WO2011060495A1

WO2011060495A1 - Sliding seal for an inflatable packer

Info

Publication number: WO2011060495A1
Application number: PCT/AU2010/001550
Authority: WO
Inventors: Ian Gray
Original assignee: Ian Gray
Priority date: 2009-11-19
Filing date: 2010-11-19
Publication date: 2011-05-26
Also published as: WO2011060493A1; CA2781001A1; CN102741497A; ZA201203565B; AU2010321679A1

Abstract

A sliding seal for sealing an end of an inflatable elastomeric sleeve to a packer mandrel. A longitudinally compressible elastomeric seal sleeve operates in an annular slot of the mandrel. One annular end of the seal sleeve is bonded in the mandrel slot, and the of they annular end of the seal sleeve is bonded to an inner, annular surface of the inflatable sleeve. A retaining ring holds an end of the inflatable sleeve in compression to the end of the seal sleeve which is bonded to the inflatable sleeve. The end of the seal sleeve that is bonded to the inflatable sleeve is longitudinally compressible as the inflatable sleeve shortens during inflation.

Description

SLIDING SEAL FOR AN INFLATABLE PACKER

Related Patent Applications

This PCT application claims the benefit of two Australian provisional applications, both filed on 19 November 2009, and accorded respective application numbers 2009905659 and 2009905660. The disclosures of the Australian provisional patent applications are incorporated herein by reference.

Technical Field of the Invention

The invention relates to the field of manufacture of inflatable packers used to seal boreholes.

Background of the Invention

Many inflatable borehole packers are constructed with a mandrel and an inflatable sleeve or tube of a reinforced elastomer covering at least a portion of the mandrel. The reinforcement of the inflatable sleeve is a thin, flexible but relatively inextensible material. The reinforcement can be a cord bonded to the elastomeric material, strips of metal, or other suitable reinforcement materials. The reinforcement to the elastomeric sleeve carries tensile loads, thus requiring the top and bottom ends of the sleeve to be anchored to the mandrel. The anchoring of the inflatable sleeve can be achieved by fastening one end of the sleeve directly to the mandrel by bonding or mechanical fastening means. The other end of the elastomeric sleeve, is free to slide on the cylindrical body of the mandrel so as to permit changes in the axial length of the sleeve brought about by inflation of the sleeve. The movable end of the inflatable sleeve remains sealed to the mandrel. Normally, this is achieved by attaching the packer sleeve to a metal seal sleeve which slides on the mandrel. The metal seal sleeve is typically constructed with a sliding hydraulic seal which maintains a seal between the movable end of the elastomeric sleeve and the mandrel during inflation of the elastomeric sleeve. On inflation, the ends of the elastomeric sleeve are restrained against expansion on the mandrel by respective packer reteoning rings which experience a significant radial force by the expanding sleeve. This radial force must be accommodated, otherwise the retaining rings would be forced away from the expanding packer sleeve. This, is sometimes achieved by providing a sleeve which bears against the packer retaining ring, and is fixed at its other end by connection to the sliding end or to the mandrel. Summary of the Invention

According to the principles and concepts of the invention, disclosed is a sealing system employed in a packer to seal an inflatable elastomeric sleeve to a mandrel. The inflatable elastomeric sleeve assembly is constructed to transfer shear forces between the reinforcing material of the inflatable sleeve and the packer retaining ring, The seal of the inflatable sleeve eliminates the need for a metallic sliding seal and optionally allows the use of an inflation valve system. One or more of these features of the invention can be incorporated into the construction and assembly of the inflatable elastomeric sleeve on the mandrel. This construction significantly facilitates manufacturing of the inflatable sleeve assembly. Within this context, the inflatable sleeve of the packer is typically built of a series of layers of elastomer and reinforcing either bonded or not bonded as dictated by the desired design. The manufacturing process typically involves the use of natural or synthetic rubbers which are laid in layers and bond together_} unless various layers are separated by a release agent or barrier. Bonding between the elastomer and metal components is achieved by abrasive blasting of the metal followed by several preparatory coats of a primer and bonding agent to ensure that a high quality bond is formed.

The inflation valve of the packer is designed to permit inflation of the elastomeric sleeve by a higher pressure fluid inside the mandrel of the packer, as compared to the fluid pressure within packer sleeve. The inflation valve comprises a flap located on the outer surface of the packer mandrel. In practice, the flap is constructed using a cylindrical sleeve of a pliable material which surrounds a number of ports drilled through the mandrel. One annular edge of the pliable cylindrical sleeve is allowed to move radially outwardly from the mandrel to uncover the respective ports. The other annular edge of the cylindrical sleeve is fixed or bonded to the mandrel. When the movable annular edge of the pliable sleeve is relaxed, it contracts and covers the ports. Pressurised fluid used to inflate the elastomeric sleeve can thus flow through the mandrel ports in one direction and displace the flap outward to open the ports, but on cessation of flow of the pressurised fluid, the ports arc closed via the elasticity of the flap. The closed ports prevent the packer sleeve from deflating. The pliable cylindrical sleeve which forms the inflation , valve flap is preferably constructed as part of the inflatable sleeve to simplify the manufacturing process. The sealing system of the packer includes a bond between the inflatable sleeve and mandrel at one end of the mandrel. The inflatable sleeve is thus fixed to the mandrel at such end. At the other end of the packer mandrel there is a sliding seal attached to the · inflatable sleeve which allows it to move axially along the outer surface of the mandrel and accommodate shortening of the packer sleeve as it is inflated and expanded radially outwardly. In most packers, this is a sliding seal in. the form of an elastomeric hydraulic seal between the sleeve and the mandrel. Such a hydraulic seal includes a substantial housing to contain it. In the preferred embodiment of the invention, the sliding hydraulic seal is replaced by a sealing sleeve of elastomeric material that is bonded at one end of the inner surface of the inflatable elastomeric sleeve at a position below a packer retaining ring, and at the other end the sealing sleeve is fixed or bonded to the packer mandrel; Thus, as the packer sleeve is inflated and shortens in a longitudinal direction, the sealing sleeve compresses longitudinally yet maintains a seal to the mandrel. The sealing sleeve is pressed by inflation pressure against the mandrel and is prevented from being torn from the packer sleeve by the packer retaining ring which maintains an outer diameter and confines the seal. In one embodiment, the packer sealing sleeve is reinforced by an open mesh^' interlayer which is placed on a bias to the packer axis to permit longitudinal changes in length. The reinforcement in the seal sleeve guards against tears by preventing excessive local strain occurring as it shortens on inflation of the packer.

The bonded sleeve system is adapted for transferring loads between the packer sleeve reinforcement and the packer retaining ring, In a packer where the inflatable sleeve is reinforced with flexible cords or straps of low inextcnsibility, the reinforcing carries tensile loads. The tensile load is retained against expansion by the packer retaining ring. The loading force on the packer retaining ring as a result of the inflation of the elastomeric sleeve comprises two components. One component is perpendicular to the retaining ring, which component is restrained by the packer retaining ring operating as hoop reinforcement. There is also an axial component of the loading force which tends to slide the packer retaining ring axially away from the inflated portion of the packer sjeevc. The tendency for the retaining ring to move axially on the inflatable sleeve is reduced or eliminated by bonding a rigid or stiff sleeve around the outer surface of the elastomeric sleeve. A respective rigid sleeve is bonded to and covers each end of the inflatable sleeve. The annular edge of each rigid sleeve abuts against a respective retaining ring, whereupon shear forces are transferred from the packer retaining rings to the sleeve reinforcement via the rigid outer sleeve. Each rigid outer sleeve can advantageously be made in a longitudinally split form to permit easy assembly and bonding to the underlying elastomer layer of the inflatable sleeve. The split nature of the rigid outer sleeves alleviates the need to manufacture the bonded sleeve system with close tolerances. The fabrication of the inflatable sleeve system is therefore cost effective and can be rapidly incorporated into the packer construction. The overall design of a packer according to the invention can therefore utilise one or more of the features, each of which is easily incorporated into the manufacture of a packer by using layers of elastomers cured together. The features include the inflation valve, which can be advantageously used with external casing packers, the sleeve sealing system and the bonded sleeve construction to retain the packer retaining ring.

According to an embodiment of the invention, disclosed is a compressible sliding seal for a packer of the type having a cylindrical, mandrel covered with an inflatable elastomeric sleeve. The sliding seal includes an annular sea) sleeve surrounding the mandrel of the packer. The seal sleeve is longitudinally compressible between an annular first end and an annular second end thereof. The annular first end of said seal sleeve is fixed to the mandrel, and the annular second end of the seal sleeve is fixed to the inflatable sleeve. The inflatable sleeve thus maintains a seal to the mandrel diiring inflation of the inflatable sleeve. According to another embodiment of the invention, disclosed is a compressible sliding seal for a packer of the type having a cylindrical mandrel covered with an inflatable elastomeric sleeve, where the compressible sliding seal includes a rigid outer sleeve bonded around the end of the inflatable sleeve. An annular seal sleeve surrounds the mandrel of the packer, and is longitudinally compressible between an annular first end and an annular second end thereof. The annular first end of the seal sleeve is bonded to the mandrel, and the annular second end of the seal sleeve is bonded to the inflatable sleeve. A retaining ring is bonded around the end of the inflatable sleeve and is axially engageable with the rigid outer sleeve, The retaining ring is located around the bond between the second end of the seal sleeve and the inflatable sleeve, whereby the retaining ring is not displaced axially under load imposed on it by the tensile load in the rigid outer sleeve.

According to yet another embodiment of the invention, disclosed is a compressible sliding seal for a packer of the type having a cylindrical mandrel covered with an inflatable elastomeric sleeve. The compressible sliding seal includes an annular slot formed in the mandrel, and an annular seal sleeve surrounding the mandrel and located in the annular slot; The seal sleeve is longitudinally compressible in the annular slot between an annular first end and an annular second end, but not radially expandable. An inner annular surface of the annular first end of the seal sleeve is bonded to a cylindrical surface of the annular mandrel slot. An outer annular surface of the second end of the seal sleeve is bonded to an inner annular surface of the inflatable elastomeric sleeve. A retaining ring holds an end of the inflatable sleeve against the mandrel, and the retaining ling is located radially adjacent the annular slot. The retaining ring prevents the end of the inflatable sleeve from inflating and expanding radially outwardly. The inflatable elastomeric sleeve thus maintains an axially movable seal in the annular mandrel slot during inflation of the inflatable sleeve.

Brief Description of the Drawings Further features and advantages will become apparent from the following and more particular description of the preferred and other embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters generally refer to the same parts, functions or elements throughout the views, and in which:

Fig. 1 is a cross-sectional view of an external casing packer which illustrates the features of the invention according to an embodiment thereof;

Fig. 2 illustrates a one-quarter longitudinal section of an upper end of the external casing packer of Fig. 1, and particularly an inflation valve constructed according to an embodiment; and

Fig. 3 illustrates a one-quarter longitudinal section of the lower end of the external casing packer of Fig. 1, and in particular a sliding sleeve seal constructed according to an embodiment. Detailed Description of the Invention

Fig. 1 illustrates an external casing packer constructed according to one embodiment of the invention, it being realised that the various components of the packer can be constructed with different materials and in different configurations and arrangements, The external casing packer comprises a mandrel 5, over which is placed a reinforced elastomeric sleeve 4. The sleeve 4 is bonded or otherwise fixed to the mandrel 5 at the top end thereof. The top portion of the inflatable sleeve 4 that is bonded to the mandrel 5 is that portion that generally underlies the rigid outer sleeve 23, The inflatable sleeve 4 is not bonded to the mandrel 5 over the remainder of its length. Between the metal packer retaining rings 20 and 21 the inflatable sleeve 4 can expand radially outward to form a seal in the annulus of the borehole. The packer retaining rings 20 and 21 are bonded to the inflatable sleeve 4 and are restrained from axial movement by the top and bottom rigid sleeves 23 and 22, which are also bonded to the respective top and bottom ends of the inflatable sleeve 4. The mandrel 5 is shown with threaded connections at the top end 26 and the bottom end 27 to permit attachment thereof to casing sections or pipes situated above and below the packer. The absence of bonding between the inflatable sleeve 4 and mandrel 5 at the lower end of the packer allows the lower end of the inflatable sleeve 4 to slide on the mandrel S as the sleeve 4 is inflated. The seal between the inflatable sleeve 4 and the mandrel 5 is shown in more detail in Fig. 3. A non-return inflation valve 7 allows pressurised fluid in the mandrel 5 to pass therethrough and inflate the sleeve 4,

Formed at the bottom of the mandrel 5 is a seat 8 constructed of cement or other suitable material. When a ball 16 is dropped down through the casing, the ball 16 rests in the seat 8 and forms a one-way valve. Prior to dropping the ball 16 down through the casing, when the casing and packer arc lowered into a borehole, fluid and liquid can pass in either direction through the seat 8,

Fig. 2 illustrates the upper zone of the packer sleeve 4, the inflation valve 7, the retaining ring 21 and the bonded elastomeric sleeve 4. The reinforced elastoraerfc sleeve 4 is of multi-layered construction, including an outer elastomer layer 40, a reinforcing layer 41 , and an inner elastomer layer 42. The reinforcing layer 41 is depicted as a single layer for diagrammatic convenience, but could be made of layers of steel cord, steel strips, or other suitable reinforcing material embedded in the elastomer. The inflatable sleeve 4 extends along a length of the outer cylindrical surface of the mandrel 5, with the central portion of the inflatable sleeve 4 being inflatable, and with the opposite cylindrical ends of the sleeve 4 being held around the body of the mandrel 5: As will be described in more detail below, one end of the elastomeric sleeve 4 is bonded and fixed to the body of the mandrel 5, and the other end of the etastonieric sleeve 4 is slideable along the mandrel 5, but maintains a seal to the mandrel 5. Both ends of the elastomeric sleeve 4 which do not inflate are held against the mandrel 5 by the rigid outer sleeves 22 and 23. The rigid outer sleeves 22 and 23 are constructed of a steel or other suitable stiff or rigid material.

The laminated or layered elastomeric sleeve 4 is bonded over surface area 43 to the outer cylindrical surface of the mandrel 5. The outer elastomer layer 40 of the reinforced elastomeric sleeve 4 is bonded to the rigid outer sleeve 23. As noted above, the rigid outer sleeve 23 bears against the packer retaining ring 21 at junction 44. The metal retaining ring 21 has acting on it the loads from the sleeve reinforcing layer 41 due to inflation of the inflatable portion of the elastomeric sleeve 4. The axial component of the load would tend to move the retaining ring 21 axially to the right (in the drawing) during inflation of the inflatable elastomeric sleeve 4. The rigid outer sleeve 23 however restrains the retaining ring 21 from being moved to the right because it is bonded to the elastomer outer layer 40 which in turn is bonded to. the reinforcing layer 41. The radial component of the load on the packer retaining ring 21 is contained by hoop stress within the metal retaining ring 21. The axial component of the bad on the retaining ring 21 is transferred through shear stress in the elastomer layer 40 back down to the reinforcing layer 41. The contact junction 44 is shown as an acute angled abutment so that the rigid outer sleeve 23 does not disengage under load from under the packer retaining ring 21. The edge of the metal retaining ring 21 is constructed with a shoulder having an undercut, formed with -an acute angle. With this construction, the edge of the rigid outer sleeve 23 overlies a portion of the shouldered edge of the retaining ring 21. The mating edge of the rigid outer sleeve 23 can also be constructed with a complementary acute angle edge for engagement under the angled shoulder of the retaining ring 21. Those skilled in the art may prefer to construct the retaining ring 21 and the rigid outer sleeve 23 as a unitary tubular member bonded to the outer elastomeric layer 40 of the inflatable sleeve 4. The inflation valve system which permits fluid to expand the packer sleeve 4 {$ fitted in a concentric recess in the mandrel 5 at location 48. Although one inflation valve 7 is illustrated, it is to be understood that a number of such valves are formed around the packer mandrel 5. At location 48, a port 47 Is drilled in the mandrel 5 to provide an inflation fluid entry point. Movement of the inflation valve 7 is provided by an elastomeric annular flapper 46 which is bonded at location 45 over the outer concentric surface of the mandrel 5. The bonding location of the annular end of the flap 46 to the mandrel 5 is under the metal retaining ring 21 to maintain the annular edge of the flapper 46 anchored to the mandrel 5. During inflation of the packer sleeve 4 through respective ports 47, the inflating fluid forces the inflation flappers 46 open, as shown in the drawing. When the pressure in the casing drops at the cessation of inflation the flapper 46 closes elastically to seal the port 47. The inflation valve 7 is held in the closed state by a differential fluid pressure contained between the packer sleeve 4 and that in the mandrel 5. The rigid outer sleeve 23 is advantageously made in longitudinally split form so as to facilitate assembly of the packer while minimising the need for precise tolerance in diameter between the rigid outer sleeve 23 and the elastomer layer 40. During assembly, the rigid split sleeve 23 is clamped into place to the underlying elastomer layer 40 to permit the formation of a bond therebetween. The bond can be achieved by vulcanisation, adhesives, or other suitable means. It should be appreciated by those skilled in the art of elastomer construction that various bond and de-bonded sections of layers are advantageous to produce the external casing packer.

Fig. 3 illustrates the structural details of sliding sleeve seal 55 which is located at the lower end of the packer sleeve 4. As noted above, the inflatable sleeve 4 is shortened during inflation, and the sliding seal sleeve 55 allows movement of the lower end of the inflatable sleeve 4 on the mandrel 5. The lower end of the packer sleeve 4 includes the sliding seal sleeve 55, the metal retaining ring 20 and the elastomeric sleeve layer 40. The arrangement of the packer sleeve 4 at the lower end thereof includes the inner elastomer layer 42, the reinforcing layer 41, the outer elastomer layer 40, the retaining ring 20. and the rigid outer sleeve 22, all of which are similar in construction to that described above in connection with the upper end of the packer in Fig. 2. The major difference is that the inner elastomer layer 42 is constructed so that it can slide over the mandrel 5 in an axial direction at surface area 53 as the packer sleeve 4 shortens during inflation. Unlike most packers which have some sliding hydraulic type of seal, the packer disclosed herein utilises an annular sleeve seal 55 made of a reinforced elastomer which is preferably of a similar construction to the sleeve 4.

The annular sleeve seaj 55 is contained in an annular external groove 54 formed in the outer surface of the mandrel 5. The annular sleeve seal 55 is bonded to the outside of the mandrel 5 over surface area 58, and to the inside of the inner elastomer layer 42 over surface area 57. The steeve seal 55 is otherwise not bonded, but is free to slide axjally on the mandrel 5 within the external groove 54. In the drawing, the packer sleeve 4 is shown in an inflated state, engaged in contact with the borehole 1. In the inflated state of the elastomeric sleeve 4, the sleeve seal 55 is longitudinally compressed from its original position where it occupies substantially the entire axial length of the external groove 54. The distance by which the sleeve seal 55 becomes compressed is shown as the dimension G. The extent of compression, of the sleeve seal 55 within the external groove 54 is generally a function of the diametric expansion of the elastomeric sleeve 4 during inflation. The sleeve seal 55 is shown in the drawing as having been manufactured with a reinforcing layer 56 embedded in the elastomeric material of the sleeve seal 55. The reinforcing layer 56 would preferably be an open weave mesh laid on the bias so that it can_, compress axially, but not annul arly in circumference. The reinforcing mesh 56 would be bonded within the elastomer layers and prevent uneven strain of the sleeve seal 55, which could otherwise lead to tears within the material of the sleeve seal 55. The sleeve seat 55 is held against the mandrel 5 within groove 54 by fluid pressure in the expanded sleeve 4 and is pi-evented from being torn from the inner elastomer layer 42 of the sleeve 4 by the tight annular restraint of the packer retaining ring 20.

While the preferred and other embodiments of the invention have been disclosed with reference to a specific sliding seal for an external casing packer, and associated methods of use and manufacture thereof, it is to be understood that many changes in detail may be made as a matter of engineering choices without departing from the spirit and scope of the invention, as defined by the appended claims.

Claims

WHAT IS CLAIMED IS;

1. A compressible sliding seal for a packer of the type having a cylindrical mandrel covered with an inflatable clastomeric sleeve, said compressible sliding seal comprising:

an annular seal sleeve surrounding the mandrel of the packer, said seal sleeve being longitudinally compressible between an annular first end and an annular second end thereof;

said annular first end of said Seal sleeve fixed to the mandrel; and

said annular second end of said seal sleeve fixed to one end of the inflatable sleeve; whereby said inflatable sleeve maintains a seal to the mandrel during inflation of the inflatable sleeve.

2. The compressible sliding seal of Claim 1, wherein said seal sleeve is reinforced with an open weave reinforcement placed on a bias (diagonal) with respect to an axial axis of the seal sleeve to thereby permit compression of the seal sleeve during inflation of the inflatable sleeve and to control local strains which can otherwise lead to tears in said seal sleeve.

3. The compressible sliding seal sleeve of Claim 1, further including an annular retaining ring which clamps the inflatable sleeve to the mandrel, and the annular second end of said seal sleeve is restrained from being torn from its attachment to the inflatable sleeve by said retaining ring.

4. The compressible sliding seal sleeve of Claim 3, further including a rigid outer sleeve bonded around said one end of the inflatable sleeve, and said rigid outer sleeve abuts against said retaining ring.

5. A packer which includes the sliding compressible seal of Claims 1, 2, 3 and 4.

6. A compressible sliding seal for a packer of the type having a cylindrical mandrel covered with an inflatable elastomeric sleeve, said compressible sliding seal comprising:

a rigid outer sleeve bonded around an end of the inflatable sleeve;

an annular seal sleeve surrounding the mandrel of the packer, said seal sleeve being longitudinally compressible between an annular first end and an annular second end; said annular first end of said seal sleeve bonded to the mandrel;

said annular second end of said seal sleeve bonded to tihe inflatable sleeve; and a retaining ring bonded around the end of the inflatable sleeve and axially engageable with said rigid outer $Ieeve, said retaining ring located around the bond of the second end of said seal sleeve to the inflatable sleeve, whereby said retaining ring is not displaced axially under load imposed on it by the tensile load in the rigid outer sleeve.

7. The compressible sliding seal of Claim 6, wherein said rigid outer sleeve is split longitudinally, wherein the split rigid outer sleeve permits greater tolerance between the underlying elastomer layer of the inflatable sleeve during manufacture.

8. The compressible sliding seal of Claim 6 and/or Claim 7, wherein said retaining ring includes a shoulder, and wherein an edge of said rigid outer sleeve seats with the shoulder formed in the packer retaining ring.

9. The compressible sliding seal of Claim 8, wherein the shoulder formed on said retaining ring is constructed with an undercut acute angle at a base thereof, and wherein said rigid outer sleeve is constructed with an acute angle which locks with the shoulder of said retaining ring to prevent radial displacement of said retaining ring under load.

10. The compressible sliding seal of Claim 6, wherein the annular second end of said seal sleeve is adapted for axial movement along the mandrel and under said retaining ring.

1 1. A packer system including the compressible sliding seal of any of Claims 1-10, further including a non-return inflation valve for inflating the inflatable sleeve, said non-return inflation valve comprising a sleeve of elastomer material bonded at one ^'annular end thereof to the mandrel, and having another end free to lift off ports in the mandrel to permit one way fluid flow.

12. A packer system incorporating any or all of the Claims 1 to 11.

13. A compressible sliding seal for a packer of the type having a cylindrical mandrel covered with an inflatable elastomeric sleeve, said compressible sliding seal comprising:

an annular slot formed in the mandrel;

an annular seal sleeve surrounding the mandrel and located in said annular slot, said seal sleeve being longitudinally compressible in said annular slot between an annular first end and an annular second end;

an inner annular surface of the annular first end of said seal sleeve bonded to a cylindrical surf ace of said annular mandrel slot;

an outer annular surface of the annular second end of said seal sleeve bonded to an inner annular surface of the inflatable elastomeric sleeve;

a retaining ring holding an end of said inflatable sleeve against the mandrel, said retaining ring located radially adjacent said annular slot, said retaining ring preventing the end of said inflatable sleeve from inflating and expanding radially outwardly; and whereby said inflatable elastomeric sleeve maintains an axially movable seal in said annular mandrel slot during inflation of the inflatable sleeve,

14. The compressible sliding seal of Claim 13, further including a rigid outer sleeve bonded to an outside surface of the end of the inflatable elastomeric sleeve.

15. The compressible sliding seal of Claim 14, further including an annular shouldered edge formed on said retaining ting, and wherein an annular edge of said rigid outer sleeve overlies the annular shouldered edge of said retaining ring,

16. The compressible sliding seal of Claim 13, wherein the inflatable sleeve is located over the slot of the mandrel so that pressurised fluid in the inflatable sleeve presses at least a portion of said seal sleeve against the mandrel.

17. The compressible sliding seal of Claim 16. wherein the annular first end of said seal sleeve is located within a portion of the inflatable sleeve which is inflated.

18. The compressible sliding seal of Claim 16, further including in combination an inflation valve for inflating the inflatable sleeve, wherein said slot in the mandrel comprises a first slot, and further including a second annular slot formed in the mandrel, said inflation valve comprising a tubular elastomeric member located in said second slot, a first end of said tubular elastomeric member fixed within said second annular slot so that the other end of said tubular elastomeric member is free to expand, and further including one or more ports formed through said second slot, and said other end of said tubular elastomeric member covering each said port.

19. The compressible sliding seal of Claim 18, wherein said retaining ring . comprises a first retaining ring, and further including a second retaining ring for holding the inflatable sleeve against the end of said tubular elastomeric member that is fixed within the second annular slot of the mandrel.

20. The compressible sliding seal of Claim 13, wherein said inflatable sleeve comprises a first sleeve, said seal sleeve comprises a second sleeve, and further including a third elastorueric sleeve, and wherein said mandrel annular slot comprises a first slot, and further including a second annular slot formed in said mandrel, said second annular slot having inflation ports formed therein, and wherein said third elastomeric sleeve is located in aaid second annular slot, and a free annular end of said third elastomeric sleeve covers said inflation ports.