US3422901A - Retrievable well packer - Google Patents

Description

Jan. 21, 1969. M. B. com 3,422,901

RETRIEVABLE WELL PACKER I N VEN TOR. M1? 77/V COA/P40 VMM@ Jan. 21, 1969 l L a, CQNRAD 3,422,901

RETR I EVABLE WELL PACKER wwf/UL Jan. 21, 1.969 M. B. CONRAD y RETRIEVABLE WELL PACKER Sheet 3 of 3 Filed March 30, 1967 INVENTOR. M477N COA/164@ United States Patent O 3,422,901 RETRIEVABLE WELL PACKER Martin E. Conrad, Carpinteria, Calif., assignor to Baker Oil Tools, Inc., City of Commerce, Calif., a corporation of California Filed Mar. 30, 1967, Ser. No. 627,190 U.S. Cl. 166-134 17 Claims Int. Cl. E21b 23/06 ABSTRACT OF THE DISCLOSURE A well packer that includes a mandrel having portions of larger and smaller diameter, a resilient annular sealing member around the larger portion of the mandrel, and slip assemblies having shoulders engaging the ends of the sealing member. The shoulders are movable toward each other in response to an upward force on the mandrel for compressing the sealing member and expanding it outwardly. A force-responsive element disconnects the mandrel from the slips upon imposing a predetermined downward load, after which the mandrel may be moved to position the smaller diameter portion within the annular member, relieving the end load on the shoulders of the slip assemblies. The mandrel then, when pulled upwardly further, releases the slips and removes the tool from the well as a unit.

BACKGROUND OF THE INVENTION Field of the invention This invention pertains to well bore tools, such as well packers or the like of the retrievable type.

Particularly, well packers of the double holding type are very difficult to release after they have been set in the well casing and subjected to high differential pressures tending to securely engage lthe upwardly and downwardly holding slips with the well casing while the packing element is disposed in sealing engagement with the well casing. More specifically, such packers may be diriicult to release due to the fact that the deformed elastomeric packing element may -be subjected to severe compressive forces which react on the anchor slip mechanisms tending to maintain the latter in forceful anchoring engagement with the well casing, even though the differential pressure across the packer assembly may have been relieved.

Summary of the invention The tool of `this invention includes a mandrel having a portion circumscribed by at least one resilient annular packing ring and an adjacent portion of smaller diameter. A slip assembly is located at either end of the packing ring, presenting shoulders that can be advanced toward each other to exp-and the packing ring outwardly against the wall of the well casing to accomplish the seal. This is achieved by the application of an upward force on the mandrel which is resisted by drag blocks, enabling the slips to become set and the tool to become packed off. For releasing the tool, a downward force is applied to shear orf the tooth of a ratcheting ring that engages the cone of one of the slip assemblies and resists downward movement of the mandrel relative to the slips and the sealing element. Once this has been sheared, tension screws are pulled apart so that the mandrel can move relative to the slips, permitting a split ring to expand outwardly into an annular space around the mandrel. Previously, this ring was received in recesses both in the mandrel and in the lower slip assembly, connecting these two elements so that an upward force on the mandrel could be translated into the slips to pack off the tool. With the split ring out of the recess and in the annular space, however, the mandrel then can move relative to the slips and the sealing member, 'bringing the portion of smaller diameter adjacent the sealing element and relieving the compression upon it. This takes olf the end load from the cones of the slip assemblies, so that further axial movement of the mandrel causes cooperating shoulders to release the slips and free the tool from restraint within the well. Release is complete so that the tool cornes out of the well readily.

An object of this invention is to provide an improved well packer.

Another object of this invention is to provide a well packer released by longitudinal loading and without rotation.

A further object of this invention is to provide a well packer that is reliable and 0f relatively simple and low cost construction.

An additional object of this invention is to provide a well packer that is run into the well, packed olf, released and removed without difficulty or complications.

Yet another object of this invention is to provide a well packer which will remain in the packed-off condition indenitely until release takes place.

These and other objects will become apparent from the following detailed description taken in connection with the accompanying drawing.

Brief description of the drawing FIGURES la and lb together constitute a longitudinal sectional view of the well packer of this invention as it is being run into a well;

FIGURE 2 is an enlarged fragmentary sectional view of the portion of the packer that includes the ring which is sheared subsequently when the tool is to be released;

FIGURE 3 is an enlarged fragmentary sectional view illustrating the connection between the lower slip assem- -bly and the mandrel through the split annular ring;

FIGURES 4a and 4b together constitute a longitudinal sectional view of the tool in the well casing, similar to FIGURES la and lb, but with the tool in the packed-oli condition;

FIGURES 5a and 5b together constitute a longitudinal sectional view of the tool following release as it is being removed from the well; and

FIGURE 6 is an enlarged fragmentary sectional view illustrating a modification in which the ring that is sheared to begin the release cycle is provided with an outwardly projecting tooth.

Description of the preferred embodiment As illustrated in FIGURES la and lb, the retrievable packer 10 of this invention is being lowered by a head assembly 11 at the end of a tubing string 12 into a well casing 13. As illustrated, the packer 10 is to be set subsequently by manipulation of the tubing, although optionally it can be adapted for wire line setting. The upper portion of the assembly 11 includes an internally threaded tubular member 14 that is connected to the tubing string 12. The opposite end of the member 14 threads into a short sleeve 15 that circumscribes a ring 16 to 'which it is connected by a shear screw 17. The ring 16 has an upper surface bearing against the lower end shoulder of an annular member 18 that is threaded onto the mandrel 19 of the packer assembly 10. The interior of the tubular member 14 also receives a member 20 provided with seals 21 and 22, which prevent uid leakage along the surface of the mandrel 19 or around the exterior of the element 20. The upper end of the mandrel 19 is provided with teeth 24 which mate with corresponding teeth 25 on the lower end of an annular member 26 which is attached to and integral with the member 14.

Beneath the head assembly 11, the mandrel 19 has an externally threaded portion 27 which is received within a threaded ring 28. The latter member is positioned at the upper end of a tubular housing 29 to which it is secured by set screws 30. The tubular housing 29 comprises a portion of a drag means 31, which provides a resistance to movement of the tool in the well casing and may be similar to that illustrated in Patent 3,135,329. Briefly, the tubular housing 29 is provided with a plurality of longitudinally extending slots 32 spaced circumferentially around the tubular housing 29.

Within the slots 32 are drag blocks 33, which are biased outwardly in the radial direction by compression springs 34 and 35. The springs cause the drag blocks to bear against the inner surface of the casing 13 to provide a yieldable resistance to the movement of the tool longitudinally within the casing. Flanges 36 and 37 overlap the drag blocks at the slots 32, so that the drag blocks are retained when the tool is removed from the well casing.

Below the friction means 31 is a slip assembly 38, which also may be similar to the corresponding item illustrated in Patent 3,135,329. The individual slip elements 39 are retained by a ring 40 which, in turn, is coupled to the tubular housing 29 by a split ring 41. The latter element has an annular recess in its inner surface that receives flanges 42 and 43 of the tubular housing 29 and the ring 40, respectively, in effecting the connection between the members 29 and 40. Unlike the design shown in Patent 3,135,329, there is a. ring 44 circumscribing the mandrel 19 at the juncture of the members 29 and 40. The ring 44 bears against the surface of the mandrel, While there is a clearance inwardly of the members 29 and 40.

The slip elements 39 are T-shaped, each having a base portion 45 received in an upwardly and outwardly inclined slot 46 in the ring 40. At the opposite end, the slips t include wickers 47 facing the wall of the casing, beneath which are downwardly sloping surfaces 48 adjacent similarly inclined surfaces 49 forming the walls of longitudinally extending recesses 50 in the upper end of a tubular member 51. Along the sides of the slips 39 are ribs 52 that t within complementary slots 53 in the member 51 at the recesses 50.

The lower end of the tubular member 51 terminates in a shoulder 54 circumscribing an annular ridge 55 on the mandrel 19. Beneath the end shoulder 54 of the member 51 is a series of three resilient elastomeric packing elements 56, 57 and 58. Metal rings 59 and 60 separate the adjacent packing rings, being interposed between the ends of packing members 56 and 57 and between the ends of members 57 and 58. The lower end of the bottom packing member 58 engages the upper radial shoulder 61 of an annular member 62 that is threaded onto the upper end of a tubular element 63 which forms a portion of a lower slip assembly 64. The latter assembly corersponds generally to the upper slip assembly 38, including a plurality of individual slip elements 65 having wickers 66 on their outer surfaces, and the slip elements 65 being received at their upper ends in recesses 67 in the member 63. This places the inclined surfaces 68 of the slip members 65 adjacent the complementarily inclined surface 69 of the tubular member 63. The base portions 70 of the slip members fit within inclined slots 71 in a sleeve member 72.

The interior surface of the tubular member 63 includes an inclined shoulder 73 which, in the position of FIG- URE lb is adjacent a similar shoulder 74 formed on the periphery of the mandrel 19. Beneath the shoulder 74, the intermediate mandrel portion 75 is of reduced outside diameter.

Above the shoulder 73, the mandrel includes teeth 76 on its periphery. As best seen in FIGURE 2, each tooth 76 includes a radial surface 77 which intersects a surface 78 that is inclined downwardly and outwardly from the root to the crest of the tooth. A split ring 79 is partially received within a recess 80 in the inner surface of the member 62 at the end of the tubular element 63. The

ring 79 includes an inwardly projecting tooth element 81 which is complementary to the teeth 76 of the mandrel 19. Thus, the tooth element 81 includes a lower surface 82, which inclines downwardly and outwardly from its crest to its root. Above the inclined surface 82 is a radial surface 83. The ring 79 is of resilient material and has a free position with a smaller diameter than the outside of the mandrel at the teeth 76, so that the ring 79 is biased inwardly against the mandrel and away from the bottom of the recess 80.

The lower end of the sleeve member 72 is threaded into a short annular member 85 the lower end of which, in turn, is received in the upper end of a collar 86. Screws 87 and 88 extend longitudinally through the collar 86 and are threaded into the end of the member 85, connecting the members 85 and 86.

The inner lower corner of the sleeve member 72 is recessed to provide a radial shoulder 89 and a circumferential surface 90 adjacent a split ring 91. The inner circumference of the split ring 91 is received in an annular recess 92 on the outer circuference of the mandrel section 75. The mandrel includes a bottom section 93tl1at threads onto the intermediate section 75, providing with its upper end the lower radial wall of the annular recess 92. The split ring 91 is resilient and has a larger free diameter than that illustrated in FIGURE 1b, so that the circumferential surface 90 of sleeve member 72 at its lower inner corner holds the split ring 91 inwardly within the recess 92, when the packer is conditioned for running and when the packer is set in the casing 13.

Beyond the `bottom end of the member 72 and between the inner and outer surfaces of the member 85 and the lower mandrel section 93 is an annular space 94, access to which is provided by threaded openings 95 in the wall yof the annular member 85. Screws are inserted in the openings 95 to force the split annular ring inwardly into the recess 92 during assembly of the tool, after which those screws are removed as sleeve member 72 holds the ring 91 in the recess.

The bottom end of the collar 86 includes an inturned ange 96, which is positioned immediately below an annular ridge 97 projecting outwardly from the outer circumferential surface of the lower mandrel section 93.

A ring 98 is threaded onto the bottom end of the lower mandrel section 93, providing a radial shoulder 99 at its upper end projecting outwardly from the mandrel section 93.

The tool of this invention is lowered into the well casing 13 with the parts in the relationship illustrated in FIGURES la and lb. While the drag blocks 33 engage the wall of the casing, the remaining components of the device are retracted and clear the surface of the casing. As the tool is being run in, the screws 87 and 88 hold the tubular member 72 in the relative longitudinal position shown, preventing any upward movement of the member 72 relative to the mandrel because of their connection to the collar 86 and the interengagement of the flange 96 and the ridge 97 on the mandrel. This assures that the member 72 does not shift away from the split ring 91 and maintains the split ring confined in the annular recess 92.

After the desired level within the well has been reached, the device is packed off to the position of FIGURES 4a and 4b. To accomplish this, rst the mandrel 19 is rotated to disconnect the threaded portion 27 from the ring 28 at the upper end of the tubular housing 29. Rotation is accomplished through the interengagement of the teeth 24 of the mandrel and the teeth 25 of the head assembly 11. The friction means 31 through the drag `blocks 33, hold the ring 28 against turning as the mandrel is rotated, enabling the threads 27 on the mandrel 19 and the cornplemental threads in the ring 28 to be disconnected.

Next, the mandrel 19 is subjected to an upward pull. This upward force is transmitted through the split ring 91 and the shoulder 89 at the inner lower corner of the sleeve 72 which it engages, through the bottom slip assembly 64, the packing elements 56, 57 and 58, to the upper slip assembly 38. In view of the resistance to movement afforded lby the drag `blocks 33, the upper slip elements 39 are set as they slide outwardly along the inclined surfaces 49 to bring the wickers 47 into contact with the wall of the casing 13. Additionally, the packing elements 56, 57 and 58 become compressed between the shoulders 54 and 61 of the members 51 and 62, respectively. With the inner circumferential surfaces of the members 56, 57 and 58 being confined by the periphery of the mandrel 19, the packing elements are squeezed outwardly to contact the wall of the casing and form a tight seal therewith. The lower slip assembly 64 also `becomes set as the slips 65 are brought outwardly so that their wickers 66 engage the wall of the casing 13. Setting of the tool, therefore, requires merely the rotation of the mandrel, followed by an upward pull, which causes it to become securely packed off, in which condition it will remain for an indefinite period of time.

As the tool is packed off, the annular mandrel 19 moves upwardly relative to the member 62 and the tubular member 63. When this occurs, the tooth 81 of the ring 79 slips over the teeth 76 of the mandrel 19, ending up at some location intermediate the ends of the toothed section -of the mandrel. This movement is possible because the ring 79 is split, and hence can be expanded as the inclined surfaces 78 of the teeth 76, by engaging the inclined surface 82 of the tooth 81, cam the ring 79 outwardly. The recess 80 is made sufiiciently deep to allow the ring 79 to 'be expanded an amount such that it can slip from one tooth 76 to the next. A ratcheting effect is accomplished in this manner.

As the mandrel is pulled upwardly by the head assembly 11 in setting the tool, the screw 17 shears, breaking the connection between the member and the ring 16. Therefore, the member 14, which is connected to the tubing string 12, is permitted a limited amount of upward movement relative to the mandrel 19 until the ange 100 of the sleeve 15 engages the lower end of the ring 16. This disengages the teeth 24 of the mandrel from the teeth 25 of the ring 26, so that the head assembly 11 thereafter can be rotated relative to the tool without also turning the mandrel.

To release the packer, the first step is to impose a downwardly directed force on the mandrel 19. This force is resisted by the split ring 79, in view of the engagement between the radial surface 83 of the tooth 81 and the corresponding radial surface 77 of one of the teeth 76 of the mandrel. In releasing the tool, the downward force is made great enough to shear off the tooth 81 of the ring 79, so that thereafter the mandrel encounters no resistance from the ring 79.

The downward force on the mandrel also is resisted by the screws 87 and 88. This comes about because the ridge 97 of the lower mandrel section 93 engages the inturned ange 96 of the collar 86 through which the screws 87 and 88 extend. Consequently, the force on the mandrel is transferred into the collar 86 and to the screws 87 and 88. The ends of the screws 87 and 88 are held fast by their threaded connection to the memlber 85 which connects to the lower slip assembly.

After the tooth 81 of the ring 79 has been sheared, the screws 87 and 88 absorb the entire downward thrust in tension. This causes the screws 87 and 88 to elongate and ybecome pulled apart.

The mandrel then, through the shoulder 101 at the upper end of the recess 92, moves the split ring 91 downwardly relative to the member 72 until the split ring 91 reaches the space 94. When this occurs, being free from the restriction imposed by the circumferential surface 90 of the member 72, the ring springs outwardly into the space 94. This frees the split ring 91 from the upper end of the lower mandrel section 93 and the shoulder 89 of the member 72. Consequently, the connection between the mandrel and the lower slip assembly is broken.

The mandrel then may move upwardly relative to the slip assemblies and the packing elements.

After imposing the downward force to shear the tooth 81 of the ring 79 and sever the screws v87 and 88, as described above, and releasing the split ring 91, an upward force then is applied to the mandrel 19. This pulls the mandrel up relative to the slip assemblies and the packing elements 56, 57 and 58, which remain stationary, locked in place against an upward force by the upper slip assembly 38. As the upward movement continues, the shoulder 74 of the mandrel 19 passes through the three packing elements S6, 57 and 58. As the shoulder moves through the packing members, they are brought into adjacency lwith the intermediate portion 75 of the mandrel, which is of reduced diameter. As a result, the inner surfaces of the packing rings no longer are held outwardly as far as before by the periphery of the mandrel. The compression on the packing elements 56, 57 and 58 is relieved in this manner, with attendant reduction in the end loading on the shoulders 54 and 61 of the slip assemblies. Also, the outward force of the packing elements against the casing is reduced.

Further upward movement of the mandrel causes the annular ridge 55 of the mandrel to be brought into engagement with the ring 44 that circumscribes the mandrel between the tubular housing 29 and the ring 40. With the members 29 and 40 being connected -by the member 41, the engagement between the ridge 55 and the ring 44 causes an upward pull on the member 40 of the upper slip assembly 38, which, in turn, pulls upwardly on the slip members 39. This releases the upper slips, The previous relief of the end load on the slip assembly resulting from the reduction of compression of the packing elements makes this release of the slips possible. The lower slips l65 then also are released as the mandrel is moved upwardly. The tool thus is free to be brought out of the well casing.

As the mandrel continues to move upwardly, the ridge 97 on the lower mandrel section 93 is brought into engagement with an inner shoulder 102 near the upper end of the tubular member 72. This causes the lower slip assembly to travel with the mandrel as the tool is withdrawn from the well. Also, the collar 86 is picked up by the shoulder 99 of the ring 98 at the lower end of the mandrel. Thus, the entire tool is pulled from the well as a unit, with the parts in the relationship shown in FIG- URES 5a and 5b. Other than the engagement of the drag blocks 33 with the well casing 13, the elements of the tool are completely retracted for removal and offer no resistance to the movement of the tool.

Consequently, tool removal becomes a simple operation, requiring only the appilcation first of a downward force followed by an upward pull on the mandrel. No rotation is required. The shifting of the mandrel to bring the portion of smaller diameter within the packing elements relieves the compression and reduces the end loading on the slip assemblies, so that further movement of the mandrel can release the slips.

The ring 79 is constructed to withstand some downward loading, so that the packer will not be released prematurely. Thus, relatively small downward loads can be absorbed lwithout shearing the tooth 81 to begin the release cycle. It is a simple matter to apply an adequate downward load on the tool, however, to shear the tooth 81 and effect the release at the appropriate time.

It is obvious that the components of the packer of this invention may have some modification within the scope of the present invention. For example, the ratcheting ring may be constructed with its tooth facing outwardly, as seen in FIGURE 6, rather than with a tooth on the inside, as described above. In the design of FIGURE 6, the ring 103 has a tooth 104 on its periphery adjacent complementary teeth 105 on an annular member 106. The latter element corresponds to the member 63 described above, and provides the cone for the lower slips, The ring 103 is split, as was the ring 79, and is slid along the teeth 105 when the tool is set. In that position, it resists downward movement of the mandrel until the tooth 104 is sheared off. Generally, it is preferred to use the ring in the form of the member 79 because of ease of assembly of the tool.

The foregoing detailed description is to be clearly understood as given by way of illustration and example only, the spirit and scope of this invention being limited solely by the appended claims.

I claim:

1. A device for use in a well comprising a body adapted to be introduced into a well, said body having a first portion of a first transverse dimension and a second portion of a second and smaller transverse dimension, a compressible member, releasable means for normally holding said body and said compressible member with said compressible member disposed about said first portion of said body, means for compressing said compressible member while inwardly confining portions of said compressible member by said first portion of said body, and means for releasing said releasable means for allowing movement of said body relative to said compressible member to bring said second portion of said body into a position of adjacency with said compressible member for removing `from said compressible `member the inward confinement of said first portion so as to reduce the compression thereof.

2. A device for being positioned in a well comprising a body adapted to be introduced into a well, said body having a first portion of a rst transverse dimension and a second portion of a second and smaller transverse dimension, at least one resilient compressible member adjacent said first portion of said body, abutment means adjacent either end of said compressible member, means for advancing said abutment means relatively toward each other for compressing said compressible member between said abutment means while said compressible member is inwardly confined by said first portion of said body for thereby expanding said compressible member outwardly responsive to movement of said body in one longitudinal direction in said well, and releasable means for allowing movement of said body further in said one longitudinal direction relative to said compressible member to bring said second portion of said body into a position of adjacency with said compressible member for removing from said compressible member the inward confinement of said first portion so as to reduce the compression thereof.

3. A device for being positioned in a well comprising a mandrel adapted to be introduced into a well easing, said mandrel having a first portion of a first exterior diameter and a second portion of a second and smaller exterior diameter, at least one resilient annular member circumscribing said mandrel at said first portion thereof, a shoulder means at either end of said resilient annular member, means for moving said shoulder means relatively toward each other to a position of relative adjacency in response to longitudinal movement of said body in one longitudinal direction in said well for thereby compressing said resilient annular member between said shoulder means while confining the inner part of said resilient lannular member by said first portion of said mandrel thereby to expand said resilient annular member outwardly, means for holding said shoulder means in said position of relative adjacency for .thereby maintaining said resilient annular member so compressed, and means for allowing movement of said mandrel relative to said resilient annular member while said shoulder means are so held for shifting said second portion of said mandrel to a position within said resilient annular member for thereby reducing the inward confinement of said resilient annular member and the compression thereof.

4. A well packer comprising a mandrel adapted to be inserted into a well casing, said mandrel having a first portion of a first outer diameter and a second portion of a second and smaller outer diameter, at least one resilient annular member circumscribing said first portion of said mandrel, a first shoulder means adjacent one end of said annular member, a second shoulder means adjacent the opposite end of said annular member, actuating means including means connecting said mandrel to said shoulder means for causing said shoulder means to move relatively toward each other to a position of relative adjacency upon axial movement of said mandrel in one direction for thereby compressing said annular member therebetween while confining the inner part of said annular member by said `first portion of said mandrel so that the outer part of said annular member is forced outwardly against the wall of said well casing, holding means for holding said shoulder means in said position of relative adjacency and for engaging the wall of a well casing for holding said annular member against longitudinal movement in said well casing, means responsive to axial movement of said mandrel in the other direction while said shoulder means are in said position of relative adjacency for disconnecting said mandrel from said shoulder means for allowing said mandrel to move further axially in said one direction relative to said annular member for bringing said second portion of said mandrel to a position within said annular member and relieving the inward confinement of said annular member and the compression thereof, and means for releasing said holding means for allowing removal of said well packer from the well casing.

5. A well packer comprising an elongated mandrel adapted to be inserted into a well casing, said mandrel having a first portion of a first outer diameter and a second portion of a second and smaller outer diameter, at least one resilient annular member circumscribing said first portion of said mandrel, slip means, said slip means including a shoulder adjacent either end of said annular member, friction means for engaging the wall of a well casing and providing a limited resistance to movement relative thereto, means connecting said mandrel to said slip means for cooperating with said friction means to move said shoulder means relatively toward other each to a position of relative adjacency upon movement of said mandrel in one longitudinal direction, said slip means including means movable outwardly upon such movement of said mandrel for gripping the wall of a well casing to hold said resilient annular member against movement in either direction in said well casing, said annular member being compressed between said shoulder means when said shoulder means are so moved to said position of relative adjacency and confined inwardly by said first portion of said mandrel so that the periphery of said annular member is expanded outwardly for engagement with the Wall of a well casing, said connecting means including means for disconnecting said mandrel from said slip means upon the application of a predetermined force and movement of said mandrel in response thereto in the opposite direction, said mandrel being subsequently movable in said one direction when so disconnected for bringing said second portion thereof into said annular member for relieving the inward confinement and the compression of said annular member, and means responsive to said subsequent movement of said mandrel in said one direction for retracting said slip means for releasing said well casing and allowing removal of said well packer from a well casing.

6. A well packer comprising a mandrel adapted to be inserted into a well casing, said mandrel having a first portion of a first outer diameter and a second portion of a second and smaller outer diameter, at least one resilient annular member circumscribing said first portion of said mandrel, friction means carried by said ymandrel for providing a limited resistance to movement in said well casing, a first slip means carried by said friction means and providing a first shoulder adjacent one end of said annular member, a second slip means providing a second shoulder adjacent the opposite end of said annular member, means connecting said mandrel to one of said slip means for cooperating with said friction means to move said shoulders relatively toward each other to a position of relative adjacency upon upward movement of said mandrel, thereby compressing said annular member between said shoulders while confining the inner surface of said annular member by the periphery of said first portion of said mandrel and expanding the outer surface of said resilient annular member outwardly into engagement with the adjacent wall of said well casing, and for causing said slip means to expand outwardly for engagement with the wall of said well casing to hold said shoulders in said position of relative adjacency, means responsive to a subsequent downward force on said mandrel of a predetermined magnitude for disconnecting said mandrel from said one slip means for allowing said mandrel thereafter to move relative to said annular member to bring said second portion of said mandrel within said annular member to reduce the inward confinement of said annular member and the compression thereof, and means for disengaging said slip means from the Wall of said well casing upon further movement of said mandrel for thereby releasing said well packer and permitting removal thereof from said well casing.

7. A device as recited in claim 6 in which said means responsive to a downward force on said mandrel includes a circumferentially expansible and contractible ring,

said ring having a tooth thereon, said mandrel and one of said slip Imeans cooperating to define a recess receiving base portions of said ring, and teeth engageable with said tooth of said ring,

said teeth having inclined surfaces for allowing said ring to move relative thereto upon relative upward movement of said mandrel, and abutment surfaces for abutting said tooth of said ring for resisting relative downward movement of said mandrel,

whereby said tooth of said ring is caused to shear off upon the imposition on said mandrel of said downward force of predetermined magnitude. 8. A device as recited in claim 6 in which said means connecting said mandrel to said one slip means includes a split annular member of resilient mtaerial, an annular recess means in said mandrel receiving said split annular member,

said split annular member having a free diameter greater than the diameter of said annular recess, said slip means having a surface holding said split annular member in said recess,

said surface of said slip means being moved away from said split annular member upon imposing on said mandrel said downward force of predetermined magnitude,

thereby to allow said split annular member to assume its free diameter and leave said annular recess for disconnecting said mandrel from said one slip means. 9. A device for being positioned in a well comprising a body adapted to be introduced into a well bore, said body having a first portion of a first transverse dimension and a second portion of a second and smaller transverse dimension, at least one resilient compressible member circumscribing said first portion of said body, shoulder `means adjacent either end of said compressible member, and means for advancing said shoulder means relatively toward each other in response to movement of said body for compressing said compressible member between said shoulder means while said compressible member is inwardly confined by said first portion of said body and thereby expanding said compressible member outwardly,

said 'means for advancing said shoulder means including an abutment on said body, an abutment on said shoulder means, an element interposed between said abutments for transmitting force from said body to said shoulder means,

said element having a normal position of disengagement from said abutments, and means for holding said element in engagement with said abutments,

said holding means including means responsive to a predetermined force on said body for `releasing said element to said element to disengage said abutments, said body being movable reltaive to said shoulder means and said compressible member when said abutments are so disengaged for bringing said second portion of said body into a position of adjacency with said compressible member for removing from said compressible member the inward confinement of said first portion of said body so as to lreduce the compression of said compressible member.

10. A device as recited in claim 9 in which said body includes an annular recess for providing said abutment on said body,

said shoulder means including Ian annular member having a recess defining said abutment of said shoulder means, and a circumferential surface, said element comprising a split ring received in said recess and having a free diameter greater than said recess,

whereby when said annular member is in its free position it disengages said abutments,

said circumferential surface engaging the periphery of said split ring for maintaining said split ring in said recess, and said means responsive to force on said body cornprises a member interconnecting said body and said shoulder means and severable upon being subjected to said predetermined force.

11. A device as recited in claim 10 in which said member connecting said body and said shoulder means cornprises a tension member extending therebetween.

12. A well packer comprising a mandrel adapted to be inserted into a well casing,

said mandrel having a first portion of a first diameter,

and a second portion of a second and smaller diameter below said first portion,

at least one resilient annular member circumscribing said first portion of said mandrel,

a first slip means above said annular member,

a second slip means ybelow said annular member,

said first slip means defining a first shoulder adjacent one end of said annular member,

said second slip means defining a second shoulder adjacent the opposite end of said annular member,

friction means on said mandrel above said first slip means for providing a limited resistance to axial movemnt in a well casing,

each of said slip means including a member defining a sloping surface and an element movable along said sloping surface to an outer position for engaging a well casing,

a shear member interposed between said member of said second slip means and said mandrel,

said member of said second slip means and said mandrel including means engaging said shear member for allowing said mandrel to move longitudinally upwardly relative to said member of said second slip means while resisting through said shear member longitudinal downward movement of said mandrel following said longitudinal upward movement thereof, said shear member being frangible upon the exertion of a predetermined downward force on said mandrel for allowing such downward movement of said mandrel following said upward movement thereof, a split annular member,

said mandrel including an annular recess receiving inner portions of said split annular member, said recess having an abutment at either end thereof for engaging said split annular member for moving said split annular member with said mandrel, said split annular member being resilient and having a free diameter larger than the periphery of said mandrel, said second slip means including a surface confining said split annular member to retain said inner portion thereof in said annular recess, said second slip means including an abutment engageable by outer Iportions of said split annular member for transmitting upward longitudinal force from said mandrel to said second slip means,

whereby upon the exertion of an upward force on said mandrel said friction means resists upward movement of said rst slip means and said mandrel applies a force through said split annular member and said abutments to advance said slip 4means relatively toward each other so that said resilient annular member is compressed between said shoulder means while being confined by the periphery of said first portion of said mandrel so that said resilient annular member is expanded outwardly for sealing engagement with the wall of a well casing, and upon application of a subsequent downward force of said predetermined magnitude said shear member is fractured for allowing said mandrel to move downwardly relative to said slip means and said resilient annular member,

said split annular member being disengageable from said surface and said abutment of said second slip means upon such subsequent downt ward movement of said mandrel,

whereby upon subsequent upward movement of said mandrel said second portion of said lmandrel is moved to a position within said resilient annular member for relieving the compression thereof and the end loading on said shoulders of said slip means, said mandrel including means for releasing said slip means upon further upward movement of saidy mandrel for thereby releasing said well packer from a wall casing and permitting removal thereof. 13. A device as recited in claim 12 in which said shear member comprises a split ring, said member of said second slip means having a recess therein receiving said split ring, said ring having a tooth protruding therefrom,

inwardly Said mandrel having teeth on the periphery thereof for meshing engagement with said tooth of said ring, said teeth of said mandrel and said tooth of said ring having inclined surfaces for allowing said ring to slip over said teeth progressively upon relative upward movement of said mandrel, said teeth of said mandrel and said tooth of said ring having radially directed surfaces interengageable for resisting relative downward movement of said mandrel,

whereby to effect such downward movement said tooth of said ring must be sheared.

14. A device as recited in claim 12 in which said shear member comprises a split ring.

said mandrel having a recess receiving said split ring,

said ring having a tooth protruding outwardly therefrom,

said member of said second slip means having teeth thereon for meshing engagement with said tooth of said ring,

Isaid teeth of said member of said second slip means and said tooth of said ring having inclined surfaces for allowing said ring to slip over said teeth progressively upon relative upward movement of said mandrel,

said teeth of said member of said second slip means and said tooth of said ring having radially directed surfaces interengageable for resisting relative downward movement of said mandrel,

whereby to effect such downward movement said tooth of said ring mu-st be sheared.

15. A well packer for packing olf a well casing comprising: an elongated tubular mandrel having axially spaced `body portions of large and small diameter; annular packing means disposed about said large diameter body portion; upwardly holding anchor means and downwardly holding anchor means at opposite ends of said packing means; said. anchor means providing opposing shoulders engaged with said packing means; friction drag means for effecting actuation of said anchor means and movement of said shoulders one toward the other to expand said packing means outwardly responsive to longitudinal movement of said mandrel relative to said friction drag means in one direction; first releasable connector means for connecting said mandrel to said friction drag means to prevent such movement of said mandrel; second releasable connector means for allowing limited movement of said mandrel in said one direction following release of said first releasable connector means, said second releasable connector means ybeing releasable upon movement of said member longitudinally in the other direction to allow further movement of said mandrel in said one direction to dispose said small mandrel body portion in said packing means to relieve outward expansion thereof.

16. A well packer for packing off a well casing comprising: an elongated tubular mandrel having axially spaced body portions of large and small diameter; annular packing means disposed about said large diameter body portion; upwardly holding anchor means and downwardly holding anchor means at opposite ends of said packing means; said anchor means providing opposing shoulders engaged with said packing means; friction drag means -for effecting actuation of said anchor means and movement of said shoulder one toward the other to expand said packing means outwardly responsive to longitudinal movement of said mandrel relative to said friction drag means in one direction; rst releasable connector means yfor connecting said mandrel to said friction drag means to prevent such movement of said mandrel; and second releasable connector means between said mandrel and said anchor means releasable for allowing longitudinal movement of 'said mandrel for disposing said small 13 14 i mandrel portion in said packing means to relieve out- References Cited ward expansion thereof. UNITED STATES PATENTS 17. A well packer as defined in claim 16, wherein said 2 652 894 9/1953 Brown et al 166 134 rst releasable connector means comprises a threaded 5 2:944604 7 /1960 Baker 'l 166 134 connection between said friction drag means and Said h mandrel; and second releasable connector means includes JAMES A' LEPPINK: Pnmay Examme means releasably responsive to longitudinal movement of U.S CL X'R.

said mandrel in the other direction. 166-139

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