SHEAR CLAW BIT

Abstract

A shear claw drill bit includes a bit body and a plurality of pick receptacles fixedly attached to the bit body. Each pick receptacle has a pick cavity. The shear claw drill bit further includes a plurality of picks. Each pick has a cutter cavity. The shear claw drill bit also includes a plurality of polycrystalline diamond compact (PDC) cutters. Each PDC cutter is disposed in the cutter cavity of a respective pick of the plurality of picks. A portion of each PDC cutter protrudes out of the cutter cavity of the respective pick.

Description

TECHNICAL FIELD

The present disclosure relates generally to downhole tools used in subterranean drilling, and more particularly, to shear claw drill bits.

BACKGROUND

Drill bits are commonly used for drilling into earth formations. Shear cutter polycrystalline diamond compact (PDC) drill bits are among the more commonly used types of drill bits. Typical PDC drill bits are bladed, and arrays of PDC cutters are disposed along the blades. The PDC cutters are typically brazed in cutter pockets formed in the blades, where the cutters are not filed replaceable. When PDC drill bits go through a complete rotation, a full bottom hole coverage is typically achieved because of a significant overlap of the PDC cutters in a rotational projection of the PDC cutters. In general, shear cutter PDC bits are extremely efficient at shearing rocks. Typically, cuttings generated along a given blade face of a PDC bit slide along the blade face to exit from the bit face of the PDC drill bit. In some cases, the cuttings may cause erosion and abrasion of the bit and may also damage the bit due to unwanted regrinding of the cuttings. In some applications, PDC bits may also experience off-center rotation due to torque moment generation along each blade.

Claw-type point attack bits are also among the more commonly used bit types. Typical claw-type point attack bits are used extensively in soft soil industrial applications such as mining. Typically, cutting picks are mounted into machined sockets in the bit body in such a way that the cutting pick are free to rotate. Because the tip of the a cutting pick is typically separated from the bit body by the shaft of the cutting pick and the sockets, cutting picks of claw-type point attack bits benefit from fluid flow around the cutting picks. In general, claw-type point attack bits do not have full bottom hole coverage in a rotational projection. Although, such full or near full bottom hole coverage is generally not a requirement in the typical application of claw-type point attack bits in soft rock formations, use of such claw-type point attack bits in harder formations may not be efficient.

Accordingly, a drill bit with a shear claw configuration that provides for efficient fluid flow around the cutters while providing a relatively wider bottom hole coverage in a rotational projection is desirable.

SUMMARY

The present disclosure relates generally to downhole tools used in subterranean drilling, and more particularly, to shear claw drill bits. In some example embodiments, a shear claw drill bit includes a bit body and a plurality of pick receptacles fixedly attached to the bit body. Each pick receptacle has a pick cavity. The shear claw drill bit further includes a plurality of picks. Each pick has a cutter cavity, where each pick is disposed in the pick cavity of a respective pick receptacle of the plurality of pick receptacles. The shear claw drill bit also includes a plurality of polycrystalline diamond compact (PDC) cutters. Each PDC cutter is disposed in the cutter cavity of a respective pick of the plurality of picks. A portion of each PDC cutter protrudes out of the cutter cavity of the respective pick.

In another example embodiment, a method of fabricating a shear claw drill bit includes attaching pick receptacles to a bit body. The picks have pick cavities. The method further includes placing picks in the pick cavities. The picks have cutter cavities. The picks are removably attached to the pick receptacles. The method also includes placing cutters in the cutter cavities and attaching the cutters to the picks within the cutter cavities.

In another example embodiment, a shear claw drill bit includes a bit body having a bit face. The shear claw drill bit further includes a plurality of columns extending out from the bit face. The plurality of columns have cutter cavities that are distal from the bit face. The bit body and the plurality of columns are made from a single structure. The shear claw drill bit also includes a plurality of cutters disposed in the cutter cavities, where a portion of each cutter of the plurality of cutters protrudes out of a cutter cavity.

In yet another example embodiment, a method of fabricating a shear claw drill bit includes carving out columns from a steel structure such that the columns protrude out from a portion of the steel structure, where the portion of the steel structure defines a bit body of the shear claw drill bit. The method further includes removing column portions of the columns to form cutter cavities in the columns. The cutter cavities are distal from the bit body. The method also includes placing cutters in the cutter cavities and attaching the cutters placed in the cutter cavities to the columns.

These and other aspects, objects, features, and embodiments will be apparent from the following description and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

FIG. 1 is a perspective view of a shear claw drill bit according to an example embodiment;

FIGS. 2A and 2B are cross-sectional views of a cutter-carrying pick disposed in the pick receptacle of the shear claw drill bit of FIG. 1 according to an example embodiment;

FIG. 3 is a cross-sectional view of a cutter-carrying pick disposed in the pick receptacle of the shear claw drill bit of FIG. 1 according to another example embodiment;

FIG. 4 is a cross-sectional view of a cutter-carrying pick disposed in the pick receptacle of the shear claw drill bit of FIG. 1 according to another example embodiment;

FIG. 5 is a perspective view of a shear claw drill bit according to another example embodiment;

FIGS. 6A and 6B are top and profile views of a steel structure used to make a bit body and columns of a shear claw drill bit such as the shear claw drill bit of FIG. 5 according to an example embodiment;

FIG. 7 illustrates a first set of illustrative cut patterns that can be made in the steel structure of FIGS. 6A and 6B during the process of making a shear claw drill bit according to an example embodiment;

FIG. 8 illustrates a second set of illustrative cut patterns that can be made in the steel structure of FIGS. 6A and 6B following the cut patterns shown in FIG. 7 or instead of the cut patterns shown in FIG. 7 according to an example embodiment;

FIG. 9A illustrates columns formed by carving the steel structure of FIGS. 6A and 6B according to an example embodiment;

FIG. 9B illustrates example columns orientations that can be formed by carving the steel structure of FIGS. 6A and 6B according to an example embodiment;

FIG. 10 illustrates nozzle holes located in the bit face shown in FIG. 9A according to an example embodiment;

FIG. 11 illustrates cutter cavities formed in the columns according to an example embodiment; and

FIG. 12 illustrates cutters disposed in the cutter cavities shown in FIG. 11 according to an example embodiment.

The drawings illustrate only exemplary embodiments of the invention and are therefore not to be considered limiting of its scope, as the invention may admit to other equally effective embodiments.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure is directed to downhole tools used in subterranean drilling. In particular, the present disclosure relates to shear claw drill bits that provide a high degree bottom hole coverage in a rotational projection of the cutters and improved flow area for cuttings to exit from a bottom hole. The present disclosure may be better understood by reading the following description of non-limiting, example embodiments with reference to the attached drawings, wherein like parts of each of the figures are identified by like reference characters, and which are briefly described as follows.

FIG. 1 is a perspective view of a shear claw drill bit 100 according to an example embodiment. The shear claw drill bit 100 includes a bit body 102 and a threaded connector 104 attached to the bit body 102. The shear claw drill bit 100 further includes pick receptacles 108 and picks 110 that are positioned in the pick receptacles 108. For example, the pick receptacles 108 may be welded to the bit face of the bit body 102. In some example embodiments, the pick receptacles 108 may be slanted, for example, 45 degrees relative to a horizontal plane. Alternatively, the pick receptacles 108 may be slanted less or more than 45 degrees relative to the horizontal plane.

In some example embodiments, a number of the pick receptacles 108 may be attached to the bit body 106 proximal to the outer perimeter of the bit face 106 and may be in a generally round configuration. Other pick receptacles 108 may be attached to the bit body 106 in the interior of the bit face and may be in a round or other configuration.

The picks 110 are disposed in the pick receptacles 108. For example, a portion of a shaft of the pick 110 may be positioned within the pick cavity of the pick receptacle 108, and another portion of the shaft of the pick 110 may protrude out from the pick receptacle 108 as illustrated in FIG. 1. In general, each pick receptacle 108 has one pick cavity, where one pick 110 is disposed in the pick cavity of the pick receptacle 108.

In some example embodiments, the picks 110 may be removably attached to the pick receptacles 108. For example, the picks 110 may be field replaceable to allow replacement of worn out or damaged picks or to allow replacement for other reasons. The picks 110 may also be rotationally fixed within the pick cavities of the pick receptacles 108. To illustrate, the pick 110 may be positioned within the pick cavity of the pick receptacle 108 such that the pick 110 does not rotate relative to the pick receptacle 108.

As illustrated in FIG. 1, the shear claw drill bit 100 includes cutters 112 that are attached to the picks 110. For example, the cutters 112 may be PDC cutters, for example, ranging in diameter from 8 millimeter (mm) to 22 mm. The cutters 112 are attached to the picks 110 at the end portion of the picks 110 distal from the bit body 102. As more clearly shown in FIGS. 2A-4, each cutter 112 may be positioned in a cutter cavity of the picks 110. For example, the cutters 112 may be fixedly attached to the picks 110 within the cutter cavities formed in the picks 110 by brazing or similar methods. A cutter cavity may be machined (e.g., drilled) into the picks 110 to have a shape and a size that allow a cutter (e.g., a PDC cutter) to be positioned in the cutter cavity. For example, the cutter cavities may have a round cross-section with a diameter that is slightly larger than a diameter of a particular PDC cutter.

In some example embodiments, each cutter 112 may have a sloped cutting surface such that the cutter 112 has a non-zero rake angle. For example, the cutters 112 may have a rake angle of approximately 20 degrees. To illustrate, one side of the cutter 112 may protrude out from the cutter cavity more than an opposite side of the cutter 112.

In some example embodiments, one or more of the picks 110 may include two or more cutter cavities such that two or more cutters are attached to the picks 110. For example, two cutters 112 may be attached to each of the picks 110 or some of the picks 110. To illustrate, some of the picks 110 may carry one cutter 112, and the remaining picks 110 may carry two or more cutters 112. For example, the cutters 112 attached the pick 110 that carries two or more cutters 112 may be smaller than the cutters 112 attached to the picks 110 that carry one cutter 112. Two or more cutters 112 attached to the single pick 110 may oriented in the same direction and may have the same rake angle.

In some example embodiments, the shear claw drill bit 100 includes nozzles openings 114 in the bit face 106 of the bit body 102. The nozzle opening 114 are used for providing drilling fluid during drilling operations.

In some example embodiments, the threaded connector 104 of the shear claw drill bit 100 may be coupled to a drill string (not shown) or some other equipment that is coupled to a drill string. The threaded connector 104 as shown in FIG. 1 is threaded on the exterior surface of the threaded connector 104. In some alternative embodiments, the threaded connector 104 may be threaded in the interior surface of the threaded connector 104 for a connection with an externally threaded connector of a drill string or other equipment.

The shear claw drill bit 100 may utilize picks 110 that carry one or more shear cutters 112 (e.g., shear PDC cutters) on an end portion of each pick distal from the bit body 102. In contrast to the typical mining pick tips of claw drill bits, the distal end portion of each pick 110 is significantly wider to provide one or more cutter cavities for corresponding one or more shear cutters. Further, because each pick 110 is rotationally fixed (e.g., keyed) with respect to the respective pick receptacle 108, the cutting edge of the shear cutter (e.g., the shear PDC cutter) remains in place to cut the preferred location along the bottom hole profile.

In contrast to typical claw-type point attack bits, the rotational projection of the cutters 112 may provide a much wider bottom hole coverage. For example, in some example embodiments, the rotational projection of the cutters 112 may provide a full or near full bottom hole coverage. Further, because the cutters 112 are disposed at the distal ends of the picks 110, cuttings generated during drilling operations may exit from the bit face 110 without causing excessive erosion or abrasion to the shear claw drill bit 100. Further, in contrast to bladed PDC bits, the cutters 112 (e.g., PDC cutters) may be replaced in the field by replacing the picks 110, which results in time and cost savings when cutters need to be replaced during drilling operations.

In some example embodiments, the bit body 102, the pick receptacles 108, and the picks 210 may be made from steel using methods known to those of ordinary skill in the art with the benefit of this disclosure. As described above, the cutters 112 may be PDC cutters.

In some example embodiments, the shear claw drill bit 100 may have fewer or more pick receptacles 108 than shown in FIG. 1. The pick receptacles 108 may also be positioned in a different configuration and/or locations than shown in FIG. 1. Further, the shear claw drill bit 100 may have a different shape than shown in FIG. 1, without departing from the scope of this disclosure.

Example uses of the shear claw drill bit 100 include oil and gas PDC bits, blast hole mining PDC bits, horizontal directional diamond (HDD) PDC bits, and underground tunneling raise bore machines.

FIGS. 2A and 2B are cross-sectional views of a cutter-carrying pick 202 disposed in the pick receptacle 108 of the shear claw drill bit 100 of FIG. 1 according to an example embodiment. The pick 202 is disposed in a pick cavity 214 of the pick receptacle 108. A PDC cutter 204 is disposed in a cutter cavity 212 of the pick 202. In some example embodiments, the pick 202 and the PDC cutter 204 may be used with the shear claw drill bit 100 of FIG. 1 in place of the pick 110 and the cutter 112, respectively.

As illustrated in FIGS. 2A and 2B, the pick 202 is positioned in the pick receptacle 108. The pick receptacle 108 may be machined (e.g., drilled) to form the pick cavity 214 that is shaped and sized to receive the pick 202. To illustrate, a portion of the pick 202 may be within the pick cavity 214, and another portion of the pick 202 may protrude outside of the pick cavity 214 as illustrated in FIG. 2A. The pick 202 may be removably attached to the pick receptacle 108 such that the pick 202 is field replaceable.

The cutter cavity 212 may be formed in the pick 202 by machining out (e.g., drilling) a portion of the pick 202 at an end portion of the pick 202 that is distal from a bottom wall 210 of the pick receptacle 108. The PDC cutter 204 may be positioned in the cutter cavity 212 and may be fixedly attach to the pick 202 by brazing. The PDC cutter 204 may have a diameter ranging from 8 mm to 22 mm.

In some example embodiments, the bottom wall 210 of the pick receptacle 108 may be welded to the bit body 102. Alternatively or in addition, the side walls of the pick receptacle 108 may be welded to the bit body 102. In some example embodiments, a portion of or the entire bottom wall of the pick receptacle 108 may be omitted such that the pick 202 protrudes out or is accessible at the bottom end of the pick receptacle 108.

In some example embodiments, the pick receptacle 108 includes protruding keying structures 206 that may be inserted into key receptors 208 formed in the pick 202 to prevent the pick 202 from rotating within the pick cavity 214. Alternatively, the pick 202, instead of the pick receptacle 108, may include keying structures that are inserted into key receptors formed in the pick receptacle 108. The keying structure 206 and the key receptor 208 allow the pick 202 to be field replaceable while preventing the pick 202 from rotating within the pick cavity 214 during drilling operations. In some example embodiments, other structures may be used instead of or in addition to the keying structures 206 and the key receptors 208 to prevent the pick 202 from rotating within the pick cavity 214 without departing from the scope of this disclosure.

As illustrated in FIGS. 2A and 2B, a portion of the PDC cutter 204 may protrude out from the cutter cavity 212. In FIG. 2A, a cutting edge 216 of the PDC cutter 204 protrudes out from the cutter cavity 214 such that the cutting surface 218 of the PDC cutter is slightly backraked relative to the horizontal plane 220 in the orientation shown in FIG. 2A. To illustrate, the PDC cutter 204 may have a non-zero rake angle. For example, the PDC cutter 204 may have a rake angle of 20 degrees. Alternatively, the PDC cutter 204 may have a rake angle that is greater or less than 20 degrees. To illustrate, the PDC cutter 204 has a larger rake angle n FIG. 2B than in FIG. 2A. For example, the rake angle of the PDC cutter 204 as shown in FIG. 2B may be approximately 40 degrees.

Although the cutting surface 218 of the PDC cutter 204 is sloped as shown in FIGS. 2A and 2B, in some alternative embodiments, the PDC cutter 204 may protrude out from the cutter cavity 214, where the cutting surface 218 is not sloped. Further, in some example embodiments, the pick 202 may protrude out from the cavity less or more than shown in FIGS. 2A and 2B.

FIG. 3 is a cross-sectional view of a cutter-carrying pick 302 disposed in the pick receptacle of the shear claw drill bit of FIG. 1 according to another example embodiment. The pick 302 is disposed in the pick cavity (i.e., the pick cavity 214 described with respect to FIG. 2A) of the pick receptacle 108. A PDC cutter 304 is disposed in a cutter cavity 312 of the pick 302. In some example embodiments, the pick 302 and the PDC cutter 304 may be used with the shear claw drill bit 100 of FIG. 1 in place of the pick 110 and the cutter 112, respectively. To illustrate, the pick receptacle 108 shown in FIG. 3 may be the same as the pick receptacle 108 of FIG. 1.

Similar to the PDC cutter 204 shown FIGS. 2A and 2B, the PDC cutter 304 may be slightly backraked. For example, the PDC cutter 304 may have a non-zero (e.g., 20 degrees) rake angle.

As illustrated in FIG. 3, the pick 302 may include a shank 306 and an end portion 308 that is wider than the shank 306. The cutter cavity 312 may be formed in the end portion 308 of the pick 302 by drilling and/or other means known to those of ordinary skill in the art with the benefit of this disclosure. The PDC cutter 304 disposed in the cutter cavity 312 may be larger than the PDC cuter 204 in the shear claw drill bit 100 shown in FIGS. 2A and 2B. To attach the PDC cutter 304 with the pick 302, the PDC cutter 304 may be positioned in the cutter cavity 312 and may be brazed to the pick 302. The PDC cutter 304 may have a diameter ranging from 8 mm to 22 mm.

The pick 302 may be made as a single structure or may be made by attaching the shank 306 and the end portion 308 together using methods such as welding. For example, the pick 302 may be made from steel or other similar materials. As described with respect to the pick 110 of FIG. 1 and the pick 202 of FIGS. 2A and 2B, the pick 302 is removably attached to the pick receptacle 108, which enables field replacement of the pick 302 for reasons such as when the pick 302 or the PDC cutter 304 being worn or damaged.

FIG. 4 is a cross-sectional view of a cutter-carrying pick 402 disposed in the pick receptacle of the shear claw drill bit of FIG. 1 according to another example embodiment. The pick 402 is disposed in the pick cavity (i.e., the pick cavity 214 described with respect to FIG. 2A) of the pick receptacle 108. PDC cutters 404 are disposed in cutter cavities 412 of the pick 402. In some example embodiments, the pick 402 and the PDC cutters 404 may be used with the shear claw drill bit 100 shown in FIG. 1 in place of the pick 110 and the cutter 112, respectively. To illustrate, the pick receptacle 108 shown in FIG. 4 may be the same as the pick receptacle 108 of FIG. 1.

Similar to the PDC cutter 204 shown FIGS. 2A, 2B, and 3, the PDC cutters 404 may be slightly backraked. For example, each one of the PDC cutters 404 may have a non-zero rake angle. For example, both PDC cutters 404 may have substantially the same rake angle (e.g., approximately 20 degrees). Alternatively, the PDC cutters 404 may have different rake angles.

As illustrated in FIG. 4, the pick 402 may include a shank 406 and an end portion 408 that is wider than the shank 406. The cutter cavity 412 may be formed in the end portion 408 of the pick 402 by drilling and/or other means known to those of ordinary skill in the art with the benefit of this disclosure. For example, the PDC cutters 404 may be smaller than the PDC cuter 204 shown in FIGS. 2A and 2B and the PDC cutter 304 shown in FIG. 3. To attach the PDC cutters 404 with the pick 402, the PDC cutters 404 may be positioned in the cutter cavities 412 and may be brazed to the pick 402. Each PDC cutter 404 may have a diameter ranging from 8 mm to 22 mm.

Similar to the pick 302 of FIG. 3, the pick 402 may be made as a single structure or may be made by attaching the shank 406 and the end portion 408 together using methods such as welding. For example, the pick 402 may be made from steel or other similar materials. As described above, the pick 402 may be removably attached to the pick receptacle 108, which enables field replacement of the pick 402 for reasons such as when the pick 402 or the PDC cutters 404 being worn or damaged.

FIG. 5 is a perspective view of a shear claw drill bit 500 according to another example embodiment. The shear claw drill bit 500 includes a bit body 502 and columns 510. The bit body 502 includes a bit shank 504. A threaded connector 506 may extend down from the bit shank 504 in the orientation of the shear claw drill bit 500 shown in FIG. 5. The columns 510 extending out from the bit face 508 of the bit body 502. The shear claw drill bit 500 further includes cutters (e.g., a PDC cutter) 512 disposed in cutter cavities formed at the end portions of the columns distal from the bit face 508 of the bit body 502.

The bit body 502 and the columns 510 are parts of a monolithic structure made from a singular structure such as a steel structure. As explained further below, the columns 510 may be machined out of a singular steel structure. In some example embodiments, the columns 510 may be distributed on the bit face 508 in the configuration shown in FIG. 5. For example, the columns 510 may be evenly distributed around the bit face 508. Alternatively, the columns 510 may be unevenly distributed around the bit face 508. To illustrate, the columns 510 may be distributed around the bit face 508 in a configuration that allows for a full or near full bottom hole coverage by the shear claw drill bit 500. Further, the columns 510 may be distributed around the bit face 508 in a configuration that also provides room for cuttings to travel between the columns 510. For example, the columns 510 may be spaced to provide adequate room between the columns 510 for cuttings to travel without excessive damage to the bit body 502 or the columns 510.

As illustrated in FIG. 5, in some example embodiments, each column 510 carries one cutter 512. A cutter cavity may be machined (e.g., drilled) into each column 510 at an end portion of the column 510 distal from the bit face 508 of the bit body 502. The cutters 512 are disposed in the cutter cavities of the columns 510 machined into the columns 510. For example, the cutters 512 may be brazed with the columns 510 within the cutter cavities.

In some example embodiments, one or more of the columns 510 may have two or more cutter cavities at the end portion of the columns 510 distal from the bit face 508. For example, one or more of the columns 510 may carry two of the cutters 512. To illustrate, one cutter 512 may be disposed in one cutter cavity of one column 510, and another cutter 512 may be disposed in another cutter cavity of the same column 510. As yet another example, one or more of the columns 510 may carry three of the cutters 512. To illustrate, some of the columns 510 may be wider than other columns 510 to accommodate more cutter cavities and more cutters 512. Alternatively, all of the columns 510 may have substantially the same width, where some of the columns 510 carry more cutters 512 than other columns 510.

In some example embodiments, the columns 510 may be substantially perpendicular to the bit face 508. For example, when the bit face 508 is substantially flat and generally in a horizontal plane, the columns 510 may extend in a substantially vertical direction as viewed in the orientation of the shear claw drill bit 500 shown in FIG. 5. In some alternative embodiments, one or more of the columns 510 may be non-perpendicular to the bit face 508. For example, one or more of the columns 510 may protrude out from the bit face 508 in a non-vertical angle.

In some example embodiments, each column 510 may extend out at least 3 inches from the bit face 508. For example, some or all of the columns 510 may extend out approximately 3.5 inches from the bit face 508. In general, the columns 510 may extend out from the bit face 508 to provide adequate room for cuttings to travel between the columns 510. To illustrate, the columns 510 may extend out from the bit face 508 to provide adequate room for cuttings exit the bit face 508 without excessive damage to the bit body 502 or the columns 510. For example, the columns 510 may have thicknesses that minimize risks of breakage during drilling operations.

In some example embodiments, each cutter 512 may range in diameter in size from 8 mm to 22 mm. For example, the cutters 512 of the shear claw drill bit 500 may all have the same size or may have different sizes.

As illustrated in FIG. 5, the cutters 512 extend beyond the columns 510. For example, a portion of each cutter 512 may protrude out of the cutter cavity of the respective column 510. For example, the cutters 512 may be slightly backraked to have a desired rake angle. In general, the cutters 512 may have a non-zero rake angle (e.g., 20 degrees).

In some example embodiments, the shear claw drill bit 500 includes nozzles openings 514 in the bit face 508 of the bit body 502. The nozzle opening 514 are used for providing drilling fluid during drilling operations. The shear claw drill bit 500 may also include junk slots 516 that facilitate efficient travel of cuttings away from the bit face 508. In some example embodiments, the junk slots 516 may be evenly distributed around the bit body 502. The junk slots 516 may be formed in the bit body using methods known to those of ordinary skill in the art.

In some example embodiments, the threaded connector 506 of the shear claw drill bit 500 may be coupled to a drill string (not shown) or some other equipment that is coupled to a drill string. In general, the threaded connector 504 corresponds to the threaded connector 104 shown in FIG. 1 and may be used in a similar manner.

In contrast to some bladed PDC bits, the shear claw drill bit 500 provides for increased room between the cutters 512 and the bit body 502 for cuttings to travel away from the bit face 508, which reduces the risk of excessive damage to the bit body 502 and to the columns 510. Further, by distribution the columns 510 on the bit face 508 in some desired configurations, the shear claw drill bit 500 may provide full or near full bottom hole coverage in a rotational projection of the cutters 512, which allows for efficient drilling. The use of shear PDC cutters as the cutters 512 also allows the shear claw drill bit 500 to be used for drilling in hard formations.

In some example embodiments, the shear claw drill bit 100 may have fewer or more columns 510 than shown in FIG. 5. Further, some or all of the columns 510 may have shapes other than shown in FIG. 5 without departing from the scope of this disclosure. Further, the shear claw drill bit 500 may have a different shape than shown in FIG. 5 without departing from the scope of this disclosure. In some example embodiments, some of the columns 510 may be formed on the gage sides of the bit body 102.

Example uses of the shear claw drill bit 500 include oil and gas PDC bits, blast hole mining PDC bits, horizontal directional diamond (HDD) PDC bits, and underground tunneling raise bore machines.

FIGS. 6A and 6B are top and profile views of a steel structure 600 used to make a bit body and columns of a shear claw drill bit such as the shear claw drill bit of FIG. 5 according to an example embodiment. FIG. 6A illustrates a top view of the steel structure 600, and FIG. 6B illustrates a side profile view of the steel structure 600. For example, the steel structure 600 may be a machined or cast steel structure. To illustrate, the steel structure 600 may be die casted to have the general outline of the shear claw drill bit 500 of FIG. 5. The steel structure 600 may also be made by a combination of die casting and machining (e.g., carving) using various tools such as drills.

To make a shear claw drill bit such as the shear claw drill bit 500, a bit designer may first determine the desired location of PDC cutters on the bit face of the planned shear claw drill bit, and then design plunge cuts to be made in the top surface 602 of the steel structure 600 that will leave steel columns in the desired locations.

In some alternative embodiments, a structure made from a material other than steel may be used instead of the steel structure 600. Further, in some embodiments, the steel structure 600 may have a shape other than shown in FIGS. 6A and 6B without departing from the scope of this disclosure. For example, the top surface 602 may have be flatter than shown in FIG. 6B without departing from the scope of this disclosure.

FIG. 7 illustrates a first set of illustrative cut patterns 702 can be made in the steel structure 600 of FIGS. 6A and 6B during the process of making a shear claw drill bit according to an example embodiment. For example, the steel structure 600 may be carved using carving tools to form steel columns. To illustrate, drills and/or end mills (e.g., narrow diameter end mills) may be used to plunge deeply into the top surface 602 of the steel structure 600 to begin to define the steel columns, which will carry the PDC cutters. For example, end mills that are approximately 1 inch may be used alone or in combination with a drill(s) to make the cut patterns 702 or other cut patterns in the steel structure 600. In some example embodiments, cut patterns may also be made in the gage side 604 of the steel column 600 shown in FIG. 6B.

The cut patterns 702 are illustrative and other cut patterns may be made in the steel body 600 to define the planned steel columns without departing from the scope this disclosure. For example, fewer, smaller, or larger cuts than represented by the example cut patterns 702 may be made in the steel body 600.

FIG. 8 illustrates a second set of illustrative cut patterns 802 can be made in the steel structure 600 of FIGS. 6A and 6B according to an example embodiment. For example, the second set of illustrative cut patterns 802 or other cut patterns may be made after the example cut patterns 802 shown in FIG. 7 are made or instead of the example cut patterns 702. For example, after the first set of example cut patterns 702 are made as shown in FIG. 7, drills and/or end mills may be used to plunge deeply into the remaining portions of the top surface 602 of the steel structure 600 to continue to define the steel columns. In some example embodiments, the cut patterns may also be made in the gage side 604 of the steel column 600 shown in FIG. 6B.

Additional cut patterns may be made as needed plunge into the top surface 602 of the steel structure 600 until the steel columns are well defined. Additional cut patterns may also be made to define the bit face of the planned shear claw drill bit. Once the primary cut patterns are made by plunging into the steel body as described above, milling operations can be performed to better define the steel columns. For example, jagged edges and rough surfaces of the steel columns can be smoothed as needed. The bit face may also be more clearly defined by performing milling operations as needed. For example, curved edges of the bit face may be more clearly defined and smoothed as needed.

The cut patterns 802 are illustrative and other cut patterns may be made in the steel body 600 to define the planned steel columns without departing from the scope this disclosure. For example, fewer, smaller, or larger cuts than represented by the example cut patterns 802 may be made in the steel body 600.

FIG. 9A illustrates columns 902 formed by carving the steel structure 600 of FIGS. 6A and 6B according to an example embodiment. FIG. 9B illustrates example column orientations that can be formed by carving the steel structure 600 of FIGS. 6A and 6B according to an example embodiment. As illustrated in FIG. 9A, the columns 902 are distributed over a bit face 904 that is exposed after removal of portions the steel body 600 to form the columns 902. Some of the columns 902 may have larger surface dimensions than others. For example, surfaces of some columns 902 may be relatively long and/or wider than of some other columns 902.

As illustrated in FIG. 9A, some of the columns 902 may be substantially perpendicular to the bit face 904 while other columns 902 may be slanted. To illustrate, some of the columns 902 in FIG. 9A may be oriented similar to the column 906 of FIG. 9B such that the columns are substantially perpendicular to the bit face 904. Similarly, some columns 902 in FIG. 9A may be slanted similar to the column 908 of FIG. 9B. Further, in some example embodiments, some of the columns 902 may be formed on the gage side 604 of the steel body 600 shown in FIG. 6B similar to the column 910 of FIG. 9B.

Although a particular distribution of the columns 902 is shown in FIGS. 9A and 9B, in alternative embodiments, the columns 902 may have a different configuration without departing from the scope of this disclosure. For example, the columns 902 may be distributed more or less evenly on the bit face 904 than shown in FIG. 9A. Further, although the columns 902 are shown in FIG. 9A as having surfaces 912 that are rectangular, the surfaces 912 may have other shapes without departing from the scope of this disclosure. In general, the columns 902 may have the surfaces 912 having other shapes including shapes with more or less than four sides without departing from the scope of this disclosure. Further, in some example embodiments, the edges of the surfaces 912 may not be as smooth as shown in FIG. 9A. In general, some or all of the columns 902 may have shapes other than shown in FIG. 9A without departing from the scope of this disclosure.

FIG. 10 illustrates nozzle holes 1002 located in the bit face 904 shown in FIG. 9A according to an example embodiment. For example, long drills and tap tools may be used to form the nozzle openings 1002 in the bit face 904 after the columns 902 are carved as described above. In some example embodiments, more or fewer than the number of nozzle openings 1002 shown in FIG. 10 may be formed in the bit face 904. Further, the nozzle openings 1002 may have a different configuration than shown in FIG. 10.

FIG. 11 illustrates cutter cavities 1102, 1104 formed in the columns 902 according to an example embodiment. For example, some of the columns 902 may have one cutter cavity 1102, and other columns 902 may have two cutter cavities 1104. In some alternative embodiments, some of the columns 902 may have more than two cutter cavities. The cutter cavities 1102, 1104 may be machined/carved into the columns 902 at the end portion of each cutter 902 distal from the bit face 904. In some example embodiments, all of the columns 902 may have one cutter cavity 1102. Alternatively, all of the columns 902 may have two cutter cavities 1104. Some of the cutter cavities 1102 may be larger than the cutter cavities 1104 to accommodate a larger cutter.

In some example embodiments, junk slots 1106 may also be formed. The junk slots facilitate efficient travel of cuttings away from the bit face 904. The junk slots 1106 may be formed by drilling or other methods known to those of ordinary skill in the art with the benefit of this disclosure.

FIG. 12 illustrates PDC cutters 1202, 1204 disposed in the cutter cavities 1102, 1104 shown in FIG. 11 according to an example embodiment. As illustrated in FIG. 12, one PDC cutter 1202 is positioned in some of the columns 902, and two PDC cutters 1204 are positioned in other columns 902. The PDC cutters 1202, 1204 may range in diameter from 8 mm to 22 mm. For example, the PDC cutters 1204 may be smaller than the cutters 1202. In some example embodiments, more than two PDC cutters (e.g., three PDC cutters 1204) may be positioned on some of the columns 902.

The PDC cutters 1202, 1204 are attached to the columns 902 within the corresponding cutter cavities 1102, 1104 of FIG. 11, for example, by brazing. In general, the cutter cavities 1102, 1104 are slightly larger than the PDC cutters 1202, 1204, respectively, to allow the PDC cutters 1202, 1204 to be placed within the cutter cavities 1102, 1104.

Similar to the cutters 512 shown in FIG. 5, the PDC cutters 1202, 1204 may protrude out of the cutter cavities 1102, 1104. Further, the PDC cutters 1202, 1204 may be slightly backraked similar to the cutters 512. The rotated profile of the PDC cutters 1202, 1204 may have full or near full bottom hole coverage, which allows for efficient drilling.

Nozzle sockets 1206 may be positioned in the nozzle openings 1002 shown in FIG. 10. The nozzle sockets 1206 are used for providing drilling fluid during drilling operations. In some example embodiments, the nozzle sockets 1206 may be positioned in the nozzle openings 1002 before the cutter cavities 1102, 1104 of FIG. 11 are formed. In general, some of the steps described with respect to FIGS. 6A-12 may be performed in a different sequence than described above.

As described above with respect to FIGS. 6A-12, shear claw drill bits such as the shear claw drill bit 500 may be made starting with a steel structure (or another similar structure) and carving out the steel columns that carry cutters such as PDC cutters.

Although some embodiments have been described herein in detail, the descriptions are by way of example. The features of the embodiments described herein are representative and, in alternative embodiments, certain features, elements, and/or steps may be added or omitted. Additionally, modifications to aspects of the embodiments described herein may be made by those skilled in the art without departing from the spirit and scope of the following claims, the scope of which are to be accorded the broadest interpretation so as to encompass modifications and equivalent structures.

Claims

1. A shear claw drill bit, comprising: a bit body;a plurality of pick receptacles fixedly attached to the bit body, wherein each pick receptacle has a pick cavity;a plurality of picks, wherein each pick is disposed in the pick cavity of a respective pick receptacle of the plurality of pick receptacles and wherein each pick has a cutter cavity; anda plurality of polycrystalline diamond compact (PDC) cutters, each PDC cutter disposed in the cutter cavity of a respective pick of the plurality of picks, wherein a portion of each PDC cutter protrudes out of the cutter cavity of the respective pick.

2. The shear claw drill bit of claim 1, wherein at least one pick of the plurality of picks has a second cutter cavity and wherein a second PDC cutter is disposed in the second cutter cavity.

3. The shear claw drill bit of claim 1, wherein each pick of the plurality of picks is removably secured in the pick cavity of the respective pick receptacle.

4. The shear claw drill bit of claim 3, wherein each pick of the plurality of picks is rotationally fixed within the pick cavity of the respective pick receptacle.

5. The shear claw drill bit of claim 1, wherein each PDC cutter of the plurality of PDC cutters is fixedly attached to the respective pick within the cutter cavity of the respective pick by brazing the PDC cutter with the respective pick.

6. The shear claw drill bit of claim 1, wherein the plurality of PDC cutters range in diameter from 8 millimeters (mm) to 22 mm.

7. The shear claw drill bit of claim 1, wherein the bit body, the plurality of pick receptacles, and the plurality of picks are made from steel.

8. The shear claw drill bit of claim 1, wherein the plurality of pick receptacles are welded to the bit body.

9. The shear claw drill bit of claim 1, further comprising a plurality of nozzle opening in a bit face of the bit body.

10. A method of fabricating a shear claw drill bit, the method comprising: attaching pick receptacles to a bit body, the picks having pick cavities;placing picks in the pick cavities, the picks having cutter cavities, wherein the picks are removably attached to the pick receptacles;placing PDC cutters in the cutter cavities; andattaching the PDC cutters to the picks within the cutter cavities.

11. The method of claim 10, wherein attaching the pick receptacle to the bit body includes welding to the pick receptacles to the bit body.

12. The method of claim 10, wherein attaching the PDC cutters to the picks includes brazing the PDC cutters with the picks within the cutter cavities.

13. The method of claim 10, wherein placing the PDC cutters in the cutter cavities includes placing a first PDC cutter in a first cutter cavity of a pick and placing a second PDC cutter in a second cavity of the pick.

14. The method of claim 10, wherein the picks are rotationally fixed within the pick cavities.

15. A shear claw drill bit, comprising: a bit body having a bit face;a plurality of columns extending out from the bit face, the plurality of columns having cutter cavities that are distal from the bit face, wherein the bit body and the plurality of columns are made from a single structure; anda plurality of cutters disposed in the cutter cavities, wherein a portion of each cutter of the plurality of cutters protrudes out of a cutter cavity.

16. The shear claw drill bit of claim 15, wherein at least one column of the plurality of columns has a first cutter cavity and a second cutter cavity, wherein a first cutter of the plurality of cutters is disposed in the first cutter cavity, and wherein a second cutter of the plurality of cutters is disposed in the second cutter cavity.

17. The shear claw drill bit of claim 15, wherein the single structure is a steel structure and wherein the columns are carved out from the steel structure.

18. The shear claw drill bit of claim 15, wherein the cutter cavities are formed by drilling into an end portion of each column distal from the bit face.

19. The shear claw drill bit of claim 15, wherein the plurality of cutters are polycrystalline diamond compact (PDC) cutters.

20. The shear claw drill bit of claim 19, wherein one or more cutters of the plurality of cutters has a non-zero degree rake angle.

21. The shear claw drill bit of claim 15, wherein the plurality of cutters are brazed to the columns within the cutter cavities.

22. The shear claw drill bit of claim 15, further comprising nozzle openings in the bit face of the bit body.

23. A method of fabricating a shear claw drill bit, the method comprising: carving out columns from a steel structure such that the columns protrude out from a portion of the steel structure, the portion of the steel structure defining a bit body of the shear claw drill bit;removing column portions of the columns to form cutter cavities in the columns, the cutter cavities being distal from the bit body;placing cutters in the cutter cavities; andattaching the cutters placed in the cutter cavities to the columns.

24. The method of claim 23, further comprising drilling nozzle holes into the bit body, wherein openings of the nozzle holes are located in the bit face.

25. The method of claim 23, wherein removing the column portions of the columns to form the cutter cavities in the columns includes forming a first cavity and a second cavity in at least one of the columns, and wherein placing the cutters in the cutter cavities includes placing a first cutter in the first cutter cavity and placing a second cutter in the second cutter cavity.

26. The method of claim 23, wherein the cutters are polycrystalline diamond compact (PDC) cutters.

27. The method of claim 26, wherein attaching the cutters to the columns includes brazing the cutters to the columns.

28. The method of claim 23, wherein carving out the columns from the steel structure includes using a drill to plunge into the steel body.