DOWNHOLE SHAPE MEMORY ALLOY ACTUATOR AND METHOD

Abstract

A downhole actuator includes, a sleeve, a mandrel, and at least one of the sleeve and the mandrel is in operable communication with a downhole tool to be actuated. The actuator further includes, a follower disposed at one of the sleeve and the mandrel, a pathway disposed at the other of the sleeve and the mandrel, the pathway being receptive to the follower and configured to cause rotational motion and limit a stroke length between the sleeve and the mandrel in response to longitudinal motion between the follower and the pathway. The actuator also has a shape memory alloy in operable communication with the sleeve and the mandrel configured to longitudinally move the sleeve in relation to the mandrel in response to temperature changes thereof.

Description

BACKGROUND

Downhole actuators employ a variety of mechanisms to generate relative motion to cause actuation. One such mechanism is a Shape Memory Alloy (SMA). A shape memory alloy changes shape in response to changes in temperature. Actuators employing shape memory alloys allow operators to actuate downhole tools in response to changing a temperature of a shape memory alloy employed therein. Typical shape memory alloy actuators are limited to a single actuation stroke length. Methods and systems to permit multiple actuation stroke lengths with a single shape memory actuator would be well received in the industry.

BRIEF DESCRIPTION

Disclosed herein is a downhole actuator. The actuator includes, a sleeve, a mandrel, and at least one of the sleeve and the mandrel are in operable communication with a downhole tool to be actuated. The actuator further includes, a follower disposed at one of the sleeve and the mandrel, a pathway disposed at the other of the sleeve and the mandrel, the pathway being receptive to the follower and configured to cause rotational motion and limit a stroke length between the sleeve and the mandrel in response to longitudinal motion between the follower and the pathway. The actuator also has a shape memory alloy in operable communication with the sleeve and the mandrel configured to longitudinally move the sleeve in relation to the mandrel in response to temperature changes thereof.

Further disclosed herein is a method of actuating a downhole tool. The method includes, altering a dimension of a shape memory alloy with altering temperature thereof, displacing a sleeve in relation to a mandrel, the sleeve and the mandrel are in operable communication with the downhole tool. The downhole tool further includes, repositioning a follower disposed at one of the sleeve and the mandrel within a pathway disposed at the other of the sleeve and the mandrel, and limiting a stroke of the sleeve in relation to the mandrel with the follower in the pathway.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIG. 1 depicts a cross-sectioned perspective view of a downhole shape memory alloy actuator disclosed herein;

FIG. 2 depicts a perspective view of a mandrel of the downhole actuator of FIG. 1 having a multi-track pathway;

FIG. 3 depicts a cross-sectional side view of the downhole actuator of FIG. 1 in operable communication with a downhole tool; and

FIG. 4 depicts a cross-sectional perspective view of an alternate downhole shape memory alloy actuator disclosed herein.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

Referring to FIG. 1, an embodiment of a downhole actuator 10 disclosed herein is illustrated. The downhole actuator 10 includes, a sleeve 14 having a follower 18, shown herein as a pin, engagable with a pathway 22, shown herein as a slot, of a mandrel 26. In this embodiment, the mandrel 26 is made of a shape memory alloy (SMA) that changes shape with changes in temperature. A collar 30 fixes a distal end portion 34 of the sleeve to a distal end portion 38 of the mandrel 26. As such, changes in length of the mandrel 26, due to changes in temperature thereof, cause relative motion between the pin 18 and the slot 22. The engagement of the pin 18 within the slot 22 limits longitudinal stroke length while controlling rotational movement therebetween. This engagement also causes the actuator 10 to have multiple stroke lengths as will be described in detail below. These multiple stroke lengths can actuate a downhole tool (not shown) that is operably connected to at least one of the sleeve 14 and the mandrel 26.

The shape memory alloy mandrel 26, in this embodiment, is configured to reduce a longitudinal length thereof in response to an increase in temperature. As such, heating of the mandrel 26 causes the slot 22 to move to towards the collar 30 while the pin 18 remains substantially stationary with respect to the collar 30. Conversely, cooling of the mandrel 26 will allow the mandrel 26 to be reshaped by external forces applied thereto. A biasing member 42, illustrated in this embodiment as a series of spring washers, will move the slot 22 away from the collar 30 while the pin 18 again remains substantially stationary, thereby elongating the mandrel 26 in the process. Alternate embodiments, however, can use shape memory alloys that function in reverse to that of the mandrel 26 such that instead of a reduction in a longitudinal length thereof there is an increase in a longitudinal length thereof in response to an increase in temperature of the shape memory alloy. Additionally, alternate embodiments may employ shape memory alloys that have a two-way memory effect. Use of such a shape memory allow can permit the slot 22 of the downhole actuator 10 to move in both directions without the use of a biasing member 42 since the shape memory alloy itself would provide driving forces needed to drive the actuator 10 in both directions.

Referring to FIG. 2, the slot 22 of the mandrel 26, receptive to the pin 18, is illustrated in greater detail. The slot 22 has multiple tracks 46A-46E to control rotational and longitudinal motion of the mandrel 26 in relation to the sleeve 14. For example, the pin 18 may initially be in contact with end 44A of track 46A. Heating of the mandrel 26, in this embodiment, causes it to longitudinally contract thereby moving the pin 18 along track 46A until the pin 18 contacts the track 46B, which is angled and thereby causes the mandrel 26 to rotate (counterclockwise as viewed from the right side of the mandrel 26 in this figure). The rotation continues until the pin 18 enters the track 46C, which is straight, so the rotation stops even as the longitudinal contraction of the mandrel 26 continues until the pin 18 contacts the end 44B. This is a stable configuration as long as a force urging the pin 18 towards end 44B is maintained. Removing the heating applied to the shape memory alloy mandrel 26, in this embodiment, allows the urging force of the biasing member 42 (FIG. 1) to move the pin 18 in the opposite direction along the track 46C until the pin 18 contacts the angled track 46D at which point the mandrel 26 will again rotate (in the counterclockwise direction) until the pin 18 enters the straight track 46D at which point the rotation ceases and only longitudinal motion continues. The longitudinal motion ceases when the pin 18 contacts the end 44C of the track 46D. The pin 18 butted against the end 44C is also a stable configuration as long as a biasing force is urging the pin 18 towards the end 44C. The slot 22, having multiple tracks 46A-46E is often referred to as a J-slot.

As mentioned above the actuator 10 has multiple stroke lengths. The multiple stroke lengths are due to the ends 44A-44C being positioned at different locations along the mandrel 26. For example, the end 44A is positioned along the mandrel 26 at a different location than end 44C. This is made clearer by observing a difference in a dimension 48A, from the end 44A to a shoulder 52, than a dimension 48C, from the end 44C to the shoulder 52. By simply setting these ends 44A-44C and any additional ends in a similar manner, an operator can set multiple actuation stoke lengths in the downhole actuator 10. An actuator 10 having multiple actuation stroke lengths and positions can be useful for actuating different downhole tools as will be discussed with reference to FIG. 3 below.

Although the embodiment illustrated herein has the pin 18 fixed to the sleeve 14 and the slot 22 located on the mandrel 26, alternate embodiments could reverse this relationship and have the pin 18 fixed to the mandrel 26 and the slot 22 located on the sleeve 14. Additionally, since actuation of the actuator 10 is defined by relative motion between the sleeve 14 and the mandrel 26, an alternate embodiment of the actuator 10 could reverse which of these two parts, the sleeve 14 and the mandrel 26, is made from the shape memory alloy. For example, embodiments could have the sleeve 14 made from a shape memory alloy while the mandrel 26 is not. Embodiments of downhole actuators employing the foregoing reversals would allow actuation in a similar fashion to the embodiment illustrated herein, albeit in an opposite direction. Additionally, the relative rotational motion between the sleeve 14 and the mandrel 26 could be employed as the motion of actuation as opposed to the longitudinal motion.

Referring to FIG. 3, the downhole actuator 10 is shown attached to a downhole tool 56, illustrated here as a flow control valve. The valve 56 includes a piston 60, threadably attached to the mandrel 26, that is longitudinally movable and sealingly engaged within a tubular 64. The tubular 64 has a plurality of ports 68 through a wall 72 thereof. Varying the longitudinal position of the piston 60 with respect to the ports 68 varies the amount of area of the ports 68 occluded by the piston 60. As such, the open area of the ports 68 that allows flow therethrough between an inner portion 74 and an outer portion 78 of the tubular 64 is varied as well to create a throttling effect of the flow control valve 56.

The valve 56 as illustrated is in a closed configuration with the mandrel 26 positioned to the right in the view of FIG. 3 due to the biasing member 42 biasing the mandrel 26 to the right. In this closed configuration the pin 18 is positioned in a track 46 of the slot 22 that permits positioning the piston 60 to this position. Opening of the valve 56 is initiated by increasing temperature of the shape memory alloy mandrel 26 with a heater 82, depicted here as an electrical heating element. The increase in temperature of the mandrel 26 causes; a longitudinal shortening of the mandrel 26, an increased compression of the biasing member 42, movement of the piston 60 toward the left, and relative motion of the pin 18 within one of the tracks 46A-46E of the slot 22. With sufficient heating and stroke length produced by the shape memory alloy such motion will continue until the pin 18 contacts an end 44 of a track 46. Accordingly, an operator can set the parameters of the foregoing structure to open the ports 68 of the valve 56 a desirable amount. Additional open settings of the valve 56 can be achieved through cooling of the shape memory alloy mandrel 26 (possibly by simply removing energy supplied to the heater 82) and allowing the biasing member 42 to stroke the pin 18 in the opposite direction relative to the slot 22 until another of the ends 44 is contacted. In so doing the number of partially opened settings of the valve 56 is limited only by the physical limitations of adding more of the tracks 46 to the mandrel 26.

Referring to FIG. 4, an alternate embodiment of a downhole actuator 110 disclosed herein is illustrated. The downhole actuator 110 is similar to the downhole actuator 10 and as such like elements are designated with the same reference characters. The downhole actuator 110 includes, the sleeve 14 having the follower 18, shown herein as a pin, engagable with the pathway 22, shown herein as a slot of the mandrel 126, and a shape memory alloy member 128. In this embodiment, unlike in the actuator 10, the mandrel 126 is a separate component from the shape memory alloy member 128 that changes shape with changes in temperature. In the actuator 10 the shape memory alloy mandrel 26 reduced in length with an increase in temperature thereof. In contrast, in the actuator 110 the shape memory alloy member 128 increases in length with an increase in temperature thereof. Since the shape memory alloy member 128 contacts a cap 132 of the sleeve 14, the increase in length of the shape memory alloy member 128 causes the mandrel 126 to move in a direction away from the cap 132, thereby moving the slot 22 in relation to the pin 18, in a similar fashion as to that of actuator 10. This movement also causes a portion 136 of the mandrel 126, on a side opposite of the shape memory alloy member 128, to move in a direction away from the cap 132, compressing the biasing member 42 against stop 140 in the process. The biasing member 42 provides a force against the shape memory alloy member 128 to return it to its shorter configuration upon reduced temperature thereof. The slot 22 is thereby moveable in a back and forth fashion, in relation to the pin 18, in response to heating and cooling of the shape memory alloy member 128. The slot 22, and the pin 18 engaged therewith, is configured to rotate the sleeve 18 in relation to the mandrel 126 resulting in a plurality of settable stroke lengths of movements therebetween.

While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.

Claims

1. A downhole actuator comprising:

a sleeve;

a mandrel, at least one of the sleeve and the mandrel being in operable communication with a downhole tool to be actuated;

a follower disposed at one of the sleeve and the mandrel;

a pathway disposed at the other of the sleeve and the mandrel, the pathway being receptive to the follower and configured to cause rotational motion and limit a stroke length between the sleeve and the mandrel in response to longitudinal motion between the follower and the pathway; and

a shape memory alloy in operable communication with the sleeve and the mandrel configured to longitudinally move the sleeve in relation to the mandrel in response to temperature changes thereof.

2. The downhole actuator of claim 1, wherein the pathway has a plurality of tracks receptive of the follower and each of the plurality of tracks defines a unique stroke limit.

3. The downhole actuator of claim 2, wherein each of the plurality of tracks causes rotational indexing of the sleeve in relation to the mandrel with each longitudinal stroke.

4. The downhole actuator of claim 1, further comprising a biasing member in operable communication with the sleeve and the mandrel to cause relative movement between the sleeve and the mandrel in a direction counter to that of the shape memory alloy.

5. The downhole actuator of claim 1, wherein the follower is a pin and the pathway is a slot.

6. The downhole actuator of claim 1, wherein increases in temperature of the shape memory alloy cause a decrease or increase in a longitudinal dimension thereof.

7. The downhole actuator of claim 1, wherein the shape memory alloy is configured to reverse the longitudinal motion between the sleeve and the mandrel in response to additional temperature changes of the shape memory alloy.

8. The downhole actuator of claim 1, wherein the sleeve and the mandrel are connectable to the downhole tool such that rotational motion between the sleeve and the mandrel cause actuation of the downhole tool.

9. The downhole actuator of claim 1, wherein the pathway is a J-slot.

10. The downhole actuator of claim 1, wherein the shape memory alloy is at least one of the sleeve and the mandrel.

11. The downhole actuator of claim 1, wherein the longitudinal motion between the sleeve and the mandrel is greater at a first portion of the sleeve and a first portion of the mandrel than at a second portion of the sleeve and a second portion of the mandrel.

12. The downhole actuator of claim 1, further comprising a heater in operable communication with the shape memory alloy.

13. A method of actuating a downhole tool, comprising:

altering a dimension of a shape memory alloy with altering temperature thereof;

displacing a sleeve in relation to a mandrel, the sleeve and the mandrel being in operable communication with the downhole tool;

repositioning a follower disposed at one of the sleeve and the mandrel within a pathway disposed at the other of the sleeve and the mandrel; and

limiting a stroke of the sleeve in relation to the mandrel with the follower in the pathway.

14. The method of actuating a downhole tool of claim 13, wherein the repositioning the follower within the pathway includes rotationally indexing the sleeve in relation to the mandrel.

15. The method of actuating a downhole tool of claim 14, wherein the rotationally indexing repositions the follower into a different track of the pathway.

16. The method of actuating a downhole tool of claim 15, wherein each different track has a different stroke limit.

17. The method of actuating a downhole tool of claim 13, wherein the altering temperature is an increasing of temperature.

18. The method of actuating a downhole tool of claim 13, wherein the altering of the dimension is a shortening or lengthening of a longitudinal dimension.

19. The method of actuating a downhole tool of claim 13, further comprising:

further altering temperature of the shape memory alloy; and

reshaping the shape memory alloy; and

repositioning the follower within the pathway.

20. The method of actuating a downhole tool of claim 13, wherein a reshaping of the shape memory alloy is in response to biasing the shape memory alloy.