Blunt-Nosed Roller Cone Hybrid Bit

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.

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.

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.

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

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

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

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

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

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

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.

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.

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.

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 further comprises at least one cutting element arranged thereon, at least one cutting element having at least one cutting edge.

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

In other embodiments, the plurality of inserts are crushing inserts.

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

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

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

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

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

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

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

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.

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.

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.

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.

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 roller cone axis may have a profile that is blunted or have a wider cross-sectional profile from that of a traditional roller cone.

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.

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.

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.

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 of a drill be to have multiple functions as well as allow for continued cutting capabilities in the event of a stalled cone.

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.

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.

illustrates an embodiment of a drilling system and downhole environment in which a drill bit, according to the present disclosure may, be used.shows one example of a drilling systemfor drilling an earth formationto form a wellbore. The drilling systemmay include a drill rigused to turn a drilling assemblywhich extends downward into the wellbore. The drilling assemblymay include a drill stringand a bottomhole assembly (BHA)attached to the downhole end of the drill string. Where the drilling systemis used for drilling formation, a drill bitcan be included at the downhole end of the bottom hole assembly or BHA.

The drill stringmay include several joints of drill pipeconnected end-to-end through tool joints. The drill stringtransmits drilling fluid through a central bore and can transmit rotational power from the drill rigto the BHA. In some embodiments, the drill stringmay further include additional components such as subs, pup joints, etc. The drill pipeprovides a hydraulic passage through which drilling fluidis pumped from the surface. The drilling fluiddischarges through selected-size nozzles, jets, or other orifices in the bitfor the purposes of cooling the bitand cutting structures thereon, for lifting cuttings out of the wellboreas it is being drilled, and for preventing the collapse of the wellbore. The drilling fluidcarries drill solids including drill fines, drill cuttings, and other swarf from the wellboreto the surface. The drill solids can include components from the earth formation, the drilling assemblyitself, from other man-made components (e.g., plugs, lost tools/components, etc.), or combinations thereof.

The BHAmay include the bitor other components. An example BHAmay include additional or other components (e.g., coupled between to the drill stringand/or the bit). Examples of additional BHA components be include drill collars, stabilizers, measurement-while-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.

In general, the drilling systemmay 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 systemmay be considered a part of the surface system (e.g., drill rig, drilling assembly, drill string, or a part of the BHA, depending on their locations and/or use in the drilling system).

The bitin the BHAmay include any features or elements suitable for degrading downhole materials. For instance, the bitmay be a drill bit suitable for drilling the earth formation. While embodiments of a drill bitfor drilling the earth formationwill 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 bitmay be used with a whipstock to mill into casinglining the wellbore. The bitmay also be a junk mill used to mill away tools, plugs, cement, other materials within the wellbore, or combinations thereof. Swarf or other cuttings formed by use of a mill may be lifted to surface by the drilling fluidor may be allowed to fall downhole. The conditions of the equipment of the drilling system, the formation, the wellbore, the drilling fluid, or other parts of the wellsite can change during operations.

illustrate a bottom view of a hybrid drill bitwith a roller coneand a fixed blade. The roller coneis often made up from a body portionconcentrically formed around a cone axis. The bodyof the roller cone(s) can have an radially positioned outer regionand a radially positioned inner region. The radially positioned inner regioncan be referred to as a nose region. The nose regioncan be positioned near a central axisabout which the drill bitcan rotate. Additionally, the roller cone(s)can have a number of different insertsdisposed on the bodyand in the noseand/or outerregions.

The roller conemay be supported by a bit bodyor by any suitable connection to the bit body. As the bit bodyrotates around the central rotational axisof the drill bit, contact between the roller coneand the formation material produces a rotation of the roller conearound the cone axis. The cone axisand subsequently the roller cone, may be oriented in such a way that the roller coneis configured to interact with the formation. As can be appreciated the position and angle of the roller coneon the cone axiscan help to increase the shear force between the cutting elementson the roller coneto reduce the torque on bit (TOB) and torque that is seen by the fixed blades. Various embodiments of a hybrid drill bitcan improve the wear life of the drill bit by having a roller conein which the roller cone cutting elementscan be configured on the roller cone in such a way that improves material removal and aids the fixed blade cutting elements. As can be seen in, the roller cone(s)have a more pointed nose portionin which the cone cutting elementscan be configured to be close to the central axis of the bit. In other words, the nose regionis narrow and forms a narrow conical cross section.

further illustrate that the center most, inner most, or nose regionpositioned close to the central axisof the drill bit. This, thereby, can position at least one roller cone cutting elementcloser to the central axisthan the fixed blade cutting elements. As described previously, the central or nose regioncan often be the least efficient cutting portion of a roller cone. As such, hybrid drill bits, similar to those illustrated in, offer further room for development to improve the cutting efficiency of the drill bit.

Referring now to, various embodiments, are directed to a hybrid drill bitwith improved roller cone(s)that offers improved cutting efficiencies within the central portion of the drill bit., for example, illustrates a conceptual bottom view of a hybrid drill bitwith one or more roller conesand one or more fixed blades. Unlike the roller cones illustrated in, embodiments illustrated incan have roller coneswith a nose sectionthat has a blunted profile. In other words, many embodiments of the roller cone nose sectioncan have an radial point or radial facelocated at a distanceradially away or back from the central axisand where the radial faceis not as pointed or has a wider profile than a traditional roller cone. In many such embodiments the radial facehas an arc that has a larger radius than a more traditional roller cone. Additionally, in various embodiments of the roller cone, the nose sectioncan be radially outward from the central axisalong a cone axis. Accordingly, such embodiments can allow for the fixed blade cutting elementsto be located closer to the central axisthan the roller cone cutting elements. This configuration can allow for the fixed blade cutting elementsto continue to cut into the formation during the drilling process, thus allowing for more efficient operation. Furthermore, the roller cone cutting elementscan be configured such they reduce the risk of core out if the conesstall during the drilling process, thus allowing for continued material removal.

Although illustrated with a planar configuration, it can be understood that the nose sectionthat has a blunted appearance, can have any suitable configuration. For example, some embodiments of the blunted nose regionmay be concave, convex, flat, variable spline, etc. In some embodiments of a hybrid drill bitone of the roller conescan have a nose regionthat are the same shape or configuration, while other embodiments may have a combination of shapes.

It should be readily appreciated, that various embodiments of a hybrid drill bitand drill bit bodymay be manufactured with any suitable method such as machining or forming using matrix powders. In numerous embodiments, the fixed bladesmay be formed as part of the bit bodyduring the bit formation. Additionally, it can be appreciated, that the roller conescan be connected to the bit bodyby any suitable means that will allow for the roller cones to rotate about their axisduring the drilling process. For example, some embodiments may include a separate roller cone attachment mechanism that can be connected to the bit bodyafter the forming process. Other embodiments may have a mechanical connection that is formed as part of the bit forming process.

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, some embodiments of a drill bit can have multiple fixed bladescombined with multiple roller cones. The roller conescan be positioned within an outer diameterof the drill bit that may be any desired diameter. For example, the diameter may be 8½″ or larger or 16″ or larger. Regardless of the size, the roller conescan be further configured in any suitable pattern or configuration within the diameter to enable the most efficient drilling performance from the drill bit. For example, in some embodiments of the drill bit, the roller conescan be positioned on opposing sides drill bit. The roller conesmay be 180° apart or may be less or more than 180° depending on the overall geometry of the drill bit.

Referring now to, a cross sectional profile of a more pointed roller cone elementis illustrated. As can be seen the nose section/regionof the roller coneis more conical and pointed in nature such that the roller cone cutting elementsare positioned to contact the formationat the nose regionrather than any of the fixed blade cutting elementscontacting the formationat the central location of the drill bit. If a line is drawn along the cone axisto the formationand extended beyond, it can be seen that a distancefrom a point on the axis to the noseis much smaller than a distancefrom a point to the fixed blade cutting elements.

In contrast,illustrates an embodiment of an improved roller cone, via a cross sectional view, with a blunted nose section. In numerous embodiments, the roller cone can have a more blunted nosesection which has a larger or less pointed cross-sectional profile. It can be appreciated that the nose sectionis 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 elementsto be more spread out on the nose sectionor have room for more cutting elements since the faceand arc is larger. Such configurations can allow for the fixed blade cutting elementsto be positioned much closer to the central axisof the drill bit. This allows for improved cutting efficiency during the drilling process because the fixed blade cutting elementswill be positioned to cut in or near the central axisas the bit rotates without relying on the roller cone cutting elements. This can be illustrated by a distancefrom the cone axisto the first roller cone cutting elementbeing close to a distancefrom the cone axisto the fixed blade cutting elements. As should be readily understood, many embodiments may have varying distancefrom the cone axisthat accommodates or creates a blunted nose portionof the roller cone. This distancecan 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 regioncan 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.

Notwithstanding, many embodiments of the roller conecan also be configured with a variety of different cutting elements or cutting elements. For example, some embodiments may have a combination of conical insertsthat are designed for crushing the formation. Other embodiments may have shear cutting elementsthat 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 elementson the roller cone to allow the roller coneto perform a variety of functions. Additionally, it should be understood that a roller conewith ultrahard and/or shear cutting elements is advantageous over traditional roller cones because the shearing cutting elementscan help to reduce the risk of core-out if the conestalls or stops rotating about the cone axis. 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.

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 elementwithin the nose regionof the roller cone such that the fixed blade cutting inertcan operate with any cutting elements of the roller cone nose region. Similar to other embodiments described above, this positioning of the fixed blade cutting elementswithin the nose cutting regioncan improve the efficiency of the drill bit by ensuring that a shear cutting element is always near the central axisof the drill bit.

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. The center-jet nozzle, in many embodiments, can be configured to provide a flow of fluidalong a path towards numerous cutting elements. The flow of fluidis 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 fluidcan be better directed towards those cutting elementsthat are positioned within a nose regionof the roller cone(s)as well as those that may overlap the nose region from the fixed blade(s).