WO2010083266A2 - Impregnated drill bit with diamond pins - Google Patents

Abstract

A method of manufacturing a drill bit and several embodiments of a drill bit for drilling a well in an earth formation. In one embodiment, the drill bit comprises a diamond impregnated bit body with one or more thermally stable pins embedded therein. More specifically, the drill bit may include a diamond impregnated bit body having a plurality of blades, with one or more of the blades having a cone section, a nose section, a shoulder section, and a gage section; a plurality of diamond impregnated cutters extending from the blades; and one or more thermally stable polycrystalline diamond pins embedded within, and possibly extending from, at least some of the cutters. In some embodiments, each cutter includes an embedded pin. Alternatively, the pin or pins may be located in the cone, shoulder, nose, and/or gauge sections.

Description

TITLE OF THE INVENTION Impregnated Drill Bit with Diamond Pins

PRIORITY CLAIM

This application claims the benefit of the filing date of United States Patent s Application Serial No. 12/355,258, filed January 16, 2009, for "IMPREGNATED DRILL BIT WITH DIAMOND PINS." This subject matter of this application is similar to the subject matter disclosed in U.S. Patent Application Serial Nos. 12/250,443, 12/250,445, 12/250,447, and 12/250,448, all filed October 13, 2008, and U.S. Patent Application Serial No. 12/274,709,

KΪ filed November 20, 2008. The above mentioned patent applications are incorporated herein by specific reference.

BACKGROUND OF THE INVENTION

Field of the Invention. The inventions disclosed and taught herein relate generally to drill bits for drilling wells; and more specifically relate to diamond 55 impregnated drill bits with super-abrasive cutting elements for drilling wells in earth formations.

Description of the Related Art.

U.S. Patent No. 4,190,126 discloses a "rotary abrasive drilling bit disclosed herein is of a construction wherein teeth are equipped on the fore part of a bit so body attached to a rotary drill pipe, each of said teeth is composed of a plurality of chips which are made of cemented tungsten carbide and the matrix thereof which is soft and inferior in abrasion resistance relative to said cutting elements or chips, each chip is shaped like a thin stick and extends along the cutting direction of said bit body, the matrix surrounds said chips, and in the as matrix of each tooth the chips are orderly arranged to leave a desired interspace along the direction of radius as well as the direction of circumference of the bit body."

U.S. Patent No. 6,095,265 discloses "a diamond impregnated bit with an adaptive matrix in the ribs. The ribs have at least two different areas of metal- s matrix composite impregnated with diamonds with different wear resistance such that during boring of formation, the areas will wear at different rates and provide fluid flow spaces across the surface of the ribs."

U.S. Patent No. 6,296,069 discloses a "drill bit as used in particular in the oil well drilling field comprising a central body (2), cutting blades (3) protruding s with respect to the body (2), both at the front of this body according to a drill direction and at the sides of this same body (2), and cutting elements (9) divided over an outer front surface (10) and over an outer lateral well sizing surface (11) comprised by each blade (3), wherein there are provided as cutting elements: in a central area (13) of the front surface (10), on at leasto one blade (3): at least one synthetic polycrystalline diamond compact cutting disc (12), and in a remaining area (14) of the front surface (10) of this blade, situated beyond said central area (13) with respect to the rotation axis, and on the other blades: thermally stable synthetic diamonds and/or impregnated diamond particles." s U.S. Patent No. 6,510,906 discloses a "drill bit employing a plurality of discrete, post-like diamond grit impregnated cutting structures extending upwardly from abrasive particulate-impregnated blades defining a plurality of fluid passages therebetween on the bit face. PDC cutters with faces oriented in the general direction of bit rotation are placed in the cone of the bit, which iso relatively shallow, to promote enhanced drilling efficiency through softer, non- abrasive formations. A plurality of ports, configured to receive nozzles therein are employed for improved drilling fluid flow and distribution. The blades may extend radially in a linear fashion, or be curved and spiral outwardly to the gage to provide increased blade length and enhanced cutting structures redundancy."

U.S. Patent No. 6,843,333 discloses a "drill bit employing a plurality of discrete, post-like, abrasive, particulate-impregnated cutting structures extending upwardly from abrasive, particulate-impregnated blades defining a plurality of fluid passages therebetween on the bit face. Additional cutting0 elements may be placed in the cone of the bit surrounding the centerline thereof. The blades may extend radially in a linear fashion, or be curved and spiral outwardly to the gage to provide increased blade length and enhanced cutting structure redundancy. Additionally, discrete protrusions may extend outwardly from at least some of the plurality of cutting structures. The discrete protrusions may be formed of a thermally stable diamond product and may s exhibit a generally triangular cross-sectional geometry relative to the direction of intended bit rotation."

U.S. Patent No. 7,234,550 discloses an "insert for a drill bit which includes a diamond impregnated body, and a shearing portion disposed on said body is shown. In addition, a method for forming a drill bit that includes (a) forming a io shearing portion on a diamond-impregnated insert body to form a cutting insert, (b) forming a bit body having a plurality of sockets sized to receive a plurality of the cutting inserts, and (c) mounting the plurality of cutting inserts in the bit body and affixing the plurality of cutting inserts to the bit body; wherein steps (a) (c) are carried out such that a total exposure of the is diamond-impregnated insert to temperatures above 1000° F. is greater than a total exposure of the shearing portion to temperatures above 1000 ° F."

Two Industrial Diamond Review (IDR) articles, one dated March 1992, and the other dated June 1993, disclose thermally stable pins (TSPs) in a diamond impregnated core bit.

,κ> European Patent No. 0391683 teaches "a rotatable crown for a rotary drill".

The inventions disclosed and taught herein are directed to an improved diamond impregnated drill bit with super-abrasive cutting elements for drilling wells in earth formations.

BRIEF SUMMARY OF THE INVENTION as The invention relates to a method of manufacturing a drill bit and several embodiments of a drill bit for drilling a well in an earth formation. In one embodiment, the drill bit comprises a diamond impregnated bit body with one or more thermally stable pins embedded therein. More specifically, the drill bit may include a diamond impregnated bit body having a plurality of blades, with se one or more of the blades having a cone section, a nose section, a shoulder section, and a gage section; a plurality of diamond impregnated cutters extending from the blades; and one or more thermally stable polycrystalline diamond pins embedded within, and possibly extending from, at least some of the cutters. In some embodiments, each cutter includes an embedded pin. Alternatively, the pin or pins may be located in the cone, shoulder, nose, and/or gauge sections.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS Figure 1 comprises an inverted perspective view of a first embodiment of a bit of the present invention;

Figure 2 is a top elevation of the bit of FIG. 1 after testing, showing wear of discrete cutting structures and PDC cutters;

Figure 3 is an enlarged perspective view of an exemplary cutting structure embodying certain aspects of the present inventions;

Figure 4 is an enlarged perspective view of another exemplary cutting structure embodying certain aspects of the present inventions;

Figure 5 is a partial cut-away view of a mold embodying certain aspects of the present inventions; and

Figure 6 is another partial cut-away view of a mold embodying certain aspects of the present inventions.

DETAILED DESCRIPTION

The Figures described above and the written description of specific structures and functions below are not presented to limit the scope of what Applicants have invented or the scope of the appended claims. Rather, the Figures and written description are provided to teach any person skilled in the art to make and use the inventions for which patent protection is sought. Those skilled in the art will appreciate that not all features of a commercial embodiment of the inventions are described or shown for the sake of clarity and understanding. Persons of skill in this art will also appreciate that the development of an actual commercial embodiment incorporating aspects of the present inventions will require numerous implementation-specific decisions to achieve the developer's ultimate goal for the commercial embodiment. Such implementation-specific decisions may include, and likely are not limited to, compliance with system-related, business-related, government-related and other constraints, which may vary by specific implementation, location and from time to time. While a developer's efforts might be complex and time- consuming in an absolute sense, such efforts would be, nevertheless, a routine undertaking for those of skill this art having benefit of this disclosure. It must be understood that the inventions disclosed and taught herein are susceptible to numerous and various modifications and alternative forms. Lastly, the use of a singular term, such as, but not limited to, "a," is not intended as limiting of the number of items. Also, the use of relational terms, such as, but not limited to, "top," "bottom," "left," "right," "upper," "lower," "down," "up," "side," and the like are used in the written description for clarity in specific reference to the Figures and are not intended to limit the scope of the invention or the appended claims.

Particular embodiments of the invention may be described below with reference to block diagrams and/or operational illustrations of methods. In some alternate implementations, the functions/actions/structures noted in the figures may occur out of the order noted in the block diagrams and/or operational illustrations. For example, two operations shown as occurring in succession, in fact, may be executed substantially concurrently or the operations may be executed in the reverse order, depending upon the functionality/acts/structure involved.

Applicants have created both a method of manufacturing a drill bit and several embodiments of a drill bit for drilling a well in an earth formation. In one embodiment, the drill bit comprises a diamond impregnated bit body with one or more thermally stable pins embedded therein. More specifically, the drill bit may include a diamond impregnated bit body having a plurality of blades, with one or more of the blades having a cone section, a nose section, a shoulder section, and a gage section; a plurality of diamond impregnated cutters extending from the blades; and one or more thermally stable polycrystalline diamond pins embedded within, and possibly extending from, at least some of the cutters. In some embodiments, each cutter includes an embedded pin. Alternatively, the pin or pins may be located in the cone, shoulder, nose, and/or gauge sections.

The present invention includes both a method manufacturing a drill bit and several embodiments of a drill bit 10 for drilling a well in an earth formation. The bit 10 may be similar to those disclosed in U.S. Patent No. 6,843,333, the disclosure of which is incorporated herein by specific reference in its entirety. Referring now to FIGs. 1 and 2, a first embodiment of the bit 10 of the present invention is depicted. In FIG. 1, the bit 10 is shown inverted from its normal face-down operating orientation for clarity. The bit 10 is, in one embodiment, 8 1/2" in diameter and includes a matrix-type bit body 12 having a shank 14 for connection to a drill string (not shown) extending therefrom opposite a bit face 16. A plurality of blades 18 extends generally radially outwardly in linear fashion to gage pads 20 defining junk slots 22 therebetween.

The bit 10 may include a plurality of discrete cutters. In one embodiment, the cutters include impregnated cutting structures 24 comprising posts extending upwardly from the blades 18 on the bit face 16. The cutting structures 24 may be formed as an integral part of the matrix-type blades 18 projecting from the matrix-type bit body 12 by hand-packing diamond grit-impregnated matrix material in mold cavities on the interior of a bit mold defining locations of the cutting structures 24 and blades 18. Thus, each blade 18 and associated cutting structure 24 may define a unitary structure. It is noted that the cutting structures 24 may be placed directly on the bit face 16, dispensing with the blades. It is also noted that, while discussed in terms of being integrally formed with the bit 10, the cutting structures 24 may be formed as discrete individual segments, such as by hot isostatic pressing, and subsequently brazed or furnaced onto the bit 10.

The discrete cutting structures 24 may be mutually separate from each other to promote drilling fluid flow therearound for enhanced cooling and clearing of formation material removed by the diamond grit. The discrete cutting structures 24 may be generally of a round or circular transverse cross-section at their substantially flat, outermost ends, but become more oval with decreasing distance from the face of the blades 18 and thus provide wider or more elongated (in the direction of bit rotation) bases for greater strength and durability. As the discrete cutting structures 24 wear, the exposed cross- section of the posts increases, providing progressively increasing contact area for the diamond grit with the formation material. As the cutting structures wear down, the bit 10 takes on the configuration of a heavier-set bit more adept at penetrating harder, more abrasive formations. Even if discrete cutting structures 24 wear completely away, the diamond-impregnated blades 18 will provide some cutting action, reducing any possibility of ring-out and having to pull the bit 10.

While the cutting structures 24 are illustrated as exhibiting posts of circular outer ends and oval shaped bases, other geometries are also contemplated. For example, the outermost ends of the cutting structures may be configured as ovals having a major diameter and a minor diameter. The base portion adjacent the blade 18 might also be oval, having a major and a minor diameter, wherein the base has a larger minor diameter than the outermost end of the cutting structure 24. As the cutting structure 24 wears towards the blade 18, the minor diameter increases, resulting in a larger surface area. Furthermore, the ends of the cutting structures 24 need not be flat, but may employ sloped geometries. In other words, the cutting structures 24 may change cross-sections at multiple intervals, and tip geometry may be separate from the general cross-section of the cutting structure. Other shapes or geometries may be configured similarly. It is also noted that the spacing between individual cutting structures 24, as well as the magnitude of the taper from the outermost ends to the blades 18, may be varied to change the overall aggressiveness of the bit 10 or to change the rate at which the bit is transformed from a light-set bit to a heavy-set bit during operation. It is further contemplated that one or more of such cutting structures 24 may be formed to have substantially constant cross-sections if so desired depending on the anticipated application of the bit 10. The discrete cutting structures 24, blades 18, and/or bit body 12 may comprise a synthetic diamond grit, such as, for example, DSN-47 Synthetic diamond grit, commercially available from DeBeers of Shannon, Ireland, which has demonstrated toughness superior to natural diamond grit. The tungsten carbide matrix material with which the diamond grit is mixed to form discrete cutting structures 24 and supporting blades 18 may desirably include a fine grain carbide, such as, for example, DM2001 powder commercially available from Kennametal Inc., of Latrobe, Pa. Such a carbide powder, when infiltrated, provides increased exposure of the diamond grit particles in comparison to conventional matrix materials due to its relatively soft, abradable nature. The base 30 of each blade 18 may desirably be formed of, for example, a more durable 121 matrix material, obtained from Firth MPD of Houston, Tex. Use of the more durable material in this region helps to prevent ring-out even if all of the discrete cutting structures 24 are abraded away and the majority of each blade 18 is worn.

It is noted, however, that alternative particulate abrasive materials may be suitably substituted for those discussed above. For example, the discrete cutting structures 24 may include natural diamond grit, or a combination of synthetic and natural diamond grit. Alternatively, the cutting structures may include synthetic diamond pins 28. Additionally, the particulate abrasive material may be coated with a single layer or multiple layers of a refractory material, as known in the art and disclosed in U.S. Pat. Nos. 4,943,488 and 5,049,164, the disclosures of each of which are hereby incorporated herein by reference in their entirety. Such refractory materials may include, for example, a refractory metal, a refractory metal carbide or a refractory metal oxide. In one embodiment, the coating may exhibit a thickness of approximately 1 to 10 microns. In another embodiment, the coating may exhibit a thickness of approximately 2 to 6 microns. In yet another embodiment, the coating may exhibit a thickness of less than 1 micron.

Alternatively, or additionally, one or more of the blades 18 may carry cutters in the form of polycrystalline diamond compact (PDC) cutting elements 26, in conventional orientations, with cutting faces oriented generally facing the direction of bit rotation. In one embodiment, the PDC cutting elements 26 are located within the cone portion 34 of the bit face 16. The cone portion 34, best viewed with reference to FIG. 1 , is the portion of the bit face 16 wherein the profile is defined as a generally cone-shaped section about the centerline of intended rotation of the drill bit 10. Alternatively, or additionally, the PDC cutting elements 26 may be located across the blades 18 and elsewhere on the bit 10.

The PDC cutting elements 26 may comprise cutters having a PDC jacket or sheath extending contiguously with, and to the rear of, the PDC cutting face and over a supporting substrate. For example, a cutter of this type is offered by Hughes Christensen Company, a wholly owned subsidiary of the assignee of the present invention, as NIAGARA™ cutters. Such cutters are further described in U.S. Pat. No. 6,401,844, the disclosure of which is incorporated herein by specific reference in its entirety. This cutter design provides enhanced abrasion resistance to the hard and/or abrasive formations typically drilled by impregnated bits, in combination with enhanced performance, or rate of penetration (ROP), in softer, nonabrasive formation layers interbedded with such hard formations. It is noted, however, that alternative PDC cutter designs may be implemented. For example, the PDC cutting elements 26 may be configured of various shapes, sizes, or materials as known by those of skill in the art. Also, other types of cutting elements may be formed within the cone portion 34 of, and elsewhere across, the bit 10 depending on the anticipated application of the bit 10. For example, the cutting elements 26 may include cutters formed of thermally stable polycrystalline diamond product (TSP), natural diamond material, or impregnated diamond.

While PDC cutting elements, such as those discussed above, are used in one embodiment, other cutters may be used alternatively and/or additionally. For example, cutters made of thermally stable polycrystalline (TSP) diamond, in triangular, pin, and/or circular configuration, cubic boron nitride (CBN), and/or other superabrasive materials may be used. In some embodiments, even simple carbide cutters may be used. An exemplary cutting structure 24 of the present invention, as shown in FIG. 3 and FIG. 4, includes a TSP pin 28 of circular, rectangular or other polygon, oval, truncated circular, triangular, or other suitable cross-section. The TSP pin 28, exhibiting a circular cross-section and an overall cylindrical s configuration, or shape, is suitable for a wide variety of drill bits and drilling applications. The TSP pins 28 are preferably embedded within the cutting structures 24. The TSP pins 28 may extend from the cutting structures 24. Additionally, or alternatively, the pins 28 may be embedded within, and may extend from, the blades 18 and/or bit body 12 themselves, with or without the to cutters and/or blades 18. Thus, the TSP pins 28 may extend from and/or through the cutters, blades 18, and/or bit body 12. As a result, as the TSP pins 28 retard wear of the cutters, blades 18, and/or bit body 12. Furthermore, the TSP pins 28 may stand out from the cutters, blades 18, and/or bit body 12, thereby giving higher point loading, before and/or after i5 wear of the cutters, blades 18, and/or bit body 12. In any case, the TSP pins 28 may make the cutters, blades 18, and/or bit body 12 more aggressive, thereby increasing ROP and/or decreasing the specific energy required.

As shown in FIG. 5 and FIG. 6, the drill bit 10 may be manufactured using a prepared mold 50. The mold 50 preferably has a bit body cavity 52 and may so have one or more blade cavities 54. The mold 50 may also have a plurality of cutter cavities 56 extending from the blade cavities 54 and/or bit body cavity 52, in cases where the cutters are to be integrally formed with the bit body 12 and/or blades 18. In cases where the cutters are to be formed separately, the mold 50 may only include one or more cutter cavities 56. In cases where the as blades 18 are to be formed separately, the mold 50 may include a plurality of cutter cavities 56 extending from one or more blade cavities 54. Finally, in cases where the pins 28 are to extend beyond the cutters, blades 18, and/or bit body 12, the mold 50 may include one or more pin cavities 58.

Once the mold 50 is properly prepared, the pins 28 are placed therein. Then, so a matrix material, such as a tungsten carbide matrix and/or a diamond grit- impregnated matrix material is packed into the mold 50. Finally, a binder material, such as liquefied copper, is allowed to flow into the mold, thereby forming the cutters, blades 18, and/or bit body 12.

It has been discovered that the blades 18 rarely wear evenly. Therefore, it may be desirable to optimize the design of the blades 18 and the distribution

5 and/or spacing of cutting material along the blades 18, to increase drill bit useful life and minimize the required specific energy while maintaining an acceptable rate of penetration and drilling efficiency. For example, the bit 10 may be designed to have more cutters and/or pins 28 in heavy, or high, wear areas. The bit 10 may also be designed such that the cutters and/or pins 28

1C exhibit an optimum bottom hole pattern for increasing ROP in one or more of types of formations.

The blades 18 of modern drill bits often have three or more sections that serve related and overlapping functions. Specifically, each blade 18 preferably has a cone section, a nose section, a shoulder section, and a gage i5 section. As discussed above, the cone section of each blade is preferably a substantially linear section extending from near a center-line of the drill bit 10 outward. Because the cone section is nearest the center-line of the drill bit 10, the cone section does not experience as much, or as fast, movement relative to the earth formation. Therefore, it has been discovered that the o cone section commonly experiences less wear than the other sections. Thus, the cone section can maintain effective and efficient rate of penetration with less cutting material. This can be accomplished in a number of ways. For example, the cone section may have no or fewer cutters, cutting structures 24, PDC cutting elements 26, and/or TSP pins 28, smaller cutters, cutting s structures 24, PDC cutting elements 26, and/or TSP pins 28, and/or more spacing between cutters, cutting structures 24, PDC cutting elements 26, and/or TSP pins 28. The cone angle for a PDC bit is typically 15-25°, although, in some embodiments, the cone section is essentially flat, with a substantially 0° cone angle.

JO The nose represents the lowest point on a drill bit. Therefore, the nose cutter is typically the leading most cutter. The nose section is roughly defined by a nose radius. A larger nose radius provides more area to place cutters in the nose section. The nose section begins where the cone section ends, where the curvature of the blade begins, and extends to the shoulder section. More specifically, the nose section extends where the blade profile substantially

5 matches a circle formed by the nose radius. The nose section experiences much more, and more rapid, relative movement than does the cone section. Additionally, the nose section typically takes more weight than the other sections. As such, the nose section commonly experiences much more wear than does the cone section. Therefore, the nose section preferably has a

10 higher distribution, concentration, or density of cutters, cutting structures 24, PDC cutting elements 26, and/or TSP pins 28 with respect to the cone section.

The shoulder section begins where the blade profile departs from the nose radius and continues outwardly on each blade 18 to a point where a slope of i5 the blade is essentially completely vertical, at the gage section. The shoulder section experiences much more, and more rapid, relative movement than does the cone section. Additionally, the shoulder section typically takes the brunt of abuse from dynamic dysfunction, such as bit whirl. As such, the shoulder section experiences much more wear than does the cone section.

20 The shoulder section is also a more significant contributor to rate of penetration and drilling efficiency than the cone section. Therefore, the shoulder section preferably has a higher distribution, concentration, or density of cutters, cutting structures 24, PDC cutting elements 26, and/or TSP pins 28 with respect to the cone section. Depending on application, the nose section

2s or the shoulder section may experience the most wear, and therefore either the nose section or the shoulder section may have the highest distribution, concentration, or density of cutters, cutting structures 24, PDC cutting elements 26, and/or TSP pins 28.

The gage section begins where the shoulder section ends. More specifically, m the gage section begins where the slope of the blade is predominantly vertical. The gage section continues outwardly to an outer perimeter or gauge of the drill bit 10. The gage section experiences the most, and most rapid, relative movement with respect to the earth formation. However, at least partially because of the high, substantially vertical, slope of the blade 18 in the gage section, the gage section does not typically experience as much wear as does the shoulder section and/or the nose section. The gage section does, s however, typically experience more wear than the cone section. Therefore, the gage section preferably has a higher distribution of cutters, cutting structures 24, PDC cutting elements 26, and/or TSP pins 28 than the cone section, but may have a lower distribution of cutters, cutting structures 24, PDC cutting elements 26, and/or TSP pins 28 than the shoulder section jo and/or nose section.

In one embodiment, a highest concentration of the cutters, cutting structures 24, PDC cutting elements 26, and/or TSP pins 28 occurs near the border between the shoulder section and the gage section. Alternative embodiments may include a highest concentration of the cutters, cutting structures 24, PDC !5 cutting elements 26, and/or TSP pins 28, in the shoulder section and/or the gage section.

Upon reading this disclosure, it can be appreciated that the design of a drill bit includes consideration of many factors, such as the size, shape, spacing, orientation, and number of blades; the size, shape, spacing, orientation, and 20 number of cutters, or cutting elements; as well as the materials of the bit body, blades, cutting tables, and substrates. All of these factors may be considered in light of the materials of the earth formation(s) for which the drill bit is designed and/or matched.

The bit 10 may employ a plurality of ports 36 over the bit face 16 to enhance

25 fluid velocity of drilling fluid flow and better apportion the flow over the bit face

16 and among fluid passages 38 between blades 18 and extending to junk slots 22. This enhanced fluid velocity and apportionment helps prevent bit balling in shale formations, for example, which phenomenon is known to significantly retard rate of penetration (ROP). Further, in combination with the a> enhanced diamond exposure of bit 10, the improved hydraulics substantially enhances drilling through permeable sandstones. Other and further embodiments utilizing one or more aspects of the inventions described above can be devised without departing from the spirit of Applicant's invention. For example, the TSP pins 28 may be embedded within the PDC cutting elements 26 as well. Additionally, or alternatively, the cutters, such as the impregnated cutting structures 24 and/or PDC cutting elements 26, with or without the TSP pins 28, may be formed separately from the bit body 12, and later secured thereto, such as by brazing. Similarly, the TSP pins 28 may be secured to, or within, previously formed cutters, blades 18, and/or the bit body 12. Furthermore, one, two, three, or more TSP pins 28 may be embedded within any one or more of the cutters. Of course, the various methods and embodiments of the drill bit 10 can be included in combination with each other to produce variations of the disclosed methods and embodiments. Reading this disclosure, it can be appreciated that there are a number of ways to impact concentrations or distributions of cutter and/or pin volume, such as by using differently sized, shaped, and/or spaced cutters and/or pins. Discussion of singular elements can include plural elements and vice-versa.

The order of steps can occur in a variety of sequences unless otherwise specifically limited. The various steps described herein can be combined with other steps, interlineated with the stated steps, and/or split into multiple steps. Similarly, elements have been described functionally and can be embodied as separate components or can be combined into components having multiple functions.

The inventions have been described in the context of preferred and other embodiments and not every embodiment of the invention has been described.

Obvious modifications and alterations to the described embodiments are available to those of ordinary skill in the art. The disclosed and undisclosed embodiments are not intended to limit or restrict the scope or applicability of the invention conceived of by the Applicants, but rather, in conformity with the patent laws, Applicants intend to fully protect all such modifications and improvements that come within the scope or range of equivalent of the following claims.

Claims

WHAT IS CLAIMED IS:

1. A method of manufacturing a drill bit having a diamond impregnated bit body and a plurality of cutters, such as for drilling into an earth formation, the s method comprising the steps of: preparing a mold having at least one cutter cavity for the cutters; placing at least one diamond pin in the cutter cavity; and forming the cutter around the pin, such that the pin is embedded within the cutter.

2. The method as set forth in claim 1, wherein the mold includes a body cavity for a bit body, a plurality of blade cavities for a plurality of blades extending beyond the bit body, and a plurality of cutter cavities for a plurality of cutters extending beyond the blades.

S 5

3. The method as set forth in claim 2, wherein the placing step includes placing a pin in each cutter cavity.

4. The method as set forth in claim 2, wherein at least some of the blade 2ϋ cavities have a cone section, a nose section, a shoulder section, and a gage section and wherein the placing step includes placing a pin in at least one cutter cavity in the cone section.

5. The method as set forth in claim 2, wherein at least some of the blade 25 cavities have a cone section, a nose section, a shoulder section, and a gage section and wherein the placing step includes placing a pin in at least one cutter cavity in the nose section.

6. The method as set forth in claim 2, wherein at least some of the blade R> cavities have a cone section, a nose section, a shoulder section, and a gage section and wherein the placing step includes placing a pin in at least one cutter cavity in the shoulder section.

7. The method as set forth in claim 2, wherein at least some of the cutter cavities include pin cavities, and wherein the placing step includes placing a pin in the pin cavity such that the pin extends beyond the cutter.

? 8. The method as set forth in claim 2, further including the step of selecting a pin long enough to extend through the cutter cavity and into the blade cavity.

9. The method as set forth in claim 1, further including the step ofs selecting a pin long enough to extend through the cutter cavity and into a bit body cavity.

10. The method as set forth in claim 1, further including the step of designing the mold to provide more pins in high wear areas of the bit. S

11. The method as set forth in claim 1, further including the step of designing the mold to provide an optimum pattern of pins for a type of formation. o

12. A drill bit, such as for drilling into an earth formation, the drill bit comprising: a bit body; a plurality of cutters; and at least one diamond pin embedded within at least one of the cutters.5

13. The drill bit as set forth in claim 12, wherein each cutter includes an embedded pin.

14. The drill bit as set forth in claim 12, wherein the bit body includes a0 cone section, a nose section, a shoulder section, and a gage section, and wherein the pin is located in the cone section.

15. The drill bit as set forth in claim 12, wherein the bit body includes a cone section, a nose section, a shoulder section, and a gage section, and wherein the pin is located in the nose section.

s 16. The drill bit as set forth in claim 12, wherein the bit body includes a cone section, a nose section, a shoulder section, and a gage section, and wherein the pin is located in the shoulder section.

17. The drill bit as set forth in claim 12, wherein the bit body includes ao plurality of blades, at least one of the blades having a cone section, a nose section, a shoulder section, and a gage section, and wherein at least one cutter in the cone section includes the pin.

18. The drill bit as set forth in claim 12, wherein the bit body includes as plurality of blades, at least one of the blades having a cone section, a nose section, a shoulder section, and a gage section, and wherein at least one cutter in the nose section includes the pin.

19. The drill bit as set forth in claim 12, wherein the bit body includes a0 plurality of blades, at least one of the blades having a cone section, a nose section, a shoulder section, and a gage section, and wherein at least one cutter in the shoulder section includes the pin.

20. The drill bit as set forth in claim 12, wherein the pin extends beyond thes cutter.

21. The drill bit as set forth in claim 12, wherein the pin extends both above and below the cutter. e

22. The drill bit as set forth in claim 12, wherein there are more pins in high wear areas of the bit.

23. The drill bit as set forth in claim 12, wherein the pins form an optimum pattern for a type of formation.

24. A drill bit, such as for drilling into an earth formation, the drill bit comprising: a diamond impregnated bit body having a plurality of blades, at least one of the blades having a cone section, a nose section, a shoulder section, and a gage section; a plurality of diamond impregnated cutters extending from the blades; and a thermally stable polycrystalline diamond pin embedded within at least some of the cutters in the shoulder section.