Patent Grant
10907432
The present invention relates in particular to apparatus for removing a section of casing or lining from a wellbore, and related methods.
In the oil and gas exploration and production industry, tubular casing or lining is commonly installed in a wellbore that has been drilled into the subsurface of the Earth. Sections are inserted in the wellbore to make up the casing or lining and these are typically cemented in place by delivering cement material into an annulus between an outside of the section of casing or lining and the wall of the wellbore into which the section of casing or lining is inserted.
The provision of casing of lining in a wellbore may typically help to stabilise of the wellbore wall, for example by preventing collapse of formation material into the wellbore, and can help to control pressure and provide fluid containment in the wellbore during use of the wellbore, such as when drilling or producing oil or gas.
In various situations it can be desirable to remove a section of the casing or lining which has previously been installed in a wellbore. Typically, this involves cutting the casing to produce a cut section of a manageable size, and then pulling out the cut section to remove it from the wellbore. Removal of casing or lining may be a necessary and important part of a plug and abandonment operation for abandoning a well, where there may typically be a need to remove the casing in order to provide a suitable plug for the well.
Previous approaches to removing sections of casing or lining have involved running a cutting tool and a pulling tool into the wellbore in separate trips for performing the cutting and pulling operations respectively. By performing these operations in separate trips however, such approaches can be inefficient and costly.
Other prior techniques are known where the cutting and pulling can be performed on the same trip in the wellbore. In such a technique, a work string may be used that incorporates a tool for cutting the casing or lining and a tool for pulling the cut section. The tools may then be inserted into the section of casing to be removed. The cutting tool may typically require rotation of the work string and circulation of fluid into and out of the wellbore to perform and facilitate a circumferential cut of the casing. The pulling tool may typically operate to engage the inner wall of the section of casing to grip onto the casing and allow the section be pulled out to remove it from the wellbore. When deployed together with the cutting tool, there is a need for the pulling tool to allow the cutting process to take place while remaining on hand for performing pulling when required.
However, when deployed together with a cutting tool, pulling tools may suffer wear and damage as result from rotating the string during a cutting operation, or may interfere with the cutting process, and/or the circulation of fluid in a cutting process.
Pulling tools are known to exist for use in work strings together with cutting tools. The inventors note however that these can suffer from drawbacks in complexity, flexibility and ability to accommodate the cutting process while remaining on hand for removing a section of casing or lining.
For example, certain pulling tools (also known as “spears”) are known to have selective actuation requiring rotation of the string, for example by turning the string a quarter turn clockwise, to move grippers on the pulling tool into or out of an engaging position with the wall of the casing section. With such kinds of actuation requirement, it can be difficult to determine whether the actuation has successfully taken place. This may in turn result in delays and/or operational uncertainty.
It is an aim of the invention to obviate or at least mitigate various drawbacks or difficulties associated with prior techniques.
In light of the above, according to a first aspect of the invention there is provided apparatus for removing a section of casing or lining from a wellbore, the tool comprising:
The switcher may typically be configured to be activated by interaction with the casing or lining at or near an uphole end of the section of casing or lining, e.g. by engaging the end of the casing, e.g. an edge surface of the uphole end of the section of casing or lining.
The sliding assembly may be operable for moving the gripper between the first and second positions by relative axial movement between the sliding assembly and the mandrel, without requiring rotation therebetween.
The sliding assembly may be movable axially along the mandrel by fluid exerting pressure on a surface of the sliding assembly, for holding the gripper away from the inner wall.
The apparatus may further comprise at least one locking member configured to lock the sliding assembly with respect to the mandrel when the gripper are held away from the inner wall in the first position. The locking member may be activated to lock by the relative axial movement between the sliding assembly and the mandrel. The locking member may comprise at least one locking pin arranged for locking between the sliding assembly and the mandrel. Upon axial movement of the sliding assembly along the mandrel, the locking pin may be moved into position for locking the sliding assembly and the mandrel to one another, such that the gripper may be held away from the wall in the first position.
The switcher may comprise at least one dog arranged to be radially depressed so that the locking member can lock the sliding assembly with respect to the mandrel in the first position in which the grippers are held away from the wall. The dog may be configured to engage with an end of the section of casing or lining in use so as to be depressed for locking by engagement of the dog against the end of the section of casing or lining.
The dog may have an engaging surface arranged to be pitched at an angle to the end of the section of casing or lining in use, such that upon engaging the end of the section of casing of lining, movement between the sliding assembly and the casing can be resisted for allowing axial movement of the mandrel to take place with respect to the sliding assembly and the dog can be activated such that a locking member on the dog may be engaged to lock between the mandrel and the sliding assembly.
The dog may be configured to be depressed to lock between the sliding assembly and the mandrel, in order to allow the apparatus to be moved through the section of casing or lining from one location to another therealong.
The apparatus may have a plurality of grippers for gripping onto an inner wall of the section of casing. The sliding assembly may comprise a sleeve which may be arranged to surround the mandrel. The grippers may be spaced apart from one another around a circumference of the sleeve. The grippers may typically comprise ribs arranged to extend along the sleeve.
The gripper may be arranged to slide on an outer surface on the mandrel. The outer surface may be inclined with respect to the longitudinal axis for positioning the gripper in a radial position dependent upon the axial position of the sliding assembly with respect to the mandrel.
The apparatus may comprise biasing means, e.g. a spring, which may be operable between the mandrel and the sliding assembly, for biasing the sliding assembly relative to the mandrel for urging the gripper toward a radially outward position and/or a radially outermost achievable position. The gripper may be configured to obtain the outermost achievable position for gripping onto the internal wall of the tubing when the sliding assembly is not locked with respect to the mandrel.
The apparatus may be configured for allowing fluid to circulate through the mandrel and through a section of an annulus between the casing or lining and an outside of the apparatus. The mandrel may further comprise a passageway for the circulating fluid to enter a region in which the fluid may exert a pressure against a surface of the sliding assembly for moving the sliding assembly axially relative to the mandrel for withdrawing the gripper away from the inner wall of the section of casing or lining.
The sliding assembly may have a first locking position along mandrel, in which the gripper may be held away from the internal wall of the casing or lining, and in which the sliding assembly may be lockable to the mandrel by a first locking member. The sliding assembly may have a second locking position in which the mandrel may be rotated with respect to the sliding assembly and the gripper may be held away from the inner wall of the casing or lining. In the second locking position, the sliding assembly may be lockable to the mandrel while the first locking member is non-active. The apparatus may comprise a clutch-based locking mechanism for locking in the second locking position. The clutch-based locking mechanism may comprise a clutch ring comprising steps which are offset axially, and a locking formation which may be arranged to be rotated relative to one another into engagement with the steps to lock the mandrel and the sliding assembly in fixed axial position relative to one another.
The apparatus may be a pulling tool. The tubular string may include a cutting tool.
According to a second aspect of the invention, there is provided apparatus for removing a section of casing or lining from a wellbore, the apparatus comprising:
According to third aspect of the invention, there is provided apparatus for removing a section of casing or lining from a wellbore, the apparatus comprising:
According to a fourth aspect of the invention, there is provided a work string for cutting a casing or lining in a wellbore and removing a section of the casing or lining from the wellbore, the work string comprising apparatus as claimed in any preceding claim, and a cutting tool for cutting a casing or lining.
The work string may typically be a tubular string. The work string may typically be a rotary string.
According to a fifth aspect of the invention, there is provided a method of using the apparatus of any of the first to third aspects in a wellbore.
According to a sixth aspect of the invention, there is provided a method of removing a section of casing or lining from a wellbore using the apparatus of any of the first to third aspects, the method comprising the steps of:
The method may further comprise: moving the apparatus to a position in the section of casing or lining where the gripper may be held away from the inner wall of the section of casing or lining, via operation of the switcher; and performing a cutting operation in the wellbore to produce a cut section of casing or lining to be removed.
Any of the aspects of the invention may include the further features as described in relation to any other aspect, wherever described herein. Features described in one embodiment may be combined in other embodiments. For example, a selected feature from a first embodiment that is compatible with the arrangement in a second embodiment may be employed, e.g. as an additional, alternative or optional feature, e.g. inserted or exchanged for a similar or like feature, in the second embodiment to perform (in the second embodiment) in the same or corresponding manner as it does in the first embodiment.
Embodiments of the invention are advantageous in various ways as will be apparent from the specification throughout.
There will now be described, by way of example only, embodiments of the invention with reference to the accompanying drawings, in which:
With reference to
The tool 10 has grippers 22, which in
The tool 10 and features of its operation will be now described in further detail, turning firstly to
A sliding assembly 18 is mounted on the mandrel 12. The sliding assembly 18 includes a sleeve 20 provided with a plurality of grippers 22 for gripping onto an inner wall of the section of casing 3c, when inserted thereinside. The grippers 22 bear against the mandrel 12 and are kept against the mandrel 12 by radial springs 19 acting between the sleeve 20 and the respective gripper 22 where the sleeve overlaps the gripper. The sliding assembly 18 is movable axially along the longitudinal axis 50 with respect to the mandrel 12. When the sliding assembly 18 is moved axially, the grippers 22 travel along the mandrel on slip surfaces 14 which are pitched at a shallow angle with respect to the longitudinal axis 50, so as to allow the grippers to move into different radial positions accordingly.
The tool 10 is further provided with a spring 31 that acts between the mandrel and the sleeve 20 to position the sliding assembly 18 axially along the mandrel, and to determine in turn the radial position of the grippers. In
Upon insertion, the grippers 22 are positioned against the inside wall of the casing section 3c, as a result of the bias exerted by the spring 31 operating on the sleeve 20. From this position, the casing section 3c can be gripped by the tool 10 by pulling the string axially uphole. The pull of the string results in the mandrel 12 being urged in the direction of the arrow A (
With reference particularly now to
This is achieved as follows. The locking dogs 42 protrude outwardly from the sleeve 20. In this way, the locking dogs 42 are arranged to engage with the end of the casing section 3c, as shown in
Notably, when placed in the locking position, the position of the sliding assembly 18 relative to the mandrel 12 is such that the grippers 22 are retracted and brought inwardly against the mandrel to obtain a radial position away from the inner wall of the casing section 3c. In this way, by axial longitudinal movement of the sliding assembly 18 along the mandrel 12, the grippers 22 can be moved to disengage from the wall.
With the grippers 22 away from the wall of the casing section 3c, various advantages are obtained. A cutting tool can be employed by way of rotating the string without the grippers 22 interfering with the cutting operation. The string may also be readily advanced further into the wellbore to access for instance a cutting location with a cutting tool, again with minimal or reduced risk of frictional wear on the grippers 22.
In the above is described a complete “normal” operational mode of the tool 10 allowing the engagement of the casing section 3c by the grippers 22 at the top end of the casing section 3c, disengagement and locking of the grippers 22 in the disengaged position. This is achieved automatically all by simple axial movements of the string along wellbore, and by axial relative movements between the mandrel 12 and the sliding assembly 18. No rotation of the string or the mandrel 12 (i.e. relative to the sliding assembly, about the axis 50) is required to lock or unlock or to engage or disengage the grippers 22 on the wall.
This facilitates simplicity of use and can reduce ambiguity as to whether the grippers 22 are engaged or disengaged from the wall of the casing section 3c. This may in turn reduce inefficiencies, potential re-runs in the wellbore, and/or possible error or damage to tools from false assumptions.
Nonetheless, the tool 10 has additional functionality. In particular, the sleeve 20 is fitted on the mandrel 12 for moving the sleeve 20 along the mandrel by fluid actuation. More specifically, fluid can access a region 60 between actuating surfaces 15, 25 of the mandrel 12 and the sleeve 20 respectively, so as to exert a pressure on the actuating surfaces 15, 25 and thereby force the mandrel and sleeve 20 to move axially with respect to one another. The pressure exerted by the fluid acts against the force of the spring 31, and when sufficiently high may exceed the spring force so as to compress the spring 31. The resulting movement of the sliding assembly 18 upward (in
If fluid pressure via the region 60 is used to force the grippers 22 into the retracted position, the status of the locking dogs 42 no longer matters. In other words, the locking dogs 42 can be unlocked, but the sliding assembly 18 is nonetheless held in the “locking” position along the mandrel 12 so that the grippers 22 are retracted although not actually locked by the dogs 42. This allows the tool 10 to be completely freed from the casing section 3c and recovered to the surface (without the casing section 3c) if required. Fluid actuation of the sleeve 20 via the region 60 may also be applied to help to move the sleeve 20 to the locking position before locking the mandrel 12 with the locking dogs 42 as described in relation to
The mandrel 12 has a passageway 61 connecting the bore 13 with the region 60 between the sleeve and the mandrel. Fluid circulated through the bore 13 of the mandrel 12 is therefore in communication with the region 60 via the passageway 61. The circulation of fluid through the bore into the wellbore can therefore be supplied to generate a suitable pressure in the region 60. In general, the pressure is low such that the sleeve 20 is biased under the force of the spring 31, but the pressure may be increased so as to compress the spring 31 and move the sleeve by fluid actuation when needed. A port 70 for letting in or out fluid is provided to equalise pressure between the region 70 and an annular space 80 of the wellbore so as to facilitate movement of the sleeve 20 along the mandrel 12.
The tool 10 also has a second locking position, which can be obtained by moving the sliding assembly 18 to a location along the mandrel 12 (e.g. first locking position) where the grippers 22 are disengaged from the wall of the casing section, and then rotating the sliding assembly relative to the mandrel 12 by turning the string into the second locking position. The rotation brings a formation (not shown) on an inside of the sleeve 20 into a J-groove in the mandrel so as to lock the sleeve 20 with respect to the mandrel 12 in the second locking position, with the grippers 22 disengaged, independent of the activation status of the locking dogs 42. Again, this allows the tool 10 to be completely freed from the casing section 3c, if the need arises and if fluid may not be available to disengage the grippers hydraulically.
Through the fluid actuation and rotational mechanical locking to hold the grippers away from the wall of the casing section 3c, the tool 10 has a release mode where the tool can be released from the casing section 3c and retrieved from the wellbore at any time.
With reference now to
In this example, like features in the tool 110 are referenced with the same numerals as in relation to the tool 10 but incremented by one hundred.
The locking dogs 142 are coupled to the sleeve 120 of the sliding assembly 118. The mandrel 112 is provided with locking recesses 117 for receiving a wedged locking member of the locking dogs 142. Depending upon the relative axial position of the sleeve 120 relative to the mandrel 112, the locking dogs 142 can be moved into a locking position in which the dogs 142 can lock the sleeve 120 to the mandrel 112, by the locking member entering the recesses 117 such that they are interlocked. As with the tool 10, such that locking is achieved by inserting the tool 110 into the casing section 3c, so that a front end of the locking dogs 142 engage an end of the casing section 3c, and then letting the weight of the string shift the mandrel 112 downward relative to the sleeve 120 while it is held on the end of the casing by the locking dogs 142. The relative movement axially between the sleeve 120 and the mandrel 112 allows the locking dogs 142 to be depressed inwards due to the contact with the end of the casing section 3c and lock onto the mandrel 112. The tool 110 can then progress further and be fully inserted into the casing section 3c. When bringing the tool 110 upward out of the casing section 3c, and the locking dogs 142 exit the end of the casing section 3c, the mandrel 112 is free to be drawn upward relative to the sleeve 120 which simultaneously is biased downward by the spring 131. As a result, the locking dogs 142 are brought out of the locking recesses 112, and the mandrel 112 and sleeve 120 are unlocked. The locking members of the locking dogs 142 are arranged to slip on a sloping surface of the recesses 117 to facilitate or urge movement into and out of the recesses 117 upon locking and unlocking respectively.
The tool 110 can also be locked with the grippers 22 held away from the wall of the casing section 3c by rotating the mandrel 112 to a second locking position, i.e. a rotated position of the mandrel with respect to the sleeve 120. This is achieved through the clutch-based locking mechanism 180.
With reference additionally to
In the configuration of the tool 110 as shown in
As seen in
The sleeve 120 and mandrel 112 may be moved into an axial relative position where the grippers 122 are withdrawn, by fluid actuation or by using the weight of the string to move the mandrel 112 while the sleeve 120 is held on the end of the casing section 3c by the locking dogs 142, as described above. The use of the clutch ring 182 with multiple steps 184 at different axial distances can be advantageous because the axial distance moved by fluid actuation or engagement of the end of the casing section 3c may differ from time to time, for example depending upon the inner diameter of the casing section 3c. If there is a larger diameter, the locking dogs 142 may not depress fully and the locking members 144 may not fully key into the recesses 117 (but the grippers 122 may still be withdrawn sufficiently that they are held away from the inner wall of the casing section 3c). Thus, the clutch-based locking mechanism 180 can allow locking by rotation in different cases, where the amount of displacement between mandrel 112 and the sleeve 120 differs, by rotation onto the steps 184, whereby the formation 193 will meet and interlock with a surface of the appropriate one of the steps 184.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1606977.5 | Apr 2016 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2017/059345 | 4/20/2017 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2017/182549 | 10/26/2017 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 2329939 | Phipps | Sep 1943 | A |
| 2627316 | Baker | Feb 1953 | A |
| 20120111556 | Palmer et al. | May 2012 | A1 |
| 20140027117 | Hekelaar | Jan 2014 | A1 |
| 20160076327 | Glaser | Mar 2016 | A1 |
| Number | Date | Country |
|---|---|---|
| 1458592 | Dec 1976 | GB |
| Entry |
|---|
| International Search Report dated Aug. 9, 2017 for PCT/EP2017/059345. |
| Number | Date | Country | |
|---|---|---|---|
| 20190048677 A1 | Feb 2019 | US |
