The invention relates generally to a wellbore apparatus and, in particular, a wellbore slip assembly.
A wellbore slip assembly is an installation mechanism for installing a wellbore structure in the well. A wellbore slip assembly is run into place in a well and installed by setting the outer slip surfaces against a wellbore wall, which may be casing or open hole. The setting process is generally by expansion radially outwardly of the slips from a smaller diameter to a diameter that bears against the wellbore wall.
Wellbore slip assemblies are included on all kinds of downhole tools that are intended to be installed in a wellbore. Such tools include, for example, plugs, bridges, packers, whipstocks, patches, liner hangers, etc.
The wellbore slip assembly is sometimes large and complex, which increases running costs. If it must be removed from the well, there are considerations regarding the time and equipment that is needed for the removal.
There is a need for a small size wellbore slip assembly. There is considerable advantage if the slip assembly facilitates removal.
A wellbore slip assembly has been invented. The wellbore slip assembly comprises of a core and a helical slip.
In accordance with a broad aspect of the invention, there is provided a wellbore slip assembly comprising: a core including an upper end, a lower end, an outer diameter tapering towards the lower end and a first lock on the outer diameter; and a helical slip including a base end, a top end, a substantially cylindrical outer surface, a bore with an inner diameter that tapers from the top end toward the base end, a second lock in the bore, the second lock configured to lock with the first lock and a spiral cut extending from the top end between the outer surface and the bore, the helical slip being configured to radially enlarge along the spiral cut by the core being forced into the bore.
In accordance with another broad aspect of the invention, there is provided a method for installing a slip assembly in a structure, comprising: running the slip assembly into place in the structure; and setting the slip assembly, including holding a helical slip of the slip assembly against axial movement; and wedging a core of the slip assembly into a bore of the helical slip, to apply a force that acts to radially enlarge the helical slip, thereby engaging an outer surface of the helical slip with a wall of the structure.
It is to be understood that other aspects of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein various embodiments of the invention are shown and described by way of illustration. As will be realized, the invention is capable of other and different embodiments and its several details are capable of modification in various other respects, all within the present invention. Furthermore, the various embodiments described may be combined, mutatis mutandis, with other embodiments described herein. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.
The present disclosure is best understood from the following detailed description when read with the accompanied figures. The drawings are not necessarily drawn to scale.
A slip assembly comprises a core and a helical slip, which is expanding helical slip with an outer surface configured to engage against a wellbore wall, cased or open hole, and has a spiral cut extending from its upper end toward its lower end.
Various embodiments of the wellbore slip assembly are illustrated and described. While the embodiments herein illustrate the wellbore slip assembly as part of a wellbore plug, it is to be understood that the wellbore slip assembly may be installed on other tools such as whipstocks, bridges, patches, etc. In these other tool configurations, the core is coupled to such as connected to or integral with the tool body.
With reference to
Briefly in operation, the core 5 acts to expand the helical slip out into engagement with a wellbore wall. Core 5 is employed like a wedge and is forced, narrow end first, into the wider end of the inner open diameter of the helical slip 6. Because of (i) cooperating frustoconical surfaces on the outer surface of the core and within the inner diameter of the slip and (ii) the helical shape of the slip 6, this wedging action by the core forces the helical slip to expand radially out into engagement with the wellbore wall. To prevent the core from backing out of the helical slip, a lock such as interacting ratcheted surfaces can be provided on each of core 5 and within the inner diameter of the helical slip.
As such, core 5 comprises a radially outwardly facing surface that has an outer surface portion 50 shaped frustoconically, which configures the core to act as a wedge. Core 5 also includes locking mechanism such as a ratcheted surface 54 on its outer-facing surface. In the illustrated embodiments of
The outer surface 50 is tapered, such that the core decreases in outer diameter from the upper end towards the lower end of the core. Thus, the outer diameter of the core is smaller across the lower end than across the upper end and is generally frustoconical. As noted the outer surface portion 50 is generally smooth, for example, without ratchet teeth.
Ratcheted surface 54 of the core has a ratchet thread form that allows axial downward movement of the core as against a ratchet interface but does not allow reverse upward movement. To facilitate movement of the ratchet teeth over the ratchet interface, ratcheted surface 54 is positioned on cylindrical arrangement of resilient collet tabs 52. Tabs 52, each being separated from adjacent tabs by a small gap, can be resiliently deformed radially inwardly toward the center axis of the core bore 56 but pop back out and bias the ratchet teeth of ratcheted surface 54 into engagement with the ratchet interface 64 of the helical slip 6. While the outer diameter of the core tapers along outer surface, tabs 52 of collet do not taper, but instead have a substantially consistent diameter along their length with ratchet teeth protruding therefrom.
Apart from the frustoconical form and the locking mechanism, the core can take various forms. For example, the core may be solid. However, as noted above slip assembly illustrated in
Alternatively, depending on need, such as in
Alternatively, another sealing mechanism, such as for example, a captured poppet valve could be employed to seal bore 56 of core 5 in both directions upward and downwardly through the bore 56.
Helical slip 6, also sometimes called an expanding load ring herein, has an annular body with an inner bore 62. The bore extends from the upper end of helical slip 6 toward its lower end. In this illustrated embodiment, bore 62 extends all the way through the helical slip from its upper end to its lower end along the long axis of the body. In the assembly, the helical slip surrounds core 5 and is the structure that engages wellbore wall 1. Specifically, the core is positioned in bore 62 of the helical slip and, in use, the core is driven deeper into the bore 62 to radially expand the helical slip. Once the core is driven to expand the helical slip 6 sufficiently to set the slip assembly in the wellbore, the core can be locked in the helical slip to ensure it remains in the expanded, set condition. For example, the core can be locked in the helical slip by the core's ratcheted area 54 on the outer surface of the core interfacing with a ratcheted form 64 on the surface within the bore 62 of the helical slip.
To permit core to be driven into the helical slip 6, the bore 62 includes a tapered portion 62a that has a tapering, frustoconical, substantially smooth inner diameter that tapers toward the bottom end of the slip. The tapering angle along the tapering portion of bore 62 is about the same as the tapering angle along outer surface 50. The maximum outer diameter across the upper end of the core, however, is greater than the maximum inner diameter across bore 62. Bore 62 also includes a deeper area, below the bottom end 62b of the tapering portion, where the inner diameter transitions to a substantially non-tapering, cylindrical portion. An end wall, inwardly projecting ledge 62c, defines the maximum depth of the substantially non-tapering, cylindrical portion. The substantially non-tapering, cylindrical portion has a side-to-side inner diameter dimension about the same as the outer diameter across the core tabs 52. The non-tapering area has an axial length longer than the length of tabs 52.
The inner surface of the non-tapering area has ratchet teeth 64 exposed thereon that are selected to lock with the teeth of ratcheted area 54 on core 5. Ratcheted area 54 and ratchet teeth 64 are configured to create a locking ratchet interface that permits core 5 to move deeper into the bore of helical slip 6, but core 5 cannot be pulled out. In other words, the ratchet teeth 54 on the core outer surface ensures that the core can move axially further down into the bore of the helical slip but cannot reverse back out of the helical slip bore. Thus, the inner bore 62 of the helical slip is shaped and configured to receive and lock the core and also shaped to receive an expansive force from the advancement of the core therein.
The annular body of helical slip 6 is a helical structure. In particular, the bore is formed as the center of a helical coil. To create the helical structure, in the illustrated embodiment, the helical slip's annular body has an angled cut, termed a spiral cut 69, which configures the annular body as a form of coil spring. The spiral cut permits the helical slip to radially enlarge, when a force is applied by the core being pushed, for example, wedged, deeper into the bore. The spiral cut extends fully through the radial thickness of the body and extends from the upper end towards the lower end of the body. The helical slip must be capable of radial enlargement, in the same mode as radial enlargement of a coil spring without failure. The spiral cut in the embodiment of
The outer surface of the helical slip has wickers 63 defined thereon. Wickers 63 are teeth with sharped outer tips for engaging the wellbore wall 1, for example of casing. The outer surface of helical slip 6 is generally cylindrical, substantially without a taper, which means that the outer surface outer diameter is substantially consistent from upper end to lower end. While the run in position of the helical slip has an outer diameter less than the inner diameter across the wellbore, the helical slip when radially expanded, by wedging the core 5 therein, can engage against and grip the wellbore wall, thereby setting the slip assembly. The slip assembly, therefore, is formed by the co-acting core and helical slip being wedged together and locked at their ratcheting surfaces 54, 64. The upper angled portion 50 of the core, which has a maximum outer diameter greater than the maximum inner diameter of bore 62, forces the upper end of the helical slip to radially enlarge when the core is fully wedged therein.
A metal-to-metal seal is created between the wellbore wall and the helical slip, as the wickers bite into the wall 1. The outer diameter of the helical slip has a large number of wickers, with a shallow depth. This shallow depth allows for full depth penetration into casing which will enhance the metal-to-metal seal. A metal-to-metal seal is also created along the spiral cut 69 as the helical turns are compressed together and any gap at the spiral cut closes. If leaks occur through the interface or along the spiral cut, a deformable seal 67 may be added to the lock ring. The deformable seal may be a continuous annular body for example on the upper end of the helical slip, which follows the circumference of the helical slip.
A setting tool 2 is used to set the slip assembly, which means the setting tool facilitates the axial advancement of core 5 into bore 62 of the helical slip to radially enlarge it. The setting tool can include various structures that hold the helical slip while the core is pushed into its bore. In one embodiment, for example, the setting device may include one or more shear pins 72a between a mandrel 3 of the setting tool and helical slip 6. In particular, in the illustrated embodiment, the lower end of the helical body is formed as a setting device mount area 7 with shear pin mounting apertures 72, which retain pins 72a.
The wellbore slip assembly parts, such as the core and helical slip, can be made of typical materials that are durable and substantially permanent in wellbore conditions, such as steel, for example mild steel or stainless steel. As noted, however, removal of the wellbore slip assembly may be of interest. Surprisingly, it has been determined that a degradable material such as a degradable metal material, for example, an aluminum/magnesium degradable material, such as a 25-45 ksi material, is strong enough to bite into the wellbore wall, and engage with the core, and also is readily enlarged without failure. At the same time, the material degrades in a reasonable period in wellbore conditions. The core and shear pins may also be constructed of a degradable material such as a degradable metal material, for example, an aluminum/magnesium degradable material, such as a 25-45 ksi material. Even the rubber elements can be formed of a material selected to degrade at wellbore conditions. These materials can degrade in a period of a day to a few months, depending on preferences.
In operation, the wellbore slip assembly is run into a well along direction RIH (
In the run in position (
Run in can be by any one of various means, such as by a connected running tool or string, herein an extension of setting tool 2, and/or by a pump down assembly. Setting can be by setting tool 2 that holds directly or indirectly the helical slip and actuates the core and helical slip so that the core is forced into the bore of the helical slip. Generally, helical slip 6 is held against axial movement, while forcing the core down into the bore of the helical slip. In the illustrated embodiment, setting tool 2 includes a mandrel 3 coupled to helical slip and a setting sleeve 4 concentric about, and axially moveable relative to, the mandrel. Setting sleeve 4 is configured to apply a downward force, see arrow SET, against core 5, while mandrel 3 holds helical slip 6 axially stationary (
Advancement of the core 5 into the helical slip is stopped either when it is sensed, for example by back pressure, that the helical slip is sufficiently expanded or the core tabs 52 are stopped against the end wall 62c.
When the wellbore slip assembly is set in the wellbore (
After the slip assembly is set and, if necessary, the running and setting tools are removed, the wellbore slip assembly holds the tool in the well. In this illustrated embodiment, where the wellbore slip assembly is part of a wellbore plug, the after setting, the plug is ready for operation to create a seal in the well (
Over time, the wellbore slip assembly including helical slip 6, core 5 and shear pins 72a will degrade at well bore conditions so that the wellbore becomes opened again.
The wellbore slip assembly has a large window of radial expansion. For example, a helical slip with a 3″ OD run in size can be expanded to set in 4½″ casing which is a significantly larger expansion capability than standard tool slips. Also, the wellbore slip assembly is useful for setting in multiple casing weights. Because of the full circumferential and substantially uniform load, the wellbore slip assembly is appropriate for use in a large variety of casing weights with a single slip design. This is very unique.
It will be appreciated that various modifications can be made to the invention. While the embodiment, of
The description of the
The core 5 comprises ratchet teeth on a major portion of outer diameter surface, including on the frustoconical surface. The embodiment, includes a plug seat 58a built into the core's open inner diameter and
The core outer surface has a higher taper angle on the upper end 54a than the lower end 54b. As such, the core outer surface has two different tapering angles, where the upper portion 54a flares out at a greater angle beyond the lower portion 54b starting at a transition circumference 55. Thus, there is one taper angle β from the uppermost end to the transition circumference and more gradual tapering angle α from the transition circumference to the lowermost end. These two tapering angles may assist in loading of the ratchet expanding helical slip. The difference between the upper and lower tapering angles may be small, such as 1-10 or possibly 1-5°.
The spiral ratchet expanding helical slip 6 is generally as described above in respect of
The spiral cut 69 of the helical slip in the embodiment of
Helical slip has a deformable seal 67 encircling its upper end. Seal 67 mitigates leaks along the wicker 63 to wall 1 interface and/or along the spiral cut 69. The deformable seal may be a continuous annular body to follow the circumference of the helical slip. If the wellbore slip assembly is selected to disintegrate at wellbore conditions, the resilient material of the seal may also be selected to break down at wellbore conditions.
While the helical slip in
Setting ring 7 also provides a useful site for a pump down assembly such as an annular wiper fin 80, which can be installed in gland 80a.
In use, the wellbore slip assembly is run in by a running tool and/or via pump down pressure against wiper fin 80.
The wellbore slip assembly is set in the wellbore by forcing core 5 down into the bore of the helical slip to radially expand it. The upper angle of the core, which has a greater taper angle, forces the upper end of the helical slip to radially enlarge ahead of the lower end of the helical slip. Thus, the wickers on the upper end of the helical slip are driven out first by the larger diameter upper end of the core and to set into the casing first. Therefore, the flaring upper end of the core may preload the helical slip, wherein the upper end of the helical slip are very quickly driven into engagement with the wellbore wall. Full load support is achieved even within the first half of the setting process.
The setting tool can be removed by shearing the ring connection 74. The setting ring may fall away from the assembly of core 5 and helical slip 6 or the setting ring may include the locking collet 76 that keeps it coupled on the bottom of the plug.
After the slip assembly is set and, if necessary, the running and setting tools are removed, the wellbore plug is ready for operation to create a seal in the well (
Over time, the plug including the lock ring, core, shear ring, ball, seal 67 and wiper fin 80 will degrade at well bore conditions so that the wellbore becomes opened again.
One or more of the optional differences described with respect to
Clause 1. A wellbore slip assembly comprising: a core including an upper end, a lower end, an outer diameter tapering towards the lower end and a ratchet thread on the outer diameter; and a helical slip including a base end, a top end, a substantially cylindrical outer surface, a bore with an inner diameter that tapers from the top end toward the base end, a ratcheted surface in the bore and a spiral cut extending from the top end between the outer surface and the bore, the helical slip being configured to radially enlarge along the spiral cut by the core being forced into the bore.
Clause 2. The wellbore slip assembly of any one or more of clauses 1-14, wherein the core outer diameter includes a frustoconical, smooth outer surface on the upper end and the ratchet thread is on the lower end and wherein the bore of the helical slip includes a tapered, smooth portion at the top end and a deeper portion closer to the bottom end, the deeper portion being substantially non-tapering and wherein the ratcheted surface is in the deeper portion.
Clause 3. The wellbore slip assembly of any one or more of clauses 1-14, wherein the core includes a collet on its lower end and the ratchet thread is on collet.
Clause 4. The wellbore slip assembly of any one or more of clauses 1-14, wherein the deeper portion has a side to side inner diameter dimension about the same as an outer diameter dimension across the collet and the deeper portion has an axial length longer than a length of the collet.
Clause 5. The wellbore slip assembly of any one or more of clauses 1-14 wherein the spiral cut terminates in the deeper portion.
Clause 6. The wellbore slip assembly of any one or more of clauses 1-14, wherein the core includes a through bore extending along its long axis from the upper end to the lower end and a plugging mechanism in the through bore, thereby configuring the wellbore slip assembly as a wellbore plug.
Clause 7. The wellbore slip assembly of any one or more of clauses 1-14, wherein the core and the helical slip are each constructed of a degradable material.
Clause 8. The wellbore slip assembly of any one or more of clauses 1-14, further comprising: a coupling mechanism to couple the helical slip to a setting tool.
Clause 9. A method for installing a slip assembly in a structure, comprising: running the slip assembly into place in the structure; and setting the slip assembly, including holding a helical slip of the slip assembly against axial movement; and wedging a core of the slip assembly into a bore of the helical slip, to apply a first force that acts to radially enlarge the helical slip, thereby engaging a ratcheted outer surface of the helical slip with a wall of the structure; and a second force that acts to axially compress the helical slip to close a spiral cut of the helical slip.
Clause 10. The method of any one or more of clauses 1-14, further comprising: locking the core into the helical slip by engaging interacting ratcheted surfaces on each of the core and within an inner diameter of the helical slip.
Clause 11. The method of any one or more of clauses 1-14, further comprising: plugging the core by receiving a plugging device in a seat of the core.
Clause 12. The method of any one or more of clauses 1-14, wherein: holding the helical slip against axial movement includes coupling a setting tool to the helical slip via one or more shear pins; and wedging the core into the bore includes pressing the setting tool axially against the core and towards the bore.
Clause 13. The method of any one or more of clauses 1-14, further comprising removing the setting tool.
Clause 14. The method of any one or more of clauses 1-14, further comprising removing the slip assembly, including by permitting one or more materials of the slip assembly to degrade.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to those embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the full scope consistent with the claims, wherein reference to an element in the singular, such as by use of the article “a” or “an” is not intended to mean “one and only one” unless specifically so stated, but rather “one or more”. All structural and functional equivalents to the elements of the various embodiments described throughout the disclosure that are known or later come to be known to those of ordinary skill in the art are intended to be encompassed by the elements of the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 USC 112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or “step for”.
Filing Document | Filing Date | Country | Kind |
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PCT/CA2021/050504 | 4/15/2021 | WO |
Publishing Document | Publishing Date | Country | Kind |
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WO2021/207840 | 10/21/2021 | WO | A |
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9157288 | Martinez | Oct 2015 | B2 |
9759029 | Davies et al. | Sep 2017 | B2 |
10605044 | Davies et al. | Mar 2020 | B2 |
20180016864 | Parekh | Jan 2018 | A1 |
Number | Date | Country |
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201367871 | Dec 2009 | CN |
106639994 | May 2017 | CN |
2384256 | Jul 2003 | GB |
Number | Date | Country | |
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20230075955 A1 | Mar 2023 | US |
Number | Date | Country | |
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63010847 | Apr 2020 | US |