Retrievable Well Packer Apparatus

Abstract

In accordance with an illustrative embodiment of the present invention, a retrievable well packer apparatus includes a body that carries upper and lower packing structures and an anchor for preventing movement in either longitudinal direction in a well bore. Each packing structure includes a settable packing element mounted on a pressure sleeve between a fixed abutment on the sleeve and a movable abutment slidable along the sleeve. A clutch means having cooperative parts on the sleeve and the movable abutment functions to retain compression loading on the packing elements in the event of loss of packing material due to extrusion or the like. A one-way check valve system between each packing structure and the mandrel enables the pressure of fluids in the annulus space between the packing structures to equalize with the lesser pressure of fluids in the well bore above or below the packer apparatus, as the case may be.

Description

BACKGROUND OF THE INVENTION

Well packers of the type shown in U.S. Pat. No. 3,279,542 have been used for a number of years to provide an anchored pack-off in a well bore. Such packers include settable packing seals that are normally retracted and are expanded by the application of oppositely directed compressive force to the ends thereof. An anchor assembly including upper and lower expanders with gripping slips located therebetween functions to prevent movement of the packer in either longitudinal direction in a well.

The packing seals are mounted on a sleeve that carries an abutment engaging the upper end of the packing. The lower end of the packing rests on an abutment that is slidable along the sleeve and is fixed to the upper expander. Thus, once the slips are set, the upper expander can not move any further downwardly, and a shoulder on the mandrel engages the upper abutment to force it and the sleeve downwardly with resulting compression and expansion of the sealing elements into contact with the casing wall. A clutch system traps the mandrel in its lower position to lock the packer in set condition, and the clutch can be released by appropriate manipulation of the pipe string to enable he packer to be retrieved.

A well packer of this type is normally used in producing, injection or acidizing operations in a well, and consequently may be subjected to high pressure differentials acting in both longitudinal directions. Moreover, the tool may be subjected to tension, compression and mechanical forces. For example, an acidizing job might be undertaken, resulting in a high differential in an upward direction on the packer, followed by a swab testing operation to return the well to production. During the test, fluid pressures below the packer may be greatly reduced, resulting in high pressure different acting in a downward direction on the packing.

Particularly where packing elements are subjected to pressures in both directions, attrition of the elements can result due to extrusion. By extrusion, packing element volume is lost so that all other things being fixed, the compression loading is lost and the elements lose their seal with the well casing wall. In short, the packer leaks, causing the well pressuring operations mentioned above to be unsuccessful.

An object of the present invention is to provide a new and improved retrievable well packer apparatus that will hold pressure acting in alternate longitudinal directions without loosing a seal due to extrusion or other attrition of the packing elements.

Another object of the present invention is to provide a new and improved retrievable well packer apparatus having an automatic take-up system to compensate for lost packing volume due to extrusion or the like, so that adequate compressive force is applied to the packing to insure a fluid-tight seal against the casing.

These and other objects are attained in accordance with the concepts of the present invention by the provision of a well packer apparatus including a mandrel or body that carries settable packing mounted around a sleeve that is slidable along the mandrel. The sleeve has an annular first abutment that engages one end of the packing. The other end of the packing is engaged by a second abutment that is slidable along the sleeve relatively toward the fixed abutment, the second abutment being fixed to an expander cone that cooperates with a typical slip system to anchor the tool in the casing. Movement of the abutments relatively toward each other will result in the application of compressive force to the ends of the packing so that it is foreshortened and expanded into sealing contact with the casing. A clutch device coacting between the mandrel and the slip assembly locks the tool in set position.

As the packing is expanded by advancement of one abutment toward the other, a ratchet or take-up device operates to trap the sleeve with respect to the second abutment and thus lock the compression energy in the packing elements. The ratchet device is releasably locked so that it will continue to function until it is desired to release it. Moreover, should there be any further movement of the abutments toward each other, such as would occur, for example, upon extrusion or loss of packing volume, the ratchet device will take up such relative movement so that the compression energy remains locked in the packing elements.

In accordance with a further feature of the present invention, upper and lower packing structures are provided as described above, such structures being located on opposite disposed. A one-way check valve system is provided between each packing structure and the mandrel, the upper valve holding pressure only in an downward direction and the lower valve holding pressure only in an upwardly direction. In this manner, the pressure of fluids in the annulus space between the packing structures always equalizes to the lesser pressures of fluids in the well bore, whether above or below the packer. Thus, a force due to a pressure difference across the tool can be developed on the sleeve that mounts the packing element primarily responsible for holding such pressure, such force acting to continue compression of the packing in the event of extrusion and to cause the ratchet to take up any movement that occurs due to such extrusion.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention both as to its organization and manner of operation together with further objects and advantages thereof may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawing, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C are longitudinal sectional views, with portions in side elevation, on a well packer apparatus in accordance with the invention. The parts being shown in relative positions for running into or out are a well casing, the latter figures forming lower continuations of previous figures;

FIGS. 2A-2C are views similar to FIGS. 1A-1C except with parts in their relative positions when the packer is set in the casing; and

FIG. 3 is a cross-section on line 3--3 of FIG. 2B.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to FIGS. 1A-1C, a well packer apparatus 10 is shown being lowered into a well casing C on a running-in string of tubing or drill pipe T. The well packer includes a mandrel or body member 11 connected to the lower end of the tubing T by a collar 12. The mandrel carries an upper packing assembly, a slip and expander assembly and a lower packing assembly indicated as 13, 14 and 15 respectively. A clutch assembly indicated generally at 16 is used to control setting and release of the packer 10 as will be more fully described below.

The upper packer assembly 13 includes an annular compression sleeve 20 that surrounds the mandrel 11 with its inner-peripheral surface spaced laterally away from the outer surface of the mandrel 11 in order to provide an annular passage 21 therebetween. An annular ring 22 is threadedly secured to the upper end of the compression sleeve 20 and provides an upper, downwardly facing abutment surface 23. Packing elements 24 and 25 can take the form of elastomeric rings, the upper ring engaging the upper abutment surface 23 and the lower ring resting on the upwardly facing lower abutment surface 26 provided by an annular ring 27, that is, movable relative to the compression sleeve 22. Advancement of the lower abutment 27 relatively toward the upper abutment 22 sill compress and expand packing elements 24 and 25 into sealing contact with the well casing wall. An annular valve seal 28 is retained within an annular recess 29 in the ring 22 and the upper end portion of the mandrel 11 has an enlarged cross-section to provide a valve head 30 which engages the seal element 28 in order to close off the bypass passage 21 to fluid flow in a lower position of the mandrel with respect to the compression sleeve 20.

The lower abutment ring 27 is attached to the upper end portion of an upper expander member 32. The lower end portion of the compression sleeve 20 extends 45 downwardly within the expander member 32 and is longitudinally slotted at circumferentially spaced locations in order to provide a plurality of downwardly depending spring fingers 33. To prevent relative rotation between the compression sleeve 20 and the expander member 32, one or more pins 88 on the expander member extend inwardly into the vacant space between the spring fingers 33. Each spring finger 33 has an enlarged head portion 34 with upwardly facing relatively course teeth 35 of the buttress type formed thereon. The head portions 34 are cooperable with a clutch nut 36 that is received within an internal annular recess 37 in the expander member 32. The clutch nut 36 is formed of a plurality of segments as shown in FIG. 3 that are urged together as a cylinder by an annular band spring 38 or the like that encircles the segments. Each nut segment has downwardly facing teeth 39 that are companion in shape to the teeth 35 on the head portions 34, and the upper end surfaces 40 on the nut inclined upwardly and inwardly and is arranged to engage a downwardly and outwardly turned surface 41 at the upper end of the recess 37. The outer peripheral surface on the nut member 36 is spaced inwardly with respect to the side wall surface of the recess 37, so that the head portions 34 can be ratcheted downwardly through the nut member. However, due to the face angles on the teeth 35 and 39 and to the interengagement on the surfaces 40 and 41, the teeth resist upward movement on the sleeve member 20. Moreover, when the head portions 34 are engaged by the nut member 36, a longitudinally grooved enlarged section 42 on the mandrel 11 is moved behind the head portions so that the fingers 33 can not resile inwardly, resulting in a lowering action whereby the sleeve member 20 is trapped in the lowermost position to which it is moved.

A plurality of normally retracted serrated slip element 45 are located between the upper expander member 32 and a lower expander member 46 (FIG. 1B). Each of the slip elements 45 has reversed tapered inclined surfaces 47 and 48, the upper surface 47 inclining in a downward and inward direction and the lower surface 48 inclining in a downward and outward direction. The expander members 32 and 46 has like tapered surfaces 49 and 50, and dovetail sliding connections 50 and 51 can be provided between the slip elements 45 and the respective expander members so that longitudinal relative motion of expanders causes corresponding lateral movement of the slips. The lower expander member 46 constitutes the upper portion of a cage or housing member 55 that carries a plurality of circumferentially spaced, radially disposed drag blocks 56. Each of the drag blocks 56 is laterally movably within a recess 57 in the housing member 55 and is urged outwardly into frictional engagement with the well casing C by coil springs 58 or the like. The drag blocks 56 resist motion in the well in a conventional manner.

The lower packing assembly 15 (FIG. 1B) is formed of substantially identical parts to those of the upper packing assembly 13 but are oppositely disposed in direction. Thus a compression sleeve 60 mounts packing rings 61 and 62 above an annular abutment ring 63, and a movable abutment 64 on the lower end of the cage 55 is slidable relatively along the compression sleeve 60 to compress and expand the packing into sealing contact with the casing C. In this case the upper end portion on the compression sleeve 60 is longitudinally slotted to provide spring fingers 65 having toothed head portions 66. A segmented nut member 67 as previously described is received in a recess 68 and is cooperable with the head portions 66 to trap the compression sleeve 60 in the uppermost position to which it is moved, as well as to take up any further motion on the sleeve that may occur. An enlarged section 69 on the mandrel 11 provides a locking surface as explained heretofore, and an annular seal element 70 (FIG. 1C) engages the peripheral surface 71 of the mandrel 11 in order to seal off a space 72 between the lower compression sleeve 60 and the mandrel 11 to fluid flow in an upward direction.

The clutch assembly 16, to enable running and retrieving the well packer 10 includes a clutch sleeve 75 connected to the lower end of the lower packing assembly 15. The clutch sleeve 75 is longitudinally slotted in order to divide the sleeve into a plurality of circumferentially spaced fingers on beams 76 capable of lateral deflection. The lower end portion of the clutch sleeve 75 has formed on its inner periphery spaced sets of threads 77 and 78 the upper threads 77 being formed on a left hand helix and the lower threads 78 being formed on a right hand helix. The lower end portion 79 of the mandrel 11 also has a upper set of threads 80 that are formed in a companion fashion to the upper threads 77 on the clutch sleeve 75 and lower threads 81 that are companion in shape to the lower threads 78 on the clutch sleeve.

In operation, the packer 10 assemblied as shown in the drawings can be connected to the running-in string T and lowered to a selected setting point within the casing C. During running, the upper packing assembly 13 and the lower packing assembly 15 are held in spaced apart relation on the mandrel 11 by the engagement of the lower threads 78 and 81 on the clutch sleeve 75 and the mandrel 11, respectively, and by engagement on an upwardly facing shoulder 83 on the mandrel with a downwardly facing shoulder 84 on the abutment ring 22. The expander 32 and 45 are also spaced apart so that the slip elements 45 are held in retracted positions. During lowering, fluids can bypass through the packing assemblies 13 and 15 via the bypass passage spaces 21 and 72 afforded between the compression sleeves 20 and 60 and the mandrel 11. The drag blocks 56 slide along in frictional engagement with the casing C and resist turning motion of the cage member 44.

As setting depth the mandrel 11 is rotated by the pipe string to the right while slacking off in order to release the connection between the lower threads 78 and 81. Then the mandrel 11 can be lowered without rotation to effect setting of the slips 45 and the upper packing assembly 13 as shown in FIGS. 2A-2C. The drag blocks 56 prevent movement of the lower expander member 46 so that lowering the mandrel 11 will cause the upper expander member 32 to move toward the lower expander member, thereby shifting the slip elements 45 outwardly into gripping contact with the casing. Lowering the mandrel 11 also causes the valve head 30 to engage the seal element 28 to close off the bypass passage space 21. The collar 12 will engage the retainer rings on the abutment member 22, and the locking section 42 of the mandrel 11 will be positioned behind the latch heads 34 on the lower end of the compression sleeve 20. As the weight of the pipe string T is applied to the mandrel 11, the upper abutment 22 will be advanced toward the lower abutment 27 in order to compress and expand the packing rings 24 and 25 into sealing contact with the casing C. As the packing is expanded, the latch heads 34 will ratchet inside the clutch nut 36 and the nut will trap the compression sleeve 20 in the lowermost position to which it is moved.

In order to set the lower packing assembly 15, the mandrel 11 is lifted. During setting of the upper packing assembly 13, the upper threads 80 on the lower end portion 79 of the mandrel 11 (FIG. 2C) will have been ratched downwardly into engagement with the upper threads 77 on the clutch sleeve 75 so that the clutch sleeve is coupled against downward movement relative to the mandrel 11. Now as the mandrel 11 is elevated, since the lower expander member 46 cannot be moved upwardly, the abutment 63 will be advanced toward the upper abutment 64 to compress and expand the lower packing rings 61 and 62 into sealing engagement with the casing C. The lower clutch nut 67 will trap the upward displacement on the compression sleeve 60 to lock the packing in set condition as heretofore described. During the initial downward movement on the mandrel 11, the enlarged section 71 of the mandrel was placed in engagement with the sealing element 70 to close off the bypass passage 72 to fluid flow in an upward direction. To complete the setting of the packer 10 the mandrel 11 is again lowered in order to ratchet the upper threads 80 on the mandrel to a further extend downwardly within the clutch sleeve 75 so that all of the packer parts are in completely set condition.

At this point, it should be noted that the upper seal ring 28 (FIG. 2A) does not fully occupy the recess 29, but rather has an upper surface 85 that is inclined. Accordingly, the seal ring 28 will hold fluid pressure only in a downward direction, whereas a greater fluid pressure below the packing rings 24 and 25 is permitted to leak past the seal ring. In the same manner, the lower seal 70 (FIG. 2C) is provided with an inclined surface 86 so that it will hold fluid pressure only in an upward direction. Thus arranged, the seal rings 28 and 70 function as one way check valves to enable fluid pressure in the annulus space between the upper and lower packing assemblies 13 and 15 to equalize to any lower fluid pressure that may exist above or below the packer 10.

In the vent that a greater fluid pressure exists in the annulus above the packer 10 than below it, the seal ring 28 will prevent fluid leakage between the compression sleeve 20 and the mandrel 11, and the packing rings 24 and 25 will pack off the annulus between the compression sleeve and the internal wall of the casing C. Should volume in the packing elements or rings 24 and 25 be lost due to extrusion or the like, the greater fluid pressure will act downwardly on a transverse area equal to the difference in areas defined by the outer diameter of the compression sleeve 20, the seal diameter of the upper seal ring 28. The resulting force will maintain the upper abutment 22 in driving contact with the upper packer ring 24 so that the packing rings remain packed off tightly against the casing C. Any downward movement of the compression sleeve 20 due to fluid pressure will be trapped by the clutch nut 36 as previously described.

In the event of a greater fluid pressure in the well bore below the packer 10 than in the annulus above it, the lower packing assembly 15 operates like the upper packing assembly 13 to retain the lower packing rings 61 and 62 tightly packed of against the casing. The lesser fluid pressure will always be reflected in the annular spaces located between the upper packing assembly 13 and the lower packing assembly 15 due to the one way sealing action of the seal rings 28 (FIG. 2A) and 70 (FIG. 2C) as previously described. Accordingly, the upper seal ring 28 will leak in an upward direction and enable the fluid pressure between the packing assemblies to equalize to the lower fluid pressure above the packer 10. In like manner, the lower seal ring 70 will leak in a downward direction to enable fluid pressures between the packing assemblies to equalize to a lower pressure that exists in the well bore below the packer 10.

In order to retrieve the packer 10 from the casing C or to move it to another setting point, the mandrel 11 is rotated to the right. Due to the left hand formation on the upper threads 80 and 77 on both the mandrel 11 and the clutch sleeve 75, right hand rotation will cause the mandrel 11 to feed upwardly relative to the outer parts of the packer 10. Upward movement will remove the locking portions 42 and 69 of the mandrel 11 from behind the head portions 34 and 66 on the upper compression sleeve 20 and the lower compression sleeve 60 respectively, and enable the head portions and spring fingers 33 and 65 to resile inwardly, thereby releasing the respective locking functions of the clutch nuts 36 and 67. The resilence of the packing rings 24, 25, 61 and 62 will cause the heads 34 (FIG. 2A) and 66 (FIG. 2C) to release from the clutch nuts 36 and 67 and as the mandrel 11 is moved upwardly and the compressive force is removed from the packing assemblies 13 and 15. As the upper mandrel threads 80 are completely released from the upper threads 77 on the clutch sleeve 75 the parts of the packer 10 are enabled to return to their normally retracted positions as depicted in FIG. 1. Eventually the lower threads 81 on the mandrel 11 will ratchet back into engagement with the lower threads 78 on the clutch sleeve 75 so that the parts of the packer 10 are returned to their retracted positions for longitudinal movement in the casing C.

While a particular embodiment of the present invention has been shown and described, it is apparent that changes and modifications may be made without departing from the concepts of the invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications falling within the true spirit and scope of the present invention.

Claims

What is claimed is:

1. A well packer apparatus comprising: a body member adapted for connection to a pipe string; a sleeve member sealingly slidable on said body member, said sleeve member having a first abutment means thereon; packing means carried by said sleeve member and having one end engaged by said first abutment means, said packing means being adapted to be compressed and expanded into sealing contact with a well conduit wall, said sleeve member having a transverse cross-sectional area subject to the difference in the pressure of fluids above and below said packing means; a second abutment means adapted to be anchored in a well bore and engaging the other end of said packing means so that movement of said first abutment means toward said second abutment means will effect compression and expansion of said packing means; and releasable clutch means on said sleeve member and said second abutment means for trapping the extent of movement of said first abutment means toward said second abutment means.

2. The well packer apparatus of claim 1 further including means on said body member for locking said clutch means to prevent movement of said first abutment means away from said second abutment means.

3. The well packer apparatus of claim 2 wherein said clutch means includes laterally flexible elements on said sleeve member and a laterally expansible and contractible element on said second abutment means, said elements having coengageable latch means for preventing relative longitudinal movement between said sleeve member and said second abutment means.

4. The well packer apparatus of claim 3 wherein said locking means includes a locking surface on said body member for preventing lateral inward flexure of said elements.

5. The well packer apparatus of claim 1 wherein said clutch means includes laterally flexible fingers on said sleeve member and an expansible and contractible nut member on said second abutment means, said fingers having head portions provided with tooth surfaces cooperable with companion tooth surfaces on said nut member to permit movement of said first abutment means toward said second abutment means but to prevent movement of said first abutment means away from said second abutment means.

6. The well packer apparatus of claim 5 further including means on said body member for locking said toothed surfaces in engagement with one another.

7. The well packer apparatus of claim 6 wherein said locking means includes an enlarged section of said body member providing a locking surface adapted to be disposed behind said head portions to prevent inward flexure of said fingers.

8. A well packer apparatus comprising: a body member adapted for connection to a pipe string, said body member carrying an upper packing assembly, a lower packing assembly and a slip and expander means intermediate said packing assemblies for anchoring against movement in a well casing; each of said packing assemblies including a sleeve member sealingly slidable on said body member and having a first abutment thereon, each packing assembly further including a second abutment adapted to be fixed in a well bore by said slip and expander means; packing means mounted on each sleeve member and adapted to be compressed and expanded into sealing contact with a well conduit wall by movement of said abutments relatively toward each other; and releasable clutch means for trapping the extent of movement of said abutments toward each other to lock compression loading in each respective packing means and thereby retain a leak proof seal with respect to a well conduit wall.

9. The well packer apparatus of claim 8 further including means between each of said sleeve members and body member for equalizing the pressure of fluids in the well bore between said packing assemblies with a lesser pressure of fluids in the well bore above or below said well packer apparatus.

10. The well packer apparatus of claim 9 wherein said equalizing means comprises seal elements, each seal element having a seal portion for blocking fluid flow in one direction and a relief portion to enable deformation of said seal portion and leakage of fluid in the opposite direction.

11. The well packer apparatus of claim 8 further including means on said body member for locking each of said clutch means to prevent movement of either of said first abutments opposite to their respective directions of displacement due to compression loading.

12. The well packer apparatus of claim 11 wherein each of said clutch means includes laterally flexible elements on said sleeve members and laterally expansible and contractible elements on a corresponding second abutment, said corresponding elements having coengageable latch means for preventing relative longitudinal movement therebetween.

13. The well packer apparatus of claim 12 wherein each of said locking means includes a locking surface on said body member for preventing lateral inward flexure of said first mentioned elements.

14. The well packer apparatus of claim 8 wherein each of said clutch means includes laterally flexible fingers on a corresponding sleeve member and expansible and contractible nut members on each of said second abutments, said fingers having head portions provided with tooth surfaces cooperable with companion tooth surfaces on a corresponding nut member to permit movement of said first abutments toward said second abutments but to prevent movement of said first abutments away from said second abutments.

15. The well packer apparatus of claim 14 further including means on said body member for locking said tooth surfaces in engagement with one another.

16. The well packer apparatus of claim 15 wherein said locking means include enlarged sections of said body member providing locking surfaces adapted to be disposed behind said head portions to prevent inward flexure of said fingers.