Patent Application
20050241831
The present invention relates generally to equipment utilized and operations performed in conjunction with a subterranean well and, in an embodiment described herein, more particularly provides an anchor for a branch wellbore liner.
In wells of the type known as multilateral wells, it is frequently the case that a liner string is conveyed into a branch or lateral wellbore through a window formed in a sidewall of a casing string in a parent or main wellbore. Sometimes, an upper end of the liner string is positioned in the branch wellbore spaced away from the casing string and is anchored in the branch wellbore using, for example, an inflatable packer. Other times it is desired to secure an upper end of the liner string to the casing string, for example, so that a mechanical, sand or pressure seal can be formed to isolate the interior of the casing and/or liner string from a formation surrounding the intersection of the parent and branch wellbores.
In the latter situation, typically either the liner string extends upwardly into the casing string above the window, or an upper portion of the liner string extending into the casing string is cut off after cementing the liner string in the branch wellbore. The first option obstructs access and flow through the casing string. The second option at times allows the remaining lower portion of the liner string to “spring back” into an interior of the casing string after the upper portion has been cut off. This is particularly troublesome at an upper end of the liner string, which is left relatively thin and flexible after the cutting procedure.
Therefore, it may be seen that it would be very desirable to provide improved systems and methods for anchoring a branch wellbore liner. Such systems and methods may find use in other applications, as well.
In carrying out the principles of the present invention, in accordance with an embodiment thereof, a system and method are provided for anchoring a branch wellbore liner string to casing in a parent wellbore, without allowing the liner string to displace back into the casing, and without unduly obstructing access through the casing.
In one aspect of the invention, a system for anchoring between an upper portion of a window formed through a sidewall of a first tubular string and an upper end of a second tubular string extending outwardly from the window is provided. The system includes a first anchoring device at the upper portion of the window, and a second anchoring device at the upper end of the second tubular string. The first and second anchoring devices are operative to secure the upper end of the second tubular string to the upper portion of the window.
In another aspect of the invention, a system of anchoring a branch wellbore liner string to a casing string in a parent wellbore is provided. The system includes a first anchoring device of the casing string and a second anchoring device of the liner string. Engagement between the first and second anchoring devices prevents an upper end of the liner string from displacing inwardly relative to the casing string.
In yet another aspect of the invention, a method of anchoring a liner string to a casing string includes the steps of: conveying the liner string through a window formed through a sidewall of the casing string; and engaging a first anchoring device of the casing string with a second anchoring device of the liner string, thereby anchoring an upper terminal end of the liner string to the casing string.
These and other features, advantages, benefits and objects 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 hereinbelow and the accompanying drawings.
Representatively illustrated in
As used herein, the terms “above” and “below,” “upper” and “lower,” and similar terms are used to indicate directions respectively closer to, and farther from, the surface along a wellbore, or along a tubular string in a wellbore. Thus, even in a perfectly horizontal wellbore, a portion of a tubular string in the wellbore which is closer to the surface along the wellbore than another portion of the tubular string is considered to be “above” the “lower” tubular string portion.
As depicted in
The wellbore 18 extends outwardly from an opening or window 20 formed through a sidewall 22 of the window joint 16. The wellbore 18 could be drilled before or after the casing string 12 is installed in the wellbore 14, and the window 20 could be positioned at the intersection between the wellbores before or after it is formed through the sidewall 22. Thus, it should be clearly understood that the principles of the invention are not limited to any particular details or order of steps related herein for the various described embodiments. Instead, it should be recognized that a wide variety of changes, alternatives, options, etc. can be made in keeping with the principles of the invention.
Referring additionally now to
The liner string 24 includes a transition joint 26 which is specially configured so that it is complementarily shaped relative to the window joint 16. For example, the transition joint 26 has an inclined face 28 which is shaped so that it fits within the window 20, preferably without protruding into the interior of the casing string 12.
An anchor 30 is used to secure the liner string 24 to the casing string 12 at an upper portion of the window 20. Preferably, the anchor 30 prevents an upper terminal end 32 of the transition joint 26 from displacing inwardly or outwardly relative to the casing string 12. Note that, with the liner string 24 extending downwardly from the window 20, the liner string is suspended by the anchor 30 at the upper end 32, thereby producing tension in the liner string below the anchor.
Although the anchor 30 is schematically depicted in
A seal 34 is used to seal between the casing string 12 and the liner string 24 at the interface between the transition joint 26 and the window 20. The seal 34 may be carried on the liner string 24 when it is conveyed through the casing string 12, or the seal could be positioned in the window 20 prior to installing the liner string. As another alternative, the seal 34 could be positioned between the casing and liner strings 12, 24 after the anchor 30 secures the transition joint 26 to the window joint 16.
The seal 34 is not necessarily a separate element of the system 10. For example, the seal 34 could be formed by expanding the transition joint 26 radially outward so that it makes contact with the window 20. This contact could form a metal-to-metal seal between the transition joint 26 and the window joint 16.
Whether or not the seal 34 is used in the system 10, the liner string 24 may be sealed and secured in the wellbore 18 by cement 36. Thus, either or both of the seal 34 and cement 36 may be used to prevent fluid, debris, sand, etc. from passing between the transition joint 26 and the window 20. In particular, the seal 34 and/or cement 36 can isolate interior fluid passages 38, 40 of the casing string 12 and liner string 24, respectively, from fluid communication with a formation 42 surrounding the intersection between the wellbores 14, 18.
Referring additionally now to
The device 44 is shown as being rigidly attached to the upper end 32 of the transition joint 26, for example, by welding the device to the transition joint. However, other methods of attaching the device 44 to the transition joint 26 could be used. The device 44 could be pivotably attached to the transition joint 26, or the device could be integrally formed on the transition joint, for example.
The device 44 includes a generally T-shaped upper end 46 having downwardly facing shoulders 56. The upper end 46 is shaped so that it operatively engages a cooperatively shaped recess, slot or keyway in the window joint 16, as described more fully below. However, it should be clearly understood that the device 44 (and the corresponding recess, slot or keyway) could have other shapes, and that the device could instead be attached to the window joint 16 while the recess, slot or keyway could be formed on the transition joint, without departing from the principles of the invention.
Referring additionally now to
Rotational alignment of the anchoring devices 44, 48 may be achieved using any appropriate method, some of which may be conventional. A running tool 52 (not shown in
Referring additionally now to
The manner in which the key device 44 engages the keyway device 48 may be more clearly seen in the schematic cross-sectional views depicted in
Note that the key device 44 is permitted to enter the keyway device 48 via a gap or opening 60 between the passage 38 and the keyway device. The running tool 52 may be used to bias the key device 44 laterally through the opening 60 into the keyway device 48. Alternatively, the key device 44 could be biased toward the keyway device 48 by its own resiliency. As another alternative, no biasing may be needed to laterally displace the key device 44 toward the keyway device 48, since lateral displacement of the transition joint 26 through the window 20 may also cause the key device to displace toward the keyway device. The branch wellbore 18 can be drilled in such a way that displacement of the transition joint 26 into the branch wellbore will bias the key device 44 toward the keyway device 48.
In
Disengagement of the key device 44 from the keyway device 48 may be prevented by optional locking devices 62. The locking devices 62 prevent upward displacement of the key device 44 relative to the keyway device 48, thereby preventing upward and inward displacement of the transition joint 26 relative to the window joint 16.
The locking devices 62 are depicted in
Referring additionally now to
Referring additionally now to
As the key device 44 of
When the shoulder 64 is aligned with the slot 68, the transition joint 26 will be permitted to displace downwardly, which may be indicated at the surface by an increased hook load. When the shoulder 64 is received in the slot 68, the key device 44 is aligned with the keyway device 48. Further downward displacement of the transition joint 26 relative to the window joint 16 will cause the key device 44 to operatively engage the keyway device 48.
Yet another option for rotationally aligning the key device 44 with the keyway device 48 could be to eliminate the profile 66. The transition joint 26 could then be positioned so that the key device 44 is within the upper portion of the window joint 16. The transition joint 26 would then be rotated until the shoulder 64 enters the slot 68, which would be indicated at the surface as an increased torque. At that point, the transition joint 26 would be lowered to operatively engage the key device 44 with the keyway device 48.
Referring additionally now to
Thus, it may be seen that a variety of methods may be used to engage the key device 44 with the keyway device 48.
Referring additionally now to
Referring additionally now to
Referring additionally now to
A locking device 76, which includes a spring-biased dog 78, is positioned proximate the keyway device 48. As the key device 44 is displaced downwardly in the keyway device 48, the opening 74 is eventually positioned opposite the dog 78, at which point the dog enters the opening and prevents further downward displacement of the key device 44. A separate locking device 76 may be provided for each of the openings 74 in the key device 44.
Referring additionally now to
The seal 34 could be made of a material which swells (i.e., increases in volume) when exposed to fluid in the wellbores 14, 18. The seal 34 could be an expandable annular barrier, such as any of the annular barriers described in U.S. Published Application No. 2004/0055758, the entire disclosure of which is incorporated herein by this reference.
Also, as noted above, it is not necessary for the seal 34 to be a separate element. The transition joint 26 could, for example, be expanded within the window 20 to thereby form a seal between the transition joint and the window joint 16 by contact therebetween. If the transition joint 26 is expanded within the window 20, the separate seal 34 could still be used to seal between the expanded transition joint and the window joint 16.
Thus, the anchoring devices 44, 48 are operative to secure the upper end 32 of the liner string 24 to the upper portion 50 of the window 20 to allow the liner string to be expanded by using various internal expansion tools, which may include mechanical and/or hydraulic expansion tools. The liner string 24 could include other elements which are expanded also, such as sand control screens, annular isolation barriers, solid tubular sections, and combination thereof, etc.
Referring additionally now to
The seal 34 could be any hardenable fluid, such as epoxies, other plastics, composites, gels, caulk-like substances, etc.
Referring additionally now to
Unfortunately, it sometimes happens that a liner string will become stuck while it is being run into a branch wellbore, or for some other reason it is not possible or desirable to fully install the liner string in the branch wellbore. If this should occur in the system 10 as depicted in
The device 82 can be engaged with the device 48 in the window joint 16 to temporarily or permanently anchor the liner string 24. The liner string 24 may be temporarily anchored until a resolution is found for whatever problem prevented the liner string from being fully installed in the branch wellbore 18. If the problem cannot be resolved, then the liner string 24 may be permanently anchored using the device 82.
If the liner string 24 is permanently anchored using the device 82, then the portion of the liner string extending into the casing string 12 may be cut off to enhance access and flow through the passage 38 of the casing string. For example, a washover tool may be used to cut off the liner string 24 where it extends into the passage 38. The liner string 24 may be cemented in the branch wellbore 18 before or after this cutting operation, or not cemented at all.
Referring additionally now to
To permit selective installation of the liner strings 24 in the respective branch wellbores 18, different anchors 84, 86, 88 may be used. Each of the anchors 84, 86, 88 may include a set of the key device 44 and keyway device 48 as described above. However, the lowermost anchor 88 may have a dimension (such as width or thickness, etc.) which is greater than that of any of the anchors 84, 86 thereabove. Similarly, the next lowermost anchor 86 may have a dimension which is greater than that of the anchor 84 thereabove.
In this manner, the key device 44 of the anchor 88 will not operatively engage any of the keyway devices 48 of the upper anchors 84, 86 when a liner string 24 is installed in the lowermost branch wellbore 18. Likewise, the key device 44 of the anchor 86 will not operatively engage the keyway device 48 of the anchor 84 when a liner string 24 is installed in the middle branch wellbore 18. Thus, the system 10 permits selective completion of the branch wellbores 18 from the lowermost proceeding upward, in that each of the key devices 44 will not operatively engage any inappropriate keyway devices 48. However, other selection methods may be used, and the branch wellbores 18 may be completed in different orders, without departing from the principles of the invention.
Referring additionally now to
With the liner string 92 extending into the passage 102, the liner string is cemented in the branch wellbore 10. After the cement has set, the portion of the liner string 92 extending into the passage 102 is cut off, for example, by using a washover tool, and retrieved from the passage.
To prevent an upper terminal end 104 of the liner string 92 from displacing inwardly relative to the casing string 96, an anchor 106 is used in the system 90. The anchor 106 is similar to the anchors 30, 84, 86, 88 described above. For example, the anchor 106 may include the keyway anchoring device 48 formed in the casing string 96 at an upper portion of the window 94.
However, the anchor 106 differs in one significant respect from the anchors 30, 84, 86, 88 in that it includes a key anchoring device 108 which is separately conveyed into the casing string 96 after the liner string 92 is cut off. That is, the key anchoring device 108 is positioned in the casing string 96 and engaged with the keyway device 48 to prevent inward displacement of the upper end 104 of the liner string 92. The key device 108 may be configured similar in many respects to the key device 44 described above (particularly in those respects which facilitate engagement with the keyway device 48), but unlike the key device 44, the key device 108 is not attached to a transition joint of the liner string 92 when it is conveyed through the casing string 96.
Referring additionally now to
The system 110 differs in one substantial respect from the system 10 in that the liner string 24 is secured at a lower end of the window 20 using a second anchor 112. Thus, in the system 110, the liner string 24 is secured both at the upper end and at the lower end of the window 20.
The anchor 112 may be similar to the anchor 30 as described above, including any of the alternate configurations described above, or the anchor 112 could be of a different type. For example, the anchor used at a lower end of a window in the LTBS™ system available from Halliburton Energy Services, Inc. of Houston, Tex. and described in U.S. Pat. No. 5,458,209, the entire disclosure of which is incorporated herein by this reference, could be used for the anchor 112. Alternatively, the anchor used at a lower end of a window in the HOOK Hanger™ system available from Baker Oil Tools of Houston, Tex. could be used for the anchor 112. Thus, a variety of anchors, anchoring devices and means of securing tubular strings may be used in keeping with the principles of the invention.
Referring additionally now to
The window joint 120 differs in one substantial respect from the window joint 16 in that it has a consistent thickness sidewall 122, i.e., it has an interior flow passage 124 which is generally concentric with an outer diameter 126 of the window joint 120. Another difference is that the window joint 120 has an anchoring device 128 which is formed at least partially on a member 130 attached externally to the sidewall 122. The member 130 could alternatively be attached to an interior of the sidewall 122, if desired. The member 130 could be attached using fasteners, by welding, or by any other method.
Use of the member 130 increases the thickness of the sidewall 122 in the area where the anchoring device 128 is located, without significantly increasing the cost of fabricating the window joint 120. The thickness of the sidewall 122 may be increased by any other method in keeping with the principles of the invention.
The anchoring device 128 is depicted in
Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the invention, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to these specific embodiments, and such changes are contemplated by the principles of the present invention. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims and their equivalents.
