Well Tool Latching System

Abstract

A system for securing well tools, such as gas lift valves, into a latching profile within a wellbore. A gas lift valve is provided having a latching arrangement wherein an apertured back-up ring is used to provide stability for the locking lugs throughout the process of latching and unlatching the gas lift valve.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to devices and methods for securing a well tool within a tubular portion of a wellbore. In particular aspects, the invention relates to a latching arrangement for releasably securing a gas lift valve within a side pocket mandrel.

2. Description of the Related Art

Secure and reliable latching arrangements are important for releasably securing devices within wellbore arrangements. Gas lift valves are one such device that is used to assist the flow of hydrocarbons to the surface in a wellbore. The gas lift valve transmits a gas, such as air which has been pumped down the annulus, into the flowbore of the production tubing to increase the flow of hydrocarbons through the production tubing and toward the surface of the well. Typically, a gas lift valve is inserted into a side pocket mandrel in a production string using a kickover tool, as is well known in the art. A latching arrangement is needed to secure the gas lift valve within a latching profile in the side pocket mandrel. If the valve is not properly latched into place, it may not function properly. In addition, a latching arrangement that malfunctions may cause the valve to become stuck in the side pocket mandrel so that it cannot be removed without significant damage to the valve or the surrounding wellbore components.

Prior art latching arrangements for gas lift valves are shown in U.S. Pat. No. 4,265,306 issued to Stout and U.S. Pat. No. 4,554,972 issued to Merritt.

SUMMARY OF THE INVENTION

The invention provides a system for securing well tools, such as gas lift valves, into a latching profile within a wellbore. In a described embodiment, a gas lift valve is provided having a latching arrangement wherein an apertured back-up ring is used to provide stability for the locking lugs throughout the process of latching and unlatching the gas lift valve. In addition, the structure of the backup ring provides a positive retractive force for urging of the locking lugs radially inwardly during withdrawal of the gas lift valve. An axially facing wall of the aperture of the backup ring exerts a compressive force upon the lower axial side of the locking lug, causing a sliding contact between a chamfered surface on the lug and a shoulder on the latching profile. This sliding contact moves the locking lug radially inwardly.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages and further aspects of the invention will be readily appreciated by those of ordinary skill in the art as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference characters designate like or similar elements throughout the several figures of the drawing and wherein:

FIG. 1 is a side, cross-sectional view of an exemplary side pocket mandrel and gas lift valve having an improved latching system, in accordance with the present invention.

FIG. 2 is a side, cross-sectional view of the devices shown in FIG. 1, now with the gas lift valve being inserted into the side pocket mandrel.

FIG. 3 is a side, cross-sectional view of the devices shown in FIGS. 1-2, now in a fully latched position.

FIG. 4 is a side, cross-sectional view of the devices shown in FIGS. 1-3, now beginning to be withdrawn from the side pocket mandrel.

FIG. 5 is a side, cross-sectional view of the devices shown in FIGS. 1-4, now further withdrawn from the side pocket mandrel.

FIG. 6 is a side, cross-sectional view of the devices shown in FIGS. 1-5, now withdrawn from the side pocket mandrel.

FIG. 7 is an axial cross-sectional view of the gas lift valve 12 taken along lines 7-7 in FIG. 1.

FIG. 8 is an isometric view of an exemplary back-up ring used in the gas lift valve shown apart from other components.

FIG. 9 is an axial cross-sectional view of the gas lift valve 12 taken along lines 9-9 in FIG. 2.

FIG. 10 is an enlarged cross-sectional detail view depicting a locking lug member and the back-up ring.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The general operation of gas lift valves and side pocket mandrels is well known in the art and described in further detail in U.S. Pat. No. 7,360,602 issued to Kritzler et al. and U.S. Pat. No. 7,228,897 issued to Holt, Jr. et al. Each of these patents is owned by the assignee of the present application and each is hereby incorporated by reference in its entirety. As is known in the art, the side pocket mandrel 10 is a pocket or recess which lies substantially parallel to and alongside of the central flowbore of a string of production tubing within a wellbore.

FIG. 1 illustrates an exemplary side pocket mandrel 10 and a gas lift valve 12 that can be removably latched within the mandrel 10. The side pocket mandrel 10 includes a housing 14 that defines a central axial bore 16. It is noted that, within the context of this discussion the terms “axial” and “axially” will refer to the direction defined by the longitudinal axis of the axial bore 16, and which is illustrated by the arrows 79 in FIGS. 1 and 2 as well as arrows 82 in FIGS. 4-6. The bore 16 of the side pocket mandrel 10 has an enlarged diameter latching profile 18. It is noted that the transition between the bore 16 and the latching profile 18 presents sloped shoulders 20, 22. Fluid openings 24 are disposed through the housing 14 proximate the lower end of the bore 16 to permit a gas that is pumped down into the external annulus 26 to enter the bore 16.

In FIG. 1, the gas lift valve 12 is depicted in an initial run-in position prior to being disposed into and latched within the bore 16. Those of skill in the art will understand that a kickover tool, of a type known in the art is used to dispose the gas lift valve 12 into the bore 16. For clarity, the kickover tool is not depicted in the drawings.

The gas lift valve 12 includes a latch head 28 that is threadedly affixed to a generally cylindrical expander shaft 30. The shaft 30 features a primary shaft portion 32 which presents a substantially uniform diameter along its length and an enlarged diameter annular portion 34. The lower end of expander shaft 30 is affixed to a bottom sub 36. A latch housing 38 radially surrounds the expander shaft 30 and is secured to the expander shaft 30 by a frangible shear member, such as shear pin 40, which passes through both the shaft 30 and the latch housing 38. A radially enlarged spring chamber 42 is defined between the latch housing 38 and the primary shaft portion 32. An axially compressible spring 44 is disposed within the spring chamber 42.

A further enlarged lug chamber 46 is defined below the spring chamber 42 between the shaft 30 and the latch housing 38. In a preferred embodiment, a number of openings (one shown) 48 are disposed through the latch housing 38 within the lug chamber 46. A back-up ring 50 is disposed within the lug chamber 46 immediately below the spring 44. The back-up ring 50 contains apertures 52. In a presently preferred embodiment, there are three apertures 52, although there may be more or fewer than three, if desired. A locking lug 54 is disposed within each of the apertures 52. It can be seen from FIG. 1 that, during initial run-in to the side pocket mandrel 10, the locking lugs 54 (one show) also reside partially within the window 48 of the latch housing 38 and abut the radially enlarged portion 34 of the expander shaft 30.

The structure and operation of an exemplary back-up ring 50, apertures 52 and locking lugs 54 are better understood with further reference to FIGS. 7-9. As depicted in FIG. 8, the ring 50 features a generally cylindrical ring body 56 with an inwardly directed flange 58 at one axial end. The apertures 52 are entirely defined within the ring body 56 so is as to each present a pair of axially facing walls 60, 62 and a pair of angularly facing walls 64, 66. In a currently preferred embodiment, the apertures 52 are generally rectangular in shape.

Each of the locking lugs 54 includes a central lug body 68 with a substantially flat radially outward face 67 and chamfered edge portions 69 (see FIG. 10). Each of the lugs 54 also has a pair of ears 70 which extend radially outwardly from the body 68. The locking lugs 54 are shaped and sized to reside within the apertures 52 in a complimentary fashion. The lug members 54 each have a curved radially inner surface 71 which will abut the outer radial surfaces 34 or 32 of the expander shaft 30, as FIGS. 7 and 9 show. The ears 70 of each locking lug 54 function to prevent the locking lug 54 from being moved radially outwardly through the windows 48 of the latch housing 38. When the locking lug 54 is disposed within the aperture 52, the axially facing walls 60, 62 prevent the lug member 54, as depicted in FIG. 10. The axially facing walls 60, 62 abut axial faces 72, 74, respectively of the lug member 54. As a result, the lug member 54 can move radially inwardly and outwardly with respect to the backup ring 50 (as illustrated by the phantom lines of 54′ in FIG. 10 illustrating a radially outwardly extended position). However, the lug member 54 is prevented from appreciably rotating away in any substantial manner from the axially facing wall 62, (in the direction illustrated by arrow 76) by the presence of the axially facing wall 60. The lug member 54 is also prevented from appreciably rotating away from the wall 60 (in the direction indicated by arrow 78) in any substantial manner by the presence of wall 62. A substantial rotation of the lug member 54 with respect to the walls 60 or 62 would be an amount of rotation that would preclude the lug member 54 from operating properly to move radially inwardly or outwardly to selectively latch the gas lift valve 12 into the side pocket mandrel 10. In addition, the angularly facing walls 64, 66 prevent angular rotation of the lug members 54, as FIGS. 7 and 9 illustrate.

The operation to insert the gas lift valve 12 into the side pocket mandrel 10 and latch it within is illustrated by FIGS. 1-3 as well as 7 and 9. Beginning with the configurations shown in FIGS. 1 and 7, a downward compression force (illustrated by arrow 79) is applied to the latch head 28 and latch housing 38. This downward force 79 compresses the spring 44 between the latch housing and the backup ring 50, as FIG. 2 depicts. The latching lugs 54 are moved from the lower end of windows 52, as illustrated in FIG. 1, to the upper end of the windows 52, as shown in FIG. 2. In addition, the downward force moves the lug members 54 from abutting the diametrically expanded section 34 of the expander shaft 30 (as shown in FIGS. 1 and 7) to a position wherein the curved faces 71 of the lug members 54 abut the reduced diameter portion 32 of the shaft 30 (see FIGS. 2 and 9). This permits the lug members 54 to be moved radially inwardly by sliding contact between a chamfered edge 69 of the lug with a sloped shoulder 80 (see FIG. 2) within the bore 16 of the side pocket mandrel 10. Once the lug members 54 have been moved radially inwardly, the compression force gas lift valve 12 is moved downwardly to the position depicted in FIG. 3 wherein the latching lug members 54 are located within the latching profile 18 of the gas lift mandrel 10. At this point the downward force 79 is removed. The compression spring 44 will move the backup ring 50 axially downwardly with respect to the latch housing 38 and expander shaft 30. The inner radial surfaces 71 of the lug members 54 will once again be abutting the expanded diameter portion 34 of the expander shaft 30. As a result, the lug members 54 will extend outwardly into the latching profile 18, thereby latching the gas lift valve 12 in place against inadvertent removal during operation.

FIGS. 4-6 illustrate removal of the gas lift valve 12 from the side pocket mandrel 10. When it is desired to remove the gas lift valve 12, an upward pulling force, or removal force) is applied to the latch head 28 (illustrated by arrow 82). As is known, the removal force is typically applied to the latch head by a suitable pulling tool (not shown). It is noted that the removal force 82 must be sufficient to shear the shear member 40. The force 82 first moves the gas lift valve 12 upwardly to the position shown in FIG. 4 wherein the upper chamfered edge 69 of the locking lugs 54 comes into contact with the shoulder 20 of the latching profile 18. However, the lugs 54 cannot be moved radially inwardly at this point due to their abutting relation with the expanded diameter portion 34 of the expander shaft 30. The removal force 82 then shears the shear pin 40, as shown in FIG. 5. When this occurs, the latching head 28 and expander shaft 30 are freed to move with respect to the surrounding latch housing 38. The radially expanded portion 34 of the expander shaft 30 will engage the flange 58 of the backup ring 50, thereby drawings it axially upwardly. The radially expanded portion 34 of the expander shaft 30 is also moved above the locking lugs 54, thereby allowing them to be moved radially inwardly to the position shown in FIG. 5, due to sliding contact with the shoulder 20. It is noted that the lower axially facing wall 60 of the backup ring 50 will exert a positive compressive force against the lower axial face 72 of the locking lugs 54. This compressive force will ensure that there is sliding contact between the upper chamfered edge 69 of the lugs 54 and the shoulder 20 of the bore 16. This sliding contact will move the lugs 54 radially inwardly. As the lugs 54 are moved inwardly, they are prevented from axial rotation with respect to the latch housing 38 by sliding contact with the axially facing walls 60, 62 of the backup ring 50. At this point, the gas lift valve 12 is freed to be removed completely from the side pocket mandrel 10, as further depicted in FIG. 6.

The foregoing description is directed to particular embodiments of the present invention for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above are possible without departing from the scope and the spirit of the invention.

Claims

1. A latching arrangement for releasably securing a well tool within a bore in a wellbore, the latching arrangement comprising:

an outer radial housing defining a window therein;

a locking lug that is at least partially disposed within the window and is moveable radially inwardly and outwardly with respect to the housing to removably lock the well tool within the bore; and

a backup ring disposed within the housing, the backup ring having a ring body having an aperture disposed therein, the aperture presenting first and second axially facing walls; and

the locking lug being at least partially disposed within the aperture of the backup ring and presenting first and second axial surfaces which adjoin the first and second walls of the backup ring, thereby precluding substantial rotation of the locking lug with respect to the backup ring.

2. The latching arrangement of claim 1 wherein the well tool is a gas lift valve.

3. The latching arrangement of claim 1 wherein the locking lug comprises a lug body and an ear portion which extends radially from the body, the ear portion preventing the locking lug from being moved entirely radially outwardly through the window.

4. The latching arrangement of claim 1 wherein:

the backup ring has three apertures; and

there are three locking lugs.

5. The latching arrangement of claim 1 further comprising a mechanism for moving the locking lug radially outwardly with respect to the housing.

6. The latching arrangement of claim 5 wherein the mechanism for moving the locking lug comprises a generally cylindrical expander shaft disposed radially within the valve housing, locking lug and backup ring, the expander shaft presents:

a first section having a first diameter;

a second section having a second diameter that is larger than the first diameter; and

wherein the expander shaft is axially moveable with respect to the locking lug to cause the locking lug to move radially outwardly as the lug is moved radially outwardly as the locking lug contacts the second section of the expander shaft.

7. The latching arrangement of claim 6 wherein the expander shaft is releasably secured to the outer radial housing by a frangible shear member.

8. A gas lift valve for use in a side pocket mandrel within a wellbore, the side pocket mandrel having a bore, the gas lift valve comprising:

a valve housing defining a window therein;

a locking lug that is moveable radially inwardly and outwardly through the window with respect to the valve housing for removably locking the gas lift valve into a latching profile in the bore;

a backup ring disposed within the valve housing, the backup ring comprising a ring body having an aperture disposed therein, the aperture presenting first and second axially facing walls; and

the locking lug being at least partially disposed within the aperture of the backup ring.

9. The gas lift valve of claim 8 further comprising a generally cylindrical expander shaft disposed radially within the valve housing, locking lug and backup ring, the expander shaft presents:

a first section having a first diameter; and

a second section having a second diameter that is larger than the first diameter.

10. The gas lift valve of claim 8 wherein the locking lug comprises a lug body and an ear portion which extends radially from the body, the ear portion preventing the locking lug from being moved entirely radially outwardly through the window.

11. The gas lift valve of claim 9 wherein the expander shaft is releasably secured to the valve housing by a frangible shear member.

12. The gas lift valve of claim 9 wherein the expander shaft is axially moveable with respect to the locking lug to cause the locking lug to move radially outwardly as the lug is moved radially outwardly as the locking lug contacts the second section of the expander shaft.

13. A method for releasably securing a well tool within a bore in a wellbore, the method comprising the steps of:

disposing the well tool within the bore proximate a latching profile in the bore, the well tool having a latch housing which defines a window therein;

urging a locking lug radially outwardly through the window and into the latching profile; and

providing sliding contact between the locking lug and at least two axially facing walls of a backup ring lying radially within the latch housing to prevent substantial axial rotation of the locking lug with respect to the latch housing during radial outward movement of the to locking lug.

14. The method of claim 13 further comprising the steps of:

moving the locking lug radially inwardly with respect to the latch housing; and

providing sliding contact between the locking lug and at least two axially facing walls of a backup ring lying radially within the latch housing to prevent substantial axial rotation of the locking lug with respect to the latch housing during radial outward movement of the locking lug.

15. The method of claim 14 wherein the locking lug is moved radially inwardly by compressive contact between the locking lug and the backup ring, which causes the locking lug to be moved inwardly by sliding contact against a shoulder within the bore.