Patent Application
20180216417
In the oil and gas industry, downhole swivels are employed to isolate rotation of a string of tubulars (e.g., casing) from a tool connected to the string. In other words, the swivel allows for relative rotation between two sections of the string of tubulars. Swivels come in a variety of configurations and are implemented across a wide range of applications. Generally, swivels include at least a pair of cylindrical bodies, which are relatively rotatable, e.g., by provision of a bearing. Some types of swivels also include a clutch, which allows one-way rotation between the cylindrical bodies, while preventing reverse rotation. Such one-way swivels can be useful when casing rotation is employed to actuate a mechanism downhole, for example. Thus, the swivel transmits the rotation from the tubular string to the tool in one direction, while allowing relative rotation of the string and the tool in the opposite direction.
Generally, such clutches are implemented with meshing teeth, i.e., a ratchet. Angled surfaces of the teeth force the teeth of a radially inner body to slide out of engagement with a tooth of an outer body, and then into engagement with the next succeeding tooth. Backwards rotation is prevented as the back-sides of the teeth are typically flat, and thus circumferential forces are not translated into the radial force that allows the teeth to move. Further, the swivels are typically made to operate either in compression or tension in the drill string. When the opposite-oriented force is applied to the swivel (e.g., tension is applied to a compression swivel) the teeth of the clutch can disengage, axially separating apart and thereby allowing for free rotation in either direction. In some situations, however, it would be beneficial to employ a swivel having a clutch that is operable both in compression and in tension.
Embodiments of the disclosure may provide a downhole tool including a first sub, a second sub, and a clutch assembly positioned between the first sub and the second sub. The clutch assembly is configured to allow rotation between the first sub and the second sub in a first direction, and to prevent rotation between the first sub and the second sub in a second, opposite direction, when a compression force is applied to the downhole tool, when a tension force is applied to the downhole tool, and when no axial force is applied to the downhole tool.
Embodiments of the disclosure may also provide a downhole tool that includes a first sub configured to connect to a first tubular, a second sub configured to connect to a second tubular, and an outer housing coupled to the second sub and extending toward and separated axially apart from the first sub. The tool also includes an inner mandrel positioned at least partially within the first and second subs, the inner mandrel being rotatable relative to the second sub and connected to and prevented from rotating relative to the first sub. The tool further includes a clutch assembly received within the outer housing and coupled with the inner mandrel, the clutch assembly including a body having a pocket formed therein, and a clutch element movably positioned in the pocket. The clutch element permits the inner mandrel to rotate in a first direction relative to the outer housing and is engageable with the body and an inner diameter surface of the outer housing to prevent rotation of the inner mandrel relative to the outer housing in a second direction.
Embodiments of the disclosure may also provide a method for isolating rotation in one direction and transmitting rotation in another direction in a tubular string. The method includes connecting a swivel to a tubular string. The swivel includes a first sub configured to connect to a first tubular, and a second sub configured to connect to a second tubular. The second sub includes an outer housing extending toward and separated axially apart from the first sub. The swivel also includes an inner mandrel positioned at least partially within the first and second subs, the inner mandrel being rotatable relative to the second sub and connected to and prevented from rotating relative to the first sub. The swivel further includes a clutch assembly received within the outer housing and coupled with the inner mandrel, the clutch assembly including a body having a pocket formed therein, and a clutch element movably positioned in the pocket. The clutch element permits the inner mandrel to rotate in a first circumferential direction relative to the outer housing and is engageable with the body and an inner diameter surface of the outer housing to prevent rotation of the inner mandrel relative to the outer housing in a second circumferential direction. The method also includes deploying the tubular string and the swivel into a well, and rotating the tubular string in the first circumferential direction. The rotation in the first circumferential direction causes first sub to rotate relative to the second sub. The method further includes rotating the tubular string in the second circumferential direction. The rotation in the second circumferential direction causes the clutch assembly to engage the body and the outer housing, such that the first and second subs to rotate together.
The present disclosure may best be understood by referring to the following description and accompanying drawings that are used to illustrate embodiments of the invention. In the drawings:
The following disclosure describes several embodiments for implementing different features, structures, or functions of the invention. Embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure may repeat reference characters (e.g., numerals) and/or letters in the various embodiments and across the Figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed in the Figures. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. The embodiments presented below may be combined in any combination of ways, e.g., any element from one exemplary embodiment may be used in any other exemplary embodiment, without departing from the scope of the disclosure.
Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities may refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function. Additionally, in the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” All numerical values in this disclosure may be exact or approximate values unless otherwise specifically stated. Accordingly, various embodiments of the disclosure may deviate from the numbers, values, and ranges disclosed herein without departing from the intended scope. Finally, unless otherwise provided herein, “or” statements are intended to be non-exclusive; for example, the statement “A or B” should be considered to mean “A, B, or both A and B.”
Embodiments of the present disclosure may provide a downhole tool, configured as a casing swivel (or another type of downhole, oilfield swivel) that is provided with a clutch assembly. The clutch assembly is operable to allow one-way rotation, while preventing rotation in the opposite direction, regardless of whether compressive or tensile loads are applied to the tool. In particular, the disclosed downhole tool may be operable at high dynamic and static loads, e.g., up to about 100,000 pounds of dynamic load and 400,000 pounds of static load.
The downhole tool 100 may include a first or “upper” sub 102, a second or “lower” sub 104, which may be spaced axially apart, such that the first and second subs 102, 104 are rotatable relative to one another, as will be described in greater detail below. The first sub 102 may be connected to an end of a tubular, such as a rotatable string of oilfield tubulars (e.g., a casing string), while the second sub 104 may be connected to another tubular, such as another part of the string of oilfield tubulars, or part of another tool or device. An inner mandrel 106 may extend between the first and second subs 102, 104. For example, the inner mandrel 106 may be coupled to the first sub 102, such that relative rotation therebetween is prevented. In a specific embodiment, the inner mandrel 106 may be threaded into the first sub 102, but, in other embodiments, the inner mandrel 106 may be coupled to the first sub 102 in a variety of ways (e.g., pinned, welded, brazed, press fit, etc.). The inner mandrel 106 may be coupled to the second sub 104 such that the second sub 104 is rotatable relative to the inner mandrel 106. For example, the inner mandrel 106 may be received into the second sub 104, and one or more seals 108 (four are shown) may be positioned in the second sub 104 (and/or in the inner mandrel 106) so as to prevent the flow of fluid or migration of debris therebetween.
The first sub 102 may define a bore 110, the inner mandrel 106 may define a bore 112, and the second sub 104 may define a bore 114. In an embodiment, either or both of the bores 110, 112 in the first and second subs 102, 104, respectively, may be recessed/undercut, so as to account for a radial thickness of the inner mandrel 106. Accordingly, as shown, the bores 110, 112, 114 may define a substantially constant inner diameter throughout the tool 100. In other embodiments, the diameter may change as proceeding through the tool 100.
The tool 100 may include an outer housing 116. The outer housing 116 may be integrally formed with the second sub 104, such that the two pieces form a single, monolithic part. In another embodiment, the outer housing 116 may be connected to the second sub 104, e.g., using fasteners, welding, brazing, etc. Either such configuration (integral formation or connection) is considered within the scope of “coupled to” as the term is used herein. Further, in either such configuration, the outer housing 116 may be generally prevented from rotation relative to (a remainder of) the second sub 104. The outer housing 116 may be generally shaped as a cylindrical sleeve and may extend axially toward the first sub 102. The outer housing 116 may be separated axially apart from the first sub 102, however, so as to allow for relative rotation therebetween. Further, the inner mandrel 106 and the outer housing 116 may be separated radially apart, such that a first annular chamber 118 is defined therebetween. As shown, the first annular chamber 118 may be formed by two or more separate sub-chambers (e.g., on either side of a shoulder 130 of the inner mandrel 106, as will be described below).
The tool 100 may include a cover 120, which may be coupled to the first sub 102 and may extend axially therefrom, toward the second sub 104. The cover 120 may be spaced axially apart from the outer housing 116, allowing for rotation therebetween. The cover 120 may be spaced radially apart from the inner mandrel 106, such that a second annular chamber 122 is defined therebetween.
The tool 100 may include one or more axial thrust bearings (two are shown: a first axial thrust bearing 124 and a second axial thrust bearing 126). In embodiments including first and second axial thrust bearings 124, 126, a load ring 128 may be interposed axially between the first and second axial thrust bearings 124, 126. For example, the load ring 128 may be received around the inner mandrel 106 and threaded (or otherwise coupled) to the outer housing 116 so as to rotate with the second sub 104. In an embodiment, the first axial thrust bearing 124 may be received in the first annular chamber 118, between the outer housing 116 and the inner mandrel 106, and the second axial thrust bearing 126 may be received in the second annular chamber 122 between the cover 120 and the inner mandrel 106. Further, the first axial thrust bearing 124 may be configured to engage the load ring 128 on one axial side and the shoulder 130 of the inner mandrel 106 on an opposite axial side. The shoulder 130 may extend radially outwards into proximity of the outer housing 116. In some embodiments, the shoulder 130 may slide against the outer housing 116. The second axial thrust bearing 126 may be configured to engage the load ring 128 on one axial side and the first sub 102 on the opposite axial side.
In an embodiment, one of the axial thrust bearings 124, 126 may be provided to facilitate rotation between the first and second subs 102, 104 under compressive loads (e.g., the first sub 102 and the second sub 104 being pushed together), and the other one of the axial thrust bearings 124, 126 may be provided to facilitate rotation between the first and second subs 102, 104 under tensile loads (e.g., the first sub 102 and the second sub 104 being pulled apart). The axial thrust bearings 124, 126 may be any suitable type of thrust bearings, with the ability to support the dynamic and static loads called for by the specific application.
The tool 100 may include one or more radial bearings (one shown: 132). The radial bearing 132 may be positioned in the first annular chamber 118, e.g., on an opposite side of the shoulder 130 from the first axial thrust bearing 124. In some embodiments, another radial bearing may be positioned on an opposite side of the load ring 128 and/or in the second annular chamber 122. The radial bearing 132 may be a plain bearing (e.g., a bushing-type bearing), but could also be a roller bearing or any other suitable bearing, e.g., depending on size constraints. The radial bearing 132 may be positioned between the inner mandrel 106 and the outer housing 116, so as to facilitate rotation therebetween and, e.g., support bending forces applied to the tool 100.
The tool 100 may include a clutch assembly 200. The clutch assembly 200 may be connected to or formed generally as a part of the inner mandrel 106, e.g., disposed in the shoulder 130. In other embodiments, the clutch assembly 200 may be a separate piece from the inner mandrel 106 and may be connected thereto. The clutch assembly 200 may allow rotation of the second sub 104 with respect to the first sub 102 in a first direction, while preventing rotation therebetween in a second, opposing direction. For example, the clutch assembly 200 may lock the inner mandrel 106 from rotation with respect to the outer housing 116 in the second direction, as explained in greater detail below. The clutch assembly 200 may be continuously engaged, meaning that it functions to prevent rotation in the second direction regardless of whether the tool 100 is in compression, tension, or no axially-directed load.
In an embodiment, the clutch assembly 200 includes a clutch body 201 in which a plurality of pockets 202 are formed. In some embodiments, the clutch body 201 may be integral with (formed as a part of) the shoulder 130 of the inner mandrel 106, but in other embodiments, may be provided by a separate (e.g., ring-shaped) structure that is connected to the inner mandrel 106. The clutch assembly 200 also includes a plurality of clutch elements 204 positioned in the pockets 202 (e.g., one clutch element 204 per pocket 202, although two or more clutch elements 204 could be provided in a single pocket 202, and/or one or more pockets 202 may not include a clutch element 204). In some embodiments, the clutch elements 204 may be rollers, such as cylindrical dowels or spherical members. In other embodiments, the clutch elements 204 may be generally wedge-shaped.
The pockets 202 may be flat sections, e.g., machined into the clutch body 201. Accordingly, in some embodiments, the pockets 202 may be formed as a flat cut out in the circumferential surface of the clutch body 201, such that a depth from the bottom 300 of the pocket 202 to the outer diameter of the clutch body 201 decreases as proceeding in a first circumferential direction (e.g., the counterclockwise direction as shown in
Optionally, one or more engaging members 302 (two are shown in each pocket 202 in this example) may extend into each of the pockets 202 from a recess 304 formed in a sidewall 306 thereof. The engaging members 302 may be, in some embodiments, generally cylindrical plungers designed to push against the clutch elements 204. A biasing member 308 may be positioned in the recess 304 and may be configured to bias the engaging member 302 into the pocket 202. For example, the biasing member 308 may fit at least partially within, or around an end of, the engaging member 302, and push the engaging member 302 into the pocket 202. The biasing member 308 may be a coiled compression spring, a leaf spring, Bellville washer, etc. In some embodiments, the biasing member 308 and/or the engaging members 302 may be omitted. The engaging members 302 may bear against the clutch elements 204, generally preventing the clutch elements 204 from engaging the sidewall 306 and, in some embodiments, preloading the clutch elements 204 against the outer housing 116.
As shown, the pockets 202 may be disposed at intervals (e.g., equiangularly) around the shoulder 130, such that the shoulder 130 resembles a toothed structure. The actual number of pockets 202 may vary, e.g., from two to about ten, or more, depending on the implementation. In some embodiments, an even number of pockets 202 (and clutch elements 204) may be provided to radial forces incident on the shoulder 130, as will be described in greater detail below.
The clutch elements 204 may be slightly smaller or larger in radial dimension (e.g., in the illustrated cylindrical clutch elements 204, the radial dimension is the diameter of the individual clutch elements 204) than the depth of the pocket 202 at the sidewall 306. Accordingly, the engaging members 302 may apply a small force on the clutch elements 204, pushing the clutch elements 204 away from the sidewall 306 until the clutch elements 204 engage, or nearly engage, the outer housing 116, thereby preloading the clutch assembly 200. When the first sub 102 (and thus the inner mandrel 106—see
In contrast, when the first sub 102, and thus the clutch body 201, rotates in the second, opposite direction D2 with respect to the outer housing 116, the engagement between the outer housing 116 and the clutch elements 204 moves the clutch elements 204 away from the sidewall 306, into the shallower region of the tapered pocket 202. As the clutch elements 204 move away from the sidewall 306, eventually, the clutch elements 204 produce a mechanical interference between the body 201 and the outer housing 116 as the clutch elements 204 wedge between the outer housing 116 and the bottom 300 of the pockets 202. Such interference/wedging acts to resist and ultimately prevent relative rotation in the second direction D2 of the clutch body 201 (and thus the inner mandrel 106 and thus the first sub 102) with respect to the outer housing 116 (and thus the second sub 104). The spring-biased engaging members 302 may serve to ensure generally simultaneous engagement between the multiple clutch elements 204 and the outer housing 116, so as to balance radial forces.
Accordingly, the clutch assembly 200 is continuously engaged, regardless of whether the axial thrust bearings 124, 126 take up axial compressive and tensile loads. This construction allows such functioning as there is no corresponding clutch structure in the outer housing 116; rather, the clutch assembly 200 interfaces with the inner diameter surface of the outer housing 116 to provide the clutching function. This contrasts with saw-tooth type clutches, which typically disengage in either compressive or tensile loads.
The method 500 may begin by connecting a swivel (e.g., the downhole tool 100) to a tubular string, as at 502. The swivel may be constructed according to any of the embodiments discussed above with respect to the downhole tool 100, or others. The method 500 may then proceed to deploying the tubular string and the swivel into a well, as at 504.
The method 500 may further include rotating the tubular string while applying tension or compression thereto, in the first circumferential direction, as at 506. The rotation in the first circumferential direction D1 causes first sub 102 to rotate relative to the second sub 104, which is allowed by the clutch assembly 200, as explained above.
The method 500 may also include rotating the tubular string while applying tension or compression thereto, in the second circumferential direction D2, as at 508. Rotation in the second circumferential direction D2 causes the clutch elements 204 of the clutch assembly 200 to engage the body 201 and the outer housing 116, such that the first and second subs 102, 104 are prevented from relative rotation, and are thus caused to rotate together by rotation of the tubular string.
As used herein, the terms “inner” and “outer”; “up” and “down”; “upper” and “lower”; “upward” and “downward”; “above” and “below”; “inward” and “outward”; “uphole” and “downhole”; and other like terms as used herein refer to relative positions to one another and are not intended to denote a particular direction or spatial orientation. The terms “couple,” “coupled,” “connect,” “connection,” “connected,” “in connection with,” and “connecting” refer to “in direct connection with” or “in connection with via one or more intermediate elements or members.”
The foregoing has outlined features of several embodiments so that those skilled in the art may better understand the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.
