Patent Application
20190032408
Embodiments of the present disclosure generally relate to moveable elements, cutters, and devices for use with earth-boring (e.g., downhole) tools. In particular, to moveable elements, cutters, and devices including at least one moveable section and one or more seals.
Various earth-boring tools such as rotary drill bits (including roller cone bits and fixed-cutter or drag bits), core bits, eccentric bits, bicenter bits, reamers, and mills are commonly used in forming bore holes or wells in earth formations. Such tools often may include one or more cutting elements on a formation-engaging surface thereof for removing formation material as the earth-boring tool is rotated or otherwise moved within the borehole.
For example, fixed-cutter bits (often referred to as “drag” bits) have a plurality of cutting elements affixed or otherwise secured to a face (i.e., a formation-engaging surface) of a bit body. Cutting elements generally include a cutting surface, where the cutting surface is usually formed out of a superabrasive material, such as mutually bound particles of polycrystalline diamond. The cutting surface is generally formed on and bonded to a supporting substrate of a hard material such as cemented tungsten carbide. During a drilling operation, a portion of a cutting edge, which is at least partially defined by the peripheral portion of the cutting surface, is pressed into the formation. As the earth-boring tool moves relative to the formation, the cutting element is dragged across the surface of the formation and the cutting edge of the cutting surface shears away formation material. Such cutting elements are often referred to as “polycrystalline diamond compact” (PDC) cutting elements, or cutters.
During drilling, cutting elements are subjected to high temperatures due to friction between the cutting surface and the formation being cut, high axial loads from the weight on bit (WOB), and high impact forces attributable to variations in WOB, formation irregularities and material differences, and vibration. These conditions can result in damage to the cutting surface (e.g., chipping, spalling). Such damage often occurs at or near the cutting edge of the cutting surface and is caused, at least in part, by the high impact forces that occur during drilling. Damage to the cutting element results in decreased cutting efficiency of the cutting element. When the efficiency of the cutting element decreases to a critical level the operation must be stopped to remove and replace the drill bit. Replacing the drill bit can be a large expense for an operation utilizing earth-boring tools.
Securing a PDC cutting element to a drill bit restricts the useful life of the cutting element. The cutting edge of the diamond table wears down as does the substrate. A so-called “wear flat” is created necessitating increased weight on bit to maintain a given rate of penetration of the drill bit into the formation due to the increased surface area presented. In addition, unless the cutting element is heated to remove it from the bit and then rebrazed with an unworn portion of the cutting edge presented for engaging a formation, more than half of the cutting element is never used.
Attempts have been made to configure cutting elements to rotate such that a majority of the cutting edge extending around each cutting element may selectively engage with and remove material. By utilizing a majority of the cutting edge, the effective life of the cutting element may be increased. Some designs utilize mechanisms and/or bearings to allow the cutting element to turn by displacing the cutting element linearly with respect to the longitudinal axis of the cutting element to engage or disengage an index positioning feature, or to float and allow free rotation. Additionally, some cutting elements displace linearly on devices such as reamers to control the width of the borehole. The ingress of debris and fluid, inherent in boreholes, into the cutting elements can damage the internal components hindering movement of the cutting element.
In some embodiments, the present disclosure includes a rotatable cutter for use on an earth-boring tool in a subterranean borehole. The rotatable cutter may comprise a rotatable element, a stationary element, and at least one seal between the rotatable element and the stationary element. The at least one seal may be configured to maintain a substantially constant sealed volume defined between the rotatable element and the stationary element. The substantially constant sealed volume may be configured to contain a fluid.
In additional embodiments, the present disclosure includes an earth-boring tool comprising a tool body and elements carried by the tool body. At least one element of the elements may comprise a moveable element, a sleeve element, and a seal arrangement between the moveable element and the sleeve element. The moveable element may be configured to engage a portion of the subterranean borehole. The seal arrangement may be configured to define and maintain a substantially constant volume. The substantially constant volume may be configured to enclose a lubricating fluid.
Further embodiments of the present disclosure include a method of sealing a rotatable cutter on an earth-boring tool for use in a subterranean borehole. The method may comprise disposing an inner cutting element at least partially within an outer sleeve. The inner cutting element may comprise a cutting surface and a support structure. The method may further comprise translating the inner cutting element between a first axial position and a second axial position along a longitudinal axis of the rotatable cutter. A sealing arrangement may be used for defining a substantially constant volume between the rotatable element and the stationary element.
While the specification concludes with claims particularly pointing out and distinctly claiming embodiments of the present disclosure, the advantages of embodiments of the disclosure may be more readily ascertained from the following description of embodiments of the disclosure when read in conjunction with the accompanying drawings in which:
The illustrations presented herein are not meant to be actual views of any particular earth-boring tool, rotatable cutting element or component thereof, but are merely idealized representations employed to describe illustrative embodiments. The drawings are not necessarily to scale.
The embodiments disclosed relate generally to rotatable or otherwise moveable devices or elements (e.g., rotatable cutting elements) for earth-boring tools that may move in order to alter the positioning of the cutting element relative to an earth-boring tool to which the cutting element is coupled. For example, such a configuration may enable the cutting element to present a continuously sharp cutting edge with which to engage a downhole formation while still occupying substantially the same amount of space as conventional fixed cutting elements. Embodiments of the disclosure include a seal or seal assembly that is positioned between moveable device (e.g., stationary element and a rotatable element). The seal or seal assembly may be configured to at least partially isolate and/or contain a volume within the moveable device. Such seals or seal assemblies may also be utilized to provide a seal for cutting elements which do not rotate but are otherwise displaced (e.g., linearly along the longitudinal axis of the cutting element) relative to the structure to which they are secured.
Moveable devices and elements may be implemented in a variety of earth-boring tools, such as, for example, rotary drill bits, percussion bits, core bits, eccentric bits, bicenter bits, reamers, expandable reamers, mills, drag bits, roller cone bits, hybrid bits, and other drilling bits and tools known in the art.
As used herein, the term “substantially” in reference to a given parameter means and includes to a degree that one skilled in the art would understand that the given parameter, property, or condition is met with a small degree of variance, such as within acceptable manufacturing tolerances. For example, a parameter that is substantially met may be at least about 90% met, at least about 95% met, or even at least about 99% met.
Referring to
In an application where the cutting elements 100 are fixed, only the edge of the cutting surface 102 of the cutting element 100 that is exposed will contact the earth formation and wear down during use. By rotating the cutting element 100, relatively more of (e.g., a majority of, a substantial entirety of) the entire edge of the cutting surface 102 may be exposed to wear and may act to extend the life of the cutting element 100.
In some embodiments, the rotatable devices and elements disclosed herein may be somewhat similar to those described in, for example, U.S. patent application 1X/XXX,XXX, filed on even date herewith and titled “ROTATABLE CUTTERS AND ELEMENTS FOR USE ON EARTH-BORING TOOLS IN SUBTERRANEAN BOREHOLES AND RELATED METHODS” (attorney docket number 1684-P13851US (CUT4-62957-US)), the disclosure of which is incorporated herein in its entirety by this reference.
Referring to
Referring to
The rotatable element 104 may comprise a cutting surface 102 over a support structure 112. The cutting surface 102 may be configured to engage a portion of a subterranean borehole. In some embodiments, the rotatable element 104 may be sized and configured such that the cutting surface 102 is at least the same diameter as the stationary element 106. In some embodiments, the support structure 112 may include a shoulder 114. The shoulder 114 may rest against the stationary element 106, for example, when the cutting surface 102 is engaged with the subterranean borehole. The lower portion of the support structure 112 may be a smaller diameter than the diameter of the cavity 110 in the stationary element 106 to facilitate being at least partially disposed within the stationary element 106.
The rotatable element 104 may be configured to rotate about and move along (e.g., move linearly along) the longitudinal axis L100 of the rotatable cutter 100 relative to the stationary element 106. There may be a slight space between the rotatable element 104 and the stationary element 106 to enable this movement. In some embodiments, the rotatable element 104 may move between a first axial position (e.g., a compressed position as shown in
In some embodiments, an index positioning feature 128 may be implemented to control movement of the rotatable cutter 100. For example, the index positioning feature 128 may be implemented to rotate the rotatable element 104 and to control that rotation. An exemplary index positioning feature 128 is detailed, for example, in the above-referenced U.S. patent application 1X/XXX,XXX, (attorney docket number 1684-P13851US (CUT4-62957-US)), The rotatable element 104 may move along the longitudinal axis L100 of the rotatable cutter 100 between the first axial position and the second axial position. The index positioning feature 128 may act as a stop preventing the rotatable element 104 from moving beyond the first axial position or the second axial position. The index positioning feature 128 may, at least partially inhibiting the rotation of the rotatable element 104 relative to the stationary element 106 when the rotatable element 104 is positioned at the first axial position and/or the second axial position. As the rotatable element 104 moves from the first axial position to the second axial position, the index positioning feature 128 may impart a force on the rotatable element 104 causing the rotatable element 104 to rotate (e.g., a select amount of degrees) relative to the stationary element 106. Similarly, the index positioning feature 128 may also impart rotation on the rotatable element 104 as the rotatable element 104 moves from the second axial position to the first axial position.
In some embodiments, a biasing element 117 may be disposed between the base 116 of the rotatable element 104 and the stationary element 106. The biasing element 117 may be configured to bias the rotatable element 104 in the first axial position (e.g., the compressed position) in a direction away from the stationary element 106. The biasing element 117 may assist in translating the rotatable element 104 between the first axial position (e.g., compressed position) and the second axial position (e.g., expanded position) along the longitudinal axis L100 of the cutting element 100. Examples of biasing elements that may be used, by way of example but not limitation, are springs, washers (e.g., Bellville washers), compressible fluids, magnetic biasing, resilient materials, or combinations thereof.
Referring still to
The seals 118, 120 may be configured to maintain a substantially constant sealed volume 126 (e.g., a substantially incompressible fluid). For example, the substantially constant sealed volume 126 may be defined between the rotatable element 104 and the stationary element 106. The substantially constant volume 126 may be defined by a first seal 118 (e.g., top seal) positioned along the longitudinal axis L100 at a first location proximate the cutting surface 102 of the rotatable element 104 and a second seal 120 (e.g., bottom seal) positioned at a second location positioned relatively further away from the cutting surface 102 of the rotatable element 104. In some embodiments, the first seal 118 and the second seal 120 may both be at least partially fixed to the same element. The first seal 118 and second seal 120 may also have substantially the same diameter. In additional embodiments, the seal arrangement may comprise more than two seals.
As depicted in
In some embodiments, the seal seats 122, 124 may be disposed within an inner portion of the stationary element 106 that is separate from or integral with the remaining outer portion of the stationary element 106 (e.g., an inner sleeve).
As discussed above, some embodiments may include an index positioning feature 128 positioned between the rotatable element 104 and stationary element 106. In some embodiments, the index positioning feature 128 may rotate the rotatable element 104 relative to the stationary element 106 when the rotatable element 104 is moved from a first axial position (e.g., compressed position), shown in
As the rotatable element 104 moves from the compressed position to the expanded position, the volume enclosed between the first seal 118 and the base 116 of the rotatable element 104 may increase as the body of the rotatable element 104 moves out of the cavity 110. Similarly, as the rotatable element 104 moves from the expanded position to the compressed position the volume enclosed between the first seal 118 and the base 116 of the rotatable element 104 may decrease as the body of the rotatable element 104 moves into the cavity 110. The second seal 120 may isolate the constant volume 126 from the total volume enclosed by the first seal 118 and the base 116 of the rotatable element 104. Thus, the seal arrangement may maintain the constant volume 126 between the first seal 118 and the second seal 120 as the rotatable element 104 moves between the first axial position and the second axial position.
Referring to
As shown in
In some embodiments, the substantially constant sealed volume 126 may contain a substantially incompressible fluid. In some embodiments, the fluid enclosed by the seal arrangement may be a lubricating fluid (e.g., oil or grease). The lubricating fluid may be used for lubricating at least one inner component of the rotatable cutting element 100.
Referring to
As depicted, the expandable seal 228 may comprise a diaphragm 228 extending between and fixed to the stationary element 206 or the rotatable element 204. The expandable seal 228 may comprise a resilient material. The expandable seal 228 may expand or compress in order to maintain the substantially constant volume 226 defined by the fixed seal 218, the expandable seal 228, the rotatable element 204, and the stationary element 206.
Referring to
Some embodiments, using an external fluid reservoir 232, may position the first seal 218 on the opposite element from the second seal 220. The external fluid reservoir 232 may compensate for the change in distance between the first seal 218, and second seal 220, when the rotatable element 204 moves relative to the stationary element 206. Similarly, in other embodiments, the first seal 218 and the second seal 220 may have different diameters. The external fluid reservoir 232 may be used to maintain the constant volume 226 by compensating for the volumetric change that may occur absent the external reservoir 232 when the rotatable element 204 moves relative to the stationary element 206.
Earth-boring tools are typically used at the end of a drill string. Drill strings are built out of sections of pipe typically 31 to 46 feet in length. The sections of pipe are connected end to end to create long drill strings which can reach lengths in excess of 40,000 feet. When an earth-boring tool fails the drill string must be removed from the borehole, one 31 to 46 foot section at a time, until the end of the drill string is accessible to change the earth-boring tool or replace the worn or damaged cutters. Changing an earth-boring tool, or tripping out the earth-boring tool to replace worn or damaged cutters, represents a large amount of time and a great expense. Improvements to the cutters on an earth-boring tool which extend the life of the tool represent a large cost savings to downhole earth boring operations.
The downhole environment includes drilling mud introduced by the nozzles as well as material and debris removed by the cutters. Additionally, there may be pressures in excess of 2000 PSI downhole. The debris and drilling mud could potentially enter the space between the rotatable element and the stationary element. If debris and/or drilling mud enters the space between the rotatable element and the stationary element, it may result in damage to bearings and other moving parts within the rotatable cutter. This damage may interfere with the rotation of the rotatable element, which may nullify the advantages of a rotatable cutter. Additionally, the damage could cause vibration to occur within the rotatable cutter during operation, which could also cause premature failure of the rotatable cutter.
Embodiments of rotatable cutters described herein may improve the serviceable life of the rotatable cutters. Rotatable cutters may experience undue wear to internal components due to the ingress of debris and fluid inherent in downhole earth boring operations. The undue wear may result in premature failure of the rotatable cutter. Sealing the rotatable cutter may inhibit the ingress of debris and fluid to the internal components of the rotatable cutters. Preventing the ingress of debris and fluid may result in longer service life for the rotatable cutters. As described above, extending the service life of a rotatable cutter may result in a significant cost savings for downhole earth boring operations using rotatable cutters.
The embodiments of the disclosure described above and illustrated in the accompanying drawing figures do not limit the scope of the invention, since these embodiments are merely examples of embodiments of the invention, which is defined by the appended claims and their legal equivalents. Any equivalent embodiments are intended to be within the scope of this disclosure. Indeed, various modifications of the present disclosure, in addition to those shown and described herein, such as alternative useful combinations of the elements described, may become apparent to those skilled in the art from the description. Such modifications and embodiments are also intended to fall within the scope of the appended claims and their legal equivalents.
