Patent Application
20160168917
In drilling a borehole in the earth, such as for the recovery of hydrocarbons or for other applications, it is conventional practice to connect a drill bit on the lower end of an assembly of drill pipe sections that are connected end-to-end so as to form a “drill string.” The bit 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 bit engages the earthen formation causing the bit to cut through the formation material by either abrasion, fracturing, or shearing action, or through a combination of all cutting methods, thereby forming a borehole along a predetermined path toward a target zone.
Many different types of drill bits have been developed and found useful in drilling such boreholes. Two predominate types of drill bits are roller cone bits and fixed cutter (or rotary drag) bits. Most fixed cutter bit designs include a plurality of blades angularly spaced about the bit face. The blades project radially outward from the bit body and form flow channels there between. In addition, cutting elements are typically grouped and mounted on several blades in radially extending rows. The configuration or layout of the cutting elements on the blades may vary widely, depending on a number of factors such as the formation to be drilled.
The cutting elements disposed on the blades of a fixed cutter bit are typically formed of extremely hard materials. In a typical fixed cutter bit, each cutting element includes an elongate and generally cylindrical tungsten carbide substrate that is received and secured in a pocket formed in the surface of one of the blades. The cutting elements typically include a hard cutting layer of polycrystalline diamond (PCD) or other super abrasive material such as thermally stable diamond or polycrystalline cubic boron nitride. A PCD layer is often fixed to a substrate (e.g., a cylindrical tungsten carbide substrate) to form a polycrystalline diamond compact (PDC). For convenience, “PDC bit” “PDC cutters” may be used to refer to a fixed cutter bit or cutting element employing a hard cutting layer of polycrystalline diamond or other super abrasive materials.
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 downhole cutting tool that includes a tool body, a plurality of blades extending a height from the tool body to an outermost surface, and a plurality of cutting elements on at least one of the plurality of blades, each cutting element having a longitudinal axis oriented substantially radially outward from the outermost surface of the blade, at least two adjacent cutting elements of the plurality of cutting elements having different axial lengths.
In another aspect, embodiments disclosed herein relate to a downhole cutting tool that includes a tool body, a plurality of blades extending a height from the tool body to an outermost surface, a plurality of cutting elements on the plurality of blades, each cutting element having a longitudinal axis oriented substantially radially outward from the outermost surface of the blades. A rotated view of the plurality of cutting elements into a single plane forms a cutting profile including a cone region, a nose region, a shoulder region, and a gage region. The downhole cutting tool may further include least one row of cutting elements, each row having at least three of the plurality of cutting elements on the outermost surface of one of the blades and defined by a straight line intersecting the longitudinal axes of each cutting element in the row, and each row of cutting elements having a cutting row density equal to the cumulative diameter of the cutting elements forming the row in at least one region divided by a length of the at least one blade measured along the outermost surface of the at least one region of the blade. The cutting row density may be greater than 65 percent.
In yet another aspect, embodiments disclosed herein relate to a method of manufacturing a downhole cutting tool that includes attaching at least three cutting elements to at least one blade extending a height from a tool body to an outermost surface, the at least three cutting elements extending substantially radially outward from the outermost surface of the at least one blade and oriented in a row, at least two adjacent cutting elements having a different axial length.
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 fixed cutter drill bits or other downhole cutting tools containing two or more cutting elements having substrates with different lengths. Other embodiments disclosed herein relate to fixed cutter drill bits containing such cutting elements, including the placement of such cutting elements on a bit and variations on the cutting elements that may be used to improve or optimize drilling.
Further, a plurality of primary cutting elements 140 may also disposed on the blades 120. In the embodiment shown, each blade 120 has a leading row of primary cutting elements 140 and a trailing row of at least three of the cutting elements 130. As used herein, a leading row and trailing row may refer to rows of cutting elements positioned relative to each other on a single blade 120 and relative to the leading face 126 or trailing face 128 of the blade 120, where a leading row of cutting elements is closer to the leading face 126 of the blade than the trailing row and the trailing row of cutting elements is closer to the trailing face 128 of the blade than the leading row. Likewise, a “primary cutting element” may refer to a cutting element positioned closer to the leading face of the blade relative to a trailing cutting element. In the embodiment shown in
Other embodiments may include a leading row and trailing row on less than each of the blades of a cutting tool, and some embodiments may include a single row of cutting elements on each blade. Further, one or more rows of cutting elements (e.g., a leading row, trailing row, or single row) on a cutting tool according to embodiments of the present disclosure may have cutting elements oriented to have their longitudinal axes extend substantially along the height dimension of the blade on which they are disposed. That is, the one or more cutting elements may extend at an angle from the height dimension of the blade such that the axial alignment the cutting elements extend substantially radially outward from the outermost surface of the blade, while one or more or no cutting elements may be oriented substantially along the width dimension of the blade on which they are disposed. For example, in the embodiment shown in
As used herein, a cutting element oriented with its longitudinal axis extending “substantially” outward from a blade outermost surface (e.g., a top surface) may include a cutting element oriented with its longitudinal axis extending along the height-dimension plane of the blade, normal to the blade profile, or may include a cutting element oriented to be tilted or deviated from a line normal to the blade profile, e.g., oriented at a back rake and/or side rake. Back rake and side rake orientations are discussed in detail below. For example,
Further, in the embodiment shown in
For ease in distinguishing between the multiple types of cutting elements, the term “cutting elements” will generically refer to any type of cutting element, while “cutter” will refer those cutting elements with a planar cutting face, and “non-planar cutting element” will refer to those cutting elements having a cutting end with a non-planar cutting face extending above a grip or base region, where the cutting end geometry may include but is not limited to, dome shaped cutting ends, generally pointed cutting ends, saddle shaped cutting ends, or chisel shaped cutting ends. As used herein, a non-planar cutting end of a non-planar cutting element is defined by the non-planar working or cutting face, while a grip region refers to the remaining region of the non-planar cutting element axially adjacent the non-planar cutting end. A diamond or other ultrahard material body may form both the non-planar cutting end and a portion of the grip region of the non-planar cutting element, or, a grip region may be formed entirely of a substrate, and the non-planar cutting end formed entirely of a diamond or other ultrahard material body. In other embodiments, a grip region may be formed of a combination of materials, for example, one or more substrate materials such as transition metal carbides, one or more transition layers including varying ratios of carbide and diamond mixtures, or a combination of substrate material, one or more transition layers and a portion of the material also forming the non-planar cutting end. Further, a non-planar cutting element may include a substantially cylindrical grip region, or a non-planar cutting element may include a grip region with a non-cylindrical shape.
A non-planar cutting element having a generally pointed cutting end has a cutting end terminating in an apex, and may include cutting elements having a conical cutting end (such as shown in
In one or more embodiments, a bullet cutting element may be used. The term “bullet cutting element” refers to cutting element having, instead of a generally conical side surface, a generally convex side surface terminated in a rounded apex. For example,
As mentioned above, the apex of the non-planar cutting element may have curvature, including a radius of curvature. In one or more embodiments, the radius of curvature may range from about 0.050 to 0.16. One or more other embodiments may use a radius of curvature of with a lower limit of any of 0.050, 0.060, 0.075, 0.085, or 0.100 and an upper limit of any of 0.075, 0.085, 0.095, 0.100, 0.110, 0.125, or 0.160, where any lower limit can be used with any upper limit. In some embodiments, the curvature may comprise a variable radius of curvature, a portion of a parabola, a portion of a hyperbola, a portion of a catenary, or a parametric spline. Further, in one or more embodiments, the different apex curvatures may be used in (the same geometry-type or different geometry type) cutting elements along a cutting profile. This may include, for example, the various embodiments described above, as well as embodiments including all conical cutting elements, or all bullet cutting elements, etc., along a cutting profile. Specifically a “blunt” cutting element may include any type of non-planar cutting element having a larger radius of curvature as compared to another, “sharp” non-planar cutting element on the same bit. Thus, the terms blunt and sharp are relative to one another, and the radius of curvatures of each may selected from any point along the radius range discussed above.
Non-planar cutting elements may be formed in a process similar to that used in forming diamond enhanced inserts (used in roller cone bits) or by brazing components together. The interface between a diamond layer (or other ultrahard material body) and a substrate (e.g., a cemented metal carbide substrate such as tungsten carbide) may be non-planar or non-uniform, for example, to aid in reducing incidents of delamination of the diamond layer from the substrate when in operation and to improve the strength and impact resistance of the element. One skilled in the art would appreciate that the interface may include one or more convex or concave portions, as known in the art of non-planar interfaces. Additionally, one skilled in the art would appreciate that use of some non-planar interfaces may allow for greater thickness in the diamond layer in the tip region of the layer. Further, it may be desirable to create the interface geometry such that the diamond layer is thickest at a zone that encompasses the primary contact zone between the cutting element and the formation. Additional shapes and interfaces that may be used for cutting elements of the present disclosure include those described in U.S. Patent Publication No. 2008/0035380, which is herein incorporated by reference in its entirety. In one or more embodiments, an ultrahard material layer may have a thickness of 0.100 to 0.500 inches from the apex to the central region of the substrate, and in one or more particular embodiments, such thickness may range from 0.125 to 0.275 inches. The ultrahard material layer and an attached cemented metal carbide substrate may have a total thickness of 0.200 to 0.700 inches from the apex to a base of the cemented metal carbide substrate. However, other sizes and thicknesses may also be used.
Further, an ultrahard material body may be formed from any polycrystalline superabrasive material, including, for example, polycrystalline diamond, polycrystalline cubic boron nitride, thermally stable polycrystalline diamond (formed either by treatment of polycrystalline diamond formed from a metal such as cobalt or polycrystalline diamond formed with a metal having a lower coefficient of thermal expansion than cobalt).
PCD may be formed by subjecting diamond particles in the presence of a suitable solvent metal catalyst material to processing conditions of high pressure/high temperature (HPHT), where the solvent metal catalyst promotes desired intercrystalline diamond-to-diamond bonding between the particles, thereby forming a PCD structure. Particularly, a microstructure of conventionally formed PCD material includes a plurality of diamond grains that are bonded to one another to form an intercrystalline diamond matrix first phase. The catalyst/binder material, e.g., cobalt, used to facilitate the diamond-to-diamond bonding that develops during the sintering process is dispersed within the interstitial regions formed between the diamond matrix first phase. The catalyst/binder material used to facilitate diamond-to-diamond bonding can be provided in the form of a raw material powder that is pre-mixed with the diamond particles or grit prior to sintering. In some embodiments, the catalyst/binder can be provided by infiltration into the diamond material (during HPHT processing) from an underlying substrate material to which the final PCD material is to be bonded. After the catalyst/binder material has facilitated the diamond-to-diamond bonding, the catalyst/binder material may be distributed throughout the diamond matrix within interstitial regions formed between the bonded diamond grains. The term “particle” refers to the powder employed prior to sintering a superabrasive material, while the term “grain” refers to discernable superabrasive regions subsequent to sintering, as known and as determined in the art. The resulting PCD structure produces enhanced properties of wear resistance and hardness, making such PCD materials extremely useful in aggressive wear and cutting applications where high levels of wear resistance and hardness are desired.
The metal catalyst, such as cobalt, used to promote recrystallization of the diamond particles and formation of the lattice structure of polycrystalline diamond may be leached to form thermally stable polycrystalline diamond. Examples of “leaching” processes can be found, for example, in U.S. Pat. Nos. 4,288,248 and 4,104,344. Briefly, a strong acid, such as hydrofluoric acid or combinations of several strong acids, may be used to treat the diamond table, removing at least a portion of the catalyst from the PDC composite. Suitable acids include, for example, nitric acid, hydrofluoric acid, hydrochloric acid, sulfuric acid, phosphoric acid, perchloric acid, or combinations of these acids. In addition, caustics, such as sodium hydroxide and potassium hydroxide, have been used by the carbide industry to digest metallic elements from carbide composites. In addition, other acidic and basic leaching agents may be used as desired. Those having ordinary skill in the art will appreciate that the molarity of the leaching agent may be adjusted depending on the time desired to leach, concerns about hazards, etc.
In some embodiments, only a select portion of a diamond composite is leached, e.g., to gain thermal stability without losing significant impact resistance. As used herein, the term TSP includes both of the above (i.e., partially and completely leached) PCD layers. Interstitial volumes remaining after leaching may be reduced by either furthering consolidation or by filling the volume with a secondary material, such as by processes known in the art and described in U.S. Pat. No. 5,127,923.
In some embodiments, TSP may be formed by forming the diamond layer in a press using a binder other than cobalt, one such as silicon, which has a coefficient of thermal expansion more similar to that of diamond than cobalt has. During the manufacturing process, a large portion, 80 to 100 volume percent, of the non-catalyst binder may react with the diamond lattice to form a carbide, such as silicon carbide when using a silicon non-catalyst binder, which may also have a thermal expansion similar to diamond. One of ordinary skill in the art would recognize that a thermally stable diamond layer may also be formed by other methods known in the art, including, for example, by altering processing conditions in the formation of the diamond layer, such as by increasing the pressure to above 50 kbars with a temperature of above 1350 degrees C.
Diamond grade (i.e., diamond powder composition including grain size and/or metal content) may be substantially uniform or may be varied within a diamond layer to form the cutting end of a cutting element. For example, in one or more embodiments, the region of diamond layer adjacent the substrate may differ in material properties (and diamond grade) as compared with the region of the diamond layer at the apex of a non-planar cutting element. Such variation may be formed by one or more step-wise layers or by a gradual transition.
According to embodiments of the present disclosure, cutting elements may be disposed in one or more rows on a blade of a downhole cutting tool, extending substantially radially outward from the blade outermost surface, where at least two adjacent cutting elements in a row have different axial lengths. Rows of cutting elements having at least two adjacent cutting elements with different axial lengths may include an increased amount of cutting elements when compared to a row having cutting elements with equal axial lengths. For example,
According to embodiments of the present disclosure, a shortest cutting element (e.g., cutting elements 810 having an axial length 814) of at least two adjacent cutting elements in a high density row may have a difference in axial length from a longest cutting element (e.g., cutting elements 810 having an axial length 812) of the at least two adjacent cutting elements that is greater than 5 percent of the axial length of the longest cutting element. In some embodiments, the difference in axial length between a shortest cutting element and a longest cutting element in a high density row may range between 5 and 35 percent of the axial length of the longest cutting element, between 8 and 25 percent of the axial length of the longest cutting element, or between 10 and 15 percent of the axial length of the longest cutting element. In some embodiments, the difference in axial length between a shortest cutting element and a longest cutting element in a high density row may range from a lower limit of 0.04 in (1 mm), 0.05 in (1.3 mm), 0.08 in (2 mm) or 0.12 in (3 mm) to an upper limit of 0.08 in (2 mm), 0.12 in (3 mm), 0.15 in (3.8 mm), 0.18 in (4.6 mm) or 0.2 in (5 mm), where any lower limit may be used in combination with any upper limit, depending on, for example, the diameter of the cutting elements and the axial length of the longest cutting element. In one or more embodiments, the diameter of a cutting element may generally range from 9 mm to 22 mm, such as 9 mm, 11 mm, 13 mm, 16 mm, 19 mm, or 22 mm.
Further, in the embodiment shown, cutting elements 810 and 820 have an exposed portion 850 extending an exposure height 816, 826 from the outermost surface 830 of the blade, where the exposure heights 816 and 826 are substantially equal. According to embodiments of the present disclosure, a high density row of cutting elements may include at least two adjacent cutting elements with different axial lengths, where the at least two adjacent cutting elements have the same exposure height. According to some embodiments, a high density row of cutting elements may include at least two adjacent cutting elements with different axial lengths, where the exposure height of the at least two adjacent cutting elements have different exposure heights. In such embodiments, the adjacent cutting elements having different exposure heights and different axial lengths may be positioned on the blade such that the base end of the cutting elements are disposed at different distances below the outermost surface of the blade.
Methods of making downhole cutting tools according to embodiments of the present disclosure may include attaching at least three cutting elements to at least one blade extending a height from a tool body to an outermost surface, where the at least three cutting elements are oriented to extend substantially outward (e.g., substantially radially outward) from the outermost surface (e.g., top surface) of the at least one blade and are oriented in a row, and where the at least two adjacent cutting elements have a difference in axial length. The cutting elements may be attached to the blade(s) by inserting each of the cutting elements into a pocket formed in the at least one blade and brazing each of the cutting elements to the pocket. The difference in axial length may be designed based on a calculated reduction in distance between the at least two adjacent cutting elements. For example, a comparison distance along the outermost surface of a blade between adjacent comparison cutting elements (between the closest points of the adjacent comparison cutting elements along the outermost surface of the blade) may be calculated, where each comparison cutting element has an equal axial length. The axial lengths of the comparison cutting elements may be equal to the axial length of the longest cutting element that will be used in the high density row being designed. The difference in axial length of the at least two adjacent cutting elements forming the high density row may then be selected to reduce the distance between the at least two adjacent cutting elements along the outermost surface by about 5 to 20 percent from the comparison distance. For example, referring again to
Adjacent cutting elements with different axial lengths forming at least a portion of a high density row of cutting elements may be disposed on selected regions of a blade. For example,
Other downhole cutting tools of the present disclosure may have different cutting profile shapes and curvatures. For example, a downhole cutting tool may have a cutting profile formed by a plurality of cutting elements disposed in one or more high density rows on a plurality of blades and rotated into a single plane. The cutting profile may include one or more convex regions having a sharper radius of curvature than the remaining regions of the cutting profile, where a region of a cutting profile may be defined along a distance of the cutting profile large enough to include at least one entire cutting element. In some embodiments, a cutting profile may include one or more regions along the tallest portions of the blades (i.e., measured by the blade height, from the tool body to the blade outermost surface). In one or more embodiments, a tallest region of a blade may also be a convex region.
According to some embodiments of the present disclosure, at least two adjacent cutting elements having different axial lengths in a high density row may be disposed in one or more convex regions of the blade cutting profile. In some embodiments of the present disclosure, at least two adjacent cutting elements having different axial lengths in a high density row may be disposed in one or more tallest regions of the blade cutting profile. In some embodiments, at least two adjacent cutting elements having different axial lengths in a high density row may be disposed in at least one of a nose region or a shoulder region of a blade cutting profile. For example, referring back to
An increased number of cutting elements in a row of radially outwardly extending cutting elements may fit in one or more regions of a blade by varying the axial length of at least two adjacent cutting elements of the row. For example, an increased number of cutting elements in a row of radially outwardly pointing cutting elements may fit in the nose region and the shoulder region of a blade by varying the axial length of at least two adjacent cutting elements of the row.
According to embodiments of the present disclosure, a downhole cutting tool may have a tool body, a plurality of blades extending a height from the tool body to an outermost surface (e.g., top surface), and an increased number of cutting elements in a row of radially outwardly extending cutting elements in one or more regions of at least one of the blades. The height of each blade along a length of the blade defines a height-dimension plane, and the dimension between a leading face and a trailing face of the blade defines its width, where the leading face faces in the direction of the rotation of the cutting tool and the trailing face is opposite the leading face. A plurality of cutting elements may be disposed on the plurality of blades and oriented substantially radially outward from the outermost surface of the blades, where a rotated view of the plurality of cutting elements into a single plane forms a cutting profile including a cone region, a nose region, a shoulder region, and a gage region. At least one row of cutting elements including at least three of the radially outward facing cutting elements may be disposed on the outermost surface (e.g., top surface) of one of the blades, where a row of cutting elements is defined by a straight line intersecting the longitudinal axes of each cutting element in the row. The row of cutting elements may extend in a single direction along the length of the blade defined along a straight line intersecting the longitudinal axes of each cutting element in the row.
By arranging cutting elements in one or more rows, the blade on which the row(s) are disposed may have a reduced width when compared with blades having one or more non-linear arrangements of cutting elements. For example, the blades retaining the non-linear arrangement 317 of cutting elements 310 shown in
Referring again to
According to some embodiments, the number of cutting elements forming a high density row in the nose region and/or the shoulder region of at least one blade may range from a lower limit of 4, 4.5, 5 or 5.5 cutting elements to an upper limit of 5, 5.5, 6, 6.5, 7, 7.5 or 8 cutting elements, where any lower limit may be used in combination with any upper limit. As used herein, a fraction of a cutting element may refer to the fraction of its diameter, e.g., 5.5 cutting elements represent 5 cutting element diameters and a radius of a cutting element disposed within the selected blade region(s). The number of cutting elements in a high density row of cutting elements on a blade may depend on, for example, the diameter of the cutting elements and the length of the blade region(s). Further, cutting elements forming a high density row of cutting elements may be designed and placed on a blade to have an increased number of cutting elements form the row according to embodiments of the present disclosure, such that the material forming the blade on which the cutting elements are disposed surround the entire base end or substrate region of each cutting element. In other words, according to embodiments of the present disclosure, a high density row of cutting elements may have an increased number of cutting elements forming the row in addition to having none of the cutting elements contacting each other.
A downhole cutting tool according to embodiments of the present disclosure may be made by attaching at least three cutting elements to at least one blade extending a height from a tool body to an outermost surface, such that the cutting elements extend substantially radially outward from the outermost surface of the at least one blade and are oriented in a row. At least two of the cutting elements may have different axial lengths. Each of the at least three cutting elements may be attached to a blade in a row by inserting each cutting element into a pocket formed in the blade and brazing each cutting elements to the pocket. In other embodiments, the pockets may extend equal depths into the blade. In some embodiments, other means of attachment may be used, such as interference fitting or mechanical retention. Further, in some embodiments, at least two of the pockets may extend different depths into the blade, where upon inserting the cutting elements with different axial lengths into the pockets with different depths, the cutting elements with different axial lengths extend substantially equal exposure heights above the blade outermost surface (e.g., top surface).
Cutting elements may be formed to have different axial lengths by forming substrates with different axial lengths, forming an ultrahard material body to have a different axial length, or by forming both the substrate and ultrahard material body to have different axial lengths than that of an adjacent cutting element. For example, a first and second non-planar cutting element may each have substrates with different axial lengths and diamond bodies with different axial lengths, where the first and second non-planar cutting elements have different total axial lengths and may be disposed adjacent to each other in a row on a blade, oriented to point radially outward from the outermost surface of the blade. Cutting elements having different total axial lengths may also have different component axial lengths when one component axial length is designed to accommodate characteristics from another component's change in axial length, for example, a substrate axial length may be increased to provide better support for a diamond body having an increased axial length.
Cutting elements extending substantially radially outward from the outermost surface of a blade may have a support disposed at least partially around its outer perimeter to improve the cutting element stability and retention to the blade. The support may be attached to the outermost surface of the blade or may be integrally formed with the blade as a protrusion extending at least partially around one or more pockets. For example, a cross-sectional view of a non-planar cutting element 1400 disposed on a blade 1450 at an angle relative to the surrounding blade outermost surface is shown in
A support 1460 extends circumferentially around a portion of the grip region outside the pocket 1452. As shown, the support 1460 may be applied around the grip region having a varied axial length along the grip region 1410, measured from the outer surface of the blade 1450 (at the opening to the pocket) to an exposed portion of the grip region 1410. Thus, although the areas 1412, 1414 outside the pocket 1452 on opposite sides have different axial lengths, the varied axial length of coverage of the support 1460 may provide an exposed portion of the grip region having a substantially uniform exposure length around the grip region. However, according to other embodiments of the present disclosure, both the axial length of the support and the exposure length of the exposed portion may vary around at least a portion of the circumference of the grip region. In yet other embodiments, a support may have a substantially uniform axial length and an exposed portion may have a varied exposure length around at least a portion of the circumference of the grip region.
The cutting elements of the present disclosure may be oriented at a back rake and/or side rake. Generally, when positioning cutting elements on a blade of a bit or reamer, the cutting elements may be inserted into cutter pockets (or holes) to change the angle at which the cutting element strikes the formation. Specifically, the back rake (i.e., a vertical orientation) and the side rake (i.e., a lateral orientation) of a cutting element may be adjusted. Generally, backrake of a cutter is defined as the angle formed between the cutting face of the cutter and a line that is normal to the formation material being cut. As shown in
However, non-planar cutting elements do not have a planar cutting face and thus the orientation of non-planar cutting elements are defined differently. When considering the orientation of non-planar cutting elements, in addition to the vertical or lateral orientation of the cutting element body, the pointed geometry of the cutting end also affects how and the angle at which the non-planar cutting element strikes the formation. Specifically, in addition to the backrake affecting the aggressiveness of the non-planar cutting element-formation interaction, the cutting end geometry (e.g., the apex angle and radius of curvature) affects the aggressiveness that a non-planar cutting element attacks the formation. Thus, in the context of a non-planar cutting element backrake orientation, backrake may be defined as an angle formed between the longitudinal axis of the non-planar cutting element and a line normal to the blade profile of the blade where the non-planar cutting element is disposed, as described above. In some embodiments, as shown in
In addition to the orientation of the axis with respect to the formation, the aggressiveness of a non-planar cutting element may also be dependent on the leading angle or specifically, the angle between the formation and the leading portion of the non-planar cutting element. The cutting end shape of the non-planar cutting elements does not have a leading edge; however, the leading line of a non-planar cutting surface may be determined to be the first most points of the non-planar cutting element at each axial point along the non-planar cutting end surface as the bit rotates. Said in another way, a cross-section may be taken of a non-planar cutting element along a plane in the direction of the rotation of the bit, as shown in
Side rake is defined for cutters as the angle between the cutting face and the radial plane of the bit (x-z plane), as illustrated in
In the context of a non-planar cutting element, as shown in
The articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements in the preceding descriptions. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. For example, any element described in relation to an embodiment herein may be combinable with any element of any other embodiment described herein. Numbers, percentages, ratios, or other values stated herein are intended to include that value, and also other values that are “about” or “approximately” the stated value, as would be appreciated by one of ordinary skill in the art encompassed by embodiments of the present disclosure. A stated value should therefore be interpreted broadly enough to encompass values that are at least close enough to the stated value to perform a desired function or achieve a desired result. The stated values include at least the variation to be expected in a suitable manufacturing or production process, and may include values that are within 5%, within 1%, within 0.1%, or within 0.01% of a stated value.
A person having ordinary skill in the art should realize in view of the present disclosure that equivalent constructions do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions, and alterations may be made to embodiments disclosed herein without departing from the spirit and scope of the present disclosure. Equivalent constructions, including functional “means-plus-function” clauses are intended to cover the structures described herein as performing the recited function, including both structural equivalents that operate in the same manner, and equivalent structures that provide the same function. It is the express intention of the applicant not to invoke means-plus-function or other functional claiming for any claim except for those in which the words ‘means for’ appear together with an associated function. Each addition, deletion, and modification to the embodiments that falls within the meaning and scope of the claims is to be embraced by the claims.
The terms “approximately,” “about,” and “substantially” as used herein represent an amount close to the stated amount that still performs a desired function or achieves a desired result. For example, the terms “approximately,” “about,” and “substantially” may refer to an amount that is within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of a stated amount. Further, it should be understood that any directions or reference frames in the preceding description are merely relative directions or movements. For example, any references to “up” and “down” or “above” or “below” are merely descriptive of the relative position or movement of the related elements.
The present disclosure may be embodied in other specific forms without departing from its spirit or characteristics. The described embodiments are to be considered as illustrative and not restrictive. Changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.
This application claims the benefit of and priority to U.S. Provisional Application 62/090,962 filed on Dec. 12, 2014, the entirety of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62090962 | Dec 2014 | US |
