Embodiments of the present disclosure relate to formation-engaging structures for earth-boring tools, earth-boring tools including such structures, and related methods.
Earth-boring tools are used to form boreholes (e.g., wellbores) in subterranean formations. Such earth-boring tools include, for example, drill bits, reamers, mills, etc. For example, a fixed-cutter earth-boring rotary drill bit (often referred to as a “drag” bit) generally includes a plurality of cutting elements secured to a face of a bit body of the drill bit. The cutters are fixed in place when used to cut formation materials. A conventional fixed-cutter earth-boring rotary drill bit includes a bit body having generally radially projecting and longitudinally extending blades. During drilling operations, the drill bit is positioned at the bottom of a well borehole and rotated.
A plurality of cutting elements is positioned on each of the blades. The cutting elements commonly comprise a “table” of superabrasive material, such as mutually bound particles of polycrystalline diamond, formed on a supporting substrate of a hard material, such as cemented tungsten carbide. Such cutting elements are often referred to as “polycrystalline diamond compact” (PDC) cutting elements or cutters. The plurality of PDC cutting elements may be fixed within cutting element pockets formed in rotationally leading surfaces of each of the blades. Conventionally, a bonding material, such as a braze alloy, may be used to secure the cutting elements to the bit body.
Some earth-boring tools may also include bearing elements that may limit the depth-of-cut (DOC) of the cutting elements, protect the cutting elements from excessive contact with the formation, enhance (e.g., improve) lateral stability of the tool, or perform other functions or combinations of functions. The bearing elements conventionally are located entirely rotationally behind associated leading cutting elements to limit DOC as the bearing elements contact and ride on an underlying earth formation, although bearing elements rotationally leading cutting elements are also known.
In one aspect of the disclosure, a formation-engaging assembly includes a formation-engaging structure holder with a side surface between a proximal end and a distal end, a receptacle in the distal end, and a lateral protrusion extending from a portion of the side surface of the formation-engaging structure holder adjacent the distal end. A formation-engaging structure may include a formation-engaging surface at a distal end opposite a proximal end along a sidewall. The proximal end and at least a portion of the sidewall of the formation-engaging structure is received within the receptacle of the formation-engaging structure holder.
In another aspect of the disclosure, an earth-boring tool may include a blade comprising a pocket having a channel extending laterally therefrom to a leading surface of the blade accepting at least a portion of a formation-engaging structure holder. A formation-engaging assembly is disposed within the pocket. The formation-engaging assembly may include a formation-engaging structure holder with a side surface between a proximal end and a distal end, a receptacle in the distal end and a lateral protrusion extending from a portion of the side surface of the formation-engaging structure holder adjacent the distal end. A formation-engaging structure may include a formation-engaging surface at a distal end opposite a proximal end along a sidewall. The proximal end and at least a portion of the sidewall of the formation-engaging structure is received within the receptacle of the formation-engaging structure holder.
While the specification concludes with claims particularly pointing out and distinctly claiming what are regarded as embodiments of the present invention, various features and advantages of disclosed embodiments may be more readily ascertained from the following description when read with reference to the accompanying drawings, in which:
The illustrations presented herein are not actual views of any particular material, cutting element, formation-engaging structure, or earth-boring tool, but are merely idealized representations employed to describe embodiments of the present disclosure. Additionally, elements common between figures may retain the same numerical designation.
The body 104 of the earth-boring tool 100 may be secured to a shank (not shown) having a threaded connection portion, which may conform to industry standards, such as those promulgated by the American Petroleum Institute (API), for attaching the earth-boring tool 100 to a drill string (not shown).
The body 104 may include internal fluid passageways that extend between fluid ports 112 at the face of the body 104 and a longitudinal bore that extends through the shank and partially through the body 104. Nozzle inserts 114 may be secured within the fluid ports 112 of the internal fluid passageways. The body 104 may further include a plurality of blades 116 that are separated by fluid courses 118, which may be referred to in the art as “junk slots.” In some embodiments, the body 104 may include wear knots 120.
Each formation-engaging assembly 106 may be positioned on a blade 116 to rotationally trail at least one cutting element 102, as shown in
Referring now to
In the embodiment of
The formation-engaging structure holder 202 may include a receptacle 212 for accepting at least a portion of the side surface 210 of the formation-engaging structure 200. The sidewall of receptacle 212 may comprise a cross-sectional shape and of a size similar to the cross-sectional shape of the side surface 210 of the formation-engaging structure 200, such that the formation-engaging structure 200 fits tightly within the receptacle 212. In some embodiments, the sizes of the cross-sectional shapes of the receptacle 212 and the side surface 210 may be chosen to provide a clearance between the side surface 210 and a sidewall of the receptacle 212 to facilitate affixing the formation-engaging structure 200 within the formation-engaging structure holder 202, with, for example, a braze or adhesive.
As a non-limiting example, the formation-engaging structure 200 may be brazed within the receptacle 212. For example, the formation-engaging structure 200 may be at least partially placed within the receptacle 212, and the side surface 210 of the formation-engaging structure 200, the sidewall of the receptacle 212, and a braze material may be heated. The braze material may be drawn into the clearance between the formation-engaging structure 200 and the sidewall of the receptacle 212 by capillary action. In embodiments in which the side surface 210 of the formation-engaging structure 200 is generally cylindrical, the formation-engaging structure 200 may be rotated within the receptacle 212 to facilitate uniform distribution of the braze material within the clearance.
In other embodiments, the formation-engaging structure 200 may be mechanically affixed within the receptacle 212 by, e.g., an interference fit. In yet other embodiments, the formation-engaging structure 200 may be affixed within the receptacle 212 by, e.g., an adhesive.
As non-limiting examples, the formation-engaging structure holder 202 may comprise a metal alloy, such as a steel alloy, or may comprise a cemented tungsten carbide matrix material.
The receptacle 212 may extend from a distal end 218 of the formation-engaging structure holder 202 a depth D into the formation-engaging structure holder 202. Depth D may be chosen based on, e.g., a desired exposure of the formation-engaging structure 200. Multiple formation-engaging structure holders 202 with different depths D of the receptacle 212 may enable a drill bit supplier or drilling operator to provide formation-engaging assemblies 106 with different exposures for formation-engaging structures 200 appropriate for different drilling conditions while using substantially identical formation-engaging structures 200. In some embodiments, the depth D may be effectively adjusted by placing one or more shims in the bottom of receptacle 212 prior to inserting the formation-engaging structure 200 within the receptacle 212.
The formation-engaging structure holder 202 may include features configured to facilitate removal of the formation-engaging assembly 106 from the body 104 of the earth-boring tool 100 (
The formation-engaging structure holder 202 may also include a relief 220 in the side surface 222. In the embodiment of
Referring now to
Referring now to
The blade 116 of the earth-boring tool 100 may include a retainer bore 406 at least partially contiguous with a retainer recess 404. In this embodiment, the retainer recess 404 may extend completely through the blade 116. In other words, the retainer recess 404 may extend from a first surface 408 of the blade 116 to a second, opposite surface (not shown in the perspective of
In some embodiments, the retaining element 407 may comprise a sheet of resilient (i.e., elastic) material (e.g., a steel alloy) rolled about a longitudinal axis. Elastic expansion of the resilient material of the retaining element 407 may exert a force against the wall of the retainer bore 406 and at least a portion of the surface of the relief 220 of the formation-engaging structure holder 202, thereby enhancing (e.g., increasing) a frictional force between the foil ration-engaging structure holder 202, the retaining element 407, and the retainer bore 406, and securing the retaining element 407 within the retainer bore 406. The resilient material of the retaining element 407 may also elastically deform to enable relative movement between the formation-engaging assembly 106 and the blade 116. For example, elastic movement between the formation-engaging assembly 106 and the blade 116 may at least partially absorb vibration generated by a drilling operation. The resilient material may enable the retaining element 407 to fit tightly within retainer bores 406 having slightly different diameters and/or irregular surface finishes resulting from normal manufacturing inconsistencies.
In other embodiments, the retainer recess 404 may only extend through a portion of the blade 116, and may comprise a threaded bore configured to accept a set screw (not shown). The set screw may be tightened such that a portion of the set screw abuts a portion of a relief 220 of a formation-engaging structure holder 202 to retain a formation-engaging assembly 106, 300 within the pocket 400 of the blade 116.
A chamfered edge 216 of a laterally extending protrusion 214 of the formation-engaging structure holder 202 may provide a gap 410 (
In some situations, it may be desirable to remove the formation-engaging assembly 106, 300 from the pocket 400. For example, the formation-engaging surface 204 of the formation-engaging assembly 106, 300 may become worn or damaged. Moreover, it may be desirable to replace the formation-engaging assembly 106, 300 with another formation-engaging assembly having different characteristics, e.g., shape or exposure, of the formation-engaging surface 204.
Accordingly, with reference now to
A clearance 506 may exist between the side surface 222 of the formation-engaging structure holder 202 (
Referring now to
Referring now to
To install the retaining element 700 within the retainer bore 706, an operator may insert the shank 704 into the retainer bore 706 until the threads on the threaded head 702 begin to engage the threads of the threaded segment 708. The operator may insert a tool into the receptacle of the threaded head 702 to rotate retaining element 700, apply torque and thread the threaded head 702 completely into the threaded segment 708 of the retainer bore 706, as shown in
At least a portion of the shank 704 of the retaining element 700 may abut a portion of the formation-engaging structure assembly 300 within a bore 224 (
To remove the retaining element 700 from the retainer bore 706, the operator may insert a tool into the receptacle of the threaded head 702 as described above and rotate retaining element 700 to apply torque in the opposite direction to loosen the threaded head 702 of the retaining element 700 from the threaded segment 708 of the retainer bore 706, as shown in
The retaining element 700 shown in
Additional non-limiting example embodiments of the disclosure are set forth below.
A formation-engaging assembly, comprising: a formation-engaging structure holder, comprising: a side surface between a proximal end and a distal end; a receptacle in the distal end; and a lateral protrusion extending from a portion of the side surface of the formation-engaging structure holder adjacent the distal end; and a formation-engaging structure with a formation-engaging surface at a distal end, a proximal end and a sidewall therebetween, wherein the proximal end and at least a portion of the sidewall of the formation-engaging structure is received within the receptacle of the formation-engaging structure holder.
The formation-engaging assembly of Embodiment 1, wherein the lateral protrusion extends from only a portion of a periphery of the side surface of the formation-engaging structure holder.
The formation-engaging assembly of Embodiment 1 or Embodiment 2, wherein the lateral protrusion comprises a chamfered edge.
The formation-engaging assembly of Embodiment 3, wherein the chamfered edge is disposed on a proximal portion of the lateral protrusion.
The formation-engaging assembly of any one of Embodiments 1 through 4, wherein the formation-engaging structure holder further comprises a relief in the side surface.
The formation-engaging assembly of Embodiment 5, wherein the relief comprises an annular groove extending around at least a portion of a periphery of the side surface.
The formation-engaging assembly of Embodiment 5 or Embodiment 6, wherein the relief comprises a bore extending through the formation-engaging structure holder.
The formation-engaging assembly of any one of Embodiments 1 through 7, wherein the formation-engaging structure is brazed within the receptacle of the formation-engaging structure holder.
An earth-boring tool, comprising: a blade comprising a pocket in a leading end thereof for accepting at least a portion of a formation-engaging structure holder, the pocket having a portion of reduced depth extending therefrom to a side surface of the blade; and a formation-engaging assembly disposed within the pocket, the formation-engaging assembly comprising: a formation-engaging structure holder, comprising: a side surface between a proximal end and a distal end; a receptacle in the distal end; and a lateral protrusion extending from a portion of the side surface of the formation-engaging structure holder adjacent the distal end received in the pocket portion of reduced depth; and a formation-engaging structure with a formation-engaging surface at a distal end, a proximal end and a sidewall therebetween, wherein the proximal end and at least a portion of the sidewall of the formation-engaging structure is received within the receptacle of the formation-engaging structure holder.
The earth-boring tool of Embodiment 9, wherein the blade of the earth-boring tool comprises a retainer bore extending into the blade from a surface thereof and at least partially intersecting the pocket, and a retaining element disposed within the retainer bore and extending at least partially within a relief in a side surface of the formation-engaging structure holder.
The earth-boring tool of Embodiment 10, wherein a portion of the retaining element abuts a portion of the formation-engaging structure holder within a relief in the side surface of the formation-engaging structure holder or extends through a bore in the side surface of the formation-engaging structure holder.
The earth-boring tool of Embodiment 10 or Embodiment 11, wherein the retainer bore extends completely through the blade of the earth-boring tool.
The earth-boring tool of Embodiment 11, wherein the retaining element comprises an elongated pin.
The earth-boring tool of any one of Embodiments 10 through 13, wherein the retainer bore comprises a threaded portion adjacent the surface of the blade of the earth-boring tool.
The earth-boring tool of Embodiment 14, wherein the retaining element comprises a set screw engaged with the threaded portion of the retainer bore.
The earth-boring tool of any one of Embodiments 9 through 15, wherein the earth-boring tool is a fixed-cutter rotary drill bit.
The earth-boring tool of any one of Embodiments 14 through 16, wherein the retaining element comprises a threaded head and a shank of lesser diameter, the threaded head engaged with the threaded portion of the retainer bore.
The earth-boring tool of any one of Embodiments 11 through 13, wherein the retaining element comprises a sheet of resilient material rolled about a longitudinal axis thereof.
Although the foregoing description contains many specifics, these are not to be construed as limiting the scope of the present invention, but merely as providing certain exemplary embodiments. Similarly, other embodiments of the invention may be devised, which do not depart from the spirit or scope of the present disclosure. For example, features described herein with reference to one embodiment also may be provided in others of the embodiments described herein. The scope of the invention is, therefore, indicated and limited only by the appended claims and their legal equivalents, rather than by the foregoing description. All additions, deletions, and modifications to the disclosed embodiments, which fall within the meaning and scope of the claims, are encompassed by the present disclosure.