THERMAL LINER TOP ANCHOR PACKER

Abstract

A liner top anchor packer apparatus include (a) an inner tubular slick joint connected to a top sub and slidably disposed within a cylindrical mandrel, the inner tubular slick joint and the mandrel connected together with at least one shear pin; and (b) a slip assembly disposed on the mandrel, and comprising a slip setting sleeve and at least one slip moveable between a running position and an actuated outward position.

Description

FIELD OF THE INVENTION

The present invention generally relates to a liner top anchor packer.

BACKGROUND

Thermal wellbores and SAGD (steam-assisted gravity drainage) wellbores conventionally include concentric casings, such as surface casing and production casing. A slotted liner is installed at a lower end of the production casing, and a casing liner is then installed, typically in a horizontal section of the wellbore. In the completion process, the casing liner is run into the hole through the production casing and into the slotted liner, such that the liner top overlaps with the lower end of the existing tubular. A running string delivers the liner using a running tool that ultimately releases from the liner once a liner hanger on the liner string is set against the existing tubular.

Such wellbores experience temperature cycling and as a result the liner pipe thermally expands and contracts. This pipe movement cause increase wear and eventual failure of the sealing element on the liner top packer.

SUMMARY OF THE INVENTION

The present disclosure relates to a liner top anchor packer apparatus, for use in thermal wellbores, such as a SAGD wellbore. In some embodiments, the apparatus hangs the liner string in the casing, provides isolation in the intermediate casing, and acts as an anchored receptacle for drilling, fracturing, and production strings. The apparatus comprises a number of concentrically arranged elements which are slidingly moveable relative to each other.

In one aspect, disclosed is a liner top anchor packer apparatus comprising:

• • (a) an inner tubular slick joint connected to a top sub and slidably disposed within a cylindrical mandrel, the inner tubular slick joint and the mandrel connected together with at least one shear pin; and
  • (b) a slip assembly disposed on the mandrel, and comprising a slip setting sleeve and at least one slip moveable between a running position and an actuated outward position.

In some embodiments, the slip assembly comprises: (a) an upper cone slidably disposed on the mandrel, and affixed to the mandrel with at least one shear screw in a running position and moveable to a slip actuating position; and (b) a lower cone affixed to the mandrel, wherein the slips are actuated outwards between the upper cone and the lower cone when the upper cone moves to a slip actuating position by action of the slip setting sleeve. Preferably, the lower cone is affixed to the mandrel by at least one shear screw, which is stronger than the at least one shear screw affixing the mandrel to inner tubular slick joint.

In some embodiments, the apparatus further comprises a packer element concentrically disposed around the mandrel and an actuating assembly for deforming the packer element outwards. Preferably, the packer element actuating assembly comprises the following elements disposed concentrically around the mandrel:

• • (a) an upper setting sleeve affixed to the mandrel in a running position by shear screws and moveable to an actuating position;
  • (b) a lock housing assembly moveable between a running position and an actuating position, comprising:
    • i. an upper lock housing having collet fingers retained within a radial groove formed on an outer surface of the mandrel by an inner surface of the upper setting sleeve, wherein the inner surface of the upper setting sleeve defines a radial groove for releasing the collet fingers of the upper lock housing when in the actuating position; and
    • ii. a lower lock housing interlocked with the upper lock housing to move in unison, the lower lock housing having a split ring lock with ratchet teeth for engaging ratchet teeth on an outer surface of the mandrel to permit downward movement of the lower lock housing on the mandrel, but not upward movement, the lower lock housing connected to the split ring lock by shear screws; and
  • (c) a lower setting sleeve;
    wherein the lock housing assembly bears on the lower setting sleeve when in its actuating position to axially compress the packer element between the lower setting sleeve and the upper cone.

In some embodiments, the apparatus may comprise any combination of features or elements described below or shown in the drawings attached.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate some, but not the only or exclusive, examples of embodiments and/or features.

FIG. 1 shows an example of an installation of one embodiment of a liner top anchor packer apparatus in a thermal wellbore.

FIG. 2 shows an example of an installation of the embodiment of FIG. 1 installed with a packer/bridge plug in a thermal wellbore.

FIG. 3 is a partial longitudinal cross-sectional view of one embodiment.

FIG. 4 is a detailed view of one portion of FIG. 3.

FIG. 5 is a cross-sectional view of a portion of the embodiment of FIG. 3 when in full slip extension position.

FIG. 6 is a cross-sectional view of the embodiment of FIG. 3 when the mandrel is released from the slips.

DETAILED DESCRIPTION

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are exemplified. Indeed, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout. It is to be understood that this invention is not limited to the particular methodology and protocols described, as such may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention.

Many modifications and other embodiments of the invention set forth herein will come to mind to one skilled in the art to which the invention pertains having the benefit of the teachings presented in the foregoing description and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

In this description, the directional prepositions of up, upwardly, down, downwardly, front, back, top, upper, bottom, lower, left, right and other such terms refer to the apparatus as it is oriented and appears in the drawings and are used for convenience only; they are not intended to be limiting or to imply that the apparatus has to be used or positioned in any particular orientation. Conventional components of the invention are elements that are well-known in the prior art and will not be discussed in detail for this disclosure.

FIG. 1 shows a schematic depiction of a wellbore which has been conventionally completed with a surface casing SC in the vertical section, a production casing PC which extends through the build section, and a slotted liner SL positioned in the horizontal section. A liner top anchor packer 100 has been utilized to deploy a production liner PL within the slotted liner SL. FIG. 2 shows a similar installation, however, the liner top packer anchor 100 has been installed together with a dual purpose packer and bridge plug DPP. The dual purpose packer and bridge plug DPP is a separate apparatus from the liner top packer anchor 100, and permits circulation through the liner during deployment and setting of the liner top packer anchor. The DPP may be redeployed and set as a bridge plug or a liner hanger packer inside the slotted liner SL and is retrievable.

In some embodiments, a slick joint 2 passes through the assembly and is permitted to slide within the assembly, such as if downhole components connected to the slick joint thermally expand. A slick joint connection 12 is provided at the uphole end of the slick joint.

FIG. 3 shows one embodiment assembled and configured to be run into the wellbore. An inner tubular slick joint 2 includes a top sub 1 which has a running tool profile and/or a castellated end to provide torque through capability. The slick joint 2 has a threaded and sealed connection to the top sub 1 with sufficient yield torque strength for the intended use.

A mandrel 3 concentrically surrounds the slick joint 2 and abuts the lower end 1a of the top sub 1. Shear pins 30b prevent longitudinal movement of the slick joint 2 relative to the mandrel 3. If sufficient force, such as that caused thermal expansion, exceeds the shear strength of the shear pins 30b, the slick joint will be free to slide within the mandrel 3, as described below.

The mandrel 3 incorporates a seal assembly between the mandrel 3 and the slick joint 2 at a lower end to prevent ingress of fluids from below the anchor packer apparatus 100. In a preferred embodiment, the seal stack comprises two V-seal stacks 33 and two bonded seals 34, to ensure pressure integrity in a debris-laden environment. An end cap 27 is affixed to the lower end of the mandrel to retain the seals in place. An O-ring wiper seal 36 and scraper element 37 is disposed between an upper end of the mandrel 3 and the slick joint 2.

A slip mechanism, which preferably comprises bi-directional slips 15, is disposed on the mandrel 3 for securing the apparatus within the casing or liner within which the apparatus is installed. In some embodiments, the slip assembly includes slip cage 13, brass rod 14, and slip springs 18. The slips 15 are activated by an upper cone 12 and a lower cone 20, as is well known in the art.

The apparatus 100 is configured and assembled to avoid pre-set in the run-in position. FIG. 4 shows a detailed view of the circled portion of FIG. 3. An upper setting sleeve 4 is secured to the mandrel 3 by a first set of shear screws or pins 32a. A lower setting sleeve 9 is held in position by a combination of an upper lock housing 5 and a lower lock housing 6, which are interlocked together to move in unison. The lower lock housing 6 is threaded to a split ring lock 7 and secured with shear screws 32b. The inner surface of the split ring lock has a thread which engages a threaded surface 9 formed on the outside of the mandrel 3. These complementary threads form ratchet teeth which permits the split ring lock 7 to slide downwards on the mandrel, but not upwards. Anti-over stroke ring 8 is disposed between lower lock housing 6 and the mandrel 3, immediately below the split ring lock 7, and prevents overstroking.

The upper lock housing 5 comprises upwardly extending collet fingers 5a which extend upwards under the upper setting sleeve 4 and which have bulbous ends 5b to engage a radial groove formed in the outer surface of the mandrel. When the upper setting sleeve 4 moves downward, an inner groove 4a allows the collet fingers 5a to release from the mandrel 3, thus permitting longitudinal movement of the upper lock housing 5 and the lower lock housing 6 relative to the mandrel 3.

Once the apparatus 100 has been lowered to the desired position within the casing, the string may then be pulled up with sufficient force to shear the first set of shear screws 32a holding the upper setting sleeve 4 in position on the mandrel 3. As a result, the upper setting sleeve 4 will slide downward relative to the mandrel 3 and the release the collet fingers 5a of the upper lock housing 5. This movement initiates slip actuation through the slip actuating element chain comprising the upper and lower lock housings 5, 6, the lower setting sleeve 9 and the upper cone 12.

In some embodiments, the apparatus 100 may comprise a packer element 11 which expands during the setting process. As the lower lock housing 6 descends together with the lower setting sleeve 9, the element 11 is compressed between the lower setting sleeve 9 and a shoulder 12a formed by the upper cone 12. The packer element 11 is preferably formed of a thermal rated elastomer with a metal mesh backup ring. The elastomer will compress and expand outward during the slip setting process.

As the compressive force on the slip actuating element chain continues to increase, the second set of shear screws 28 which connect the upper cone 12 to the mandrel 3 shear, thereby releasing the upper cone 12. The bidirectional slips are actuated outwards between the upper cone 12 and the lower cone 20 as the upper cone 12 moves downwards. Once the slips 15 bite into the casing, increased compression of the slip actuating chain will cause further deformation of the packer element 11 to seal against the casing.

A gauge ring 22 is positioned below the slip assembly with a ring retainer 21 and a split ring 23 which engages the mandrel 3 to hold the gauge ring 22 in place. The gauge ring 22 preferably has a beveled leading edge and an OD which closely matches the casing or lining within which the apparatus will be installed. As a result, as the apparatus 100 is lowered into position, the gauge ring will clear any obstructions which could damage the slip assembly during installation.

In some embodiments, at maximum slip extension as shown in FIG. 5, the slip assembly is still fixed relative to the mandrel with shear screws 30a which secure the lower cone 20 to the mandrel 3. The slick joint 2 is fixed to the mandrel with shear screws 30b, which are weaker than shear screws 30a. As a result, upon thermal expansion of the liner, the slick joint 2 will be urged upward through the mandrel 3 and if the thermal expansion force overcomes the shear screws 30b, the slick joint will be free to slide within the mandrel, as may be seen in FIG. 6. The lower cone 20 will still be fixed to the mandrel 3 with shear screws 30a.

If it is desired to retrieve and pull the apparatus 100 out, a casing cutter may be used to cut the casing below the apparatus and a spear (not shown) may then be run in to engage the slick joint 2, the top sub 1, or the casing joint directly below the apparatus 100 that is above the cut, that includes a casing collar (not shown). A pulling force will shoulder up to the mandrel 3 and casing collar with sufficient force to shear the shear screws 30a, thereby collapsing the slips, as shown in FIG. 6, and permit the entire assembly to be retrieved.

Interpretation.

The forgoing description supplies specific details in order to provide a thorough understanding. Nevertheless, the skilled artisan would understand that the apparatuses, systems, and associated methods of using the apparatuses and systems can be implemented and used without employing these specific details. Indeed, the apparatuses, systems, and associated methods can be placed into practice by modifying the illustrated apparatus and associated methods and can be used in conjunction with any other apparatus and techniques conventionally used in the industry.

The corresponding structures, materials, acts, and equivalents of all means or steps plus function elements in the claims appended to this specification are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed.

References in the specification to “one embodiment”, “an embodiment”, etc., indicate that the embodiment described may include a particular aspect, feature, structure, or characteristic, but not every embodiment necessarily includes that aspect, feature, structure, or characteristic. Moreover, such phrases may, but do not necessarily, refer to the same embodiment referred to in other portions of the specification. Further, when a particular aspect, feature, structure, or characteristic is described in connection with an embodiment, it is within the knowledge of one skilled in the art to affect or connect such module, aspect, feature, structure, or characteristic with other embodiments, whether or not explicitly described. In other words, any module, element or feature may be combined with any other element or feature in different embodiments, unless there is an obvious or inherent incompatibility, or it is specifically excluded.

It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for the use of exclusive terminology, such as “solely,” “only,” and the like, in connection with the recitation of claim elements or use of a “negative” limitation. The terms “preferably,” “preferred,” “prefer,” “optionally,” “may,” and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention.

The singular forms “a,” “an,” and “the” include the plural reference unless the context clearly dictates otherwise. The term “and/or” means any one of the items, any combination of the items, or all of the items with which this term is associated. The phrase “one or more” is readily understood by one of skill in the art, particularly when read in context of its usage.

As will also be understood by one skilled in the art, all language such as “up to”, “at least”, “greater than”, “less than”, “more than”, “or more”, and the like, include the number recited and such terms refer to ranges that can be subsequently broken down into sub-ranges as discussed above. In the same manner, all ratios recited herein also include all sub-ratios falling within the broader ratio.

Claims

1. A liner top anchor packer apparatus comprising:

(a) an inner tubular slick joint connected to a top sub and slidably disposed within a cylindrical mandrel, the inner tubular slick joint and the mandrel connected together with at least one shear pin; and

(b) a slip assembly disposed on the mandrel, and comprising a slip setting sleeve and at least one slip moveable between a running position and an actuated outward position.

2. The apparatus of claim 1 wherein the slip assembly comprises: wherein the slips are actuated outwards between the upper cone and the lower cone when the upper cone moves to a slip actuating position by action of the slip setting sleeve.

(a) an upper cone slidably disposed on the mandrel, and affixed to the mandrel with at least one shear screw in a running position and moveable to a slip actuating position; and

(b) a lower cone affixed to the mandrel.

3. The apparatus of claim 2 wherein the lower cone is affixed to the mandrel by at least one shear screw, which is stronger than the at least one shear screw affixing the mandrel to inner tubular slick joint.

4. The apparatus of claim 1 further comprising a packer element concentrically disposed around the mandrel and an actuating assembly for deforming the packer element outwards.

5. The apparatus of claim 4 wherein the packer element actuating assembly comprises the following elements disposed concentrically around the mandrel: wherein the lock housing assembly bears on the lower setting sleeve when in its actuating position to axially compress the packer element between the lower setting sleeve and the upper cone.

(a) an upper setting sleeve affixed to the mandrel in a running position by shear screws and moveable to an actuating position;

(b) a lock housing assembly moveable between a running position and an actuating position, comprising: i. an upper lock housing having collet fingers retained within a radial groove formed on an outer surface of the mandrel by an inner surface of the upper setting sleeve, wherein the inner surface of the upper setting sleeve defines a radial groove for releasing the collet fingers of the upper lock housing when in the actuating position; and ii. a lower lock housing interlocked with the upper lock housing to move in unison, the lower lock housing having a split ring lock with ratchet teeth for engaging ratchet teeth on an outer surface of the mandrel to permit downward movement of the lower lock housing on the mandrel, but not upward movement, the lower lock housing connected to the split ring lock by shear screws; and

(c) a lower setting sleeve;