or ROP. In some embodiments, cutter elements disclosed herein can be reused one or more times after the initial cutting edge is sufficiently worn, which offers the potential to enhance the useful life of such cutter elements.
Referring now to
Drilling assembly 90 includes a drillstring 20 and a drill bit 100 coupled to the lower end of drillstring 20. Drillstring 20 is made of a plurality of pipe joints 22 connected end-to-end, and extends downward from the rotary table 14 through a pressure control device 15, such as a blowout preventer (BOP), into the borehole 26. The pressure control device 15 is commonly hydraulically powered and may contain sensors for detecting certain operating parameters and controlling the actuation of the pressure control device 15. Drill bit 100 is rotated with weight-on-bit (WOB) applied to drill the borehole 26through the earthen formation. Drillstring 20 is coupled to a drawworks 30 via a kelly joint 21, swivel 28, and line 29 through a pulley. During drilling operations, drawworks 30 is operated to control the WOB, which impacts the rate-of-penetration of drill bit 100 through the formation. In this embodiment, drill bit 100 can be rotated from the surface by drillstring 20 via rotary table 14 and/or a top drive, rotated by downhole mud motor 55 disposed along drillstring 20 proximal bit 100, or combinations thereof (e.g., rotated by both rotary table 14 via drillstring 20 and mud motor 55, rotated by a top drive and the mud motor 55, etc.). For example, rotation via downhole motor 55 may be employed to supplement the rotational power of rotary table 14, if required, and/or to effect changes in the drilling process. In either case, the rate-of-penetration (ROP) of the drill bit 100 into the borehole 26 for a given formation and a drilling assembly largely depends upon the WOB and the rotational speed of bit 100.
During drilling operations a suitable drilling fluid 31 is pumped under pressure from a mud tank 32 through the drillstring 20 by a mud pump 34. Drilling fluid 31 passes from the mud pump 34 into the drillstring 20 via a desurger 36, fluid line 38, and the kelly joint 21. The drilling fluid 31 pumped down drillstring 20 flows through mud motor 55 and is discharged at the borehole bottom through nozzles in face of drill bit 100, circulates to the surface through an annular space 27 radially positioned between drillstring 20 and the sidewall of borehole 26, and then returns to mud tank 32 via a solids control system 36 and a return line 35. Solids control system 36 may include any suitable solids control equipment known in the art including, without limitation, shale shakers, centrifuges, and automated chemical additive systems. Control system 36 may include sensors and automated controls for monitoring and controlling, respectively, various operating parameters such as centrifuge rpm. It should be appreciated that much of the surface equipment for handling the drilling fluid is application specific and may vary on a case-by-case basis.
Referring now to
The portion of bit body 110 that faces the formation at downhole end 100b includes a bit face 111 provided with a cutting structure 140. Cutting structure 140 includes a plurality of blades 141, 142, which extend from bit face 111. In this embodiment, cutting structure 140 includes three angularly spaced-apart primary blades 141, and three angularly spaced apart secondary blades 142. Further, in this embodiment, the plurality of blades (e.g., primary blades 141, and secondary blades 142) are uniformly angularly spaced on bit face 111 about bit axis 105. In this embodiment, bit 100 includes five total blades 141, 142—three primary blades 141 and two secondary blades 142. The five blades 141, 142 are uniformly angularly spaced about 72° apart. In other embodiments, the blades (e.g., blades 141, 142 may be non-uniformly circumferentially spaced about bit face 111). Although bit 100 is shown as having three primary blades 141 and two secondary blades 142, in other embodiments, the bit (e.g., bit 100) may comprise any suitable number of primary and secondary blades such as two primary blades and four secondary blades or three primary blades and three secondary blades.
In this embodiment, primary blades 141 and secondary blades 142 are integrally formed as part of, and extend from, bit body 110 and bit face 111. Primary blades 141 and secondary blades 142 extend generally radially along bit face 111 and then axially along a portion of the periphery of bit 100. In particular, primary blades 141 extend radially from proximal central axis 105 toward the periphery of bit body 110. Primary blades 141 and secondary blades 142 are separated by drilling fluid flow courses 143. Each blade 141, 142 has a leading edge or side 141a, 142a, respectively, and a trailing edge or side 141b, 142b, respectively, relative to the direction of rotation 106 of bit 100.
Referring still to
As will also be described in more detail below, each cutter element 200 has a cutting face 220. In the embodiments described herein, each cutter element 200 is mounted such that its cutting face 220 is generally forward-facing. As used herein, “forward-facing” is used to describe the orientation of a surface that is substantially perpendicular to, or at an acute angle relative to, the cutting direction of the bit (e.g., cutting direction 106 of bit 100).
Referring still to
Referring now to
Composite blade profile 148 and bit face 111 may generally be divided into three regions conventionally labeled cone region 149a, shoulder region 149b, and gage region 149c. Cone region 149a defines the radially innermost region of bit body 110 and composite blade profile 148, and extends from bit axis 105 to shoulder region 149b. In this embodiment, cone region 149a is generally concave. Adjacent cone region 149a is the generally convex shoulder region 149b. The transition between cone region 149a and shoulder region 149b, typically referred to as the nose 149d, occurs at the axially lowermost/outermost portion of composite blade profile 148 where a tangent line to the blade profile 148 has a slope of zero. Moving radially outward, adjacent shoulder region 149b is the gage region 149c which extends substantially parallel to bit axis 105 at the outer radial periphery of composite blade profile 148. As shown in composite blade profile 148, gage pads 147 define the gage region 149c and the outer radius R110 of bit body 110. Outer radius R110 extends to and therefore defines the full gage diameter of bit body 110. As used herein, the term “full gage diameter” refers to elements or surfaces extending to the full, nominal gage of the bit diameter.
Referring now to
As best shown in
Referring now to
In this embodiment, cutter element 200 includes a base or substrate 201 and a cutting disc or layer 210 bonded to the substrate 201. Cutting layer 210 and substrate 201 meet at a reference plane of intersection 209 that defines the location at which substrate 201 and cutting layer 210 are fixably attached. In this embodiment, substrate 210 is made of tungsten carbide and cutting layer 210 is made of an ultrahard material such as polycrystalline diamond (PCD) or other superabrasive material. Part and/or all of the diamond in cutting layer 210 may be leached, finished, polished, and/or otherwise treated to enhance durability, efficiency and/or effectiveness. While cutting layer 210 is shown as a single layer of material mounted to substrate 210, in general, the cutting layer (e.g., layer 210) may be formed of one or more layers of one or more materials. In addition, although substrate 201 is shown as a single, homogenous material, in general, the substrate (e.g., substrate 201) may be formed of one or more layers of one or more materials.
Substrate 201 has a central axis 205, a first end 201a bonded to cutting layer 210 at plane of intersection 209, a second end 201b opposite end 201a and distal cutting layer 210, and a radially outer surface 202 extending axially between ends 201a, 201b. In this embodiment, substrate 201 is generally cylindrical, and thus, outer surface 202 is generally cylindrical. As best shown in
Referring still to
The outer surface of cutting layer 210 at first end 210a defines the cutting face 220 of cutter element 200 and is designed and shaped to engage and shear the formation during drilling operations. In this embodiment, a chamfer or bevel 211 is provided at the intersection of cutting face 220 and outer surface 212 about the entire outer periphery of cutting face 220.
As best shown in the top view of cutter element 200 in
For purposes of clarity and further explanation, the three cutting regions 221 of cutting face 220 are labeled 221a, 221b, 221c and the three relief regions 222 of cutting face 220 are labeled 222a, 222b, 222c. As previously described, regions 221, 222 are arranged in an circumferentially alternating manner such that regions 221, 222 are positioned circumferentially adjacent each other with each region 221 circumferentially disposed between a pair of circumferentially-adjacent regions 222, and each region 222 circumferentially disposed between a pair of circumferentially-adjacent regions 221. More specifically, relief region 222a extends circumferentially from cutting region 221a to cutting region 221b, relief region 222b extends circumferentially from cutting region 221b to cutting region 221c, and relief region 222c extends circumferentially from cutting region 221c to cutting region 221a. Thus, each cutting region 221a, 221b, 221c extends circumferentially between a pair of circumferentially adjacent regions 222a, 222b, 222c, and each relief region 222a, 222b, 222c extends circumferentially between a pair of circumferentially adjacent cutting regions 221a, 221b, 221c.
As best shown in
As previously described, in this embodiment, cutting regions 221a, 221b, 221c intersect central region 225 at defined linear edges 226a, 226c, 226e, relief regions 222a, 222b, 222c intersect central region 225 at defined linear edges 226b, 226d, 226f, and cutting regions 221a, 221b, 221c intersect relief regions 222a, 222b, 222c at defined linear edges 224a, 224b, 224c, 224d, 224e, 224f. However, in other embodiments, the cutting regions (e.g., cutting regions 221a, 221b, 221c) may intersect the central region (e.g., central region 225) at smoothly curved, continuously contoured surfaces, the relief regions (e.g., relief regions 222a, 222b, 222c) may intersect the central region at smoothly curved, continuously contoured surfaces, the cutting regions may intersect the relief regions at smoothly curved, continuously contoured surfaces, or combinations thereof.
Each linear edge 224a, 224b, 224c, 224d, 224e, 224f extends generally radially from central region 225 to outer surface 212 and chamfer 211. In this embodiment, linear edges 224a, 224f are parallel to each other moving radially along cutting region 221a from central region 225 to outer surface 212 and chamfer 211, linear edges 224b, 224c are parallel to each other moving radially along cutting region 221b from central region 225 to outer surface 212 and chamfer 211, and linear edges 224d, 224e are parallel to each other moving radially along cutting region 221c from central region 225 to outer surface 212 and chamfer 211. In contrast, linear edges 224a, 224b defining the circumferential ends of relief region 222a slope or taper away from each other moving radially along relief region 222a from central region 225 to outer surface 212 and chamfer 211, linear edges 224c, 224d defining the circumferential ends of relief region 222b slope or taper away from each other moving radially along relief region 222b from central region 225 to outer surface 212 and chamfer 211, and linear edges 224e, 224f defining the circumferential ends of relief region 222c slope or taper away from each other moving radially along relief region 222c from central region 225 to outer surface 212 and chamfer 211. Consequently, each pair of linear edges 224a, 224b, 224c, 224d, 224e, 224f defining the circumferential ends of relief regions 222a, 222b, 222c are oriented at an angle α relative to each other in top view. The angle α between linear edges 224a, 224b, the angle α between linear edges 224c, 224d, and the angle α between linear edges 224e, 224f are each preferably between 45° and 75°, and more preferably between 55° and 65°. In this embodiment, each angle α is 60°. It should be appreciated that as the number of relief regions (e.g., relief regions 222a, 222b, 222c) increase, the angle α associated with each relief region may decrease; and as the number of relief regions decreases, the angle α associated with each relief region may increase.
Referring still to
In this embodiment, the width W221 of each cutting region 221a, 221b, 221c is the same and the length L221 of each cutting region 221a, 221b, 221c is the same. However, in other embodiments, the width of any two or more cutting regions (e.g., width W221 of any two or more cutting regions 221a, 221b, 221c) may be the same or different, the width of any one or more cutting regions may vary moving radially along the cutting region from the central region (e.g., central region 225) to the outer surface (e.g., outer surface 212), the length of any two or more cutting regions (e.g., the width L221 of any two or more cutting regions 221a, 221b, 221c) may be the same or different, or combinations thereof.
Referring now to
Referring again to
Although cutting regions 221a, 221b, 221c are planar in this embodiment, in other embodiments, the cutting regions (e.g., cutting regions 221a, 221b, 221c) may be convex or bowed outwardly. In embodiments described herein, each cutting region 221a, 221b, 221c is preferably polished to an average roughness Ra of less than 1000 nanometers, and preferably less than 500 nanometers.
As will be described in more detail below, cutter elements 200 are mounted to cutter supporting surfaces 144 of blades 141, 142 with the radially outer end (relative to axis 205) of one of the cutting regions 221a, 221b, 221c of each cutter element 200 positioned to engage and shear the formation. Accordingly, the edge at the radially outer end of each cutting region 221a, 221b, 221c distal central region 225 (e.g., at the intersection of each cutting region 221a, 221b, 221c and chamfer 211) defines a cutting edge 223 of cutter element 200.
Referring again to
Although relief regions 222a, 222b, 222c are planar in this embodiment, in other embodiments, the relief regions (e.g., relief regions 222a, 222b, 222c) may be convex or bowed outwardly. In embodiments described herein, each relief region 222a, 222b, 222c is preferably polished to an average roughness Ra of less than 1000 nanometers, and preferably less than 500 nanometers.
Referring to
Referring again to
During drilling operations, each cutting face 220 engages, penetrates, and shears the formation as the bit 100 is rotated in the cutting direction 106 and is advanced through the formation. Due to the orientation of cutter elements 200, the cutting edges 223 defining the extension heights of cutter elements 200 function as the primary cutting edges as cutter elements 200 engage the formation. The sheared formation material slides along the corresponding cutting regions 221 and the pairs of circumferentially adjacent relief regions 222 as cutting faces 220 pass through the formation. Thus, as each cutting face 220 advances through the formation, it cuts a kerf in the formation generally defined by the cutting profile of the cutting face 220. The geometry of cutting face 220 is particularly designed to offer the potential to improving cutting efficiency and cleaning efficiency to increase rate of penetration (ROP) and durability of bit 100. In particular, the downward slope of cutting regions 221 toward base 201 moving from central region 225 to outer surface 212 increases relief relative to the corresponding cutting edge 223, which allows drilling fluid to be directed toward the cutting edge 223 and formation cuttings to efficiently slide along cutting face 220. The downward slope of the pair of circumferentially adjacent relief regions 222 toward base 201 moving laterally from the cutting edge 223 allows cutting face 220 to draw the extrudates of formation material.
As previously described, embodiments of cutter elements 200 include a plurality of circumferentially-spaced cutting edges 223. In the embodiment of cutter element 200 shown in
In the embodiment of cutter element 200 previously described and shown in
Referring now to
Cutting face 320 is substantially the same as cutting face 220 previously described. In particular, cutting face 320 includes a central region or surface 225, a plurality of uniformly circumferentially-spaced cutting regions or surfaces 221 extending radially from central region 225 to outer surface 212 and chamfer 211, and a plurality of relief regions or surfaces 222 extending from central region 225 and cutting regions 221 to outer surface 212 and chamfer 211. Regions 221, 222 are circumferentially disposed about axis 205 and central region 225, and are arranged in an circumferentially alternating manner such that regions 221, 222 are positioned circumferentially adjacent each other with each region 221 circumferentially disposed between a pair of circumferentially-adjacent regions 222, and each region 222 circumferentially disposed between a pair of circumferentially-adjacent regions 221. In this embodiment, cutting face 320 includes three cutting regions 221 angularly spaced 120° apart about axis 205 and three relief regions 222 angularly spaced 120° apart about axis 205. For purposes of clarity and further explanation, cutting regions 221 may also be labeled 221a, 221b, 221c and relief regions 222 may also be labeled 222a, 222b, 322c.
As best shown in
The pair of linear edges 224a, 224b, 224c, 224d, 224e, 224f defining the circumferential ends of each relief region 222a, 222b, 222c are oriented at an angle α relative to each other in top view. The angle α between linear edges 224a, 224b, the angle α between linear edges 224c, 224d, and the angle α between linear edges 224e, 224f are each preferably between 45° and 75°, and more preferably between 55° and 65°. In this embodiment, each angle α is 60°.
Cutting regions 221 are as previously described with the exception of the width of cutting regions 221. In particular, as best shown in
Moreover, each cutting region 221a, 221b, 221c is planar and slopes axially downward toward base 201 moving radially outward from central region 225 to outer surface 212 and chamfer 211. In particular, as best shown in
Referring still to
Cutting regions 221 and relief regions 222 generally slope axially downward toward substrate 201 moving from central region 225 to outer surface 212 and chamfer 211. As a result, central region 225 defines a peak along cutting face 320. Thus, as shown in
Referring again to
Cutting elements 300 are mounted in bit body 110 in the same manner and orientation as cutter elements 200 previously described. More specifically, each cutter element 300 is mounted to a corresponding blade 141, 142 with substrate 201 received and secured in a pocket formed in the cutter support surface 144 of the blade 141, 142 to which it is fixed by brazing or other suitable means. In addition, each cutter element 300 is oriented with axis 205 oriented generally parallel or tangent to cutting direction 106 and such that the corresponding cutting face 320 is exposed and leads the cutter element 300 relative to cutting direction 106 of bit 100. Further, cutter elements 300 are oriented one cutting edge 223 distal the corresponding cutter supporting surface 144 and defining the extension height of the cutter element 300.
During drilling operations, cutting faces 320 of cutter elements 300 engage, penetrate, and shear the formation in the same manner as cutting faces 220 of cutter elements 200 previously described. In the same manner as previously described with respect to cutter element 200, since cutting faces 320 of cutter elements 300 include a plurality of cutting edges 223 (e.g., three cutting edges 223), one cutting edge 223 of each cutter element 300 can be used first to engage, penetrate, and shear the formation, and then when those cutting edges 223 are sufficiently worn (e.g., the cutting efficiency and rate of penetration of the bit are sufficiently low), cutter elements 300 can be removed from the bit body 110, and then re-mounted to bit body 110 with one of the other cutting edges 223 positioned to engage, penetrate and shear the formation. The ability to reuse cutter elements 300 after one cutting edge 223 is sufficiently worn offers the potential to significantly increase the operating lifetime of cutter elements 300 as compared to other cutter elements that include only one primary cutting edge.
In the embodiments of cutter elements 200, 300 previously described and shown in
Referring now to
Cutting face 420 is substantially the same as cutting face 320 previously described. In particular, cutting face 320 includes a central region or surface 225 and a plurality of uniformly circumferentially-spaced cutting regions or surfaces 221 extending radially from central region 225 to outer surface 212 and chamfer 211. Central region 225 and cutting regions 221 are each as previously described with respect to cutter element 300. This embodiment also includes a plurality of relief regions or surfaces 422 extending from central region 225 and cutting regions 221 to outer surface 212 and chamfer 211. Regions 221, 422 are circumferentially disposed about axis 205 and central region 225. In addition, regions 221, 422 are arranged in an circumferentially alternating manner such that regions 221, 422 are positioned circumferentially adjacent each other with each region 221 circumferentially disposed between a pair of circumferentially-adjacent regions 422, and each region 422 circumferentially disposed between a pair of circumferentially-adjacent regions 221. However, unlike planar relief regions 222 previously described, in this embodiment, relief regions 422 are smoothly curved and continuously contoured. More specifically, each relief region 422 is concave or bowed inwardly between corresponding linear edges 224a, 224b, 224c, 224d, 224e, 224f and between the corresponding circumferentially adjacent cutting edges 223. In addition, each relief region 422 generally slopes axially downward toward base 210 moving circumferentially from each pair of circumferentially adjacent edges 224a, 224b, 224c, 224d, 224e, 224f toward the circumferential center of the relief region 422. More specifically, in side view, the slope of each region 422 generally decreases moving circumferentially from each pair of circumferentially adjacent edges 224a, 224b, 224c, 224d, 224e, 224f toward the circumferential center of the relief region 422.
Cutting elements 400 are mounted in bit body 110 in the same manner and orientation as cutter elements 200 previously described. More specifically, each cutter element 400 is mounted to a corresponding blade 141, 142 with substrate 201 received and secured in a pocket formed in the cutter support surface 144 of the blade 141, 142 to which it is fixed by brazing or other suitable means. In addition, each cutter element 400 is oriented with axis 205 oriented generally parallel or tangent to cutting direction 106 and such that the corresponding cutting face 420 is exposed and leads the cutter element 400 relative to cutting direction 106 of bit 100. Further, cutter elements 400 are oriented one cutting edge 223 distal the corresponding cutter supporting surface 144 and defining the extension height of the cutter element 400.
During drilling operations, cutting faces 420 of cutter elements 400 engage, penetrate, and shear the formation in the same manner as cutting faces 220 of cutter elements 200 previously described. In the same manner as previously described with respect to cutter element 200, since cutting faces 420 of cutter elements 400 include a plurality of cutting edges 223 (e.g., three cutting edges 223), one cutting edge 223 of each cutter element 400 can be used first to engage, penetrate, and shear the formation, and then when those cutting edges 223 are sufficiently worn (e.g., the cutting efficiency and rate of penetration of the bit are sufficiently low), cutter elements 400 can be removed from the bit body 110, and then re-mounted to bit body 110 with one of the other cutting edges 223 positioned to engage, penetrate and shear the formation. The ability to reuse cutter elements 400 after one cutting edge 223 is sufficiently worn offers the potential to significantly increase the operating lifetime of cutter elements 400 as compared to other cutter elements that include only one primary cutting edge.
In embodiments described herein, central region 225, cutting regions 221a, 221b, 221c, and relief regions 222a, 222b, 222c are described as preferably being polished to an average roughness Ra of less than 1000 nanometers, and preferably less than 500 nanometers. However, it should be appreciated that on a given cutting face (e.g., cutting face 220, 320, 420), any two or more of regions 225, 221a, 221b, 221c, 222a, 222b, 222c, may have different average roughnesses Ra and/or any one or more of regions 225, 221a, 221b, 221c, 222a, 222b, 222c may not be polished to a particular average roughness Ra.
While preferred embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the scope or teachings herein. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the systems, apparatus, and processes described herein are possible and are within the scope of the disclosure. For example, the relative dimensions of various parts, the materials from which the various parts are made, and other parameters can be varied. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims. Unless expressly stated otherwise, the steps in a method claim may be performed in any order. The recitation of identifiers such as (a), (b), (c) or (1), (2), (3) before steps in a method claim are not intended to and do not specify a particular order to the steps, but rather are used to simplify subsequent reference to such steps.
This application is a continuation of U.S. application Ser. No. 16/673,515 filed Nov. 4, 2019, and entitled “Drill Bit Cutter Elements and Drill Bits Including Same,” which is hereby incorporated herein by reference in its entirety for all purposes.
Number | Date | Country | |
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Parent | 16673515 | Nov 2019 | US |
Child | 17528751 | US |