US2988148A - Subsurface well bore packing element - Google Patents

Description

June 13, 1961 M. B. CONRAD ETAL 2,988,148

sUBsuREACE WELL BORE PACKING ELEMENT Original Filed May 14. 1956 2'United States Patent O i 11 claims. (cl. 16e- 187) The present invention relates to packing elements, and more particularly to packing elements adapted to be lowered in a well bore to effect a seal against a confining well casing, well liner, tubing string, or similar tubular conduit string positioned in the well bore.

This application is a continuation of application Serial No. 584,649, led May 14, 1956, for Subsurface Well Bore Packing Element, abandoned December 25, 1958.

Chip type of packing elements are run in a well bore to effect a seal against a well casing, or the like, disposed therein. Such packing elements slide along the wall of the well casing in sealing contact therewith while being y lowered in the well bore, and need not be expanded by application of a mechanical or other external force into engagement with the casing wall, Fluid pressure applied within the cup type of packing element maintains its sealing engagement with the casing wall and actually increases its sealing effectiveness, which is a pronounced advantage over other types of packing elements.

Although an initial fluid seal against the casing is secured without external assistance, in the case of a cup type packing element, it possesses certain disadvantages and defects. In lowering a tool embodying a cup packing element in a well casing, with the elements slidably sealing against the wall of the well casing, fluid circulation around the exterior of the element cannot be obtained, and it is necessary for such uid to be by-passed through the interior of the tool, where circulation areas are usually limited. In addition, the extensive sliding action of the cup packing element, and particularly its lip portion, along the wall of the casing, during lowering of the tool in the latter, oftentimes causes pronounced wear on the packing element to the point of leaking, even when subjected to low pressures, which results in failure of the element.

As distinguished from a cup type of packing element, an initially retracted packing element does not slide along the walls of the well casing while being lowered therein, avoiding wear on the packing element. Moreover, since such initially retracted packing element is spaced substantially from the casing wall while being run in the latter, ample space is provided therearound through which the well bore iluid can by-pass. However, when the location is reached at which the retracted packing element is to effect a seal against the well casing, it must be expanded, which requires the application of some external mechanical force thereon, such as a compressive force which will foreshorten the packing element and expand it into rm sealing engagement with the casing wall. To insure the maintenance of a proper seal, especially one capable of withstanding high pressures, the compressive force must be relatively hig An object of the present invention is to provide a subsurface well bore tool embodying an initially retracted packing element that can be expanded against the well casing with the application of a relatively low external force thereon, and which functions as a cup type of packing when expanded, in order that an increase of fluid pressure thereon tends to increase its sealing effectiveness against the casing. When the packing element is relieved of the uid pressure and external expanding force, it returns inherently to its retracted position.

2,988,148 Patented .lune 13, 1961 Another object of the invention is to provide a subsurface well bore tool embodying an initially retracted packing element that is expandible against the well casing by the application of an external force thereon, and which functions as opposed packings of the cup type to seal against the casing and prevent uid ow thereby in both directions under both low and high pressure conditions. Again, the relieving of the fluid pressure and external expanding force permits the packing element to return automatically to its retracted position.

A further object of the invention is to provide a subsurface well bore tool embodying an initially retracted packing element of the sleeve type, which is expandible into contact with a well casing by foreshortening the packing element, the element automatically forming one or more cup type portions when engaged with the casing. More specifically, the element automatically forms opposed cup type portions when engaged with the casing to seal thereagainst, resisting uid pressures acting on the packing element in both longitudinal directions.

An additional object of the invention is to provide a subsurface well bore tool embodying an initially retracted packing element that can be foreshortened and expanded against the well casing upon application of a lesser force thereto than was heretofore necessary, which enables the packing element to be made of harder rubber or rubberlike material, the expanded packing element still being able to withstand high pressure differentials without leakage.

Yet another object of the invention is to provide initially retracted packing elements having the aforenoted characteristics and advantages.

Still a further object of the invention is to provide packing elements that combine the advantages of cup type packings and initially retracted packings.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

FIGURE 1 is a combined longitudinal section and side-elevational view of a well packer disposed in a well casing, with certain parts in their retracted positions;

' FIGURE 2 is a view similar to FIGURE l disclosing the packing structure expanded against the well casing;

FIGURE 3 is a cross-section taken along the line 33 on FIGURE 2;

FIGURE 4 is a fragmentary longitudinal section through a well bore tool embodying a known cup type of packing element.

The apparatus disclosed in the drawings includes portions of a Well packer of the retrievable type, which is adapted to be run in a well casing, sealed-off therewithin, and then released from the casing to be shifted to a different location therewithin, or to be withdrawn cornpletely from the well casing. The invention will be described herein by 1way of example only in connection with the specific well packer of the kind disclosed in the application of Martin B. Conrad, Serial No. 536,415, filed September Z6, 1955, for Retrievable Double Holding Subsurface Well Tool. It is to be understood, however, that the invention is applicable to other specific types of well tools, and to packing structures generally.

As illustrated specifically in the above-identified patent application, a tubular packer body 10 is provided, which is suitably connected to a tubular string (not shown), such as drill pipe or tubing extending to the top of a Well casing A, in which the apparatus is movable longitudinally and in which it is used. This body is adapted to be releasably anchored to the well casing, as by providing a plurality of circumferentially spaced slips 11 around the body having wickers or teeth 12 engageable with the wall of the well casing. The slips are urged outwardly into engagement with the casing by a tapered or frusto-conical expander 13 slidably mounted on the body 10` of the tool, which has a tapered expander surface 114 adapted to coact with companion inner tapered surfaces 15 on the slips. Relative upward movement of t-he expander 13 within the slips 11 shifts the latter outwardly into anchoring engagement with the wall of the well casing, after which a normally retracted packing structure 16 is expanded outwardly into sealing engagement with the wall of the well casing A.

The packing structure includes a compression or booster sleeve 17 slidably mounted upon the body of the tool and threadedly secured to the lower portion of the expander 13. This expander actually forms an upper abutment for a pliant, elastic packing sleeve 1S, which may be made of rubber or rubber-like material, in conjunction with an upper gauge ring portion 19 of the expander, which is threadedly secured to the main portion of the expander. The packing sleeve 18 is an inherently contractible member disposed around the compression sleeve 17, ywith the upper end of the sleeve being located within a recess or pocket 211 dened between the lower part 21 of the upper gauge ring 19 and the compression sleeve.

The lower portion of the non-metallic rubber-like packing sleeve 1S is disposed within a lower pocket 22 delined between the upper portion 25 of a lower gauge ring 24 and the compression sleeve 17, the lower gauge ring being threadedly secured to a thrust tube or sleeve Z5, the lower end of which is, in turn, threadedly secured to a guide 26 threadedly attached to the main body 10 o-f the well packer.

The lower gauge ring 24 is slidable along the booster sleeve 17 toward and from the upper gauge ring 19 and expander 13, downward movement of the lower gauge ring along the booster sleeve being limited by its engagement with an upper shoulder 27 provided by the upper end of an outwardly directed ange 28 extending from the lower portion of the booster sleeve.

To prevent leakage of uid through the working clearance space between the body 10 and the compression sleeve 17 and expander 13, a suitable non-metallic seal ring Z9, such as a rubber or rubber-like O ring, is disposed in an internal groove 30 in the expander for slidable sealing against the periphery of the body. Similarly, to prevent fluid leakage between the lower gauge ring or abutment 24 and the booster sleeve 17, a nonmetallic seal ring 31, such as a rubber or rubber-like O ring, is disposed in an internal groove 32 in the lower gauge ring for slidable sealing with the periphery of the booster sleeve.

In the use of the apparatus so far described, it is lowered in the well casing A to the location at which it is to be anchored in packed-oli condition therewithin. When this position is reached, the slips 11 are prevented from moving upwardly by suitable means (not shown), which form no part of the present invention and which are specifically disclosed and described in the aboveidentified patent application, whereupon the body 10' is `moved upwardly by the tubing string (not shown), the upward movement being transmitted through the guide member 26, thrust sleeve 2S, and lower gauge ring 24 to the packing sleeve 18. The packing sleeve transmits the longitudinal force of the body 10 to the upper expander member 13, carrying the latter upwardly within the slips -11 and expanding the latter radially outwardly into firm anchoring engagement with the wall of the well casing.

Following the anchoring of the slips against the well casing, the expander 13 is prevented by the slips from moving upwardly to any further extent. Accordingly, a continuation of the upward movement and force of the body 10 will then shift the lower gauge ring 214, which may be considered as constituting a lower abutment member, towards the upper expander 13 and upper gauge ring portion 19, which may be considered as constituting an upper abutment member. This movement of the lower abutment device toward the upper abutment device foreshortens and compresses the packing sleeve 18 in a longitudinal direction causing it to expand outwardly into sealing engagement with the wall of the well casing A.

The present invention provides a particular type of packing element or sleeve 18, which does not rely upon it being foreshortened and compressed between the up per and lower abutments 13, 24 to hold it in sealing engagement with the wall of the well casing. Such sealing engagement is maintained by the lluid pressure acting on the packing element, either from a location therebelow or from a location thereabove. In addition, a much lessened force is required to expand the inherently retractible packing element 18 into initial sealing engagement with the wall of the well casing.

In general, the present invention combines the advantageous features of an initially retracted packing sleeve and a cup-type packing, while minimizing, if not completely eliminating, the disadvantages associated with the two types of packing structures when considered along.

In FIG. 4, a known cup type of packing element 40 is disclosed. This packing element is mounted upon a tubular body 41 which is adapted to be connected to a tubular running-in string (not shown) extending to the top of the Well casing A in which the apparatus is located. The packing element includes a base portion 42 resting against a thimble 43` threadedly, or otherwise suitably, secured on the tubular body, the packing element being held against the thimble by a clamp nut v44 threaded on the body and engaging the base portion 42 of the packing element.

yFrom its base portion 42, the packing cup extends laterally outward and longitudinally to its sleeve portion 45, which is adapted to seal against the wall of the well casing. The free end of the sleeve portion merges into a lip portion 46 that makes an initial sealing contact with the well casing. The sleeve portion 45 and lip portion 46 of the packing cup are spaced a substantial distance from the clamp nut 44 to permit fluid pressure to act on the interior 47 of the packing cup and urge it outwardly against the wall of the well casing.

In lowering the device shown in FIG. 4 in the well casing, its lip portion 46 and its sleeve portion 45 remain in slidable sealing engagement with the wall of @the Well casing, the cup type of packing maintaining a constant seal with the well casing A and preventing fluid from passing upwardly beyond the packing element. Instead, all of the well bore fluid being displaced must pass upwardly through the tubular body 41. Accordingly, the apparatus can only be lowered inthe well casing in a relatively slow manner. In addition to the foregoing disadvantage, the lip portion 46 and also part of the sleeve portion 45 are constantly sliding against the wall of the well casing, which might result in damage to these parts, due to wear or cutting, tothe point at which leakage around the packing element 46 can occur.

Assuming no essential damage to the parts, when the location in the well casing is reached at which pressure is to be applied to the fluid below the tool, it is unnecessary to effect any expansion of the packing element, since it is already in sealing engagement with the wall of the well casing A. Any pressure below the packing cup will act on its interior 47 and expand it more firmly and to a greater extent against the wall of the well casing, to eiect a seal therewith.

assen/is The packing element 18 disclosed in FIGS. 1 to 3 of the drawings is constructed and arranged to provide a retracted structure, but one which will function as a cup type of packing when expanded against the wall of the well casing. To accomplish this purpose, the packing sleeve 18 has an upper base portion 50 received within the upper pocket 20, the exterior 51 of the packing sleeve being substantially cylindrical when it is in retracted position, the sleeve extending outwardly no further than the peripheries of the upper and lower gauge rings 19, 24, which have substantial clearance with the wall of the well casing. However, the inner surface S2 of the upper portion of the packing sleeve is generally frusto-conical in shape, tapering in a downward and outward direction from the booster sleeve 17 and upper base portion 50 toward the mid-portion 53- of the packing element or sleeve, the thickness of the packing element immediately above the mid-portion S3 being substantially less than the thickness of the packing element across the base portion 50. This relatively narrow section 54 of packing element may be considered to be a lip portion, the part of the packing element between the base portion 50 and the lip portion 54 constituting an upper sleeve portion 55 of the packing element.

The packing sleeve also has a lower base portion 50a received within the pocket 22 provided by the lower gauge ring 24 and booster sleeve 17. This lower base portion 50a also merges into a lower sleeve portion 55a that has the cylindrical periphery 51, when the packing element is in retracted position, which conforms to the periphery of the upper sleeve portion 515, and essentially the same frusto-conical inner surface 52a, which is arranged opposite to the upper frusto-conical surface 52 by tapering in an upward and outward direction toward a thinner lip portion 54a. The upper lip portion 54 and the lower lip portion 54a merge into the intermediate portion 53 which extends inwardly from the cylindrical periphery 51 of the packing element toward the booster sleeve 17. In eifect, the intermediate portion 53` is constituted as an inwardly directed circumferential rib which extends inwardly to the booster sleeve. The rib S3 is integral with the upper and lower lip portions 54, 54a. As a matter of fact, the entire packing element 18 is a unitary or integral rubber or rubber-like structure.

It is to be noted that the upper frusto-conical inner surface 52 provides an internal space 6i) with the compression sleeve 17, and that a lower space 60a is also dened between the lower frusto-conical surface 52a and the booster sleeve. It is desired that fluid under pressure be permitted to pass into such spaces 60, 60a, and for that reason the rib 53 has circumferentially spaced radial holes 61 therein extending from the outer periphery of the sleeve into longitudinal slots or grooves 62 formed along the entire thickness of the rib. It is evident that the holes 61 and grooves 62 provide communication between the upper and lower spaces 60, 60a in the packing element and its exterior.

The thickened mid-section or rib 53 of the packing element will resist and prevent the outer surface 63 of the packing element in alignment with the rib from sealing against the wall of the well casing, when the abutments 13, 24 are relatively moved toward each other to foreshorten the packing element 18 and expand it into sealing engagement with the wall of the well casing. When the lower abutment 24 is moved toward the upper abutment 13, the sleeve 18 is foreshortened and is expanded laterally in an outward direction until the upper sleeve portion 55 and the lower sleeve portion 55a come into sealing contact with the wall of the well casing A, which also will cause the upper and lower lip portions 54, 54a to seal against the wall of the well casing. However, the outer surface 63 of the packing in transverse alignment with its thickened medial portion 53 does not contact the wall of the well casing, there being a peripheral groove 64 formed in the packing sleeve between the 6 upper and lower lip portions 54, 54a, as disclosed in FIG. 2.

When there is tluid under pressure below the expanded packing element 18, such fluid under pressure will force itself past the lower cup-forming portion of the packing sleeve, moving past its lower sleeve portion 55a and lower lip portion 54a into the peripheral groove 64, and then passing through the radial holes 61 into the slots or grooves 62, from where it will tiow into the space 60 within the upper sleeve portion. The pressure acts on such sleeve portion 54, 55, 50 to urge and hold it in an outward direction in firm sealing engagement with the wall of the well casing. It is evident that with pressure imposed on the packing element 18 from a location therebelow, its upper portion is sealed olic firmly against the wall of the well casing in much the same manner as the cup type of packing disclosed in FIG. 4.

If the packing element 18 has been initially expanded in the well casing (as in FIG. 2), and if pressure is applied to the fluid in the annulus between the body 10 of the tool and the well casing A above the packing element, such duid under pressure will by-pass around the exterior of its upper portion 55, 54 into the peripheral groove 64, the fluid pressure being transmitted through the radial holes 61 and slots 62 to the interior 60a of the lower portion of the packing element. 'I'he pressure acts in an outward direction on the packing element to force the lower sleeve and lip portions 55a, 54a more firmly against the wall of the well casing, much in the same manner as the fluid pressure acting on the cup type of packing as disclosed in FIG. S, if it were placed in an inverted position in the well casing.

Upon relieving the pressure dilerential acting on the packing element 18, and upon lowering the lower abutment 24 away from the upper abutment 13, the packing element will inherently retract to its initial position disclosed in FIG. l. Such retraction of the packing element coupled with lowering of the expander 13 with respect to the slips 11, will enable the slips to retract, as described in the above-identified patent application, and the tool to be shifted to another position in the well casing, or to be removed entirely therefrom.

If deemed necessary, a positive limit can be placed on the movement of the lower abutment device 24 toward the upper abutment device 13, 19 to foreshorten the packing sleeve 18 and expand it into initial contact with the wall of the well casing A. As specifically illustrated, a stop sleeve 70 may be disposed within the thrust sleeve 25 between the guide 26 and the ilange 28 of the compression sleeve 17, the upper end of this stop sleeve being spaced initially yfrom the lower end of the flange 28. When the body 10 is moved upwardly to expand the slips 11 and foreshorten the packing sleevel 18, the extent of movement of the lower abutment 24 toward the upper abutment 13 is limited by engagement of the upper end of the stop sleeve 70 with the lower end of the flange 28, as disclosed in FIG. 2. However, it is to be understood that the stop sleeve 70 need not be used, inasmuch as the packing structure functions properly in its absence. The stop sleeve 70 is used in a precautionary sense, to prevent an unlimited compressive force to be imposed on the packing sleeve 18 as the result of upward movement of the body 10 and the lower abutment 24 with respect to the upper abutment device and expander I3, 19.

Inasmuch as the packing element 18 has much thinner cross-sectional area than would be the case if its inner surfaces engaged the compression sleeve 17 along its entire length, the packing sleeve can be foreshortened and expanded outwardly against the well casing A with the application of a much lesser compressive force than was heretofore necessary. This factor permits the packing element to be made of a much harder rubber than if it were devoid of the frusto-conically shaped recesses 60, 60a therewithin, resulting in greater resistance to extrusion of the packing material into the clearance spaces around the upper and lower lgauge rings 19, 24, when the packing element is subjected to very high pressures or high temperatures, or combinations of the two. A high foreshortening or compressive force is not necessary to secure leak-proof engagement of the packing element 18 with the wall of the well casing under high pressure conditions, as well as under low pressure conditions, since the fluid pressure can act in both directions on the packing element, moving into its interior to more rmly seal it against the -well casing, in the manner of a cup type of packing structure.

Accordingly, it is evident that the present packing element embodies all of the advantages of a retractable packing element of the sleeve type, while avoiding its disadvantages. At the same time, it possesses the advantages of the cup type of packing element, whereby the pressure tends to more rmly seal it against the well casing, while avoiding the disadvantages of the cup type of packing element resulting from inability to by-pass fluid therearound, and the wearing and cutting action of the packing cup on the wall of the well casing while being moved longitudinally therewithin.

The inventors claim:

1. In a well tool to be lowered in a well conduit disposed in Va well bore: mounting means; upper and lower abutments mounted on said mounting means and movable longitudinally with respect to each other; an inherently retractable, normally retracted, pliant, elastic packing mounted on said mountingl means between and engageable with said abutments; said packing including upper and lower base portions engaging said upper and lower abutments, respectively, and upper and lower lip portions between and spaced longitudinally from said base portions, said base portions being substantially thicker in cross-section than said lip portions to provide upper and lower spaces within said packing, said packing having an intermediate portion between and integral with said lip portions, said intermediate portion having fluid passage means extending from its exterior between said lip portions to said spaces to permit iluid under pressure to pass into said spaces and act on said lip portions after said abutments have been moved toward each other to foreshorten said packing and expand said lip portions outwardly into engagement with the well conduit.

2. In a well tool to be lowered in a well conduit disposed in a well bore; mounting means; upper and lower abutments mounted on said mounting means and movable longitudinally with respect to each other; an inherently retractable, normally retracted, pliant, elastic packing mounted on said mounting means between and engageable with said abutments; said packing including upper and lower base portions engaging said upper and lower abutments, respectively, and upper and lower lip portions between and spaced longitudinally from said base portions, said base portions being substantially thicker in cross-section than said lip portions to provide upper and lower spaces within said packing, said packing having an intermediate portion between and integral with said lip portions extending inwardly of said lip portions between said spaces and having a substantially greater radial thickness than said lip portions, said intermediate portion having uid passage means extending from its exterior between said lip portions to said spaces to permit fluid under pressure to pass into said spaces and act on said lip portions after said abutments have been moved toward each other to foreshorten said packing and expand said lip portions outwardly into engagement with the well conduit.

3. In a well tool to be lowered in a well conduit disposed in a well bore: mounting means; upper and lower abutments mounted on said mounting means and movable longitudinally with respect to each other; an inherently retractable normally retracted, pliant, elastic packing mounted on said mounting means between and engageable with said abutments; said .packing including upper and lower base portions engaging said upper and lower abutments, respectively, and upper and lower lip portions between and spaced longitudinally from said base portions, the inner surface of said packing between each base portion and lip portion being inclined in a laterally outward direction from a base portion toward an associated lip portion to provide base portions substantially thicker in cross-section than said lip portions and an upper space within said packing between said upper base portion and upper lip portion and a lower space within said packing between said lower base portion and lower lip portion, said packing having an intermediate portion between and integral with said lip portions, said intermediate portion having iluid passage means extending from its exterior between said lip portions to said spaces to permit fluid under pressure to pass into said spaces and act on said llip portions after said abutments have been moved toward each other to foreshorten said packing and expand said lip portions outwardly into engagement with the well conduit, said packing being imperforate between said intermediate portion and each base portion.

4. ln a well tool to be lowered in a well conduit disposed in a well bore: mounting means', upper and lower abutments mounted on said mounting means and movable longitudinally with respect to each other; an inherently retractable, normally retracted. pliant, elastic packing mounted ou said mounting means between and engageable with said abutments; said packing including upper and lower base portions engaging said upper and lower abutments, respectively, and upper and lower lip portions between and spaced longitudinally from said base portions, the inner surface of said packing between each base portion and lip portion being inclined in a laterally outward direction from a base portion toward an associated lip portion to provide base portions substantially thicker in cross-section than said lip portions and an upper space within said packing between said upper base portion and upper lip portion and a lower space within said packing between said lower base portion and lower lip portion, said packing having an intermediate portion between and integral with said lip portions extending .inwardly of said lip portions between said spaces and having a substantially greater radial thickness than said lip portions, said intermediate portion having iluid passage means extending from its exterior between said lip portions to said spaces to permit fluid under pressure to pass into said spaces and act on said lip portions after said abutments have been moved toward each other to foreshorten said packing and expand said lip portions outwardly into engagement with the well conduit.

5. in a well tool to be lowered in a well conduit disposed in a wel-l bore: mounting means; upper and lower abutments mounted on said mounting means and movable longitudinally with respect to each other; an inherently retractable, normally retracted, pliant, elastic packing mounted on said mounting means between and engageable with said abutments; said packing having a substantially cylindrical periphery when retracted and including upper and lower base portions engaging said upper and lower abutments, respectively, and upper and lower lip portions between and spaced longitudinally from said base portions, the inner surface of said packing between each base portion and lip portion being inclined in a laterally outward direction from the base portion toward an associated lip portion to provide base portions substantially thicker .in cross-section than said lip portions and an upper space within said packing between said base portion and upper lip portion and a lower space within said packing between said lower base portion and lower lip portion, said packing having an intermediate portion between and integral with said `lip portions extending inwardly of said lip portions between said spaces substantially to said mounting means and having a substantially greater radial thickness than said lip portions, said intermediate portion forming a partition between said spaces and having passages establishing communication between said spaces, said intermediate portion having openings from its exterior between said'lip portions to said passages to permit fluid under pressure to pass from the exterior of said packing into said spaces and act on said lip portions after said abutments have been moved toward each other to foreshorten said packing and expand said ylip portions outwardly into engagement with the well conduit.

6. An inherently retractable normally retracted, pliant, elastic packing, including upper and lower base portions and upper and lower lip portions between and spaced longitudinally from said base portions and adapted to en- 'gage the inner wall of a surrounding well conduit when disposed therein, said base portions being substantially thicker in cross-section than said lip portions to provide upper and lower spaces within said packing, said packing having an intermediate portion between and integral with said lip portions, said intermediate portion having uid passage means extending from its exterior between said lip portions to said spaces to permit lluid under pressure to pass vfrom the exterior of said packing into said spaces and act on said lip portions to expand said lip portions outwardly; said packing being imperforate between said intermediate portion and each base portion; the base portions, lip portions and intermediate portions having a cylindrical external periphery.

7. A normally retracted, pliant, elastic packing, including upper and lower base portions and upper and lower lip portions between and spaced longitudinally `from said base portions, said base portions being substantially thicker in cross-section than said lip portions to provide upper and lower spaces within said packing, said packing having an intermediate portion between and integral with said lip portions extending inwardly of said lip portions between said spaces and having a substantially greater radial thickness than said lip portions, said intermediate portion having lluid passage means extending from its exterior between said lip portions to said spaces to permit iluid under pressure to pass into said spaces and act on said lip portions to expand said lip portions outwardly.

8. An inherently retractable normally retracted, pliant, elastic packing, including upper and lower base portions and upper and lower lip portions between and spaced longitudinally lfrom said base portions, the inner surface of said packing between each base portion and lip portion being inclined in a `laterally outward direction from a base portion toward an associated lip portion to provide a base portion substantially thicker in cross-section than said lip portion and an upper space within said packing between said upper base portion and upper lip portion and a lower space within said packing between said lower base portion and lower lip portion, said packing having an intermediate portion between and integral with said lip portions extending inwardly of said lip portions between said spaces and having a substantially `greater radial thickness than said lip portions, said intermediate portion having lluid passage means extending from its exterior to said spaces to permit fluid under pressure to pass into said spaces and act on said lip portions to expand the lip portions outwardly, said packing being imperforate between said intermediate and each base portion.

9. In a well tool to be lowered in a well conduit disposed in a well bore: upper and lower abutments movable longitudinally with respect to each other; an inherently retractable, normally retracted, pliant, elastic packing between and engageable with said abutments; said packing including upper and lower base portions engaging said upper and lower abutments, respectively, and upper and lower lip portions between and spaced longitudinally vfrom said base portions, said base portions being substantially thicker in cross-section than said lip portions to provide upper and lower spaces within said packing, said packing having an intermediate portion between and integral with said lip portions, said intermediate portion having uid passage means extending lfrom its exterior between said -lip portions to said spaces to permit fluid under pressure to pass into said spaces and act on said lip portions after said abutments have been moved toward each other to =foreshorten said packing and expand said lip portions outwardly into engagement with the well conduit.

10. In a well tool to be lowered in a well conduit disposed in a well bore: mounting means; upper and lower abutments mounted on said mounting means and movable longitudinally with respect to each other; an inherently retractable, normally retracted, pliant, elastic one-piece packing mounted on said mounting means between and engageable with said abutments; said packing including upper and lower base portions engaging said upper and lower abutments, respectively, a mid-portion, and an imperforate portion between said mid-portion and each base portion adapted to be expanded into sealing engagement with the well conduit upon movement of said abutments toward each other to move said base portions toward each other, said imperforate portions having spaces therewithin when mounted on said mounting means and when said packing is retracted, said mid-portion having fluid passage means extending from its exterior between said imperforate portions to said spaces to permit fluid under pressure to pass from the exterior of said packing into said spaces and act on said imperforate portions to `force said imperforato portions outwardly into engagement with the wel] conduit.

l1. In a well tool to be lowered in a well conduit disposed in a well bore: mounting means; upper and lower abutments mounted on said mounting means and movable longitudinally with respect to each other; an inherently retractable, normally retracted, pliant, elastic, one-piece packing mounted on said mounting means between and engageable with said abutments; said packing including upper and lower base portions engaging said upper and lower abutments, respectively, a mid-portion, and an imperforate portion between said midportion and each base portion adapted to be expanded into sealing engagement with the well conduit upon movement of said abutments toward each other to move said base portions toward each other, said midportion having fluid passage means extending from its exterior between said imperforate portions to the interiors of said imperforate portions to permit uid under pressure to pass from the exterior of said packing into the interiors of said imperforate portions to force said imperforate portions outwardly against the well conduit after said abutments have been moved toward each other to expand said imperforate portions outwardly into engagement with the well conduit, the internal diameter of said imperforate portions adjacent said mid-portion becoming larger as said abutments move toward each other.

References Cited in the tile of this patent UNITED STATES PATENTS 1,954,608 Winter Apr. 10, 1934 2,233,013 Humason et al. Feb. 25, 1941 2,751,235 Watts et al June 19, 1956 2,754,136 Phillips July 10, 1956

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