Patent Application
20110147013
The invention relates generally to equipment utilized in conjunction with subterranean wells and, more particularly, to retrieving packers or other downhole tools having opposed slip assemblies to secure the tool in a cased wellbore. This invention would be especially useful with high performance tools designed for use in high pressure and high temperature environments.
Current practices used to unset and retrieve opposed slip type packers and other tools, such as plugs, particularly those used in extreme pressure and temperature environments, have not proven to be efficient or reliable due to various limitations. Further, the methods for retrieving such tools often result or require the destruction of the tool or parts thereof, such as by drilling, milling and the like.
Various patents describe mechanisms for setting, unsetting and retrieving downhole tools such as packers, including U.S. Pat. Nos. 4,151,875 to Sullaway, 5,224, 540 and 5,271,468 to Streich, 5,727,632 to Richards, 7,080,693 to Walker, and 7,198,110 to Kilgore, all of which are herby incorporated for all purposes.
It is desirable to provide a tool release and retrieval method which results in a more efficient and reliable retrieval process. Further, it would be desirable to retrieve the entire downhole tool, including all of its component parts. Further, it would be desirable to release and retrieve the entire tool with a single trip within the wellbore.
A method is described, which provides for the release and retrieval of an opposed slip type down hole tool by reducing the compressive forces on the sealing elements prior to unsetting the upper slip assembly. Further, the method does so without damaging the slip assemblies. The method provides for the retrieval of the entire downhole tool, including all of its component parts, requiring but a single trip within the wellbore.
A method is described for utilizing an opposed-slip type downhole tool in a subterranean wellbore having a casing. The tool is positioned in a subterranean wellbore having a casing. The tool has upper and lower slip assemblies positioned on opposite sides of a sealing assembly. The sealing assembly has at least one compressible, annular sealing element. The tool is then set in the wellbore by radially expanding the slip assemblies into gripping engagement with the casing, and by longitudinally compressing and radially expanding the sealing element into sealing engagement with the casing. When the tool is to be retrieved, the sealing element is disengaged from the casing by relaxing the compression forces on the sealing element. Then the slip assemblies are disengaged from the casing such that the slip assemblies are no longer in gripping engagement with the casing. The tool is then retrieved from the wellbore.
The step of disengaging the sealing assembly can be performed by radially contracting the sealing element with or without longitudinally expanding the sealing element.
In a preferred method, the tool includes a sealing element retainer assembly having a sealing element retainer, which is moved with respect to the sealing element to reduce the compression forces on the sealing element. The sealing element retainer can be moved longitudinally or otherwise. Movement of the sealing element retainer results in relaxation of, or reduction of compressive forces in, the sealing element. In a preferred embodiment, the sealing element retainer is an annular member in sliding engagement with a mandrel of the tool, the sealing element retainer connected to the upper wedge assembly by a releasable connection. The sealing element retainer is released to move with respect to the upper wedge assembly during the step of disengaging the sealing element. In the exemplary embodiment, the releasable connection includes a toothed, collapsible C-ring, the teeth of which engage a corresponding toothed portion of the upper wedge assembly. The C-ring cooperates with and collapses into a reduced-diameter portion of the outer surface of the mandrel during the step of disengaging the sealing element.
In an alternative embodiment, the sealing element is relaxed by allowing radial contraction without allowing longitudinal expansion. The sealing element retainer is moved longitudinally during the step of disengaging, the movement of the retainer relaxing the compression force acting against the interior surface of the sealing element by aligning a reduced-diameter portion of the mandrel with the sealing element, thereby reducing the compression force on the sealing element and allowing the sealing element to relax.
Alternate embodiments are described and these and other features, advantages, benefits and objectives of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the invention herein below and the accompanying drawings.
In the following description of the tool and other apparatus and methods described herein, directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used only for convenience in referring to the accompanying drawings. Additionally, it is to be understood that the various embodiments of the present invention described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of the present invention.
While the making and using of various embodiments of the present invention are discussed in detail below, a practitioner of the art will appreciate that the present invention provides applicable inventive concepts, which can be embodied in a variety of specific contexts. The specific embodiments discussed herein are illustrative of specific ways to make and use the invention and do not delimit the scope of the present invention.
Representatively illustrated in
The tool 10 described herein is an example of an “opposed slip” type well tool which may be run, set, unset and retrieved in a wellbore having a casing using the principles of the invention. The tool 10 is a well tool of the type which, when set, dually grips the wellbore preventing either upward or downward tool movement. The opposed upper and lower slip assemblies function to anchor the tool against movement in both axial directions. The gripping or anchoring function is performed by the upper and lower slip assemblies 20 and 60 when in the set position, as seen in
Consequently, the use of the term “opposed slip type tool” as used herein is limited to downhole tools having an upper and lower slip assembly on opposite sides (above and below) a sealing assembly. The tool 10 is illustrated as a packer, however, the invention applies equally to all opposed slip type tools having slip assemblies above and below a sealing assembly, including plugs, valves, etc., as will be apparent to one of skill in the art. The invention lies in the methods and apparatus for releasing and retrieving the tool as claimed, rather than in the function of the tool when set in the wellbore.
The terms “uphole” and “upward” refer to the direction toward the wellbore surface. The terms “downhole” and “downward” refer to the direction of away from the wellbore surface. While it is anticipated that the surface is generally upward from any downhole location, the tool may be utilized in a deviated or horizontal wellbore, in which case the terms refer to the directions indicated rather than relative vertical placement.
When in the set position, compressive forces are “trapped” in the sealing assembly 40. That is, compressive forces are applied to the sealing assembly during the setting process in order to radially expand the sealing elements 42 into sealing engagement with the wellbore. These compressive forces remain acting on the sealing assembly while the tool is in the set position, the relative spacing of the upper and lower slip assemblies maintaining the sealing assembly in a radially expanded and longitudinally shortened position. After being set in the wellbore, and prior to retrieval, the invention enables the compressive forces on the sealing assembly 40 of the tool 10 to be reduced or relaxed before unsetting the slip assemblies 20 and 60.
This method of relaxing the sealing assembly before release of the slip assemblies results in a more reliable and efficient process of retrieval of the downhole tool. The methods included in the invention also permit the full retrieval of the packer and all of its components as a single unit. The methods also permit, but do not require, the release and retrieval of the well tool in a single trip within the wellbore.
As used herein the term “set” is used to refer to an operation producing a gripping and sealing engagement between the well tool and the casing of the wellbore. The “set position” is used to refer to the tool when in a position having the slip assemblies in a radially expanded position in gripping engagement with the casing and the sealing assembly radially expanded and in sealing engagement with the casing. The terms “release” or “unset” are used to refer to an operation, which moves the tool out of gripping and sealing engagement with the casing of the wellbore to permit removal or retrieval of the tool from the wellbore. While it is preferable that the unsetting of the tool will move the tool out of all contact with the casing, it is recognized that this may not always be the case. If the wellbore is horizontal, or other than vertical, the tool may still contact the casing as it lies in the wellbore. Further, the sealing assembly, once expanded, may not radially reduce in diameter sufficiently to prevent all contact with the casing. However, the sealing assembly must be unset, or radially contract, enough to allow relatively easy removal from the well. The term “nm-in position” refers to the tool when in an initial position for running the tool into the wellbore, wherein the slip assemblies are radially contracted and the sealing assembly radially contracted. Similarly, the term “unset position” or “released position” refers to the tool when after being in the set position, is in a position with the slip assemblies radially contracted and the sealing assembly radially contracted.
Turning to
In
The mandrel 11 is shown threadedly connected to an upper sub 16 and a lower sub 18. Alternately, the tool and subs can be formed as a single solid piece. The upper sub 16 is designed for connection to a tubing string, coiled tubing or the like as is known in the art. Further or alternately, the upper sub is configured to receive and releasably connect to a stinger, setting tool, actuating or operating tool, hydraulic actuator, or other well tool as is known in the art. The lower sub 18 can also be configured as desired.
The upper and lower slip assemblies 20 and 60 have upper and lower slip elements 22 and 62, respectively. In the embodiment shown, the slip elements are part of a circumferentially continuous, axially-slotted, barrel-type slip of the type known in the art. However, it is to be clearly understood that the slip assemblies may be differently configured without departing from the principle of the present invention. For example, the slip elements 22 can be comprised of a plurality or series of slip elements which are independent and separated from one another, or partially segmented and movably joined to one another, circumferentially discontinuous, divided, slotted, etc. The slip assemblies may include further elements not shown, such as retaining rings or devices, to maintain the slips in the run-in position until setting the tool. The slip assemblies 20 and 60, as shown have shear mechanisms 26 and 66, to maintain the slip assemblies in their run-in position. The shear mechanisms, here pins, are sheared as an initial step in setting the tool to allow relative longitudinal motion between the slip elements and the mandrel. Other methods of maintaining the slip assemblies in a run-in position are known in the art and may be employed. The upper slip assembly 20 further includes an upper slip support 25, in this case an enlarged portion of the lower end of the upper sub 16. The slip support 25 abuts the upper end of the upper slip elements 22, maintains the relative positions of the assemblies during run-in, and communicates setting force during setting. In this case, the upper slip support 25 does not move relative to the mandrel 12 during setting. Other slip support mechanisms are known in the art and may be used.
The slip assemblies 20 and 60 have a plurality of longitudinal slots 24 and 64, respectively. The slots 24 of the upper slip assembly 20 cooperate with lugs 14, which are integrally formed on the mandrel 12 and extend radially from the mandrel body into the slots. Each of the slots 24 has a closed upper end 27, which the lugs 14 will contact during the unsetting or releasing step. As the mandrel 12 is moved longitudinally during the unsetting or disengaging process, the lugs move longitudinally with respect to the upper slip assembly 20. The lugs 14 contact the upper ends 27 of the slots 24 of the barrel slip and unset the slip assembly. That is, the slips 22 are pulled off of the wedges of the wedge assembly 30. The slip assembly then radially contracts, thereby disengaging with the casing wall. The tool 10 is designed such that the upper slip assembly is not unset or disengaged until after the sealing assembly is disengaged from the casing. The lugs 14 move longitudinally along the slots 24 as the groove 78 on the mandrel is moved into alignment with the release mechanism 75, as described below, but do not contact the upper ends of the slots 24 until after the groove and release mechanism are aligned and the prop member 72 telescopes with respect to the upper wedge assembly 30. Thus, the upper slip assembly is not disengaged until after the sealing assembly is disengaged.
Each of slip elements 22 and 62 contains a series of serrated outwardly protruding teeth 28 and 68, respectively, thereon for gripping the casing wall or other conduit within the wellbore. The teeth or gripping structures 28 and 68 of the slip assemblies 20 and 60 may be of any design known in the art, such as integrally formed on the slip elements, separately attached to the assemblies (such as “button slips”), etc. Incorporated herein by reference for all purposes is U.S. Pat. No. 5,224,540 to Streich which describes and refers to various setting mechanisms, slip configurations, slip supports, and teeth among other things
The upper wedge assembly 30 is carried on the mandrel 12. The upper slip assembly 20 and the upper wedge assembly 30 have cooperating sloped surfaces 29 and 32, which cause the upper slip assembly 20 to expand radially as the upper wedge assembly 30 is moved longitudinally relative to the upper slip assembly 20. To “expand radially”, as used herein in reference to the upper 20 and lower 60 slip assemblies, means to expand their outer diameters rather than suggesting a volumetric increase of the components. The radial expansion of the upper slip assembly 20 causes their gripping surfaces 28 to come into contact with the interior surface of the wellbore casing. With sufficient radial expansion, the upper slip assembly 20 becomes grippingly engaged with the casing, preventing upward movement of the tool 10 in the wellbore.
Similarly, the lower wedge assembly 50 is carried on the mandrel 12. The lower slip assembly 60 and the lower wedge assembly 50 have cooperating sloped surfaces 62 and 52, which cause the lower slip assembly to expand radially as the lower wedge assembly is moved longitudinally relative to the lower slip assembly. This radial expansion causes the lower slip assembly 60 to become grippingly engaged with the wellbore casing as described with respect to the upper assembly above. The lower slip support 65 is shown as abutting the lower end of the lower wedge assembly 60. The slip support, as described above, is utilized to maintain the wedge and slip assemblies in position during run-in and to communicate setting force to the wedge and slip assemblies during setting. In this case, the lower slip support 65 moves upward relative to the mandrel 12 during the setting process. The lower slip support 65 is shown having a shearing mechanism 26 to hold the slip support in place until the setting process is begun.
As shown in
In the run-in position, the sealing elements 42 are carried on the packer element assembly in an unexpanded position having a radial diameter smaller than when in the set position. In the set position, as shown in
Once the tool 10 has been lowered into the desired position in the wellbore, that is, a selected distance from surface, the tool 10 is set or moved into a set position, as seen in
This invention provides a method to improve the reliability and efficiency of unsetting and retrieving the packer 10 by making it possible to reduce, relieve, or relax the compressive forces within the sealing assembly 40. The compressive forces on the sealing elements 42 are relaxed or released before attempting to unset either slip assembly. To this end, the tool 10 further includes a prop assembly 70 or sealing element retainer assembly 70, as seen in
A preferred embodiment is shown in
In the set position, as seen in
In the unset or released position, seen in
The releasable connector assembly 74 can be of other design without departing from the spirit of the invention. For example, the releasable connector assembly can include a collet assembly with cooperating collet fingers and grooves or lips. The releasable assembly can further be a shearing mechanism, such as shear pins or rings, or the like. Other releasable connectors can be utilized as will be recognized by those of skill in the art.
In this preferred embodiment, the prop assembly has a prop member, which moves longitudinally upward to allow the sealing elements and assembly to relax. As those skilled in the art will recognize, the assembly can be arranged such that downward movement will affect relaxation of the sealing elements. Further, other movement and mechanical designs for the prop member can be employed. The key is that the prop assembly moves to allow the sealing assembly to relax. The prop assembly can allow the sealing elements to expand longitudinally, thereby contracting radially, as seen in the embodiment in
The preferred embodiment described in detail above is but one method of reducing the compressive forces in the sealing elements before tool retrieval. In the above method, these compressive forces are reduced by the use of a sealing element retainer member 72 held in an extended position by a releasable connector assembly. The releasable connector is released by relative movement of the mandrel, which aligns a groove 78 with the release mechanism 75. In turn, this allows the prop member 72 to move longitudinally, thereby reducing the compression forces on the sealing elements. The sealing elements are free to longitudinally lengthen or expand, which results in radial contraction of the elements.
In another embodiment of this invention, illustrated in
Also illustrated in
Alternatively to the embodiment shown in
In use, the tool 10 is lowered into a subterranean wellbore having a casing. Then, the tool 10 is set using a setting assembly, such as the hydraulic setting assembly 100 shown. While the tool 10 is held in position by a tubing string or the like, hydraulic fluid is forced by an actuator tool (not shown) through the inlet port 104 into the fluid chamber 106, thereby forcing the piston 102 upward. The upward movement of the piston 102 forces the lower slip support 65, the lower wedge assembly 30, and the lower slip assembly 60 upward. Upward movement of the lower wedge assembly 60 compresses the sealing assembly 40. The sealing elements 42 are moved to a set position, radially expanded and longitudinally shortened, wherein the sealing elements of the sealing assembly sealingly engage the wellbore casing. Further, the upper 20 and lower 60 slip assemblies move longitudinally relative to their respective wedge assemblies 30 and 50. The slip assemblies, and in particular the slip elements, are radially expanded into a set position in gripping engagement with the casing. The timing and relative motions of these elements of the tool during setting are controlled by use of shear pins and the like as is known in the art and not detailed here.
The tool 10 is then in a set position, the sealing assembly providing an annular seal between the mandrel and casing, and the slip assemblies providing a gripping engagement with the casing. The tool can be left in place in the set position as desired. During operations in the wellbore, the differential pressure across the tool may alternate, resulting in the cinching-up described elsewhere herein.
To unset and retrieve the tool 10, the mandrel 12 is moved longitudinally upward relative to the set slip and sealing assemblies. For example, a retrieving tool is run into the wellbore on a tubing string or coiled tubing and connected to the upper sub 16 of the tool. In the embodiment illustrated in
Further upward movement of the mandrel disengages the sealing elements 42 from the casing by relaxing the compression forces on the sealing elements 42. The mandrel 12 is moved upwardly relative to the slip and wedge assemblies, sealing assembly, and prop assembly. As the mandrel is pulled upward, the groove 78 on the mandrel 12 moves into alignment with the releasable mechanism 75. The collapsible C-ring 75 collapses, or radially contracts, into the groove 78, thereby releasing the interlocking toothed portions 76 and 34 of the releasable connector 75 and upper wedge assembly 30, respectively. Consequently, the prop member 72 is able to move relative to the upper wedge assembly. An arm 73 of the prop member 72 telescopes with a corresponding arm 36 of the upper wedge assembly 30, as seen in
After the step of disengaging the sealing assembly, the slip assemblies are disengaged from gripping engagement with the casing. In the embodiment shown, the upper slip assembly 20 is mechanically unset by pulling the upper slips off the upper wedge. Further upward movement of the mandrel 12 moves the lugs 14 into contact with the upper ends 27 of the slots 24 of the upper slip assembly 20 as seen in
In the embodiment shown, the lugs contact the closed ends of the slots simultaneously, thereby pulling the slip elements off the wedge at approximately the same time. It is to be understood, however, that simultaneous or sequential unsetting of the slip elements can be performed. Sequential unsetting of the slip elements may be preferred where the slip assembly has a plurality of separated slip elements. Such methods are known in the art and taught in U.S. patents incorporated herein, for example.
Further, in the preferred embodiment, the lower slip assembly is then unset and disengaged from the casing due to further upward movement of the mandrel 12, which will result in the lower slip assembly being pulled off the lower wedge assembly 60. After the compression forces are released in the sealing assembly and the upper slip assembly is unset, there are no remaining compression forces maintaining the lower slips on the lower wedge. Upward movement of the tool will drag the lower slips downward and off the lower wedge.
The upper slip assembly is preferably unset and disengaged, as illustrated, before the lower slip assembly is unset and disengaged. However, the particular order can be reversed or the slip assemblies can be disengaged simultaneously.
Finally, a lower catch mechanism 19, such as shown in
Finally, the tool 10 is then retrieved from the wellbore by continuing to pull the toll upward toward the surface.
A similar method is utilized in relation to the embodiment of the tool shown in
The wellbore tool used above to describe the principles of this invention is a packer. Any other wellbore tool set with opposed slips can be substituted for the packer without departing from the principles on this invention. Likewise, the wellbore envisioned in the above description may be used for any purpose, such as, production, injection, observation, testing, etc., without departing from this invention's principles.
The principles of this invention would also apply if the sealing and/or gripping assemblies were comprised of inflatable components. While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.
