US3208532A

US3208532A - Releasable inflatable well packer

Info

Publication number: US3208532A
Application number: US250541A
Authority: US
Inventors: David V Chenoweth
Original assignee: Baker Oil Tools Inc
Current assignee: Baker Hughes Oilfield Operations LLC
Priority date: 1963-01-10
Filing date: 1963-01-10
Publication date: 1965-09-28
Anticipated expiration: 1982-09-28

Description

Sept. 28, 1965 D. v. cHl-:NowETH RELEASABLE INFLATABLE WELL PACKER 2 Sheets-Sheet 1 Filed Jan. l0, 1965 INVENTOR.

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Sept. 28, 1965 D. v. CHENOWETH RELEASABLE INFLATABLE WELL PACKER 2 Sheets-Sheet 2 o gag Filed Jan. l0, 1963 INVENTOR.

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United States Patent O 3,208,532 RELEASABLE INFLATABL'E WELL PACKER David V. Chenoweth, Houston, Tex., assignor to Baker Oil Tools, Inc., Los Angeles, Calif., a corporation of California Filed Jan. 10, 1963, Ser. No. 250,541 9 Claims. '(Cl. 166-187) The present invention relates to subsurface well bore equipment, and more particularly to well packers adapted to be packed off against the walls of well bores.

An object of the present invention is to provide a well packer having an inflatable packing element of rubber or rubber-like material, in which the tensile stresses to which the packing element is subjected when inflated are reduced considerably.

Another object of the invention is to provide a Well packer having an inflatable packing element, in which the inflated element is subject to an endwise compressive force, as well as to the inflating effect, thereby increasing the sealing eifectiveness of the packing element against the wall of the surrounding well bore and its effective range of expansion.

A further object of the invention is to provide an improved well packer having an inliatable packing element, in which the inilating pressure can be trapped in the element to hold it in expanded or inated condition, and in which application and trapping of the pressure in the element, followed by its relief to secure packing retraction, can occur repeatedly and as often as desired.

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 side elevational view and longitudinal section through a well packer embodying the invention, with the packing element in retracted position;

FIGS. 2 and 2a together constitute an enlarged longitudinal section through the well packer with the packing element expanded, FIG. 2a being the lower continuation of FIG. 2;

FIG. 3 is a view similar to FIG. 2, illustrating the packer in condition for deation or release of the inated packing from the wall of the well bore;

FIG. 4 is an enlarged longitudinal section of the check valve portion of the apparatus.

As specifically illustrated in the drawings, the well packer A is adapted to be lowered in a well bore C on a tubular running-in string B, such as a rotary drill string, and may be mounted at some intermediate point in the rotary drill string above a rotary drill bit (not shown) used in drilling the well bore. The Well packer can be packed-oli against the wall of the well bore in connection with a particular operation to be performed therewithin, after which it can be released from and retracted from the well bore wall to permit the drilling operation to continue. The packing off of the well packer against the wall of the well bore and its retraction therefrom can occur repeatedly.

As shown in the drawings, the well packer A includes a main body comprising an upper body section or sub 11 having an upper threadedbox 12 for threaded connection to a lower pin end 13 of a drill pipe section B thereabove. The upper body section 11 has a lower threaded box 14 threadedly connected to the upper pin end 15 of ICC an elongate intermediate body section 16 having a lower threaded pin 17 threadedly connected to the threaded box portion 18 of a lower body section or sub 19. This lower sub may have a lower threaded box 20 for threaded connection to the upper threaded pin end 21 of a tubular catcher and by-pass member 22, which may have a transverse pin 23 for the purpose of supporting a ball valve member 24. The inside diameter of the catcher housing or sub 22 is substantially greater than the diameter of the ball 24 to permit fluid to ow around the ball. It is to be noted that the lower body section or sub 19 has a portion 25 of smaller diameter than the diameter of the ball 24, providing a seat 26 to be engaged by the ball. As pointed out hereinbelow, the ball 24 may be made of rubber or rubber-like material, capable of being deformed by liuid pressure and squeezed through the restricted body passage 25 into the catcher 22 therebelow.

An elongate inflatable rubber or rubber-like packing element 27 surrounds the intermediate body section 16 and inherently tends to assume a retracted and cylindrical condition, such as illustrated in FIG. l. The upper portion 28 of the packing sleeve is of reduced external diameter and is disposed within an encompassing piston skirt 29 depending from an upper piston head 30 slidable along the periphery of the intermediate body section 16, but which has some clearance therewith so that fluid can pass between the upper head 30 :and the intermediate body section 16. When the packing element 27 is in its retracted position, the

piston

29, 30 is in its uppermost position along the body 10 and closely adjacent to an upper cylinder head 31 provided by the lower end of the upper body section 11. Surrounding this cylinder head 31 is a cylinder skirt 32 which has a threaded connection 33 with the upper body section 11 and which encompasses the

upper piston

29, 30.

The upper piston is slidable along the body 10 and the upper cylinder sleeve 32 from a position closely adjacent to the upper cylinder head 31 to a lower position, the extent of downward movement of the piston being limited. As disclosed, a two-part limit sleeve 34 is disposed within the cylinder sleeve 32, this limit sleeve having a lower inwardly directed iiange 35 received within a companion peripheral groove 36 in the piston head 30, and an upper inwardly directed flange 37 received within an elongate peripheral groove 38 in the upper cylinder head 31. The extent of downward movement of the

upper piston

29, 30 along the cylinder sleeve 32 is limited by engagement of the upper flange 37 of the limit sleeve with the lower end 39 of the head groove. When so engaged, the

piston

29, 30 will still be disposed substantially within the upper cylinder sleeve 32.

The lower portion 40 of the packing sleeve 27 also has a reduced external diameter, being snugly received within an upwardly projecting piston skirt 41 integral with a lower piston head 42 disposed within `a lower cylinder sleeve 43 having a threaded connection 44 with the lower body section or sub 19. The lower head 42 also has a working clearance with the periphery of the intermediate body section 16 to permit fluid to pass therebetween, the

lower piston

41, 42 initially occupying a lower position closely adjacent to .a lower cylinder head 45 provided by the upper portion of the lower body section or sub 19. The extent of upward movement of the

lower piston

41, 42 along the body 10 and the lower cylinder sleeve 43 is also limited. As shown, a lower two-piece limit sleeve 46 is disposed within the lower cylinder sleeve, having an upper inwardly directed ange 47 received within a companion peripheral groove 48 in the lower piston head 42, and :a lower inwardly directed ange 49 received within an elongate peripheral groove 50 in the lower cylinder head 45. Engagement of the lower flange with the upper end 51 of the cylinder head groove will limit the extent of upward movement of the

lower piston

41, 42 along the body and the lower cylinder sleeve 43. When such engagement occurs, the lower piston will still be disposed substantially within the lower cylinder sleeve.

In order to protect the packing sleeve 27 when in its `fully retra-cted position, the upper piston skirt 29 and the lower piston skirt 41 have outwardly directed flanges 52 in juxtaposition to the ends of the upper and

lower cylinder sleeves

32, 43, as shown in FIG. 1, so that drill bit cuttings, .and the like, cannot engage any exposed shoulders or ends of the inflatable packing sleeve 27 and possibly damage the latter during the drilling oper-ation.

The upper and

lower ends

28, 40 of the packing sleeve are sealed against the upper and

lower piston skirts

29, 41, respectively, to prevent fluid leakage therebetween. The upper piston head 30 has a suitable side seal 55 for sealing against the inner wall of the upper cylinder sleeve 32 to prevent fluid leakage therebetween. Similarly, the lower piston head 42 has a suitable side seal 56 thereon eng-aging the inner wall of the lower cylinder sleeve 43 to prevent leakage of fluid therebetween. Leakage of fluid between the upper cylinder head 31 and intermediate body section 16 is prevented by a suitable side seal 57 on the head engaging the periphery of the body section; whereas, upward leak-age of fiuid between the upper cylinder sleeve 32 and the upper body section 11 is prevented by an upper side seal ring 58 on the body section enga-ging the inner wall of the upper cylinder sleeve.

A suitable side seal ring 59 is mounted on the lower cylinder head `45 in sealing engagement with the inner wall of the lower cylinder sleeve 43 to prevent fluid leak- -age therebetween, leakage of fiuid between the lower cylinder head 45 and the lower portion of the intermediate body section 16 being prevented by a suitable inner side seal 60.

Fluid under pressure can pass to the upper cylinder space 61 between the upper piston 30 and 4head 31, to the lower cylinder space 62 between the lower piston 42 and head 45, and into the packing element 27 therebetween. As disclosed in the drawings, an inlet port 63 communicating with the central passage 64 through the tubular body 10 also communicates with an aligned inlet port 65 in a hollow valve body 66 disposed within a radial bore 67 in the upper tubular body section 11 above its cylinder head 31. The outer portion of the valve body 66 communicates with a longitudinal passage 68 formed in the exterior of the upper body section 11 and opening into the peripheral groove 38 that -communicates with t-he upper cylinder space 61 through the gaps between the two parts of the limit sleeve 34 and through the clearance spaces between this limit sleeve and the head 31 and cylinder sleeve 32. The upper end of this longitudinal passage 68 communicates with an annular passage 69 between the upper portion of the upper cylinder sleeve 32 and the upper body section 11, which -communicates with a relief or exhaust port 70 extending through the upper body section and adapted to communicate with its central passage 64. This exhaust port can be Iclosed by a valve sleeve 71 disposed thereacross land having suitable side seals 72 engaging the inner wall of the upper body section 11 on opposite sides thereof. The valve sleeve 71 is releasably held in port closing position by the reception of outwardly directed latch fingers 73 in an internal -groove 74 in the upper body section, the fingers 4being integral with longitudinally extending arms 75 integral with and projecting upwardly from the circumferentially continuous port closing portion 76 of the valve sleeve. The arms 75 and fingers 73 inherently tend to spring outwardly to hold the lingers in the lock groove 74. The fingers also have inner portions 77 projecting slightly inwardly of the arms 75, the outer portions of the fingers having lower tapered surfaces 78 inclined in a downward and inward direction and engaging a companion tapered surface 79 at t-he lower side of the internal groove 74.4 The lower end of the valve sleeve 71 has an inwardly directed flange 80 providing a seat or stop for a companion member 81, described hereinbelow, and which is used for shifting the sleeve valve 71 between its exhaust port opening and closing positions.

Fluid can only flow through the

inlet ports

63, 65 in one direction, as in an outward direction. The v-alve body 66 forms part of a check valve providing a valve seat 82 surrounding its inlet port 65. A suitable valve element 83, such as a ball, is urged against this seat by a helical -compression spring 84 engaging the ball, the outer end of the spring engaging a spring seat 85 held within the valve body. Leakage of fiuid between the body `66 and the wall of the surrounding bore 67 is prevented by a suitable side seal ring 86. When fluid at sufficient pressure is present in the body passage 64, it will shift the ball 83 -outwardly against the for-ce of the spring 84, such fluid pressure then passing into the longitudinal passage 68 and into the upper cylinder space 61, also passing downwardly through the clear-ance space between t-he upper piston 30 and the intermediate body section 16 into the packing element 27 itself, and continuing on through the clearance space between the lower piston 42 and the intermediate body section 16 into the lower cylinder space 62. The spring 84 exerts a predetermined force, so that a unit pressure substantially greater than the normal pressure of the fluid used in drilling the well bore is necessary to open the Icheck valve, and for the fiuid under pressure to pass into the

cylinder spaces

61, 62 and the inliatable packing element 27.

Such pressure can be obtained by pumping or dropping the rubber or rubber-like ball 24 down through the tubular string B, such ball passing freely through the sleeve valve 71 Iand engaging the ball seat 26 in the lower body section 19. The pressure of t-he fiuid in theY tubular drill string B and body 10 can then be increased to a sufficient extent to overcome the force of the check valve spring 84 and open the check valve, the Huid pressure then passing through the passage 68 into the

cylinder spaces

61, 62 and the inflatable packing element 27, to inflate the latter against the wall of the well bore C. The fluid pressure also acts axially in opposite directions upon the upper and

lower pistons

30, 42 moving such pistons in their respective cylinders toward one another and imposing an endwise compression on the packing element 27, insuring its greater sealing effectiveness against the wall of the well bore (FIGS. 2, 2a). In view of the ,ability of the

ends

28, 40 of the packing element to shift toward each other, the tensile stresses to which the packing element 27 is subjected are reduced. In view of the fact that the ends of the packing element can move toward one another, the packing element can have a lgreater range of expansion into effective sealing engage, ment with the wall of the confining well bore.

In the event that the fluid pressure in the rotary drill string B and the body 10 is relieved, the ball check valve element 83 will engage its seat 82 and trap the pressure within the cylinders and within the packing element, the latter remaining in packed-oft condition against the wall of the well bore.

With the packing element 27 sealed against the wall of the well bore C, a desired operation can be performed in the well bore. If a fiuent sealing material is pumped down through the tubular string B, the downward pumping pressure will force the rubber-like element 24 through its seat 26 and the passage 25 into the catcher 22 therebelow, the fluent material being capable of flowing around the ball valve element 24 and through the. drill pipe therebelow, discharging from the drill bit (not shown) and entering the well bore below the packing element 27. The sealing material can then effectively seal the wall of the well bore, as, for example, for the purpose of shutting off encroaching water, in the event that the drilling operation is being performed with the use of air or gas as the fiuid medium.

After the formation has been sealed, drilling is to be resumed in the usual manner by rotating the drill string B. Before such action can occur, however, the inflatable packing element 27 is to be retracted. Such retraction occurs by lowering a suitable releasing bar 81 on a wire line (not shown) through the rotary drill string B (FIG. 3). This releasing bar has a lower head 90 adapted to pass through the finger projections 77 when the fingers 73 are disposed in the internal groove 74, the head having a diameter slightly less than the internal diameter of the circumferentially continuous sleeve portion 76, and coming to rest upon the sleeve liange 80. A downward force imposed on the release bar 81 will now cause the iingers 73 to be cammed inwardly out of the groove 74 and the sleeve 71 to shift downwardly to an exhaust port opening position, as determined by engagement of the lower end of the sleeve 71 with a stop shoulder 91 in the upper body section 11. The iiuid that has been trapped in the

cylinder spaces

61, 62 and the inflated packing element 27 can now escape back through the

passage

68, 69 and the open exhaust port 70 to the interior 64 of the body 10 and the tubular string B.

The packing element 27 will retract inherently to its initial position, shifting the

upper piston

30, 29 back within its cylinder to its initial position, and the

lower piston

42, 41 within the lower cylinder to its initial position, such as disclosed in FIG. 1. The releasing bar 81 is now elevated by elevating the wire line, Since the fingers 73 have been projected laterally inwardly by the wall of the upper body section 11 below the groove 74, their inwardly projecting portions 77 overlie and are engaged by the upwardly facing shoulder 92 of the release bar head 90, the sleeve 71 being shifted by the release bar, as it is elevated, upwardly until the arms 75 inherently re-expand the iingers 73 back into the groove 74, thereby increasing the effective diameter of the inner projections 77 and allowing the head 90` to pass upwardly therethrough, the releasing bar 81 then being adapted to be withdrawn through the drill string B to the top of the well bore. The sleeve 71 has then been shifted back to a closed position across the exhaust port 70.

Drilling can now proceed in the usual manner, the drlling iiuid, such as air, being pumped down through the drill string, or externally around the drill string B. The iiuid pressure normally employed during the drilling operation is incapable of opening the check valve 83 and reinflating the packing element 27. If iniiation of the packing element is again desired, rotation of the drill string can cease and another rubber or rubberlike ball member 24 pumped or lowered down through the drill string into engagement with its companion ball seat 26 in the lower body section 19. If desired, in lieu of pumping the rubber ball element 24 through the body passage 2S, it could be attached to and lowered on a wire line through the drill string B into engagement with its companion seat 26, and after packing inflation has occured, removed Ifrom the body passage 64 and the rotary drill string B to the top of the well bore.

I claim: y

1. In a well packer: a tubular body adapted to b connected to a tubular string to be disposed in a well bore; upper and lower cylinders on said body; an inflatable packing element on Said body between said cylinders; upper and lower pistons in said upper and lower cylinders, respectively, and shiftable along said body and surrounding the upper and lower end portions of said packing element; said cylinders and the interior of said packing element being in communication with each other externally of said body to permit fluid to pass therebetween; and means for conducting fluid under pressure from the interior of said body to one of said cylinders, whereby said iiuid under pressure passes to the interior of said packing and into the other cylinder to 5 simultaneously inflate said packing element and shift said pistons and the end portions of said lpacking element toward each other.

2. In a well packer: a tubular body adapted to be connected to a tubular string to be disposed in a well bore; upper and lower cylinders on said body; an inilatable packing element on said body between said cylinders; upper and lower pistons in said upper and lower cylinders, respectively, and engaging the upper and lower end portions of said packing element; said cylinders and the interior of said packing element being in communication with each other externally of said body to permit fluid to pass therebetween; means for conducting iiuid under pressure from the interior of said body to one of said cylinders, whereby said iiuid under pressure passes to the interior of said packing element and into the other of said cylinders to simultaneously iniiate said packing element and move said pistons toward each other to move said end portions of said packing element toward each other; and means closing said conducting means to trap said fluid under pressure in said cylinders and the interior of said packing element.

3. In a well packer: a tubular body adapted to be connected to a tubular string to be disposed in a well bore; upper and lower cylinders on said body; an inflatable packing element on said body between said cylinders; upper and lower pistons in said upper and lower cylinders, respectively, and engaging the upper and lower end portions of said packing element; said cylinders and the interior of said packing element being in communication with each Vother externally of said body to permit iiuid to pass therebetween; means for conducting fluid under pressure from the interior of said body to one of said cylinders whereby said fluid under pressure passes to the interior of said packing element and into the other of said cylinders to simultaneously inflate said packing element and move said pistons toward each other to move said end portions of said packing element toward each other; means closing said conducting means to trap said fluid under pressure in said cylinders and the interior of said packing element; and means communicating with said conducting means for relieving said trapped iiuid under pressure.

4. In a well packer: a tubular body adapted to be connected to a tubular string to be disposed in a well bore; an inflatable packing element -on said body; means on said body engaging the end portions of said packing element and including iiuid operated means engaging one of said end portions for moving said one end portion toward the other of said end portions; means for conducting iluid under pressure from the interior of said body to said iiuid operated means and from said fluid operated means to the interior of said packing element to simultaneously inflate said packing element and move said iiuid operated means toward the other :of said end portions to decrease the overall length of said packing element; means for closing said conducting means to trap said iiuid under pressure in said iiuid operated means and in the interior of said packing element; and means communicating with said conducting means for relieving said trapped fluid under pressure.

5. In a well packer: a tubular body adapted to be connected to a tubular string to be disposed in a well bore; upper and lower cylinders on said body; and an inliatable packing element on said body between said cylinders; upper and lower pistons in said upper and lower cylinders, respectively, .and shiftable along said body and surrounding the upper and lower end portions of said packing element; said cylinders and the interior of said packing element being in communication with each other externally of said body to permit iiuid to pass therebetween; said body having inlet passage means between its interior .and one of said cylinders for conducting fluid under pressure from the interior of said body to said one cylinder, whereby said iiuid under pressure passes from said one cylinder to the interior of said packing element and to said other cylinder to simultaneously inate said packing element and shift said pistons toward each other and the end portions of said packing element toward each other; and check valve means in said passage means for trapping said fluid under pressure in said cylinders and packing element.

6. In a well packer: a tubular body adapted to be connected to a tubular string to be disposed in a well bore; upper and lower cylinders on said body; an inatable packing element on said body between said cylinders; upper and lower pistons in said upper and lower cylinders, respectively, and shiftable along said body and surrounding the upper and lower end portions of said packing element; said cylinders and the interior of said packing element being in communication with each other externally of said body to permit fluid to pass therebetween; said body having inlet passage means between its interior and one of said cylinders for conducting fluid under pressure from the interior of said body to said one cylinder, whereby said fluid under pressure passes from said one cylinder to the interior of said packing element and to said other cylinder to simultaneously inflate said packing element and shift said pistons toward each other and the end portions of said packing element toward each other; check valve means in said passage means for trapping 'said fluid under pressure in said cylinders and packing element; said body having exhaust passage means for relieving the fluid pressure in said cylinders and packing element; means for closing said exhaust passage means; and means for shifting said closing means to open position.

7. In a well packer: a tubular body adapted to be connected to a tubular string to be disposed in a well bore; upper and lower cylinders on said body; an inflatable packing element on said body between said cylinders; upper and lower pistons in said upper and lower cylinders, respectively, and shiftable along said body and surrounding the upper and lower end portions of said packing element; said cylinders yand the interior of said packing element being in communication with each other externally of said body to permit fluid to pass therebetween; said body having inlet passage means between its interior and one of said cylinders for conducting fluid under pressure from the interior of said body to said one cylinder, whereby said fluid under pressure passes from said one cylinder to the interior of said packing element and to said other cylinder to simultaneously inflate said packing element and shift said pistons toward each other and the end portions of said packing element toward each other; check valve means in said passage means for trapping said fluid under pressure in said cylinders and packing element; said body having exhaust passage means for relieving the fluid pressure in said cylinders and packing element; a sleeve valve in said body adapted to close said exhaust passage means; `and means for shifting said sleeve valve between positions opening and closing said exhaust passage means.

8. In`a well packer: a tubular body .adapted to be connected to a tubular string to be disposed in a well bore; upper and lower cylinders on said body; an inflatable packing element on said body between said cylinders; upper and lower pistons in said upper and lower cylinders, respectively, and shiftable along said body and surrounding the upper and lower end portions of said packing element; said cylinders and the interior of said packing element being in communication with each other externally of said body to permit fluid to pass therebetween; said body having inlet passage means between its interior and one of said cylinders for conducting lluid under pressure from the interior of said body to said one cylinder, whereby said fluid under pressure passes from said one cylinder to the interior of said packing element andto said other cylinder to simultaneously inate said packing element and shift said pistons toward each other and the end portions of said packing element toward each other; check valve means in said passage means for trapping said fluid under pressure in said cylinders and packing element; said body having exhaust passage means for relieving the fluid pressure in said cylinders and packing element; a sleeve Valve in said body; coengaging means on said sleeve valve `and body releasably retaining said sleeve valve in position closing said exhaust passage means; and actuating means adapted for movement into engagement with said sleeve valve for releasing said retaining means and shifting said sleeve valve to a position opening said exhaust passage means.

9. In a well packer: a tubular body adapted to be connected to a tubular string to be disposed in a well bore; upper and lower cylinders on said body; an inflatable packing element on said body between said cylinders; upper and lower pistons in said upper and lower cylinders, respectively, and shiftable along said body and surrounding the upper and lower end portions of said packing element; said cylinders and the interior of said packing element being in communication With each other externally of said body to permit uid to pass therebetween; said body having inlet passage means between its interior ,and one of said cylinders for conducting uid under pressure from the interior of said body to said one cylinder, whereby said lluid under pressure passes from said one cylinder to the interior of said packing element and to said other cylinder to simultaneously inflate said packing element and shift said pistons toward each other and the end portions of said packing element toward each other; check valve means in said passage means for trapping said uid under pressure in said cylinders and packing element; said body having exhaust passage means for relieving the fluid pressure in said cylinders yand packing element; a sleeve valve in said body; coengaging means on said sleeve valve and body releasably retaining said sleeve vale in position closing said exhaust passage means; and actuating means adapted for movement into engagement with said sleeve valve for releasing said retaining means and shifting said sleeve valve to a position opening said exhaust passage means; said actuating means and sleeve valve having coengageable means for enabling said actu- Iating means to shift said sleeve valve to a position` closing said exhaust passage means.

References Cited by the Examiner UNITED STATES PATENTS 2,159,640 5/39 Strom 166-122 2,370,832 3/45 Baker 166-187 X 2,828,823 4/58 Mounce 166-187 2,872,983 2/59 Renouf 166--187 X 3,053,322- 9/62 Kline 166-187 X 3,080,923 3/63 Brown l166-120 CHARLES E. OCONNELL, Primary Examiner.

Claims

1. IN A WELL PACKER: A TUBULAR BODY ADAPTED TO BE CONNECTED TO A TUBULR STRING TO BE DISPOSED IN A WELL BORE; UPPER AND LOWER CYLINDERS ON SAID BODY; AN INFLATABLE PACKING ELEMENT ON SAID BODY BETWEEN SAID CYLINDERS; UPPER AND LOWER PISTONS IN SAID UPPER AND LOWER CYLINDRES, RESPECTIVELY, AND SHIFTABLE ALONG SAID BODY AND SURROUNDING THE UPPER AND LOWER END PORTIONS OF SAID PACKING ELEMENT; SAID CYLINDERS AND THE INTERIOR OF SAID PACKING ELEMENT BEING IN COMMUNICATION WITH EACH OTHER EXTERNALLY OF SAID BODY TO PERMIT FLUID TO PASS THEREBETWEEN; AND MEANS FOR CONDUCTING FLUID UNDER PRESSURE FROM THE INTERIOR OF SAID BODY TO ONE OF SAID CYLINDRS, WHEREBY SAID FLUID INDER PRESSURE PASSES TO THE INTERIOR OF SAID PACKING AND INTO THE OTHER CYLINDER TO