Cutting elements and geometries for vibration reduction, earth-boring tools, and related methods

Abstract

A cutting element for an earth-boring tool includes a substrate and a volume of polycrystalline diamond on the substrate. The volume of polycrystalline diamond has an outer surface defining a front cutting surface, a peripheral edge, and at least one pair of angled bit surfaces defining at least one cutting bit between the pair of angled bit surfaces. The front cutting surface includes a first planar region and a second planar region, one or both of which may include a cutting bit. The front cutting surface may be characterized as being generally concave. Earth-boring tools include a tool body and one or more such cutting elements secured to the tool body.

Description

[0001] Cross - Reference to Related Applications

[0002] This patent application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 384,709, filed on November 22, 2022, under 35 U.S.C.§ 119(e), the disclosure of which is hereby incorporated by reference in its entirety. Technical Field

[0003] The present disclosure generally relates to cutting elements used on earth - boring tools during earth - boring operations. In particular, embodiments of the present disclosure relate to cutting elements having geometries for improving mechanical efficiency. Background Art

[0004] Wellbores are formed in subterranean formations for various purposes including, for example, the extraction of oil and gas from subterranean formations and the extraction of geothermal energy from subterranean formations. Earth - boring tools, such as earth - boring rotary bits, can be used to form wellbores in subterranean formations. The earth - boring rotary bit is rotated and advanced into the subterranean formation. When the earth - boring rotary bit rotates, cutting elements or their abrasive structures cut, crush, shear, and / or abrade formation material to form the wellbore.

[0005] The earth - boring rotary bit is directly or indirectly coupled to the end of what is known in the art as a "drill string," which includes a series of elongated tubular sections connected end - to - end that extend from the surface of the earth above the subterranean formation being drilled into the wellbore. Various tools and components (including the bit) can be coupled together at the distal end of the drill string located at the bottom of the wellbore being drilled. Such an assembly of tools and components is known in the art as a "bottom - hole assembly" (BHA).

[0006] The earth - boring rotary bit can be rotated within the wellbore by rotating the drill string from the surface of the formation; or the bit can be rotated by coupling the bit to a downhole motor that is coupled to the drill string and is disposed near the bottom of the wellbore. The downhole motor can include, for example, a hydraulic Moineau - type motor having a shaft on which the earth - boring rotary bit is mounted. By pumping a 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 of nozzles in the bit, and causing the fluid to return upward through the annulus between the outer surface of the drill string and the exposed formation surface within the wellbore to the surface of the formation, the rotation of the bit can be caused. The downhole motor can operate with or without rotation of the drill string.

[0007] Different types of earth-boring rotary drill bits are known in the art, including fixed cutter bits, rolling cutter bits, and hybrid bits (which may include, for example, both fixed and rolling cutter elements). In contrast to roller cone bits, fixed cutter bits have no moving parts and are designed to rotate about the longitudinal axis of the drill string. Most fixed cutter bits employ polycrystalline diamond compact (PDC) cutter elements. The cutting edges of the PDC cutter elements drill into the rock formation by shear, like the cutting action of a lathe, as opposed to roller cone bits that drill by indentation and crushing of the rock. The cutting action of the cutting edges plays a major role in the amount of energy required to drill into the rock formation.

[0008] PDC cutter elements typically consist of a thin layer of polycrystalline diamond (e.g., from about 0.3 mm to about 5 mm) bonded to a cutter element substrate at an interface. The polycrystalline diamond material is often referred to as the "diamond table". PDC cutter elements are typically cylindrical, with a diameter ranging from about 8 mm up to about 24 mm. However, PDC cutter elements can have other forms, such as oval or triangular, and can be larger or smaller than the above dimensions.

[0009] PDC cutter elements can be made independently of the drill bit body and are fixed within cutter element pockets formed in the outer surface of the blades of the drill bit body. A bonding material such as an adhesive or more typically a brazing alloy can be used to secure the PDC cutter element within the pocket by its support substrate. The diamond table of the PDC cutter element is formed by sintering and bonding relatively small diamond grains together in a high temperature high pressure (HTHP) sintering process. The sintering process is typically carried out in the presence of a catalyst material (such as, for example, cobalt, iron, nickel, or their alloys and mixtures) to form a layer or "table" of polycrystalline diamond material on the cutter element substrate. SUMMARY OF THE INVENTION

[0010] In some embodiments, the present disclosure includes a cutting element for an earth-boring tool. The cutting element includes a substrate and a volume of polycrystalline diamond on the substrate. The volume of polycrystalline diamond has an outer surface defining a front cutting surface, a peripheral edge, and a pair of angled tip surfaces that define a cutting tip located between the pair of angled tip surfaces. The front cutting surface includes a first planar region and a second planar region. The second planar region includes the cutting tip. The second planar region is oriented at an angle relative to the first planar region such that the front cutting surface is generally concave. The second planar region is oriented at an acute angle relative to a plane perpendicular to the longitudinal axis of the cutting element.

[0011] According to advantageous features of the cutting element, alone or in any practicable combination:

[0012] The cutting insert may extend to a certain height above a first planar region of the front cutting surface;

[0013] The first planar region of the front cutting surface may be oriented perpendicular to the longitudinal axis of the cutting element;

[0014] The outer surface of a volume of polycrystalline diamond may further define angled plowing surfaces on opposite lateral sides of the cutting insert, and the angled plowing surfaces may be disposed at an acute angle relative to a plane perpendicular to the longitudinal axis of the cutting element;

[0015] The cutting insert may have an insert width in the range of 0.080 inches (0.203 cm) to 0.173 inches (0.439 cm);

[0016] The angled insert surfaces may be planar and oriented at an insert angle of approximately 90° relative to each other;

[0017] The substrate may be cylindrical;

[0018] The cutting insert may have a double cutting peak;

[0019] The outer surface of a volume of polycrystalline diamond may further define another pair of angled insert surfaces that define another cutting insert located between the another pair of angled insert surfaces, the first planar region including the another cutting insert; and / or

[0020] The cutting insert and the another cutting insert may each have a double cutting peak.

[0021] In an additional embodiment, the present disclosure includes a cutting element for a downhole tool, the cutting element including a substrate and a volume of polycrystalline diamond on the substrate. The volume of polycrystalline diamond has an outer surface defining a front cutting surface, a peripheral edge, and angled insert surfaces that define a cutting insert located between the angled insert surfaces. The front cutting surface includes an upper left plowing surface, an upper right plowing surface, a lower left plowing surface, and a lower right plowing surface. The lower left plowing surface and the lower right plowing surface include the cutting insert. A first ridge line at the intersection between the lower left plowing surface and the lower right plowing surface is oriented at an acute angle relative to a plane perpendicular to the longitudinal axis of the cutting element. The cutting insert extends to a certain height above a second ridge line at the intersection between the upper left plowing surface and the upper right plowing surface.

[0022] According to advantageous features of the cutting element, individually or in any practicable combination:

[0023] The second ridge line may be perpendicular to the longitudinal axis of the cutting element;

[0024] The angled insert surfaces may be planar and oriented at an acute angle relative to a line tangent to a side surface of the cutting element;

[0025] The upper left plow surface and the upper right plow can each be oriented at an acute angle of 10° relative to a plane perpendicular to the longitudinal axis of the cutting element;

[0026] The cutting tip can have a tip width in the range of 0.080 inches (0.203 cm) to 0.173 inches (0.439 cm); and / or

[0027] The angled tip surfaces can be planar and oriented at a tip angle of approximately 90° relative to each other.

[0028] In an additional embodiment of the present disclosure, a cutting element for an earth boring tool includes a substrate and a volume of polycrystalline diamond on the substrate. The volume of polycrystalline diamond has an outer surface defining a front cutting surface, a peripheral edge, and a pair of angled tip surfaces that define a cutting tip located between the pair of angled tip surfaces. The front cutting surface includes a first planar region and a second planar region. The second planar region is oriented at an angle relative to the first planar region such that the front cutting surface is generally concave. The second planar region is oriented at an acute angle relative to a plane perpendicular to the longitudinal axis of the cutting element. The front cutting surface further includes a planar region at the cutting tip, and the planar region is oriented perpendicular to the longitudinal axis of the cutting element.

[0029] According to advantageous features of the cutting element, individually or in any practicable combination:

[0030] The cutting tip can have a double cutting peak;

[0031] The outer surface of the volume of polycrystalline diamond can further define another pair of angled tip surfaces that define another cutting tip located between the other pair of angled tip surfaces, and the front cutting surface can further include another planar region at the other cutting tip, the other planar region being oriented perpendicular to the longitudinal axis of the cutting element; and / or

[0032] Each of the cutting tip and the other cutting tip can have a double cutting peak. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] To understand the present disclosure in detail, reference should be made to the following detailed description in conjunction with the accompanying drawings, in which like elements are generally represented by like numerals, and in which:

[0034] Figure 1 is a front elevational plan view of a cutting element according to an embodiment of the present disclosure and is labeled to illustrate the tip angle and tip width of the cutting element;

[0035] Figure 2is a side view of a cutting element according to an embodiment of the present disclosure and is labeled to illustrate a recess in the front cutting surface of the cutting element;

[0036] Figure 3 is a perspective view of a cutting element according to an embodiment of the present disclosure and illustrates the plow angle of the cutting element;

[0037] Figure 4 is a perspective view of a cutting element according to an embodiment of the present disclosure and illustrates the front cutting surface of the cutting element having an edge geometry and is labeled to illustrate the edge depth, edge width, and edge interior angle of the edge geometry;

[0038] Figure 5 is a diagram illustrating example parameter ranges of certain characteristics exhibited by features of embodiments of the cutting element of the present disclosure, these characteristics including plow angle, cutting head width, cutting head angle, recess depth, and chamfer size;

[0039] Figure 6 is a perspective view of an embodiment of the cutting element of the present disclosure;

[0040] Figure 7 is a perspective view of an embodiment of the cutting element of the present disclosure;

[0041] Figure 8 is a perspective view of an embodiment of the cutting element of the present disclosure;

[0042] Figure 9 is a perspective view of an embodiment of the cutting element of the present disclosure;

[0043] Figure 10 is a perspective view of an embodiment of the cutting element of the present disclosure;

[0044] Figure 11 is a perspective view of an embodiment of the cutting element of the present disclosure;

[0045] Figure 12 is a perspective view of an embodiment of the cutting element of the present disclosure;

[0046] Figure 13 is a perspective view of an embodiment of the cutting element of the present disclosure;

[0047] Figure 14 is a table including a list of Figures 6 to 9 certain characteristics and features of a cutting element relative to two other geometries of the cutting element;

[0048] Figure 15 is similar to Figure 14 and includes a list of Figures 10 to 13Table of certain characteristics and features of a cutting element relative to two other identical geometries of the cutting element;

[0049] Figure 16 is a perspective view of an embodiment of a cutting element of the present disclosure;

[0050] Figure 17 is a perspective view of an embodiment of a cutting element of the present disclosure;

[0051] Figure 18 is a perspective view of an embodiment of a cutting element of the present disclosure;

[0052] Figure 19 is a perspective view of an embodiment of a cutting element of the present disclosure;

[0053] Figure 20 is a perspective view of an embodiment of a cutting element of the present disclosure;

[0054] Figure 21 is a perspective view of an embodiment of a cutting element of the present disclosure;

[0055] Figure 22 is a perspective view of an embodiment of a cutting element of the present disclosure;

[0056] Figure 23 is a perspective view of an embodiment of a cutting element of the present disclosure;

[0057] Figure 24 is a perspective view of an embodiment of a cutting element of the present disclosure;

[0058] Figure 25 is a perspective view of an embodiment of a cutting element of the present disclosure;

[0059] Figure 26 is a perspective view of an embodiment of a cutting element of the present disclosure;

[0060] Figure 27 Illustrates ways to change Figures 16 to 26 certain features of the cutting edge of the front cutting surface of the cutting element; and

[0061] Figure 28 is a perspective view of a downhole tool in the form of a fixed cutter rotary drill bit according to another embodiment of the present disclosure, which may include any embodiment of the cutting element as described herein. Detailed Description

[0062] The illustrations presented herein are not actual views of any cutting element or downhole tool or any of their components, but are merely idealized representations for describing embodiments of the present invention.

[0063] As used herein, the singular forms of "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0064] As used herein, the term "can" with respect to a material, structure, feature, or method act indicates that this is contemplated for implementing embodiments of the present disclosure, and this term is preferentially used over the more restrictive term "is" so as to avoid any implication that other compatible materials, structures, features, and methods that may be combined with it should or must be excluded.

[0065] As used herein, any relative terms, such as any relative terms like "first", "second", "top", "bottom", "upper", "lower", "above", "below", "side", "up", "down", etc. are used for the purpose of clearly and conveniently understanding the present disclosure and the drawings, and do not imply or depend on any particular preference or order unless the context clearly states otherwise. For example, these terms may refer to the orientation of any cutting element or element of a well drilling tool when used in a conventional manner. Additionally, as shown in the drawings, these terms may refer to the orientation of any cutting element or element of a well drilling tool.

[0066] As used herein, the term "substantially" with respect to a given parameter, characteristic, or condition means and includes to a degree that a person skilled in the art would understand that the given parameter, characteristic, or condition is met with a small degree of difference (such as within acceptable manufacturing tolerances). By way of example, depending on the particular parameter, characteristic, or condition that is substantially met, the parameter, characteristic, or condition may be met to at least 90.0%, at least 95.0%, at least 99.0%, or even at least 99.9%.

[0067] As used herein, the term "about" used with respect to a given parameter includes the stated value and has a meaning determined by the context (e.g., it includes the degree of error associated with the measurement of the given parameter, as well as variations caused by manufacturing tolerances, etc.).

[0068] As used herein, the term "well drilling tool" means and includes any type of drill bit or tool used for drilling a borehole during the formation or enlargement of a wellbore, and includes, for example, rotary drill bits, percussion drill bits, core bits, eccentric bits, bi-center bits, reamers, mills, drag bits, roller cone bits, hybrid bits, and other drill bits and tools known in the art.

[0069] As used herein, the term "polycrystalline material" refers to and includes any material containing a plurality of material grains or crystals that are directly bonded together by intergranular bonds. The crystal structures of the individual material grains may be randomly oriented in the space within the polycrystalline material.

[0070] As used herein, the term "polycrystalline composite piece" means and includes any structure containing a polycrystalline material that is formed by a process involving the application of pressure (e.g., compaction) to one or more precursor materials used to form the polycrystalline material.

[0071] As used herein, the term "intercrystalline bond" means and includes any direct atomic bond (e.g., covalent bond, metallic bond, etc.) between atoms in adjacent grains of a material.

[0072] As used herein, the term "catalyst material" refers to any material that can catalyze the formation of intercrystalline bonds between the grains of a hard material during a sintering process (e.g., a high temperature and high pressure (HTHP) sintering process). For example, catalyst materials for diamond include, but are not limited to, cobalt, iron, nickel, other elements from Group VIII-A of the periodic table, and alloys thereof.

[0073] As used herein, the term "hard material" means and includes any material having a Knoop hardness value of about 3,000 kg f / mm 2 (29,420 MPa) or greater. Hard materials include, for example, diamond and cubic boron nitride.

[0074] Embodiments of the present disclosure include cutting elements having a shape and geometry that can be used to reduce or eliminate the likelihood of initiating destructive vibrations and frequencies that may occur during a drilling process.

[0075] Field and laboratory tests have shown that cutters having features typically associated with aggressiveness tend to produce better torsional stability compared to using standard flat cutting elements. The unique shapes in the present disclosure incorporate sharper "V"-shaped cutting edges, various horizontal and vertical plow angles, recesses, and a design with a bimodal cutting edge. These designs enhance the features that can produce improved vibration mitigation when drilling. These novel cutting element shapes help reduce or eliminate the likelihood of initiating destructive vibrations during a drilling process. In some cases, destructive vibrations may ultimately lead to increased wear on the tool, poor drilling performance, and / or complete tool failure. The more aggressive cutting element shapes in the present disclosure may require less drill pressure to drill and effectively reduce the risk of destructive torsional vibrations and stick-slip when drilling at higher weights on bit (WOB). Due to the more aggressive cutting characteristics and geometry of the cutting elements, the cutting element shapes can also be helpful in situations where the drill rig is only able to apply limited weight and / or torque.

[0076] The cutting element geometry of the present disclosure helps reduce and / or eliminate destructive vibrations while maintaining good rate of penetration (ROP) performance and durability at lower WOB. Finite element simulations of the cutting element geometry have shown stress levels comparable to currently known cutting element designs, with expected improvements in vibration mitigation due to parameters that also affect aggressiveness.

[0077] The cutting elements of the present disclosure may have a generally cylindrical shape, but have a tip or cutter head at a location on the peripheral edge of the cutting element intended to contact the formation during drilling. For example, see Figure 1 , the cutting element 10 according to the present disclosure has a front cutting face 12, which may be planar or non-planar. The peripheral edge 14 of the front cutting surface 22 may be generally cylindrical. However, the cutting element 10 may include a tip or cutter head 16 defined between angled cutter head surfaces 18, which are generally oriented at an angle relative to a line extending between the center point of the cutting element on the front cutting face 12 and the center of the cutter head 16 on the peripheral edge 14.

[0078] Figures 1 to 4 Illustrates various characteristics and features that may be incorporated into embodiments of the cutting elements of the present disclosure, and Figure 5 is a diagram illustrating non-limiting examples of ranges of parameters that the cutting elements of the present disclosure may exhibit with respect to those characteristics and features.

[0079] For example, as Figure 1 shown, the cutting elements of the present disclosure may be provided with a "cutter head width", which may be defined as the shortest linear distance between two angled cutter head surfaces 18 that define the cutter head 16, as measured on the peripheral edge 14. The cutting elements of the present disclosure may be provided with a "cutter head angle", which may be defined as the minimum angle between two angled cutter head surfaces 18 that define the cutter head 16 on the peripheral edge 14, as measured in a plane perpendicular to the longitudinal axis of the cutting element. As Figure 5 shown, the cutter head width may be between about 0.050 inches (0.127 cm) and about 0.250 inches (0.635 cm), or even between about 0.100 inches (0.254 cm) and about 0.200 inches (0.508 cm) (e.g., about 0.150 inches (0.381 cm)), and the cutter head angle may be between about 60° and about 110°, or even between about 75° and about 100° (e.g., about 90°).

[0080] Figure 2 is a side view of another cutting element 20, which has a front cutting surface 22, a peripheral edge 24, and a cutter head 26 defined between angled cutter head surfaces 28. As Figure 2As shown, the cutting element of the present disclosure may be provided with a non-planar front cutting surface 22. Figure 2 The cutting element 20 has a concave front cutting surface 22, which results in a "recess depth" with a positive value. As Figure 2 shown, the recess depth can be measured as the maximum distance between the front cutting surface 22 and a plane perpendicular to the longitudinal axis of the cutting element 20 and intersecting the peripheral edge 24 at the cutting tip 26. In embodiments where the front cutting surface 22 is convex, the recess depth will be negative. As Figure 5 shown, the recess depth can be between approximately -0.138 inches (-0.350 cm) and approximately 0.136 inches (0.345 cm), between approximately -0.060 inches (-0.152 cm) and approximately 0.060 inches (0.152 cm), between approximately -0.040 inches (-0.101 cm) and approximately 0.040 inches (0.101 cm), or even between approximately -0.020 inches (-0.050 cm) and approximately 0.020 inches (0.050 cm). In embodiments where the front cutting surface 22 is flat, the depth of the recess will be zero inches.

[0081] Also as Figure 2 shown, embodiments of the cutting element of the present disclosure may further include one or more chamfer surfaces 29 at the peripheral edge 24 of its front cutting face 12. The chamfer surface 29 may be oriented at a chamfer angle with respect to the longitudinal axis of the cutting element and may have a chamfer dimension, which can be defined as the shortest linear distance on the chamfer surface 29 at the cutting tip 26. As Figure 5 shown, the chamfer dimension can be between approximately 0.005 inches (0.012 cm) and approximately 0.050 inches (0.127 cm), or even between approximately 0.012 inches (0.030 cm) and approximately 0.034 inches (0.086 cm) (e.g., approximately 0.016 inches (0.040 cm)). Additionally, the chamfer surface 29 may be oriented at a chamfer angle of approximately 10° to approximately 80° with respect to the longitudinal axis of the cutting element.

[0082] Figure 3 is a perspective view of another cutting element 30, which has a front cutting surface 32, a peripheral edge 34, and a cutting tip 36 defined between angled cutting tip surfaces 38, as previously referenced Figure 1 and Figure 2 described. As Figure 3 shown, the cutting element of the present disclosure may further include angled "plow" surfaces 39 on opposite lateral sides of the cutting element 30. The angled plow surfaces 39 may be oriented and configured to facilitate plowing the cutting element through the formation near the cutting tip 36 and through the drill cuttings removed from the formation by the cutting tip 36 during drilling. As Figure 3As shown, the cutting element 30 has two angled plowing surfaces 39 that are oriented at an angle with respect to a plane perpendicular to the longitudinal axis of the cutting element 30. This "plowing angle" is an acute angle. As Figure 5 shown, the plowing angle of each angled plowing surface 39 can be independently selected to be between approximately -40° and approximately 40°, or even between approximately -20° and 20°.

[0083] Figure 4 is a perspective view of another cutting element 40 having a front cutting surface 42, a peripheral edge 44, and a cutting head 46 defined between angled surfaces 48, as previously described herein. Figure 4 The cutting element of has an edge geometry. In particular, the front cutting surface 42 has a central recess to define a protruding edge 49 that extends around the periphery of the cutting element 40. As Figure 4 shown, the edge 49 can have an edge width and an edge depth. The edge width can be between approximately 0.020 inches (0.050 cm) and approximately 0.500 inches (1.27 cm), or even between approximately 0.100 inches (0.254 cm) and approximately 0.250 inches (0.635 cm). The edge depth can be between approximately 0.020 inches (0.050 cm) and approximately 0.200 inches (0.508 cm), or even between approximately 0.050 inches (0.127 cm) and approximately 0.100 inches (0.254 cm). Additionally, as Figure 4 shown, the inner surface of the edge 49 can be oriented at an "edge interior angle" with respect to the front cutting surface 42. The edge interior angle can be between approximately 80° and approximately 160°, between approximately 90° and approximately 140°, or even between approximately 100° and 120°.

[0084] Cutting elements having an edge geometry and cutting elements having a concave surface can provide similar advantages in terms of cutting performance and can be alternative solutions to similar problems associated with inadequate evacuation of drill cuttings during drilling and resulting bit balling, vibration, etc.

[0085] Figures 6 to 13 illustrates various PDC cutting elements according to the present disclosure, each PDC cutting element including, for example, a volume of polycrystalline diamond on a sintered tungsten carbide substrate, and Figure 14 and Figure 15 is an illustration Figures 6 to 9 and Figures 10 to 13 of the parameter values of the different features and characteristics of the PDC cutting elements of relative to those of two other cutting elements, respectively.

[0086] Figure 6is a perspective view of another cutting element 50 having a front cutting surface 52, a peripheral edge 54, and a cutting head 56 defined between angled cutting head surfaces 58, as previously described herein. Figure 6 The cutting element 50 of Figure 6 has a front cutting surface 52 that includes two planar regions 52A and 52B. The upper planar region 52A, which does not include any portion of the cutting head 56, is oriented perpendicular to the longitudinal axis of the cutting element 50. The lower planar region 52B, which includes a portion of the cutting head 56, is oriented at an angle relative to the upper planar region 52A so that the front cutting surface 52 has a generally concave shape. As Figure 14 shown in the table of Figure 14 , Figure 6 the cutting element 50 of Figure 6 is concave, and the lower planar region 52B is oriented at an acute angle of 10° relative to a plane perpendicular to the longitudinal axis of the cutting element 50 (and relative to the upper planar region 52B) (referred to as the "spoon angle" in Figure 14 ). For a cutting element 50 with a diameter of 0.625 inches (1.587 cm), this results in the cutting head 56 extending 0.052 inches (0.132 cm) in height above the upper planar region 52A. The cutting element 50 has a face cutting head width of 0.173 inches (0.439 cm) and a face cutting head angle of 90°. The cutting head 56 has a chamfered surface at the cutting edge of the cutting head, and the chamfered surface is oriented at an angle of 45° relative to a plane perpendicular to the longitudinal axis of the cutting element, and the chamfer height of the chamfered surface is 0.016 inches (0.040 cm) as measured from a plane perpendicular to the longitudinal axis. The cutting head 56 is defined by angled cutting head surfaces 58 that are planar and oriented at an angle of 6° relative to a line tangent to the cylindrical side surface of the cutting element 50 (referred to as the "relief taper" in Figure 14 ). Figure 6 The cutting element 50 of Figure 6 does not include an angled plowing surface.

[0087] Figure 6 The cutting element 50 of Figure 6 may further include an edge geometry on the lower planar region 52B. The edges may each have a width and depth of 0.050". For example, the top and bottom edges of the edge (the side surfaces of the edge) may have a 0.016" chamfered surface oriented at a 45° angle.

[0088] Figure 7 is a perspective view of another cutting element 60 having a front cutting surface 62, a peripheral edge 64, and a cutting head 66 defined between angled cutting head surfaces 68, as previously described herein. Figure 7The cutting element 60 has a front cutting surface 62, which includes two planar regions 62A and 62B. The upper planar region 62A, which does not include any part of the cutting tip 66, is oriented perpendicular to the longitudinal axis of the cutting element 60. The lower planar region 62B, which includes a part of the cutting tip 66, is oriented at an angle with respect to the upper planar region 62A so that the front cutting surface 62 has a generally concave shape. As Figure 14 shown in the table of Figure 7 the cutting element 60 is concave, and the lower planar region 62B is oriented at an acute angle of 10° with respect to a plane perpendicular to the longitudinal axis of the cutting element 60 (and with respect to the upper planar region 62A). In Figure 14 it is called the "spoon angle". For the cutting element 60 with a diameter of 0.625 inches (1.587 cm), this results in the cutting tip 66 extending 0.052 inches (0.132 cm) above the upper planar region 62A. The cutting element 60 has a face cutting tip width of 0.100 inches (0.254 cm) and a face cutting tip angle of 90°. The cutting tip 66 has a chamfered surface at the cutting edge of the cutting tip, and the chamfered surface is oriented at an angle of 45° with respect to a plane perpendicular to the longitudinal axis of the cutting element, and the chamfer height of the chamfered surface is 0.016 inches (0.040 cm) as measured from a plane perpendicular to the longitudinal axis. The cutting tip 66 is defined by an angled cutting tip surface 68, which is planar and oriented at an angle of 10° with respect to a line tangent to the cylindrical side surface of the cutting element 60. In Figure 14 it is called the "relief taper". Figure 7 The 10° higher relief taper angle of the cutting element 60 of Figure 6 compared to the 6° lower relief taper angle of the cutting element 50 of Figure 7 results in the cutting element 60 having a smaller cutting tip width than the cutting element 50.

[0089] Figure 8 is a perspective view of another cutting element 70, which has a front cutting surface 72, a peripheral edge 74, and a cutting tip 76 defined between angled cutting tip surfaces 78, as previously described herein. The cutting element 70 also includes an angled plowing surface 79. Figure 8 The cutting element 70 has a front cutting surface 72, which includes two planar regions 72A and 72B. The upper planar region 72A, which does not include any part of the cutting tip 76, is oriented perpendicular to the longitudinal axis of the cutting element 70. The lower planar region 72B, which includes the cutting tip 76, is oriented at an angle with respect to the upper planar region 72A so that the front cutting surface 72 has a generally concave shape. As Figure 14 shown in the table of Figure 8The cutting element 70 is concave, and the lower planar region 72B is oriented at an acute angle of 10° with respect to a plane perpendicular to the longitudinal axis of the cutting element 70 (and with respect to the upper planar region 62B) (referred to as the "spoon angle" in Figure 14 ). For a cutting element 70 with a diameter of 0.625 inches (1.587 cm), this results in the cutting tip 76 extending 0.052 inches (0.132 cm) in height above the upper planar region 72A. The cutting element 70 has a face cutting tip width of 0.100 inches (0.254 cm) and a face cutting tip angle of 90°. The cutting tip 76 has a chamfered surface at the cutting edge of the cutting tip, and the chamfered surface is oriented at an angle of 45° with respect to a plane perpendicular to the longitudinal axis of the cutting element 70, and the chamfer height of the chamfered surface is 0.016 inches (0.040 cm) as measured from a plane perpendicular to the longitudinal axis. The cutting tip 76 is defined by an angled cutting tip surface 78 that is planar and oriented at an angle of 10° with respect to a line tangent to the cylindrical side surface of the cutting element 70 (referred to as the "relief taper" in Figure 14 ). Figure 8 The cutting element 70 of

[0090] Figure 9 also includes an angled plowing surface 79 that is oriented at an angle of 20° with respect to a plane perpendicular to the longitudinal axis of the cutting element 70 (outside the cutting tip width). Figure 14 As shown in the table of Figure 9 The cutting element 80 is concave, and the ridge line at the intersection between the lower angled plowing surfaces 89A and 89B is oriented at an acute angle of 10° with respect to a plane perpendicular to the longitudinal axis of the cutting element 80 (and with respect to the ridge line at the intersection between the upper angled plowing surfaces 89C and 89D) (in Figure 14oriented (referred to as "spoon corner" in Figure 14 ), for a cutting element 80 having a diameter of 0.625 inches (1.587 cm), this results in the tip 86 of the cutting head extending 0.052 inches (0.132 cm) in height above the ridge at the intersection between the upper angled plow surfaces 89C and 89D. The cutting element 80 has a face tip width of 0.080 inches (0.203 cm) and a face tip angle of 90°. The tip 86 has a chamfered surface at the cutting edge of the tip, and the chamfered surface is oriented at an angle of 45° with respect to a plane perpendicular to the longitudinal axis of the cutting element 80, and the chamfer height of the chamfered surface is 0.016 inches (0.040 cm) as measured from the plane perpendicular to the longitudinal axis. The tip 86 is defined by an angled tip surface 88 that is planar and oriented at an angle of 10° with respect to a line tangent to the cylindrical side surface of the cutting element 80 (in Figure 14 referred to as "relief cone"). The upper angled plow surfaces 89C and 89D are oriented at an angle of 10° with respect to a plane perpendicular to the longitudinal axis of the cutting element 80 up to the ridge at the intersection between the upper angled plow surfaces 89C and 89D.

[0091] Figure 10 is a perspective view of another cutting element 90 having a front cutting surface 92, a peripheral edge 94, a tip 96 defined between angled surfaces 98 as previously described herein, and an angled plow surface 99. Figure 10 The cutting element has a front cutting surface 92 that includes two symmetric planar regions 92A and 92B extending between two tips 96. The upper planar region 92A and the lower planar region 92B are oriented at an angle with respect to each other such that the front cutting surface 92 has a generally concave shape. As Figure 15 shown in the table of Figure 10 the cutting element 90 is concave, and the upper planar region 92A and the lower planar region 92B are each oriented at an acute angle of 10° with respect to a plane perpendicular to the longitudinal axis of the cutting element 90 (in Figure 15oriented as described in the [referred to as "spoon corner" in the text], for a cutting element 90 with a diameter of 0.625 inches (1.587 cm), this results in each cutting tip 96 extending a height of 0.052 inches (0.132 cm) above the intersection line between regions 92A and 92B. The cutting tip 96 of the cutting element 90 has a face cutting tip width of 0.100 inches (0.254 cm) and a face cutting tip angle of 90°. Each cutting tip 96 has a chamfered surface at the cutting edge of the cutting tip, and the chamfered surface is oriented at an angle of 45° with respect to a plane perpendicular to the longitudinal axis of the cutting element 90, and the chamfer height of the chamfered surface is 0.016 inches (0.040 cm), as measured from a plane perpendicular to the longitudinal axis. Each cutting tip 96 is defined by an angled cutting tip surface 98, which is planar and oriented at an angle of 30° with respect to a line tangent to the cylindrical side surface of the cutting element 90 (in the Figure 15 referred to as "relief taper" in the text) orientation. The front cutting surface 92 also includes a planar region 93 at each cutting tip 96, and the planar region 93 is oriented perpendicular to the longitudinal axis of the cutting element 90. Figure 10 The cutting element 90 includes angled plowing surfaces 99, each of which is oriented at a plowing angle of 20° with respect to a plane perpendicular to the longitudinal axis of the cutting element 90 (outside the cutting tip width).

[0092] Figure 11 is a perspective view of another cutting element 100, which has a front cutting surface 102, a peripheral edge 104, and cutting tips 106 defined between angled cutting tip surfaces 108, as previously described herein. The cutting element 100 also has angled plowing surfaces 109. Figure 11 The cutting element 100 has a front cutting surface 102, which includes two symmetric planar regions 102A and 102B each having a cutting tip 106. The upper planar region 102A and the lower planar region 102B are oriented at an angle with respect to each other so that the front cutting surface 102 has a generally concave shape. As Figure 15 shown in the table of Figure 11 the cutting element 100 is concave, and the upper planar region 102A and the lower planar region 102B are each oriented at an acute angle of 10° with respect to a plane perpendicular to the longitudinal axis of the cutting element 100 (in the Figure 15oriented as described in the [referred text] as "spoon angle"), for a cutting element 100 with a diameter of 0.625 inches (1.587 cm), this results in each cutting tip 106 extending a height of 0.052 inches (0.132 cm) above the intersection line between regions 102A and 102B. The cutting tip 106 of the cutting element 100 has a face cutting tip width of 0.100 inches (0.254 cm) and a face cutting tip angle of 90°. Each cutting tip 106 has a chamfered surface at the cutting edge of the cutting tip, and the chamfered surface is oriented at an angle of 45° with respect to a plane perpendicular to the longitudinal axis of the cutting element 100, and the chamfer height of the chamfered surface is 0.016 inches (0.040 cm) as measured from the plane perpendicular to the longitudinal axis. Each cutting tip 106 is defined by adjacent angled cutting tip surfaces 108, which are planar and oriented at an angle of 30° with respect to a line tangent to the cylindrical side surface of the cutting element 100 (in the [referred text] Figure 15 described as "relief cone"). Figure 11 The cutting element 100 includes angled plowing surfaces 109, each of which is oriented at a plowing angle of 20° with respect to a plane perpendicular to the longitudinal axis of the cutting element 100 (outside the cutting tip width).

[0093] Figure 12 is a perspective view of another cutting element 110, which has a front cutting surface 112, a peripheral edge 114, and cutting tips 116 defined between angled surfaces 118, as previously described herein. The cutting tip 116 has a double cutting peak 117, which will be described in further detail below. The cutting element 110 also has angled plowing surfaces 119. Figure 12 The cutting element 110 has a front cutting surface 112, which includes two symmetric planar regions 112A and 112B each having a cutting tip 116, and each cutting tip has a double cutting edge or peak. The upper planar region 112A and the lower planar region 112B are oriented at an angle with respect to each other so that the front cutting surface 112 has a generally concave shape. As Figure 15 shown in the table of Figure 12 the cutting element 110 is concave, and the upper planar region 112A and the lower planar region 112B are each oriented at an acute angle of 10° with respect to a plane perpendicular to the longitudinal axis of the cutting element 110 (in the [referred text] Figure 15oriented (referred to in Figure 15 as "relieved taper" in Figure 12 ), the cutting element 110 includes angled plowing surfaces 119, each of which is oriented at a plowing angle of 25° relative to a plane perpendicular to the longitudinal axis of the cutting element 110 (outside the cutter head width).

[0094] Figure 13 is a perspective view of another cutting element 120 having a front cutting surface 122, a peripheral edge 124, and a cutter head 126 defined between angled surfaces 128, as previously described herein. The cutter head 126 has double cutting peaks 127, as described in further detail below. The cutting element 120 also has angled plowing surfaces 129. Figure 13 The cutting element 120 of Figure 15 has a front cutting surface 122 that includes two symmetric planar regions 122A and 122B that each extend toward the cutter head 126. The upper planar region 122A and the lower planar region 122B are oriented at an angle relative to each other such that the front cutting surface 122 has a generally concave shape. As Figure 13 shown in the table of Figure 15oriented (referred to as "spoon corners" in Figure 15 the context) such that for a cutting element 120 having a diameter of 0.625 inches (1.587 cm), this results in each cutting tip 126 extending 0.052 inches (0.132 cm) in height above the intersection line between regions 122A and 122B. Each cutting tip 126 of the cutting element 120 has a double cutting peak 127, each cutting peak having a cutting edge thereon. Each cutting peak of the double cutting peaks 127 has a face cutting tip width of 0.080 inches (0.203 cm), and each cutting peak of the double cutting peaks 127 has a face cutting tip angle of 90°. Each cutting tip 126 has a chamfered surface at the cutting edge of the cutting tip, and the chamfered surface is oriented at an angle of 45° relative to a plane perpendicular to the longitudinal axis of the cutting element 120, and the chamfer height of the chamfered surface is 0.016 inches (0.040 cm) as measured from the plane perpendicular to the longitudinal axis. Each cutting tip 126 is defined by adjacent angled cutting tip surfaces 128, the cutting tip surfaces being planar and oriented at an angle of 25° relative to a line tangent to the cylindrical side surface of the cutting element 120 (in Figure 15 the context referred to as "relief taper"). The front cutting surface 122 also includes a planar region 123 at each cutting tip 126, and the planar region 123 is oriented perpendicular to the longitudinal axis of the cutting element 130. Figure 13 The cutting element 120 includes angled plow surfaces 129, each of the plow surfaces being oriented at a plow angle of 25° relative to a plane perpendicular to the longitudinal axis of the cutting element 120 (outside the cutting tip width).

[0095] Extending the length of the drilling section from shank to shank is required to effectively drill high cutting depth sections while maintaining durability in the lower transition section. Figures 16 to 26 Illustrates various embodiments of a cutting element having a novel cutting surface geometry that is designed and configured to facilitate the generation of multiple cracks in the cutting area.

[0096] The geometry allows these cutting elements to perform differently at different depths of cut (DOC). The geometry makes the cutting elements durable and efficient at low DOC, provides point loading, and may have a polished surface to achieve efficiency in sticky shale formations. The cutting elements may also have a recessed surface at high DOC to reduce weight requirements.

[0097] Figure 16Illustrated is a cutting element 130 having a front cutting surface 132. The front cutting surface 132 is symmetric about a horizontal centerline between two cutting tips 133, each cutting tip having a peripheral cutting edge 134. The front cutting surface 132 has a central recess 135. The region of the front cutting surface 132 within the central recess 135 may be substantially planar and oriented perpendicular to the longitudinal axis of the cutting element 130, and the shape of the recess 135 may be characterized as being generally elliptical. On each lateral side of the central recess 135 is a generally concave ridge 136. Each ridge 136 may include an inclined surface 137, which may be planar or curved, so as to provide a generally concave geometry for each ridge 136 7 . The cutting edge 134 of the cutting tip 133 may include a chamfered surface 138 as previously described herein. Figure 16 The cutting element 130 further includes an angled plowing surface 139, each of the plowing surfaces of which may be oriented at a plowing angle relative to a plane perpendicular to the longitudinal axis of the cutting element 130, as previously described herein.

[0098] Figure 17 Illustrated is a cutting element 140 having a front cutting surface 142 similar to Figure 16 . The front cutting surface 142 is symmetric about a horizontal centerline between two cutting tips 143, each cutting tip having a peripheral cutting edge 144. The front cutting surface 142 has a central recess 145. The region of the front cutting surface 142 within the recess 145 may be substantially planar and oriented perpendicular to the longitudinal axis of the cutting element 140, and the shape of the recess 145 may be characterized as being generally elliptical. On each lateral side of the central recess 145 is a generally concave ridge 146. Each ridge 146 may include an inclined surface 147, which may be planar or curved, so as to provide a generally concave geometry for each ridge 146 7 . The cutting edge 144 of the cutting tip 143 may include two or more adjacent chamfered surfaces 148. Figure 17 The cutting element 140 further includes an angled plowing surface 149, each of the plowing surfaces of which may be oriented at a plowing angle relative to a plane perpendicular to the longitudinal axis of the cutting element 140, as previously described herein.

[0099] Figure 18 Illustrated is a cutting element 150 having a front cutting surface 152 also similar to Figure 16 . The front cutting surface 152 is symmetric about a horizontal centerline between two cutting tips 153, each cutting tip having a peripheral cutting edge 154. The front cutting surface 152 has a central recess 155. At Figure 18In an embodiment, the region of the front cutting surface 152 within the recess 155 may include two substantially inwardly inclined planar surfaces that are oriented at an angle with respect to each other and with respect to a plane perpendicular to the longitudinal axis of the cutting element 150 such that the region of the front cutting surface 152 within the recess 155 has a generally concave shape. On each transverse side of the central recess 155 is a generally concave ridge 156. Each ridge 156 may include an inclined surface 157 that may be planar or curved to provide a generally concave geometry for each ridge 156. The cutting edge 154 of the cutting tip 153 may include a chamfered surface 158 as previously described herein. Figure 18 The cutting element 150 further includes an angled plowing surface 159, each of which may be oriented at a plowing angle with respect to a plane perpendicular to the longitudinal axis of the cutting element 150, as previously described herein.

[0100] Figure 19 Illustrated is a cutting element 160 having a front cutting surface 162. The front cutting surface 162 is symmetric about a horizontal centerline between two cutting tips 163, each having a peripheral cutting edge 164. The front cutting surface 162 has a central recess 165. In Figure 19 an embodiment, the region of the front cutting surface 162 within the recess 165 may be substantially planar and oriented perpendicular to the longitudinal axis of the cutting element 160, and the shape of the recess may be characterized as generally elliptical. On each transverse side of the central recess 165 is a generally concave ridge 166. Each ridge 166 may include an inclined surface 167 that may be planar or curved to provide a generally concave geometry for each ridge 166. The cutting edge 164 of the cutting tip 163 may include a chamfered surface 168 as previously described herein. Figure 19 The lateral side surface of the diamond table of the cutting element 160 further includes a region 169 adjacent to each cutting tip 163 that has a greater radius of curvature relative to the remainder of the lateral side surface of the diamond table. In other words, region 169 may be relatively flatter or less curved compared to the surrounding region of the lateral side surface of the diamond table. For example, region 169 may be formed by laser machining the lateral side surface of the diamond table.

[0101] In an additional embodiment, the cutting element 160 may include one or more additional ridges in the central region of the front cutting surface 162 within the recess 165.

[0102] Figure 20Illustrates a cutting element 170 having a front cutting surface 172. The front cutting surface 172 is symmetric about a horizontal centerline between two cutting tips 173, each cutting tip having a peripheral cutting edge 174. The front cutting surface 172 has a central recess 175, the shape of which can be characterized as being generally elliptical. In Figure 20 an embodiment, the region of the front cutting surface 172 within the central recess 175 can be substantially planar and oriented perpendicular to the longitudinal axis of the cutting element 170. On each transverse side of the central recess 175 is a generally concave ridge 176. Each ridge 176 can include an inclined surface 177, which can be planar or curved to provide a generally concave geometry for each ridge 176. The cutting edge 174 of the cutting tip 173 can include a chamfered surface 178 as previously described herein. Similar to Figure 19 the cutting element 160, Figure 20 the transverse side surface of the diamond table of the cutting element 170 also includes a region 179 adjacent to each cutting tip 173, which has a greater radius of curvature relative to the remainder of the transverse side surface of the diamond table. In other words, the region 179 can be relatively flatter or less curved compared to the surrounding region of the transverse side surface of the diamond table. For example, the region 179 can be formed by laser machining the transverse side surface of the diamond table. Figure 20 the cutting element 170 also includes an angled plowing surface 171, each of which can be oriented at a plowing angle relative to a plane perpendicular to the longitudinal axis of the cutting element 170, as previously described herein.

[0103] In an additional embodiment, the cutting element 170 can include one or more additional ridges in the central region of the front cutting surface 172 within the recess 175.

[0104] Figure 21 Illustrates a cutting element 180 having a front cutting surface 182. The front cutting surface 182 is symmetric about both a horizontal centerline between two cutting tips 183 and a vertical centerline extending vertically through the cutting tips 183. Each cutting tip 183 has a peripheral cutting edge 184. The front cutting surface 182 has a central recess 185, which has an elongated diamond shape elongated in the direction of the cutting tips 183, as Figure 21 shown. In Figure 21In an embodiment, the region of the front cutting surface 182 within the central recess 185 may be substantially planar and oriented perpendicular to the longitudinal axis of the cutting element 180. A generally annular ridge 186 surrounds the central recess 185, and the cutting head 183 includes an end region of the elongate annular ridge 186. The annular ridge 186 has a relatively uniform width around the circumference of the annular ridge 186. Four sector surfaces 189 surround the annular ridge 186, and each of the sector surfaces defines a concave recess in the front cutting surface 182 of the cutting element 180. Lateral ridges 187 extend from the annular ridge 186 in a lateral direction to the outer diameter of the cutting element 180, as Figure 21 shown. The lateral ridges 187 are integral with the generally annular ridge 186. The lateral ridges 187 may taper away from the plane of the outer surface of the annular ridge 186 in a direction toward the base of the cutting element 180. The cutting edge 184 of the cutting head 183 may include a chamfered surface 188 as previously described herein.

[0105] Figure 22 An illustration shows a cutting element 190 having a front cutting surface 192. The front cutting surface 192 is symmetric about both a horizontal centerline between two cutting heads 193 and a vertical centerline extending vertically through the cutting heads 193. Each cutting head 193 has a peripheral cutting edge 194. The front cutting surface 192 has a central recess 195 that has a generally elongate but irregular diamond shape that elongates in the direction of the cutting heads 193, as Figure 22 shown. In Figure 22 an embodiment, the region of the front cutting surface 192 within the central recess 195 may be substantially planar and oriented perpendicular to the longitudinal axis of the cutting element 190. A generally annular ridge 196 surrounds the central recess 195, and the cutting head 193 includes an end region of the elongate annular ridge 196. The annular ridge 196 has a varying width around the circumference of the annular ridge 196, which results in an irregular diamond shape. As Figure 22 shown, the width of the ridge may be thicker closer to the cutting head 193 and thinner at positions further away from the cutting head 193. Four sector surfaces 199 surround the annular ridge 196, and each of the sector surfaces defines a concave recess in the front cutting surface 192 of the cutting element 190. Lateral ridges 197 extend from the annular ridge 196 in a lateral direction to the outer diameter of the cutting element 190, as Figure 22 shown. The lateral ridges 197 are integral with the generally annular ridge 196. The lateral ridges 197 may taper away from the plane of the outer surface of the annular ridge 196 in a direction toward the base of the cutting element 190. The peripheral cutting edge 194 of the cutting head 193 may include a chamfered surface 198 as previously described herein.

[0106] Figure 23Illustrated is a cutting element 200 having a front cutting surface 202. The front cutting surface 202 is symmetric about both a horizontal centerline between two cutting inserts 203 and a vertical centerline extending vertically through the cutting inserts 203. Each cutting insert 203 has a peripheral cutting edge 204. The front cutting surface 202 has a central recess 205 which has a generally elongate rectangular shape with rounded end corners, and the central recess 205 is elongate in the direction of the cutting insert 203, as Figure 23 shown. In Figure 23 an embodiment, the region of the front cutting surface 202 within the recess 205 may be substantially planar and oriented perpendicular to the longitudinal axis of the cutting element 200. A generally annular diamond-shaped ridge 206 surrounds the central recess 205, and the cutting insert 203 includes an end region of the elongate annular ridge 206. The annular ridge 206 has a varying width around the circumference of the ridge 206. As Figure 23 shown, the width of the ridge may be thinner closer to the cutting insert 203 and thicker at positions further away from the cutting insert 203. Four fan-shaped surfaces 209 surround the ridge 206, and each of the fan-shaped surfaces defines a concave recess in the front cutting surface 202 of the cutting element 200. Lateral ridges 207 extend from the annular ridge 206 in a lateral direction to the outer diameter of the cutting element 200, as Figure 23 shown. The lateral ridges 207 are integral with the generally annular ridge 206. The lateral ridges 207 may taper away from the plane of the outer surface of the ridge 206 in a direction towards the base of the cutting element 200. The cutting edge 204 of the cutting insert 203 may include a chamfered surface 208 as previously described herein.

[0107] Figure 24 Illustrated is a cutting element 210 having a front cutting surface 212. The front cutting surface 212 is symmetric about both a horizontal centerline between two cutting inserts 213 and a vertical centerline extending vertically through the cutting inserts 213. Each cutting insert 213 has a peripheral cutting edge 214. The front cutting surface 212 has a central recess 215 which has a generally elongate rectangular shape, and the recess 215 is elongate and extends to the peripheral cutting edge 214 of the insert 213 in the direction of the peripheral cutting edge of the insert 213, as Figure 24 shown. In Figure 24 an embodiment, the region of the front cutting surface 212 within the recess 215 may be substantially planar and oriented perpendicular to the longitudinal axis of the cutting element 210. Generally triangular-shaped ridges 216 are provided on each lateral side of the central recess 215, and the cutting insert 213 includes an end region of the triangular ridge 216 and an end region of the front cutting surface within the recess 215. As Figure 24As shown, the width of the triangular ridge 216 is thinner closer to the cutting tip 213 and thicker at positions farther away from the cutting tip 213. Four fan-shaped surfaces 219 surround the ridge 216, and each of the fan-shaped surfaces defines a concave recess in the front cutting surface 212 of the cutting element 210. The lateral ridges 217 extend from each of the ridges in the ridge 216 in the lateral direction to the outer diameter of the cutting element 210, as Figure 24 shown. The lateral ridges 217 are integrally formed with the triangular ridges 216 respectively. The lateral ridges 217 can taper away from the plane of the outer surface of the ridge 216 in the direction towards the base of the cutting element 210. The cutting edge 214 of the cutting tip 213 can include a chamfered surface 218 as previously described herein.

[0108] Figure 25 An illustration shows a cutting element 220 having a front cutting surface 222. The front cutting surface 222 is symmetric along both the horizontal centerline between the two cutting tips 223 and the vertical centerline extending vertically through the cutting tips 223. Each cutting tip 223 has a peripheral cutting edge 224. The front cutting surface 222 has a central recess 225, which has a generally elongated rectangular shape, and the recess 225 is elongated in the direction of the peripheral cutting edge 224 of the cutting tip 223 and extends to the peripheral cutting edge, as Figure 25 shown. In Figure 25 the embodiment, the area of the front cutting surface 222 within the recess 225 is curved and generally concave. As shown, the recess 25 can be configured with two inwardly inclined peripheral flat portions on the sides of the central flat portion. A generally triangular-shaped ridge 226 is provided on each lateral side of the central recess 225, and the cutting tip 223 includes an end region of the elongated triangular ridge 226 and an end region of the concave surface within the recess 225. As Figure 25 shown, the width of the triangular ridge 226 is thinner closer to the cutting tip 223 and thicker at positions farther away from the cutting tip 223. Four fan-shaped surfaces 229 surround the ridge 226, and each of the fan-shaped surfaces defines a concave recess in the front cutting surface 222 of the cutting element 220. The lateral ridges 227 extend from each of the ridges in the ridge 226 in the lateral direction to the outer diameter of the cutting element 220, as Figure 25 shown. The lateral ridges 227 are integrally formed with the triangular ridges 226 respectively. The lateral ridges 227 can taper away from the plane of the outer surface of the ridge 226 in the direction towards the base of the cutting element 220. The cutting edge 224 of the cutting tip 223 can include a chamfered surface 228 as previously described herein.

[0109] Figure 26Illustrated is a cutting element 230 having a front cutting surface 232. The front cutting surface 232 is symmetric about both a horizontal centerline between two cutting inserts 233 and a vertical centerline extending vertically through the cutting inserts 233. Each cutting insert 233 has a peripheral cutting edge 234. The front cutting surface 232 has a central recess 235, which has a generally elongated leaf-shaped or dog-bone shape with rounded end corners, and the recess 235 is elongated in the direction of the insert 233, as Figure 26 shown. Thus, the transverse width of the recess 235 is narrowest at the center of the recess 235 and widest at the longitudinal ends of the recess 235 adjacent to the cutting inserts 233. In Figure 26 an embodiment, the region of the front cutting surface 232 within the recess 235 may be substantially planar and oriented perpendicular to the longitudinal axis of the cutting element 230. A generally annular diamond-shaped ridge 236 surrounds the central recess 235, and the cutting inserts 233 include end regions of the elongated annular ridge 236. The annular ridge 236 has a varying width around the circumference of the ridge 236. As Figure 26 shown, the width of the ridge may be thinner closer to the cutting inserts 233 and thicker nearer the center point between the cutting inserts 233. Four fan-shaped surfaces 239 surround the ridge 236, and each of the fan-shaped surfaces defines a concave recess in the front cutting surface 232 of the cutting element 230. Lateral ridges 237 extend from the annular ridge 236 in a lateral direction to the outer diameter of the cutting element 230, as Figure 26 shown. The lateral ridges 237 are integral with the generally annular ridge 236. The lateral ridges 237 may taper away from the plane of the outer surface of the ridge 236 in a direction toward the base of the cutting element 230. The cutting edge 234 of the cutting insert 233 may include a chamfered surface 238 as previously described herein.

[0110] Regarding all cutting elements disclosed herein, the edges of the features on the front cutting surface of the cutting element may be chamfered or rounded to have a radius, for example, to provide improved toughness. Figure 27 is a diagram illustrating various edge variations that may be introduced in any embodiment of the cutting elements described herein. As shown therein, the edges may be chamfered or rounded to have a radius. The radius may vary along any given edge such that the radius of curvature of the rounded edge varies along the length of any given edge.

[0111] The polycrystalline diamond of the various cutting elements disclosed herein may be machined, for example, using a laser machining process or a grinding process to form the geometries disclosed herein. Alternatively, the cutting element may be formed to have the disclosed shape in a high temperature high pressure (HTHP) sintering process for forming such polycrystalline diamond compact (PDC) cutting elements.

[0112] In addition, a chemical polishing process, a chemical mechanical polishing process, or a laser polishing process can be used to polish the outer surface of the polycrystalline diamond to reduce the surface roughness of the outer surface.

[0113] Finally, the interstitial metal-solvent catalyst material in the interstitial regions between the interbonded diamond grains in the polycrystalline diamond of the PDC cutting element can be selectively removed from regions of the cutting element, such as regions near the cutting edges and cutting tips that will contact the formation during drilling. Acid leaching processes are known in the industry for removing such interstitial metal-solvent catalyst materials, and removing this interstitial metal-solvent catalyst material is known to make the cutting element more thermally stable during drilling.

[0114] The PDC cutting element as described herein can be attached to a tool body of a well drilling tool and used to form and / or enlarge a wellbore in a subterranean formation. For example,

[0115] Figure 28 An embodiment of the well drilling tool of the present disclosure is illustrated. Figure 28 The well drilling tool is a fixed cutter rotary bit 250 having a bit body 251 that includes a plurality of blades 252 that project outwardly from the bit body 251 and are separated from each other by fluid flow channels 253. The portion of the fluid flow channels 253 that extends along the radial side (the "gauge" region of the bit 250) is often referred to in the art as a "chip groove". The bit body 251 also includes a generally cylindrical internal fluid pressurization chamber and fluid channels that extend through the bit body 251 to the outer surface of the bit body 251. Nozzles 258 can be fixed within the fluid channels, near the outer surface of the bit body 251, for controlling the hydraulic pressure of the bit 250 during drilling. A plurality of cutting elements 260 are mounted to each of the blades 252. The cutting elements 260 can be any of the various embodiments of the PDC cutting elements as described herein, or include any of the various embodiments of the PDC cutting elements as described herein.

[0116] During a drilling operation, the bit 250 can be coupled to a drill string (not shown). When the bit 250 rotates within the wellbore, drilling fluid can be pumped down the drill string, through the internal fluid pressurization chamber and fluid channels within the bit body 251 of the bit 250, and pumped out of the bit 250 through the nozzles 258. Formation cuttings generated by the cutting elements 260 of the bit 250 can be carried with the drilling fluid around the bit 250 through the fluid flow channels 253 and returned to the wellbore through the annulus outside of the drill string within the wellbore.

[0117] The embodiments of the present disclosure described above and illustrated in the accompanying drawings do not limit the scope of the present disclosure, which is covered by the scope of the appended claims and their legal equivalents. Any equivalent embodiments are within the scope of the present disclosure. Indeed, various modifications of the present disclosure other than those shown and described herein (such as alternative useful combinations of elements described in various embodiments of the cutting elements disclosed herein) will become apparent to those skilled in the art in light of the description. It is contemplated that, where technically feasible, the surfaces or geometries disclosed with respect to one embodiment of the cutting elements may be incorporated, in whole or in part, into other disclosed embodiments of the cutting elements. Such modifications and embodiments are also intended to fall within the scope of the appended claims and equivalents.

Claims

1. A cutting element for a earth-boring tool, the cutting element comprising: a substrate; and a volume of polycrystalline diamond on the substrate, the volume of polycrystalline diamond having an outer surface defining a front cutting surface, a peripheral edge, and a pair of angled cutting head surfaces, the pair of angled cutting head surfaces defining a cutting head located between the pair of angled cutting head surfaces, wherein the front cutting surface includes a first planar region and a second planar region, the second planar region includes the cutting head, the second planar region is oriented at an angle relative to the first planar region such that the front cutting surface is generally concave, and the second planar region is oriented at an acute angle relative to a plane perpendicular to the longitudinal axis of the cutting element.

2. The cutting element according to claim 1, wherein the cutting head extends to a certain height above the first planar region of the front cutting surface.

3. The cutting element according to claim 1, wherein the first planar region of the front cutting surface is oriented perpendicular to the longitudinal axis of the cutting element.

4. The cutting element according to claim 1, wherein the outer surface of the volume of polycrystalline diamond further defines angled plowing surfaces on opposite lateral sides of the cutting head, the angled plowing surfaces being set at an acute angle relative to a plane perpendicular to the longitudinal axis of the cutting element.

5. The cutting element according to any one of claims 1 to 4, wherein the cutting head has a cutting head width in the range extending from 0.080 inches (0.203 cm) to 0.173 inches (0.439 cm).

6. The cutting element according to any one of claims 1 to 4, wherein the angled cutting head surfaces are planar and oriented at a cutting head angle of approximately 90° relative to each other.

7. The cutting element according to any one of claims 1 to 4, wherein the substrate is cylindrical.

8. The cutting element according to any one of claims 1 to 4, wherein the cutting head has a double cutting peak.

9. The cutting element according to any one of claims 1 to 4, wherein the outer surface of the volume of polycrystalline diamond further defines another pair of angled cutting head surfaces, the another pair of angled cutting head surfaces defining another cutting head located between the another pair of angled cutting head surfaces, and the first planar region includes the another cutting head.

10. The cutting element according to claim 9, wherein the cutting head and the another cutting head each have a double cutting peak.

11. A cutting element for a earth-boring tool, the cutting element comprising: a substrate; and A volume of polycrystalline diamond on the substrate, the volume of polycrystalline diamond having an outer surface defining a front cutting surface, a peripheral edge, and an angled cutting head surface, the angled cutting head surface defining a cutting head located between the angled cutting head surfaces, wherein the front cutting surface includes an upper left plowing surface, an upper right plowing surface, a lower left plowing surface, and a lower right plowing surface, the lower left plowing surface and the lower right plowing surface include the cutting head, a first ridge line at the intersection between the lower left plowing surface and the lower right plowing surface is oriented at an acute angle with respect to a plane perpendicular to the longitudinal axis of the cutting element, and the cutting head extends a certain height above a second ridge line at the intersection between the upper left plowing surface and the upper right plowing surface.

12. The cutting element according to claim 11, wherein the second ridge line is perpendicular to the longitudinal axis of the cutting element.

13. The cutting element according to claim 11, wherein the angled cutting head surface is planar and is oriented at an acute angle with respect to a line tangent to a side surface of the cutting element.

14. The cutting element according to claim 13, wherein the upper left plowing surface and the upper right plowing surface are each oriented at an acute angle of 10° with respect to a plane perpendicular to the longitudinal axis of the cutting element.

15. The cutting element according to any one of claims 11 to 14, wherein the cutting head has a cutting head width in the range extending from 0.080 inches (0.203 cm) to 0.173 inches (0.439 cm).

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