Blunt-nosed roller cone hybrid bit

Abstract

A roller cone for a drill bit that is configured with a number of different inserts thereon. The roller cone is also configured to have a blunted nose region where the blunted nose region is positioned radially away from a central or rotational axis of a drill bit thereby allowing for additional fixed blade cutting elements to be positioned closer to the central or rotational axis of the drill bit.

Description

TITLEBLUNT-NOSED ROLLER CONE HYBRID BITCROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to and the benefit of United States Provisional Patent Application No. 63 / 662,618, filed June 21, 2024, entitled “BLUNT-NOSED ROLLER CONE HYBRID BIT”, the disclosure of which is incorporated herein by reference in its entirety.BACKGROUND

[0002] The majority of footage drilled in an earth formation uses a plurality of fixed cutting elements to scrape and fracture rock and other material in the downhole environment. The torque experienced by the cutting elements of the drill bit varies with the radial position of the cutting element as well as the depth of cut and strength of the formation. The various positions of the cutting elements can have an impact on the cutting efficiency of the bit and overall process.

[0003] Well bore drill bits can be configured in a variety of different configurations that can include fixed inserts, moving elements, or a combination of fixed and moving elements. The various configurations can be based on the formation in which drilling is to take place. Cutting efficiency is highly important to improve the time it takes to drill the wellbore and produce the oil and gas needed. Accordingly, there is a need to develop improved drill bits and drill bit components to aid in the overall efficiency of the system.SUMMARY

[0004] Many embodiments are directed towards a roller cone with a body concentrically formed around a cone axis, the body extending from an outer region to a nose region, wherein the nose region is positioned radially outward from a point along the cone axis at a distance such that the nose region has a blunted cross-sectional shape. The blunted cross-sectional shape is configured to contact a formation with a wider surface area. The cone also has a plurality of inserts disposed on the body of the roller cone and a plurality of cutting elements disposed on the nose region, wherein at least one of the plurality of cutting elements has at least one cutting edge.

[0005] In other embodiments, the plurality of inserts on the body are crushing inserts

[0006] In yet other embodiments, at least a second of the plurality of cutting elements has more than one cutting edge.

[0007] In still yet other embodiments, at least a second of the plurality of cutting elements has three cutting edges.

[0008] In other embodiments, at least a second of the plurality of cutting elements has four or more cutting edges.

[0009] In yet other embodiments, the at least one cutting edge is a continuous cutting edge.

[0010] In still yet other embodiments, the blunted cross-sectional shape is selected from a group consisting of concave, convex, flat, and variable spline.

[0011] Other embodiments are directed towards a roller cone for a drill bit with a body concentrically formed around a cone axis, the body extending from an outer region to a nose region, wherein the nose region is positioned radially outward from a point along the cone axis at a distance such that the nose region has a blunted cross-sectional shape. The blunted cross- sectional shape is configured to contact a formation with a wide surface area. The bit also has a plurality of inserts disposed on the body of the roller cone and a plurality of cutting elements disposed on the nose region, wherein the plurality of cutting elements comprises at least one cutting element with a continuous cutting edge and at least a second cutting element with at least one cutting edge.

[0012] In other embodiments, the cone has at least a third cutting element disposed on the nose region, wherein the at least a third cutting element has more than one cutting edge.

[0013] Other embodiments are directed towards a drill bit with a bit body having a rotational axis. A roller cone supported by the bit body, the roller cone including: a nose region, the nose region being positioned radially back from the rotational axis at a distance thereby forming a wide surface area and a blunted design. The nose region further comprises a plurality of cutting elements arranged thereon. At least one of the plurality of cutting elements has at least one cutting edge. The bit also has a first fixed blade fixed relative to the bit body with fixed blade cutting elements affixed thereto radially overlapping at least the first central region.

[0014] In yet other embodiments, the bit has at least a second roller cone. The at least second roller cone further being supported by the bit body. The at least second roller cone includes_a second cone nose region, the second cone nose region being positioned radially back from the rotational axis thereby forming a wide surface area and a blunted design. The second cone nose region furthercomprises at least one cutting element arranged thereon, at least one cutting element having at least one cutting edge.

[0015] In still yet other embodiments, the roller cone further comprises a plurality of inserts on a roller cone body.

[0016] In other embodiments, the plurality of inserts are crushing inserts.

[0017] In yet other embodiments, the at least second roller cone comprises a plurality of second cone inserts on a second roller cone body.

[0018] In still yet other embodiments, the plurality of second cone inserts are crushing inserts.

[0019] In other embodiments, at least a second of the plurality of cutting elements has more than one cutting edge.

[0020] In yet other embodiments, the at least a second of the plurality of cutting elements has three cutting edges.

[0021] In still yet other embodiments, the at least a second of the plurality of cutting elements has four or more cutting edges.

[0022] In other embodiments, the at least one cutting edge is a continuous cutting edge.

[0023] In yet other embodiments, the distance of the nose region is at least 10% of a drill bit body diameter.

[0024] This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

[0025] Additional features and aspects of embodiments of the disclosure will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of such embodiments. The features and aspects of such embodiments may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features will become more fully apparent from the following description and appended claims or may be learned by the practice of such embodiments as set forth hereinafter.BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to describe the manner in which the above-recited and other features of the disclosure can be obtained, a more particular description will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. For better understanding, the like elements have been designated by like reference numbers throughout the various accompanying figures. While some of the drawings may be schematic or exaggerated representations of concepts, non-schematic drawings should be considered as being to scale for some embodiments of the present disclosure, but not to scale for other embodiments contemplated herein. Understanding that the drawings depict some example embodiments, the embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0027] Fig. 1 illustrates an embodiment of a drilling system and downhole environment in which a drill bit, according to the present disclosure, may be used.

[0028] Fig. 2A and 2B illustrate a bottom view of a hybrid roller cone drill bit in accordance with embodiments.

[0029] Figs. 3 A and 3B illustrate a bottom view of a hybrid roller cone drill bit in accordance with embodiments.

[0030] Fig. 4 illustrates a side view of a hybrid roller cone drill bit with a pointed nose geometry in accordance with embodiments.

[0031] Fig. 5 illustrates a side profile view of a roller cone with a blunted nose geometry in accordance with embodiments.

[0032] Fig. 6 illustrates a cutter profile of a roller cone in accordance with embodiments.

[0033] Fig. 7 illustrates a side view of a roller cone and a center jet nozzle in accordance with embodiments.

[0034] Fig. 8 illustrates a bottom view of a roller cone profile in accordance with embodiments.

[0035] Fig. 9 illustrates a bottom view of a roller cone profile with various cutting elements in accordance with embodiments.

[0036] Fig. 10 illustrates a side profile view of a roller cone with various cutting elements in accordance with embodiments.

[0037] Figs. 11A and 11B illustrate profile views of a cutter for use in a drill bit in accordance with embodiments.

[0038] Figs. 12A through 18B illustrate various embodiments of a cutter with different cutting edges.DETAILED DESCRIPTION

[0039] Embodiments of the present disclosure generally relate to devices, systems, and methods for drilling in an earth formation. More particularly, some embodiments of the present disclosure relate to hybrid drill bits for degrading and / or removing material from the earth formation. In some embodiments, a drill bit includes a roller cone and a fixed blade in sequence to crack, crush, deform, or otherwise degrade the material of the earth formation before removing the degraded material. In some embodiments, the roller cone rolls across a surface of the formation material of the earth formation to apply a compression force and / or a shear force to degrade the formation material into a degraded material, and the fixed blade drags across or through the degraded material to remove at least a portion of the degraded material.

[0040] In some embodiments, a drill bit according to the present disclosure includes a bit body with a rotational axis. The roller cone is supported by the bit body and rotatable around a cone axis that is oriented substantially radially to the rotational axis of the bit body, such that the roller cone rotates around the cone axis while the bit body rotates around the rotational axis. In some embodiments, the drill bit may further include a fixed blade that is fixed relative to and / or integrally formed with the bit body. The roller cone and the fixed blade each may include a plurality of cutting elements affixed thereto. In various embodiments, the cutting elements affixed to the roller cone may be located closest to the rotational axis of the drill bit such that they are closer to the axis than those on the fixed blade.

[0041] In many embodiments, the roller cone may have a plurality of regions in the axial direction of the cone axis (i.e., the axis around which the roller cone rotates as the bit body rotates around the rotational axis). In some embodiments, the roller cone may include a innermost region proximate to a first axial end of the cone axis and proximate to the rotational axis of bit body, where the innermost region may have a blunted profile. In other words, various embodiments may have a roller cone profile in which the innermost region is positioned radially outward along the roller cone axis away from the bit axis such that the arc formed by the nose region is of a larger radius. In many embodiments, the innermost region positioned radially outward along the rollercone axis may have a profile that is blunted or have a wider cross-sectional profile from that of a traditional roller cone.

[0042] Roller cone bits, including hybrid bits, have been in practice for some time. Roller cone bits often include one or more moving or rolling cone elements. The roller cone elements can have a variety of different cutting elements disposed thereon that traditionally have been used for crushing the formation in which the drill bit contacts. The crushing inserts are often pointed, or conical in shape and designed to break up the formation. In some hybrid configurations the drill bit may have fixed blades attached to or formed as part of the bit body. The fixed blades are often configured with multiple cutting elements that are designed to cut away the formation rather than crush it. Accordingly, such fixed blade cutting elements tend to be made from an ultrahard material, thus allowing for hybrid bits to do both crushing and cutting.

[0043] More traditional roller cone and hybrid drill bits often only use the ultrahard cutting elements on the fixed blade portions while reserving the crushing type inserts for the roller cone. As such many of the more traditional designs fail to take advantage of improved designs in which roller cones can be configured with more than just crushing inserts. For example, in some cases a drilling bit that is configured with one or more rolling cones can be prone to stalled movement or a situation in which the roller cone stops rolling during the movement of the drill bit. As such, the roller cone will be stuck in a position in which the crushing inserts are in a fixed position and are no longer performing the task at which they are designed. This can cause undue wear on the roller cone as well as increased torque on the bit and any fixed blade inserts of the bit.

[0044] Additionally, many traditional roller cone drill bits have cutting elements positioned near a central axis of the drill bit. These traditional roller cone configurations offer less efficient cutting or crushing near the central axis of the drill bit making the use of such less desirable, because the drill bit can lose efficiency in the drilling process.

[0045] Accordingly, many embodiments described herein have improved designs of the roller cones to include improved cutting profiles and improved roller cone profiles that improve the effective cutting capabilities of the roller cone, both near the central axis as well as on an outer surface or shoulder region. Some embodiments can allow for the use of PDC cutting elements in combination with crushing inserts, where various embodiments can include PDC cutting elements located close to the tip of the roller cone. These configurations can allow a roller cone element ofa drill be to have multiple functions as well as allow for continued cutting capabilities in the event of a stalled cone.

[0046] As will be described in more detail herein, a drill bit experiences the greatest torque from cutting elements in a portion or region of the drill bit often referred to as the shoulder region or areas or regions axially located close thereto in the cutting profile of the drill bit. In some embodiments, more aggressive degrading of formation material by the roller cone can reduce the torque experienced at the shear cutting elements of the fixed blades of the drill bit. In various embodiments, the roller cone profile may be configured with various PDC cutting elements having a variety of different cutting edge configurations that allow for improved cutting capabilities of the roller cone or roller cones. Additionally, in many embodiments, the roller cone(s) can have a roller cone cross sectional profile in which the inner most tip located radially outward from a central axis of the drill bit such that the cross sectional profile has a blunted design.

[0047] In some embodiments, the roller cone regions can be at least partially aligned with the dimensions and / or positions of the primary, secondary, and tertiary fixed blades. In some embodiments, a drill bit, according to the present disclosure can remove material in challenging earth formations with greater drilling rate, less torque, greater weight-on-bit, less wear or damage to the drill bit, or any combinations thereof relative to conventional drag bits or fixed blade drill bits.

[0048] FIG. 1 illustrates an embodiment of a drilling system and downhole environment in which a drill bit, according to the present disclosure may, be used. FIG. 1 shows one example of a drilling system 100 for drilling an earth formation 101 to form a wellbore 102. The drilling system 100 may include a drill rig 103 used to turn a drilling assembly 104 which extends downward into the wellbore 102. The drilling assembly 104 may include a drill string 105 and a bottomhole assembly (BHA) 106 attached to the downhole end of the drill string 105. Where the drilling system 100 is used for drilling formation, a drill bit 110 can be included at the downhole end of the bottom hole assembly or BHA 106.

[0049] The drill string 105 may include several joints of drill pipe 108 connected end-to-end through tool joints 109. The drill string 105 transmits drilling fluid through a central bore and can transmit rotational power from the drill rig 103 to the BHA 106. In some embodiments, the drill string 105 may further include additional components such as subs, pup joints, etc. The drill pipe 108 provides a hydraulic passage through which drilling fluid 111 is pumped from the surface.The drilling fluid 11 1 discharges through selected-size nozzles, jets, or other orifices in the bit 1 10 for the purposes of cooling the bit 110 and cutting structures thereon, for lifting cuttings out of the wellbore 102 as it is being drilled, and for preventing the collapse of the wellbore 102. The drilling fluid 111 carries drill solids including drill fines, drill cuttings, and other swarf from the wellbore 102 to the surface. The drill solids can include components from the earth formation 101, the drilling assembly 104 itself, from other man-made components (e.g., plugs, losttools / components, etc.), or combinations thereof.

[0050] The BHA 106 may include the bit 110 or other components. An example BHA 106 may include additional or other components (e.g., coupled between to the drill string 105 and / or the bit 110). Examples of additional BHA componentsbe include drill collars, stabilizers, measurementwhile-drilling (MWD) tools, logging-while-drilling (LWD) tools, downhole motors, underreamers, directional steering tools, section mills, hydraulic disconnects, jars, vibration dampening tools, other components, or combinations of the foregoing.

[0051] In general, the drilling system 100 may include other drilling components and accessories, such as special valves (e.g., kelly cocks, blowout preventers, safety valves, centrifuges, shaker tables, and rheometers). Additional components included in the drilling system 100 may be considered a part of the surface system (e.g., drill rig 103, drilling assembly 104, drill string 105, or a part of the BHA 106, depending on their locations and / or use in the drilling system 100).

[0052] The bit 110 in the BHA 106 may include any features or elements suitable for degrading downhole materials. For instance, the bit 110 may be a drill bit suitable for drilling the earth formation 101. While embodiments of a drill bit 110 for drilling the earth formation 101 will be described herein, it should be understood that, in some embodiments, features described herein are applicable to a mill used for removing metal, composite, elastomer, other materials downhole, or combinations thereof. For instance, the bit 110 may be used with a whipstock to mill into casing 107 lining the wellbore 102. The bit 110 may also be a junk mill used to mill away tools, plugs, cement, other materials within the wellbore 102, or combinations thereof. Swarf or other cuttings formed by use of a mill may be lifted to surface by the drilling fluid 111 or may be allowed to fall downhole. The conditions of the equipment of the drilling system 100, the formation 101, the wellbore 102, the drilling fluid 111, or other parts of the wellsite can change during operations.

[0053] Figs. 2A and 2B illustrate a bottom view of a hybrid drill bit 210 with a roller cone 212 and a fixed blade 213. The roller cone 212 is often made up from a body portion 214 concentricallyformed around a cone axis 215. The body 213 of the roller cone(s) can have an radially positioned outer region 216 and a radially positioned inner region 217. The radially positioned inner region217 can be referred to as a nose region. The nose region 217 can be positioned near a central axis218 about which the drill bit 210 can rotate. Additionally, the roller cone(s) 212 can have a number of different inserts 220 disposed on the body 214 and in the nose 217 and / or outer 216 regions.

[0054] The roller cone 212 may be supported by a bit body 222 or by any suitable connection to the bit body 222. As the bit body 222 rotates around the central rotational axis 218 of the drill bit 210, contact between the roller cone 212 and the formation material produces a rotation of the roller cone 212 around the cone axis 214. The cone axis 214 and subsequently the roller cone 212, may be oriented in such a way that the roller cone 212 is configured to interact with the formation. As can be appreciated the position and angle of the roller cone 212 on the cone axis 214 can help to increase the shear force between the cutting elements 220 on the roller cone 212 to reduce the torque on bit (TOB) and torque that is seen by the fixed blades 224. Various embodiments of a hybrid drill bit 210 can improve the wear life of the drill bit by having a roller cone 212 in which the roller cone cutting elements 220 can be configured on the roller cone in such a way that improves material removal and aids the fixed blade cutting elements 226. As can be seen in Figs. 2A and 2B , the roller cone(s) 212 have a more pointed nose portion 217 in which the cone cutting elements 220 can be configured to be close to the central axis of the bit 218. In other words, the nose region 217 is narrow and forms a narrow conical cross section.

[0055] Figs. 2A and 2B further illustrate that the center most, inner most, or nose region 217 positioned close to the central axis 218 of the drill bit 210. This, thereby, can position at least one roller cone cutting element 220 closer to the central axis 218 than the fixed blade cutting elements 226. As described previously, the central or nose region 217 can often be the least efficient cutting portion of a roller cone 212. As such, hybrid drill bits, similar to those illustrated in Figs. 2A and 2B, offer further room for development to improve the cutting efficiency of the drill bit.

[0056] Referring now to Figs. 3A and 3B, various embodiments, are directed to a hybrid drill bit 310 with improved roller cone(s) 312 that offers improved cutting efficiencies within the central portion of the drill bit. Fig. 3A, for example, illustrates a conceptual bottom view of a hybrid drill bit 310 with one or more roller cones 312 and one or more fixed blades 314. Unlike the roller cones illustrated in Figs. 2A and 2B, embodiments illustrated in Figs. 3A and 3B can have roller cones 312 with a nose section 316 that has a blunted profile. In other words, many embodimentsof the roller cone nose section 316 can have an radial point or radial face 318 located at a distance 320 radially away or back from the central axis 322 and where the radial face 318 is not as pointed or has a wider profile than a traditional roller cone. In many such embodiments the radial face 318 has an arc that has a larger radius than a more traditional roller cone. Additionally, in various embodiments of the roller cone 312, the nose section 316 can be radially outward from the central axis 322 along a cone axis 323. Accordingly, such embodiments can allow for the fixed blade cutting elements 324 to be located closer to the central axis 318 than the roller cone cutting elements 326. This configuration can allow for the fixed blade cutting elements 324 to continue to cut into the formation during the drilling process, thus allowing for more efficient operation. Furthermore, the roller cone cutting elements 326 can be configured such they reduce the risk of core out if the cones 312 stall during the drilling process, thus allowing for continued material removal.

[0057] Although illustrated with a planar configuration, it can be understood that the nose section 316 that has a blunted appearance, can have any suitable configuration. For example, some embodiments of the blunted nose region 316 may be concave, convex, flat, variable spline, etc. In some embodiments of a hybrid drill bit 310 one of the roller cones 312 can have a nose region 316 that are the same shape or configuration, while other embodiments may have a combination of shapes.

[0058] It should be readily appreciated, that various embodiments of a hybrid drill bit 310 and drill bit body 328 may be manufactured with any suitable method such as machining or forming using matrix powders. In numerous embodiments, the fixed blades 314 may be formed as part of the bit body 328 during the bit formation. Additionally, it can be appreciated, that the roller cones 312 can be connected to the bit body 328 by any suitable means that will allow for the roller cones to rotate about their axis 323 during the drilling process. For example, some embodiments may include a separate roller cone attachment mechanism that can be connected to the bit body 328 after the forming process. Other embodiments may have a mechanical connection that is formed as part of the bit forming process.

[0059] As can be appreciated, many embodiments of a drill bit can have any variety of configurations of roller cones and / or combinations of roller cones and fixed blades. As illustrated in Figs. 3A and 3B, some embodiments of a drill bit can have multiple fixed blades 314 combined with multiple roller cones 312. The roller cones 312 can be positioned within an outer diameter330 of the drill bit that may be any desired diameter. For example, the diameter may be 8 Vi or larger or 16” or larger. Regardless of the size, the roller cones 312 can be further configured in any suitable pattern or configuration within the diameter to enable the most efficient drilling performance from the drill bit 310. For example, in some embodiments of the drill bit, the roller cones 312 can be positioned on opposing sides drill bit 310. The roller cones 312 may be 180° apart or may be less or more than 180° depending on the overall geometry of the drill bit 310.

[0060] Referring now to Fig. 4, a cross sectional profile of a more pointed roller cone element 410 is illustrated. As can be seen the nose section / region 412 of the roller cone 410 is more conical and pointed in nature such that the roller cone cutting elements 414 are positioned to contact the formation 416 at the nose region 412 rather than any of the fixed blade cutting elements 418 contacting the formation 416 at the central location of the drill bit. If a line is drawn along the cone axis 420 to the formation 416 and extended beyond, it can be seen that a distance 422 from a point on the axis to the nose 412 is much smaller than a distance 424 from a point to the fixed blade cutting elements 422.

[0061] In contrast, Fig. 5 illustrates an embodiment of an improved roller cone 510, via a cross sectional view, with a blunted nose section 512. In numerous embodiments, the roller cone can have a more blunted nose 512 section which has a larger or less pointed cross-sectional profile. It can be appreciated that the nose section 512 is formed of an arc that has a larger radius than a traditional roller cone; causing the roller cone to have a blunted appearance. Accordingly, many embodiments can configure the cone cutting elements 514 to be more spread out on the nose section 512 or have room for more cutting elements since the face 515 and arc is larger. Such configurations can allow for the fixed blade cutting elements 516 to be positioned much closer to the central axis 518 of the drill bit. This allows for improved cutting efficiency during the drilling process because the fixed blade cutting elements 516 will be positioned to cut in or near the central axis 518 as the bit rotates without relying on the roller cone cutting elements 514. This can be illustrated by a distance 520 from the cone axis 522 to the first roller cone cutting element 514 being close to a distance 524 from the cone axis 522 to the fixed blade cutting elements 516. As should be readily understood, many embodiments may have varying distance 524 from the cone axis 522 that accommodates or creates a blunted nose portion 512 of the roller cone 510. This distance 524 can be any suitable distance. In some embodiments, the distance may be 10% of the bit diameter. In other embodiments it may be less than or more than 10% of the bit diameter.Additionally, it should be appreciated that having a blunted nose region 512 can allow for additionally types of cutting elements to be positioned thereon to improve the cutting efficiency of the roller cone in the event of a stalled roller cone.

[0062] Notwithstanding, many embodiments of the roller cone 510 can also be configured with a variety of different cutting elements or cutting elements 514. For example, some embodiments may have a combination of conical inserts 526 that are designed for crushing the formation 528. Other embodiments may have shear cutting elements 530 that are designed for cutting and removing material from the formation, similar to those on the fixed blade. As can be appreciated, many embodiments may include a mixture of cutting elements 514 on the roller cone to allow the roller cone 510 to perform a variety of functions. Additionally, it should be understood that a roller cone 510 with ultrahard and / or shear cutting elements is advantageous over traditional roller cones because the shearing cutting elements 530 can help to reduce the risk of core-out if the cone 510 stalls or stops rotating about the cone axis 522. Core-out, as recognized within the industry is a term used when the roller cone stops rotating during the rotation of the drill bit and the cutting elements near the center of the bit are wore down. This tends to reduce the effectiveness of the roller cone in the typical crushing capabilities. Therefore, roller cones, in accordance with the many embodiments described herein, can continue to be effective tools in the event a stall.

[0063] Fig. 6 illustrates an overlay of a hybrid drill bits cutting elements, both fixed blade and roller cone. In many embodiments, a blunted nose design of a roller cone can position a fixed blade cutting element 610 within the nose region 612 of the roller cone such that the fixed blade cutting inert 610 can operate with any cutting elements of the roller cone nose region 614. Similar to other embodiments described above, this positioning of the fixed blade cutting elements 610 within the nose cutting region 612 can improve the efficiency of the drill bit by ensuring that a shear cutting element is always near the central axis 616 of the drill bit.

[0064] There are various advantages to having a blunt nosed roller cone or roller cones on a hybrid bit. In various embodiments, the bit can have a central or center-jet nozzle as illustrated in Fig. 7. The center-jet nozzle 710, in many embodiments, can be configured to provide a flow of fluid 712 along a path towards numerous cutting elements. The flow of fluid 712 is used to help clear debris from the formation that has been cut away or removed. The removal or clearing of the debris can help preserve or prolong the life of the cutting elements on both the fixed blade(s) as well as the roller cone(s). In many embodiments, the flow of fluid 712 can be better directed towards thosecutting elements 714 that are positioned within a nose region 716 of the roller cone(s) 718 as well as those that may overlap the nose region from the fixed blade(s) 720.

[0065] Figs. 8 and 9 illustrate bottom views of a roller cone nose region with various types and configurations of cutting elements in the roller cone blunted nose region. For example, Fig. 8 illustrated a nose region on a first roller cone 810 having at least three cutting elements 812. The second roller cone 814 can have one or more cutting elements 816. It can be appreciated that any suitable cutting element can be used in the roller cone nose region. For example, some embodiments may use crushing elements, shearing elements, scraping type elements, or any combination thereof. Crushing elements can be referred to as elements that are designed to break up the formation or loosen the formation. Shearing cutting elements can be considered cutting elements that have an edge or cutting edge that is designed to cut into a formation and remove material . Traditional conical inserts are designed to crush the formation. In other words, the conical inserts help soften the formation so that shearing type cutting elements can remove the material. As described throughout this document, there are various advantages to having a blunt nosed roller cone with shear cutting elements in the nose region.

[0066] In some embodiments of a hybrid drill bit, the roller cone 814 can be protected by the use of additional inserts that are placed on or near the fixed blades 818. For example, various embodiments may have an insert 820 located radially inward and close to the central port 822 of the drill bit. This centrally located insert can help to protect the fixed blades and fixed blade cutting elements during the drilling operations. It should be appreciated, that the insert 820 can any suitable configuration and any suitable shape. For example, some embodiments of the insert may be a crushing insert while other embodiments may be a shear cutting element. As should be readily appreciated, the insert or cutting element 820 can have any combination of shearing, gouging, or crushing geometries based on the kinematics and engagement direction with the formation.

[0067] As should be appreciated, the blunt nose design of a roller cone can add additional surface area in which to install multiple cutting elements. For example, Fig. 9 illustrates a first roller cone 910 with a plurality of shear cutting elements 912 in the nose region 914. Additionally, many embodiments may have a variety of configurations of inserts on the roller cone 910 such as additional crushing inserts 916 positioned on a body portion or outer portion of the roller cone. The shear cutting elements in many embodiments can have one or more cutting edges. For example, the shear cutting elements 912 in Fig. 9 have multiple cutting edges 918. Multiple cuttingedges 918 can be advantageous over other shear cutting elements, especially when located on a roller cone. For example, if the roller cone were to stall, then a cutting element with multiple cutting edges can help to ensure a greater likelihood that roller cones are still able to cut and remove material from the formation. This is because there are more likely to be one or more cutting edges 918 that are positioned such that the edges are effectively removing material regardless of stalled cone orientation. This can prevent core-out and undue wear that would commonly occur if only conical inserts were in the nose region.

[0068] As can be appreciated, embodiments of a roller cone with a blunted nose region can have a variety of different combinations. For example, Fig. 10 illustrates a side view of a roller cone 1010 with a blunted nose region 1012. In the blunted nose region 1012 are a number of shear cutting elements 1014; each having numerous cutting edges, in accordance with many embodiments. Additionally, various embodiments can have rows or any suitable arrangement of conical inserts 1016 positioned on the body of the roller cone 1018 such that the conical inserts may extend radially outward to the outside most region 1020 of the roller cone. It should be understood that the configuration of either shear cutting elements 1014 and / or conical inserts can have any configuration on the roller cone and that such a configuration can be based on any number of desired characteristics and capabilities of the roller cone. For example, some embodiments may configure the conical inserts in a pattern that has higher and lower density regions that may be based on the formation as well as the desired output from the drill bit. Likewise, the shear cutting elements, can have any suitable arrangement on the nose region such that they are configured to produce the desired output within a particular formation. It should also be readily understood that the shear cutting elements that may be configured on the blunted nose region of a cone can be any combination of cutting elements. For example, some embodiments may have one or more omnidirectional cutting elements. Said embodiments may also combine the omnidirectional cutting elements with those that have two or more cutting edges. Thereby creating a unique configuration of cutting elements on the nose region of a roller cone.

[0069] In accordance with many embodiments, the shear cutting elements can have any suitable configuration and shape with any number of different cutting edges. To better understand the concept of a cutting edge, Figs. 11A and 11B, illustrate a variety of different cutting element profiles to help illustrate a cutting edge and where one may be found on a cutting element in accordance with numerous embodiments. The cutting edge can be defined as any portion of thecutting element that has a defined transition creating an angle between two faces. In terms of function, a cutting edge can be defined as any edge that is intended to remove formation material by scraping. Geometrically, this can be done where any two adjacent surfaces or lines form an angle between the two surfaces. For example, Fig. 11A illustrates several cutting elements 1110 with different profiles. Each profile illustrates an angle 1112 between two adjacent surfaces 1113a and 1113b or faces that can form a cutting edge 1114. As illustrated, cutting elements 1110 can have a second cutting edge 1115 formed by a second angle 1116 and two adjacent surfaces 1117a and 1117b. As can be appreciated, many embodiments of cutting elements may have multiple cutting edges formed by one or more angles between surfaces. In accordance with many embodiments the angle formed between the two adjacent faces can be any suitable angle or may fall within a range of angles. Some preferred embodiments may have an angle of 110 ° between faces. Some embodiments may have a smaller angle or a larger angle depending on the formation.

[0070] In various embodiments of a cutting element, a cutting edge may also be represented by two adjacent lines that may be separated by a bevel, chamfer, or even a small radius. For example, Fig. 11B illustrates two cross sectional profdes of cutting elements 1110 that have two adjacent surfaces 1120a and 1120b separated by a small radius or chamfer or bevel 1122. Each of the two adjacent surfaces 1120a and 1120b still maintaining a defined angle between them such that the small bevel, chamfer, or radius, forms the cutting edge capable of removing formation material. The bevel, chamfer, and / or radius can be any size that is suitable to maintain a cutting edge. Some embodiments may have a size up to 0.100 in or it may be smaller than 0.090 in. As can be appreciated, many embodiments of cutting elements can have any number of different cutting edges and any combination of different cutting edges within a single cutting element to provide a highly efficient cutting element.

[0071] Figs. 12A through 18A illustrate various embodiments of cutting elements that can be used in any number of configurations. Additionally, it should be understood that the cutting elements can be used in the blunted nose portion of a roller cone or a fixed blade or both. Figs. 12A and 12B illustrate an embodiment of a cutting element 1200 with at least two cutting edges 1210 defined by a cutting ridge 1212 spanning the diameter of the cutting element between the cutting edges. 1210. Figs. 13A and 13B illustrate an embodiment of a cutting element 1300 with three defined cutting edges 1310. Figs. 14A and 14B illustrate an embodiment of a cutting element 1400 that has at least five cutting edges 1410. It should be understood that embodiments of cutting elementscan have any number of cutting edges. Additionally, in various embodiments the cutting edges can be symmetrical or asymmetrical. For example, Figs. 15A and 15B illustrate an embodiment of a cutting element 1500 with an asymmetrical configuration of three distinct cutting edges 1510.

[0072] Furthermore, many embodiments of cutting elements can have a continuous or multiple continuous cutting edges. For example, Fig. 16A and 16B illustrate an embodiment of a cutting element 1600 with a single continuous cutting edge 1610 and a sloping internal surface 1612 that slopes away from cutting edge towards a central axis of the cutting element 1600. This can create a concave type of upper surface that can allow for material to be scooped away as it is removed from the formation. Although illustrated as a concave design, other embodiments of a cutting element with a continuous cutting edge can have a convex surface or flat surface.

[0073] Effectively, the continuous cutting edge can be considered an omnidirectional cutter because it would perform its cutting functions in any orientation. Additionally, embodiments with continuous cutting edges can aid in a roller cone configuration in the event of a cone stall. This is because it would ensure that a cutting edge is always positioned to contact the formation regardless of the rotational point of a roller cone. Although illustrated with a concave central portion, some embodiments may have a singular cutting edge with flat upper surface where the sides of the insert slope upward and inward toward the flat upper surface. Similarly, Figs. 17A and 17B illustrate an embodiment of a cutting element 1700 with multiple continuous cutting edges 1710-1714. These can improve the cutting efficiency of a drill bit by having multiple areas of contact with the formation with a single cutting element.

[0074] Other embodiments of cutting elements can combine both crushing and shear cutting aspects. For example, Figs. 18A and 18B illustrate an embodiment of a cutting element 1800 that has a conical crushing feature 1810 combined with a shear cutting edge 1812. Such embodiments can be used in particular situations in which it may be anticipated that the formation may require different cutting configurations.

[0075] It should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. For example, any element described in relation to an embodiment herein may be combinable with any element of any other embodiment described herein, to the extent such features are not described as being mutually exclusive. Numbers, percentages, ratios, or other values stated herein are intended to include that value, andalso other values that are “about”, “substantially”, or “approximately” the stated value, as would be appreciated by one of ordinary skill in the art encompassed by embodiments of the present disclosure. A stated value should therefore be interpreted broadly enough to encompass values that are at least close enough to the stated value to perform a desired function or achieve a desired result. The stated values include at least the variation to be expected in a suitable manufacturing or production process, and may include values that are within 5%, within 1%, within 0.1%, or within 0.01% of a stated value.

[0076] The terms “approximately,” “about,” and “substantially” as used herein represent an amount close to the stated amount that is within standard manufacturing or process tolerances, or which still performs a desired function or achieves a desired result. For example, the terms “approximately,” “about,” and “substantially” may refer to an amount that is within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of a stated amount. Further, it should be understood that any directions or reference frames in the preceding description are merely relative directions or movements. For example, any references to “up” and “down” or “above” or “below” are merely descriptive of the relative position or movement of the related elements.

[0077] A person having ordinary skill in the art should realize in view of the present disclosure that equivalent constructions do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions, and alterations may be made to embodiments disclosed herein without departing from the spirit and scope of the present disclosure. Equivalent constructions, including functional “means-plus-function” clauses are intended to cover the structures described herein as performing the recited function, including both structural equivalents that operate in the same manner, and equivalent structures that provide the same function. It is the express intention of the applicant not to invoke means-plus-function or other functional claiming for any claim except for those in which the words ‘means for’ appear together with an associated function. Each addition, deletion, and modification to the embodiments that falls within the meaning and scope of the claims is to be embraced by the claims. The described embodiments are therefore to be considered as illustrative and not restrictive, and the scope of the disclosure is indicated by the appended claims rather than by the foregoing description.

Claims

CLAIMSWhat is claimed is:

1. A roller cone comprising:A body having concentrically formed around a cone axis, the body extending from an outer region to a nose region, wherein the nose region is positioned radially outward from a point along the cone axis at a distance such that the nose region has a blunted cross- sectional shape such that the blunted cross-sectional shape is configured to contact a formation with a wider surface area;A plurality of inserts disposed on the body of the roller cone; andA plurality of cutting elements disposed on the nose region, wherein at least one of the plurality of cutting elements has at least one cutting edge.

2. The roller cone of claim 1, wherein the plurality of inserts on the body are crushing inserts.

3. The roller cone of claim 1, wherein at least a second of the plurality of cutting elements having more than one cutting edge.

4. The roller cone of claim 3, wherein the at least a second of the plurality of cutting elements has three cutting edges.

5. The roller cone of claim 3, wherein the at least a second of the plurality of cutting elements has four or more cutting edges.

6. The roller cone of claim 1, wherein the at least one cutting edge is a continuous cutting edge.

7. The roller cone of claim 1, wherein the blunted cross-sectional shape is selected from a group consisting of concave, convex, flat, and variable spline.

8. A roller cone for a drill bit comprising:A body concentrically formed around a cone axis, the body extending from an outer region to a nose region, wherein the nose region is positioned radially outward from a point along the cone axis at a distance such that the nose region has a blunted cross- sectional shape such that the blunted cross-sectional shape is configured to contact a formation with a wide surface area;A plurality of inserts disposed on the body of the roller cone; andA plurality of cutting elements disposed on the nose region, wherein the plurality of cutting elements comprises at least one cutting element with a continuous cutting edge and at least a second cutting element with at least one cutting edge.

9. The roller cone of claim 8, further comprising at least a third cutting element disposed on the nose region, wherein the at least a third cutting element has more than one cutting edge.

10. A drill bit comprising: a bit body having a rotational axis; a roller cone supported by the bit body, the roller cone including: a nose region, the nose region being positioned radially back from the rotational axis at a distance thereby forming a wide surface area and a blunted design, and wherein the nose region further comprises a plurality of cutting elements arranged thereon, at least one of the plurality of cutting elements has at least one cutting edge; and a first fixed blade fixed relative to the bit body with fixed blade cutting elements affixed thereto radially overlapping at least the first central region.

11. The drill bit of claim 10, further comprising at least a second roller cone, the at least second roller cone further being supported by the bit body, the at least second roller cone including: a second cone nose region, the second cone nose region being positioned radially back from the rotational axis thereby forming a wide surface area and a blunted design, and wherein the second cone nose region further comprises at least one cutting element arranged thereon, at least one cutting element having at least one cutting edge.

12. The drill bit of claim 10, wherein the roller cone further comprises a plurality of inserts on a roller cone body13. The drill bit of claim 12, wherein the plurality of inserts are crushing inserts.

14. The drill bit of claim 11, wherein the at least second roller cone comprises a plurality of second cone inserts on a second roller cone body.

15. The drill bit of claim 14, wherein the plurality of second cone inserts are crushing inserts.

16. The drill bit of claim 10, wherein at least a second of the plurality of cutting elements has more than one cutting edge.

17. The drill bit of claim 16, wherein the at least a second of the plurality of cutting elements has three cutting edges.

18. The drill bit of claim 16, wherein the at least a second of the plurality of cutting elements has four or more cutting edges.

19. The drill bit of claim 10, wherein the at least one cutting edge is a continuous cutting edge.

20. The drill bit of claim 11, wherein the at least one cutting element has a continuous cutting edge.

21. The drill bit of claim 11, further comprising at least two cutting elements.

22. The roller cone of claim 1, wherein the distance is at least 10% of a drill bit body diameter.

23. The drill bit of claim 10, wherein the distance is at least 10% of a diameter of the bit body.

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