Retrievable Well Packer Apparatus

Abstract

In accordance with an illustrative embodiment of the present invention, a retrievable well packer apparatus includes a mandrel adapted for connection to a pipe string and carrying normally retracted slips that can be expanded into anchoring engagement with a well casing; a slip expander assembly on the mandrel below the slips and movable upwardly to expand the slips, and instrumentalities responsive to rotation of the mandrel by the pipe string for mechanically retracting the slips so that the slips cannot be accidentally set as the packer is being withdrawn from a well.

Parent Case Text

This application is a division of application Ser. No. 174,598, filed Aug. 25, 1971.

Description

This invention relates generally to well packers used in well bores, and more specifically to a well packer apparatus having new and improved means for preventing inadvertent setting of the packer as it is being retrieved to the surface after use.

Retrievable well packers commonly used for isolating well bore zones are generally lowered into the well bore on a running-in string of tubing or drill pipe. The packer has normally retracted slips which can be expanded into engagement with the well casing to anchor the tool at a preselected depth, as well as expansible packing that functions when expanded to seal off the annulus between the pipe string and the surrounding well conduit wall. When it is desired to retrieve the tool, both the slips and the packing can be retracted to positions enabling free running in the well bore.

It is highly undesirable for the slips or the packing to be accidentally operated while the tool is being moved through the well casing because this may result in damage to the tool or to the well casing or both. Particularly when retrieving the tool, such premature operation may also result in damage to the running-in string which is being pulled in tension at the surface. In any event, it is desirable to have provision for disarming the well packer so that it is not possible to accidentally operate the slips or the packing as the tool is being withdrawn from the well casing.

It is the principal object of the present invention to provide a new and improved retrievable well packer apparatus having means for positively preventing accidental operation of the tool as it is being retrieved to the surface.

This and other objects are attained in accordance with the concepts of the present invention through the provision of a well packer apparatus including a body member which is adapted to be secured to a running-in string and to be moved by the string in a well bore. The body member carries normally retracted slips which can be shifted outwardly into gripping contact with the well bore wall by upper and lower expanders which are movable longitudinally on the body member and relative to the slip means for shifting the slip means outwardly. The upper expander has a slidable spline connection to the slips. A lug sleeve threadedly secured to the mandrel has lugs that engage in a channel system formed in a control sleeve that is rigidly attached to the upper expander. The lug sleeve occupies one position on the mandrel during lowering and cooperates with the channel sytem to prevent setting until such time as the mandrel is appropriately manipulated to enable such setting. When it is desired to retrieve the well packer to the surface, with the slips set the mandrel can be rotated to cause the lug sleeve to feed upwardly to another position along the mandrel where outwardly directed shoulders thereon engage downwardly facing shoulders on the control sleeve. Further rotation causes the control sleeve and upper expander to move relatively upwardly along the mandrel to effect a mechanical retraction of the slips. When mechanical retraction has occurred, it is impossible to set the slips during upward movement so that the packer is completely disarmed and can be retrieved to the surface without accidental setting.

The present invention has other objects and advantages which will become more clearly apparent in connection with the following detailed description, taken in conjunction with the accompanying drawings in which:

FIGS. 1A and 1B are longitudinal sectional views, with portions in side elevation, of a well packer apparatus in accordance with this invention, FIG. 1B forming a lower continuation of FIG. 1A;

FIG. 2 is a cross-section on line 2--2 of FIG. 1A;

FIG. 3 is a schematic plan view of a channel configuration which is used to enable selective control over relative movement between parts;

FIG. 4 is a cross-section taken on line of FIG. 1A;

FIGS. 5A and 5B are longitudinal sectional views similar to FIGS. 1A and 1B, except with the parts of the packer shown in the relative positions they occupy when the packer is set in a well casing; and

FIG. 6 is a view similar to FIG. 1A except showing the slips in mechanically retracted condition.

Referring initially to FIGS. 1A and 1B, a well packer constructed in accordance with the principles of the present invention includes a tubular body member or mandrel 10 having a central passage 11 through which fluid can flow. A threaded collar 12 is provided at the upper end of the mandrel 10 and is adapted to couple the mandrel to the lower end of a running-in string of drill pipe or tubing 13. The mandrel 10 carries, from top to bottom, an upper drag assembly 15 that is coupled by a control sleeve 16 to an upper expander 17 which is movable relatively toward a lower expander 18 in order to expand normally retracted slips 19 into gripping contact with the well casing. The lower expander 18 is secured to the upper end of a lower drag assembly 20. A packing structure 21 has normally retracted elements 22 which when expanded seal off the cross-sectional area of the well bore between the mandrel 10 and the surrounding well casing wall. The slips 19 function to prevent longitudinal movement in either direction in the well casing, and the packing 21 prevents fluid flow in either longitudinal direction past its sealing point, so that the well zone below the packer is isolated from the well fluids thereabove.

The upper drag assembly 15 includes an annular cage member 24 having a gauge ring 25 secured by bolts or the like to its upper end. The cage member 24 has a plurality of radially directed, circumferentially spaced recesses 26, each of which receives a drag block 27. Each drag block 27 is urged outwardly by springs 28 having one end engaged within a recess 29 in the drag block and the other end pressing against the back surface of a respective recess. Stop shoulders 30 at each end of each drag block 27 limit outward movement thereof with respect to the cage member 24. The control sleeve 16 is threadedly secured to the lower end of the cage member 24 by an annular cap 32, and the lower end of the control sleeve 16 is threadedly secured to the upper expander 17. Formed through the wall of the control sleeve 16 at diagonally opposed positions is a channel configuration 33 shown in plan view in FIG. 3. Each channel has a transverse pocket 34 in its lower end that is connected by a short vertical portion 35 to an intermediate transverse portion 36. The portion 36 connects with a lengthy vertical portion 37. The generally stepped formation of the channel 33 provides two circumferentially spaced, axially facing shoulders 38 and 39. Each channel is adapted to receive a lug 40 formed by an outwardly directed shoulder on a lug sleeve 41 that is secured to the mandrel 10 by companion jack threads 42 and 43. As shown in FIG. 1A, the lug sleeve 41 normally occupies a lower position on the mandrel 10 and is made up tightly at the lower end portion of the threads 42. If desired, a compression coil spring 44 can be positioned between the lower end of the lug sleeve 41 and an outwardly directed shoulder 45 on the mandrel 10 in order to provide an axial load on the threads and thereby inhibit turning motion of the lug sleeve in response to low torque values. As shown in FIG. 2, two diametrically opposed lugs 40 are used although it will be appreciated that at least one is required and that more than two can be used. An outer barrier sleeve 46 can be positioned over the control sleeve 16 to prevent entry of particles of foreign matter that may be in the well fluids into the channels 33.

The slip assembly 19 is constituted by a plurality of circumferentially spaced individual slip elements 50 that are slidably coupled to the upper expander 17 and are mounted on the mandrel 10 for both longitudinal and lateral movement relative thereto. Each slip element 50 has peripheral wickers or teeth 51 which can bite into and grip the well casing in order to prevent movement in either direction therein, and also has upper and lower inclined surfaces 52 and 53 that are adpated to slidably engage companion inclined surfaces 54 and 55 on the upper and lower expanders 17 and 18, respectively. The slip elements 50 are mounted on a ring member 54 which is relatively slidable on the mandrel 10 below an annular stop shoulder 55. The ring member 54 can be an integral piece as shown in cross-section in FIG. 4, or can be formed in segments secured together by threaded studs. In any event, the ring member 54 has circumferentially spaced, radially directed recesses 56, each of which receives a central portion 57 of a respective slip element to provide a lateral guide therefor. As previously noted, the ring member 54 can slide downwardly relative to the mandrel 10, however upward movement is limited by the downwardly facing stop shoulder 55. Each slip element 50 is coupled to the upper expander 17 through a "dove tail" sliding connection that can be formed, for example, by keys 58 that are suitably secured to the upper expander 17 by studs, each key slidably fitting within a slot 59 in a respective one of the slip elements.

The lower drag assembly 20 is formed by a cage member 61 having a plurality of circumferentially disposed, radially extending recesses 62, each of which receives a drag block 63. The drag blocks are urged outwardly by coil springs 64 in the same manner as discussed above with respect to the upper drag assembly 15. Upward movement of the lower drag assembly 20 is limited by engagement between an upwardly facing shoulder 65 on a gauge ring 66 that is attached to the lower end of the cage member with a downwardly facing shoulder 67 formed by an annular enlargement on the mandrel 10.

The packing structure 21 includes an annular compression sleeve 70 which is threaded to the upper end of a bottom sub 71 which is in turn threadedly fixed to the lower end of the mandrel 10. The compression sleeve 70 carries the annular packing elements 22 constructed of a suitable elastomeric material. The lower packing ring is engaged by an upwardly facing lower abutment 72, whereas the upper ring is engaged by a downwardly facing upper abutment 73 which is slidable relatively along the compression sleeve 70. The upper abutment 73 is secured to a spline collar 74 having an inwardly thickened piston section 75 at its upper end which is sealed with respect to the mandrel 10 by an O-ring 76 or the like. The upper abutment 73 is also sealed with respect to the compression sleeve 70 through use of an O-ring 77. The inner wall surface of the compression sleeve 70 is spaced laterally with respect to the outer wall surface of the mandrel 10 to provide a fluid passage space 78 in communication with the well annulus below the packing by one or more ports 79 through the wall of the bottom sub 71. Thus, it will be appreciated that the pressure of fluids in the well bore below the packing is communicated by the ports 79 and the annular passage space 78 into a chamber 80 located interiorly of the spline collar 74 for purposes to be more fully described hereafter.

To prevent relative rotation between various parts of the packer, the upper end portion of the compression sleeve 70 has splines 82 which slidably engage in companion spline grooves 83 formed in the collar 74. Moreover, the upper end of the spline collar 74 is provided with a plurality of upwardly extending clutch pins 84 which engage like clutch pins 85 on the lower end of the gauge ring 66 when the parts are slidably disposed in engagement with each other. In engaged condition, the spline collar 74 cannot rotate with respect to the compression sleeve 70, nor can the lower drag assembly 20 rotate with respect to the spline collar 74.

In operation of the structure described above, it will be apparent that the assembled tool can be connected to the lower end of the pipe string 13 and pushed downwardly along the well casing to setting depth as additional joints of pipe string are added in end-to-end relation. The lower drag blocks 63 slide along the well casing, and the coengaged shoulders 65 and 67 on the mandrel 10 and the cage member 61 maintain the lower expander 18 in spaced relation to the slip elements 50. The upper drag blocks 27 are also sliding along the casing wall as the downward movement of the mandrel 10 is being transmitted thereto by engagement of the lugs 40 in the lower transverse pockets 34 of the channels 33. The slip elements 50 are being held in retracted positions by their sliding connection with the upper expander 17, together with engagement of the mounting ring 54 underneath the mandrel shoulder 55. Of course, the packing rings 22 are in their inherently retracted positions so that well fluids can pass between the rings in the well casing wall.

When it is desired to set the packer, the tool is halted and right-hand torque coupled with an upward strain applied to the pipe string 13 will position the lugs 40 within the elongated vertical portions 37 of the channels 33. As previously described, the drag blocks 27 function to prevent movement of the upper cage member 24, the control sleeve 16 and the upper expander 17. As the mandrel 10 is pulled upwardly, the packing structure 21 is elevated until the upper end of the spline collar 74 engages the lower end of the lower drag assembly 20, whereupon the packing structure and the lower expander 18 are jointly elevated toward the slip elements 50. This results in outward shifting of the slip elements 50 until their teeth 51 bite into and grip the well casing wall. Then the upper abutment 73 cannot move any further upwardly, whereby continued upward movement of the mandrel 10 telescopes the compression sleeve 70 upwardly within the upper abutment 73 and effects compression and lateral expansion of the packing rings 22 until their outer peripheries seal against the well casing wall. A predetermined amount of upward strain is maintained on the pipe string 13 at the earth's surface in order to maintain the tool in set condition within the casing 88 as shown in FIGS. 5A and 5B.

It should be specifically noted at this point that both of the expander members 17 and 18 are engaging the slip elements 50. This engaged relation will be maintained during the operation of the packer and until it is desired to release the tool for retrieval from the well. With the slip elements 50 set and the packing elements 22 expanded, the well bore below the tool can be pressurized as desired and the slip elements will prevent upward movement while the packing rings seal off the well annulus.

Should a sufficiently high pressure exist in the annulus above the packer, the packing structure 21 and the mandrel 10 can shift downwardly to a limited extent in the casing, such limited shifting being accompanied by stretching of the pipe string. However, the slip elements 50 remain in anchoring position and engaged by both expander members 17 and 18. Downward movement of the mandrel 10 will bring the lugs 40 against the shoulder surfaces 38, whereupon downward force on the mandrel 10 is imposed by the upper expander member 17 on the slip elements 50 which prevent further downward movement.

During this movement, the packing rings 22 merely slide downwardly along the casing 88 in expanded condition and remain sealed there against. This will occur because the lesser fluid pressure is acting on the lower face 89 of the piston section 75, while the greater pressure is acting on the upper face 90 thereof, the pressure differential acts on the piston area as downward force which is applied to the upper end of the packing rings 22 by the upper abutment 73. It will be remembered that upward strain is still being exerted on the pipe string 13 so that compressive force is being applied continuously to the lower end of the packing rings by the lower abutment 72. Accordingly, since compressive force is being exerted on both ends of the packing rings 22, they will not retract but will slide downwardly along the casing wall in expanded and sealing condition. The actual extent of downward shifting of the mandrel 10 and the packing assembly 21 is actually quite short compared to prior art devices of this general type, and may be only two or three inches.

If the pressure in the annulus above the packer is reduced, of course tension is still being held on the pipe string 13 and the string can contract and shift the packing assembly 21 and the mandrel 10 back upwardly to their original position with the upper and lower expanders 17 and 18 cooperating with the slip elements 50 to prevent further upward movement. In fact as long as tension is held on the pipe string 13, the packing structure 21 and the mandrel 10 can shift back and forth and it will be appreciated that the well bore remain sealed off to prevent any fluild movement past the tool. Moreover, the slip elements 50 remain anchored against the well casing wall and remain supported in anchored position by both the upper and lower expander members in simultaneous engagement therewith.

To unset the tool, pressures above and below the packer are equalized by operation of a suitable bypass valve (not shown) as upward strain on the pipe string 13 is relieved and as the mandrel 10 is moved downwardly by lowering the pipe string. This relieves the compressive force on the packing rings 22 so that they can inherently retract. The mandrel shoulder 67 will engage the cage shoulder 65 to push the lower expander 18 out from behind the slip elements 50. The lugs 40 are manipulated back into the lower transverse pockets 34 of the channels 33 to lock the upper expander 17 and the upper drag assembly 15 in their upper positions on the mandrel 10. Then an upward pull on the pipe string 13 will lift the upper expander 17 and cause the slips 50 to shift inwardly along the inclined surfaces of the expander to their retracted positions, whereupon the tool is free to be moved upwardly or downwardly within the casing 88.

As previously discussed, it is often times desirable to be able to "safety" the tool during removal thereof from the well. In other words, some operators may desire to completely disarm the tool immediately before retrieving it so that it is impossible to again set the slips and the packing in the well bore. One typical circumstance where this is particularly desirable is where the pipe string is "rotated" out of the hole. This is a procedure wherein the rotary table is used to break and back off pipe joints at the surface. Since the pipe is being rotated a substantial number of turns to the right (the direction that is normally used to condition the tool for setting) there would normally be a substantial risk to accidental setting. To prevent accidental setting in accordance with the principles of the present invention the structure previously described can be operated as follows. With the slips 50 set against the casing, a certain amount of weight, for example, 3,000-5,000 lbs., is slacked off onto the tool and the pipe string 13 is rotated to the right. With the tool set the lugs 40 are in the elongated portions 37 of the channels 33 shown in FIG. 3. Since the upper drag assembly 15 and the temporarily set condition of the slips 50 prevents rotation of the control sleeve 16 within the casing, rotation of the mandrel 10 will cause the lugs sleeve 41 to feed relatively upwardly along the mandrel 10 until the upper end surface 92 thereof comes against the downwardly facing shoulder 93 provided by the lower end of the cage member 24. When this has occurred, further rotation moves the lugs sleeve 41 upwardly and the mandrel 10 downwardly with corresponding movement of expander 17 and the slips 50. Since the slips can move upwardly only as limited by the shoulder 55, the "dove tail" connections 58, 59 effect a retraction of the slips as shown in FIG. 6. Actually the ships 50 are only set for a brief period of time for the purpose of preventing rotation of the upper expander 17 (since these two members have a spline connection), during which time a fairly high torque may be applied to the threaded connection 42, 43 between the lug sleeve 40 and the mandrel 10 to initiate upward feeding of the lug sleeve along the mandrel. Once the lug sleeve 40 starts its upward travel along the mandrel 10 however, the torque requirements are substantially lessened and the lug sleeve will feed freely along the mandrel until it comes into engagement with the shoulder 93 and causes the control sleeve 16 to move upwardly, drawing the upper expander 17 upwardly therewith. With the slips 50 mechanically retracted as discussed above, the tool cannot again be set on this trip into the well and the operator can pull the tool from the well as fast as he desires, and can rotate the pipe string 13 freely, without fear that the tool will, by some fortuitous circumstance, accidentally hang up and set in the casing.

In accordance with an additional safety feature, the thread 95 which joins the bottom sub 71 to the lower end of the mandrel 10 can be formed on a left-hand helix. It is thus possible to manipulate the packer as previously discussed in order to effect a setting thereof with the pipe string in tension, and then rotate the pipe string to the right. Since the compression sleeve 70 and the spline collar 74 are corotatively coupled, as are the spline collar 74 and the lower drag assembly 20, the slips 50 serve to frictionally hold the various members against rotation in the casing 88, and the right-hand rotation will effect unthreading of the thread 95 between the mandrel and the bottom sub. When such unthreading has occurred, it is possible to remove the mandrel 10 and all parts of the well packer above the lower expander member 18 from the well, leaving the balance of the parts behind for subsequent retrieval by a fishing operation with typical equipment.

It will be appreciated that the entire tool shown in the drawings could be inverted or turned upside down and then run into the well bore, in which case the tool could be set in compression by pipe weight if desired. Also, of course the rotational directions for setting and unsetting movement applied to the pipe string at the suface are a function of the configuration of the slot system, which can be arranged for right-hand or left-hand torque as desired.

It will now be apparent that the present invention provides a new and improved retrievable well packer apparatus which can be set in packed off condition against longitudinal movement in a well bore, and includes structure for disarming the slips so that it is impossible to set the slips and the packing during retrieval of the packer from the well bore. Since certain changes or modifications may be made by those skilled in the art without departing from the inventive concepts involved, it is the aim of the appended claims to cover all such changes or modifications falling within the true spirit and scope of the present invention.

Claims

I claim:

1. A well packer apparatus comprising: a body member adapted for connection to a pipe string; normally retracted slip means on said body member arranged to be expanded into anchoring engagement with a well casing wall; upper expander means above said slip means and lower expander means below said slip means, said lower expander means being movable upwardly by said body member relatively toward said upper expander means and said slip means to expand said slip means; normally retracted packing means on said body member below said lower expander means and adapted to be compressed and expanded by movement of said body member upwardly relative to said slip means and said lower expander means; means providing a slidable spline connection between said slip means and said upper expander means; means for limiting upward movement of said slip means along said body member; and safetying means responsive to rotation of said body member for causing said slidable spline connection to effect a mechanical retraction of said slip means and to a condition such that said lower expander cannot contact said slip means during upward movement in a well bore.

2. The well packer apparatus of claim 1 wherein said safetying means includes a sleeve structure connected to said upper expander means, drag means to inhibit rotation of said sleeve structure in a well bore, and control means having threaded connection to said body member and outwardly directed shoulder extending into a channel means in said sleeve structure, rotation of said body member relative to said control means and said sleeve structure causing said control means to feed upwardly along said body member until said outwardly directed shoulder contacts an inwardly directed shoulder on said sleeve structure, whereupon continued rotation will feed said sleeve structure upwardly relative to said slip means to cause said slidable spline connection to retract said slip means.

3. The well packer apparatus of claim 2 wherein said channel means extends generally longitudinally of said sleeve structure and includes a transverse portion adapted to receive said outwardly directed shoulder during downward movement of said apparatus in a well bore.