CN112534115A

CN112534115A - Centralizer with atmospheric chamber for expansion in response to hydrostatic pressure

Info

Publication number: CN112534115A
Application number: CN201980051276.3A
Authority: CN
Inventors: 乔纳森·巴克兰
Original assignee: Downhole Products Ltd
Current assignee: Downhole Products Ltd
Priority date: 2018-08-10
Filing date: 2019-07-24
Publication date: 2021-03-19
Also published as: EP3833846A1; WO2020031010A1; EA202190187A1; US20210270092A1

Abstract

A centralizer for use in a wellbore, comprising: a body disposed about a periphery of a casing or liner string, the body having a plurality of bow springs biased toward an expanded position; a mandrel disposed about a periphery of the casing or liner string; a piston disposed about the spindle and movable between a locked position and a released position; a plurality of pawls, each pawl mounted to or integrally formed with a respective bow spring and captured by the piston in the locked position to retain the bow springs in the retracted position; an atmospheric chamber formed between the piston and the spindle; and a fastener for releasably connecting the piston to the mandrel in the locked position.

Description

Centralizer with atmospheric chamber for expansion in response to hydrostatic pressure

BACKGROUND OF THE DISCLOSURE

Technical Field

The present disclosure generally relates to a centralizer (centralizer) having an atmospheric chamber for expanding in response to hydrostatic pressure.

Description of the related Art

US 4,523,640 discloses a logging instrument (well logging instrument) comprising a body member supporting one or more arm members which may be biased outwardly against a side wall of a borehole. The arm member may be retained in a closed position adjacent the body member during entry into the bore by the heat sensitive retaining member. When the instrument is exposed to the borehole temperature, the heat sensitive retaining member will release the arm member within a preselected temperature range to allow the arm member to expand outwardly from the body member into contact with the sides of the borehole.

US 5,097,905 discloses a centralizer for a well casing comprising an externally threaded upper anchor secured to the casing, an upper collar threaded to the upper anchor, a lower anchor secured to the casing, a lower collar supported against the lower anchor, and a plurality of relatively flexible metal strips extending between the collars. The centralizer fits over a section of well casing when the casing is run into the well. When the casing reaches its final depth, the casing is rotated so that the anchor rotates with the casing, while the collar and the strip remain stationary as the strip engages the wellbore. When the sleeve is so rotated, the upper collar moves along the threads of the upper anchor toward the lower collar, and axial movement of the lower collar is prevented by the lower anchor. This forces the strip to bulge outwardly away from the casing, pushing the casing towards the centre of the borehole.

US 5,261,488 discloses in fig. 18 and 18A and column 7, line 40 to column 8, line 2a centralizer that is restrained in a retracted position by a strap that is released by a hydrostatic-pressure controlled piston.

US 8,360,161 discloses a temperature activated actuator mounted on a tube for actuating an adjacent device, which actuator may comprise one or more shape memory alloy elements. These elements may be coupled between the first and second portions of the device, or these elements may be coupled between the tube and a portion of the device. The element is activated by raising the temperature to a transition temperature to cause a metallurgical phase change, thereby shrinking the element and displacing at least a portion of the device. The actuator may be used, for example, to actuate the centralizer from run-in mode to deployed mode, or alternatively, to actuate the packing member from run-in mode to isolation mode. For example, nitinol may be used as the shape memory alloy material from which the shape memory element is made.

US 9,580,976 discloses a centralizer assembly which allows the assembly to be deployed in situ. The centralizer assembly includes a flexible member that can be extended in situ into the wellbore by activation of the gas generating device. The centralizer assembly can support a large load carrying capacity with little or no installation resistance compared to conventional bow springs. Furthermore, a greater displacement can be produced to center the extremely inclined sleeve.

US 2015/0034336 discloses a centraliser having a bow spring in a retracted position to facilitate passage through a restrictor. After passing through the limiter, the bow spring may expand to support the cannula. In one embodiment, the bow spring may be expanded using a movable sleeve.

Summary of the disclosure

The present disclosure relates generally to a centralizer having an atmospheric chamber for expanding in response to hydrostatic pressure. In one embodiment, a centralizer for use in a wellbore comprises: a body disposed about a periphery of a casing or liner string, the body having a plurality of bow springs biased toward an expanded position; a mandrel disposed about a periphery of the casing or liner string; a piston disposed about the spindle and movable between a locked position and a released position; a plurality of jaws (dog), each jaw mounted to or integrally formed with a respective bow spring and captured by the piston in a locked position to retain the bow springs in a retracted position; an atmospheric chamber formed between the piston and the spindle; and a fastener for releasably connecting the piston to the mandrel in the locked position.

Brief Description of Drawings

So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

FIG. 1 shows a casing or liner string equipped with a plurality of centralizers each having an atmospheric chamber for expanding in response to hydrostatic pressure in accordance with an embodiment of the present disclosure.

Figures 2A, 2B and 3A show one typical centralizer of the centralizers in a retracted position.

Figures 2C, 2D and 3B show one typical centralizer of the centralizers in an expanded position.

Detailed Description

FIG. 1 shows a casing or liner string 1 equipped with a plurality of centralizers 2a-2e, each having an atmospheric chamber 8 (FIG. 3A) for expanding in response to hydrostatic pressure, according to one embodiment of the present disclosure. The centralizers 2a-2e may each be installed along at least a portion of a casing or liner string 1 to the casing or liner string 1, which casing or liner string 1 is to be cemented into a wellbore (not shown). The centralizers may be spaced at regular intervals along the portion of the casing or liner string 1. Each centralizer 2a-2e may be initially restrained in a retracted position (centralizer 2a-2c) and may be actuated to an expanded position (

centralizer

2d, 2e) in response to being lowered in the wellbore beyond an actuation depth 3. Each centralizer 2a-2e may be arranged to be actuated to an expanded position at the same actuation depth 3, or the centralizers may be arranged to different depths depending on their position along the casing or liner string 1. Having the centralizers 2a-2e in the retracted position reduces frictional resistance when running the casing or liner string 1 into the wellbore and/or may prevent damage caused by an expanding centralizer scraping against sensitive components (e.g., a seal bore of a wellhead).

Figures 2A, 2B and 3A show an exemplary one 2 of the centralizers 2A-2e in a retracted position. A typical centralizer 2 may include a pair of

collars

4p, 4w, a body 5, a plurality of jaws 6, a piston 7p, a mandrel 7m, an atmospheric chamber 8, shearable fasteners 9, and an anchor 10. The body 5 may have a pair of

end rings

5p, 5w and a plurality of bow springs 5b extending between the pair of

end rings

5p, 5 w. Bow springs 5 may be spaced at regular intervals around body 5 (eight bow springs are shown spaced at forty-five degree intervals). A bypass passage may be formed between the bow springs 5b to accommodate fluid flow through an annulus (annulus) formed between the casing or liner string 1 and the wellbore. Bow springs 5B may be identical to each other and may be radially movable between an expanded position (fig. 2C, 2D, and 3B) and a retracted position (shown). Bow spring 5b may have a parabolic shape in the expanded position.

The body 5 may extend longitudinally when moving from the expanded position to the retracted position and contract longitudinally when moving from the retracted position to the expanded position. The bow spring 5b may naturally be biased towards an expanded position and the expanded diameter of the centralizer 2 may correspond to the diameter of the wellbore. The engagement of the bow springs 5b with the wall of the wellbore may move the casing or liner string 1 towards a central position within the wellbore to ensure that a uniform cement sheath is formed around the casing or liner string 1 during the cementing operation. The body 5 may be formed from a single piece of spring steel by cutting slots to form a strip which will become the bow spring 5 b. The body 5 may be formed into a tubular shape by rolling the cut sheet and welding the seams of the

end rings

5p, 5w together. Bow spring 5b may have a natural bias toward the expanded position by remaining in body 5 during heat treatment of body 5.

After the body 5 has been formed, each

collar

4p, 4w may be inserted into a

respective end ring

5p, 5 w. Each

collar

4p, 4w may form a tight fit within the

end ring

5p, 5 w. Each

collar

4p, 4w may then be spot welded to the

respective end ring

5p, 5 w. The lip of each

end ring

5p, 5w that extends beyond the

respective collar

4p, 4w may be segmented into a plurality of tabs (either before or after insertion of the collar) and the tabs may be bent over the respective collar to mount the collar to the body 5 (in addition to spot welding). The anchor 10 may include a locking ring 10r and a plurality of set screws (set screws) 10 s. The locking ring 10r may have a plurality of threaded seats (threaded sockets) formed through the wall of the locking ring and spaced around the locking ring. Set screws 10s can be driven into threaded seats and into engagement with the periphery of the casing or liner string 1 to mount the locking ring 10r to the casing or liner string. A locking ring 10r may be positioned between the

collars

4p, 4w by being inserted through one of the slots between the bow springs 5b before the centralizer 2 is slid over the periphery of the casing or liner string 1. The arrangement of the anchors 10 can hold the centralizer 2 in place along the casing or liner string 1 while allowing limited longitudinal movement of the body 5 relative to the casing or liner string 1 to accommodate movement between locations.

One of the jaws 6 may be mounted to each bow spring 5b at a mid portion of each bow spring 5 b. The middle portion of each bow spring 5b may have a recess formed therein for receiving a respective jaw 6, and each jaw may be mounted (e.g., by welding) to a respective bow spring. The mandrel 7m may be disposed around the periphery of the casing or liner string 1 and may be located between the anchor 10 and the upper collar 4 p. When the centralizer 2 is in the retracted position, the mandrel 7m may abut the locking ring 10 r. The mandrel 7m may have an upper sleeve with a reduced outer diameter, a lower leg with an increased outer diameter, and a shoulder connecting the sleeve and the leg. The legs of the stem 7m may have upper grooves formed on the periphery of the legs and lower grooves formed on the periphery of the legs. The upper groove of the mandrel 7m may carry an elastomeric seal 11 (e.g., an o-ring) and the lower groove may carry a shearable fastener 9 (e.g., a shear ring).

Alternatively, each pawl 6 may be formed integrally with the respective bow spring 5 b. Alternatively, each jaw 6 may be mounted to the respective bow spring 5b by winding the wing around the respective bow spring (instead of by welding).

The piston 7p may be disposed around the periphery of the mandrel 7m and may be located between the anchor 10 and the upper collar 4 p. The piston 7p may have an upper head with a reduced inner diameter, a lower sleeve with an increased inner diameter, and a shoulder connecting the sleeve and the head. The head of the piston 7p may have a groove formed in the inner surface of the head. The groove of the piston 7p may carry an elastomeric seal 11 (e.g. an o-ring). The head diameter of the piston 7p may correspond to the sleeve diameter of the mandrel 7m, and the sleeve diameter of the piston may correspond to the leg diameter of the mandrel. The piston 7p may be longitudinally movable relative to the spindle 7m between an upper locking position (shown) and a lower release position (fig. 2D and 3B). The head of the piston 7p can clamp the jaws 6 therein in the locked position, thereby restraining the bow spring 5b in the retracted position against its natural bias towards the expanded position. To reduce friction and/or cause the jaws 6 to exert a downward force on the piston 7p, the inner surface of the head of the piston may have a tapered portion for receiving the jaws, and the outer surface of each jaw may have an inclined portion for engaging the tapered portion of the head.

Alternatively, the inner surface of the head of the piston 7p may have a straight portion (straight portion) for receiving the jaws 6 and the outer surface of each jaw may have a straight portion for engaging with the straight portion of the head, or the inner surface of the head of the piston may be partially straight and partially tapered and the outer surface of each jaw may be partially straight and partially inclined.

An atmospheric chamber 8 may be formed radially between the sleeve of the mandrel 7m and the sleeve of the piston 7p and longitudinally between the shoulder of the mandrel and the shoulder of the piston. The interface between the piston 7p and the spindle 7m may be sealed by the engagement of the seal 11 of the spindle 7m with the sleeve of the piston 7p and the engagement of the seal of the piston with the sleeve of the spindle. During running of the centralizer 2 into the wellbore, the head of the piston 7p may be exposed to hydrostatic pressure. A piston 7p is provided which can be in a release position when the bow spring 5b is retracted using the strap. The piston 7m can then be moved to the locked position and the shearable fasteners 9 are then inserted into the lower recess of the mandrel 7 m. To facilitate assembly, the shearable fasteners 9 may be snap rings (snap rings). The strap can then be released from bow spring 5 b. The outer diameter of shearable fasteners 9 may correspond to the outer diameter of piston 7p such that the shearable fasteners releasably connect the piston to mandrel 7m, thereby preventing the piston from moving from the locked position to the released position.

Figures 2C, 2D and 3B show an exemplary one 2 of the centralizers 2a-2e in an expanded position. When the centralizer 2 reaches the actuation depth 3, the force exerted on the piston 7p by the hydrostatic pressure acting on the piston head reaches a threshold force that breaks the shearable fasteners 9, allowing the piston 7p to move downwards from the locking position to the release position and release the jaws 6 from a restrained condition. The natural bias of the bow spring 5b may move the centralizer 2 from the retracted position towards the expanded position (or at least until stopped by the bow spring's engagement with the wellbore wall).

Furthermore, since the mandrel 7m may not be anchored to the locking ring 10r, the hydrostatic pressure may exert a force on the legs of the mandrel which may push the mandrel towards the piston 7p, effectively increasing the area of the piston.

Alternatively, the casing or liner string 1 may be lowered to the deployed depth while all the centralizers 2a-2e are still in the retracted position, and then the annulus pressure or hydrostatic pressure in the wellbore may be increased to actuate the piston 7 p. The annulus pressure may be increased by closing the blowout preventer and circulating fluid down the casing or liner string 1 and through a choke line at the wellhead. Hydrostatic pressure may also be increased by lowering a casing or liner string using a less dense fluid in the wellbore, and then replacing the less dense fluid with a more dense fluid after the casing or liner string has been lowered to deployment depth.

While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

1. A centralizer for use in a wellbore, comprising:

a body disposed about a periphery of a casing or liner string, the body having a plurality of bow springs biased toward an expanded position;

a mandrel disposed about the periphery of the casing or liner string;

a piston disposed about the mandrel and movable between a locked position and a released position;

a plurality of pawls, each pawl mounted to or integrally formed with a respective bow spring and captured by the piston in the locked position to retain the bow springs in a retracted position;

an atmospheric chamber formed between the piston and the mandrel; and

a fastener for releasably connecting the piston to the mandrel in the locked position.

2. The centralizer of claim 1 wherein:

the inner surface of the piston has a portion for receiving the jaws, and

an outer surface of each jaw has a portion for engaging the portion of the inner surface of the piston.

3. The centralizer of claim 2 wherein:

said portion of said inner surface of said piston is at least partially conical, and

the portion of the outer surface of each jaw is at least partially inclined.

4. The centralizer of claim 1 wherein:

the body also has a pair of end rings, an

The centralizer further includes a pair of collars, each collar mounted to a respective end ring.

5. A centralizer according to claim 4,

further comprising the casing or liner string; and is

Also included is an anchor engaged with the periphery of the casing or liner string,

wherein the anchor is disposed between the collars.

6. A centraliser according to claim 5, wherein the mandrel abuts the anchor when the bow spring is in the retracted position.

7. A method of installing a casing or liner string into a wellbore, comprising:

forming an assembly comprising the casing or liner string and the centralizer of claim 1 in a retracted position; and

lowering the assembly into the wellbore, wherein upon reaching an actuation depth, hydrostatic pressure exerted on the piston releases the fastener and moves the piston from the locked position to the released position, thereby releasing the pawl and allowing the bow spring to move toward the expanded position.

8. A method of installing a casing or liner string into a wellbore, comprising:

forming an assembly comprising the casing or liner string and the centralizer of claim 1 in a retracted position;

lowering the assembly into the wellbore with the centralizer remaining in the retracted position; and

after lowering the assembly to a deployed depth, increasing pressure in the well bore, wherein the increased pressure in the well bore is exerted on the piston, thereby releasing the fastener, moving the piston from the locked position to the released position, releasing the pawl, and allowing the bow spring to move toward the expanded position.