US3303884A

US3303884A - Mechanism for use in a well bore

Info

Publication number: US3303884A
Application number: US404894A
Authority: US
Inventors: Jr Erskin L Medford
Original assignee: Halliburton Co
Current assignee: Halliburton Co
Priority date: 1964-10-19
Filing date: 1964-10-19
Publication date: 1967-02-14
Anticipated expiration: 1984-02-14

Description

Feb 14, 1967 E. l.. MEDFoRD, .1R

MECHNISM FOR USE IN A WELL BORE 2 Sheets-Sheet l Filed Oct. 19, 1964 INVENTOR Feb. 14, 1967 E. L.. MEDFQRD, JR

MECHANISM FOR USE IN A WELL BORE 2 Sneets-Sheet 2 Filed Oct. 19, .T964

FIGB

FIG?

INVENTOR ERSKIN l.. MEDI-'ORD ,JR

United States Patent Patented Feb. lll, i957 3,303,884 MECHANHSM FR USE HN A WELL BQRE Erslrin L. Medford, Jr., Duncan, Ulrla., assigner to Halliburton Company, Duncan, Okla., a corporation of Delaware Filed Oct. i9, 1964, Ser. No. 404,394 8 Claims. (Cl. 166-63) This invention relates to a mechanism for use in a well bore. In particular, it relates to a force transmitting mechanism adapted to effect the eflcient actuation of apparatus such as packers.

A variety of setting tools have heretofore been developed to facilitate the setting or actuation of devices such as packers within a well bore in response t-o a setting force remotely generated within the well bore. In general, however, such setting mechanisms have not made the most effective utilization of the available setting force during portions of the apparatus setting cycle when different levels of force could be most efficiently employed. In addition, previously known setting tools have often failed to cause movable, apparatus setting members to move at the most effective rates during portions of the apparatus setting or actuating cycle.

It is an object of the present invention to provide apparatus which, in response to available force, effectively varies this force during the cycle of setting an apparatus within a -well bore to obtain improved efiiciency.

A related, principal object of the invention is to provide such an apparatus which varies the rate of movement of apparatus setting or actuating members during a setting cycle so as to obtain improved setting eiliciency.

A more specific object of the invention is to provide an apparatus for use in a well bore which, in response to force remotely generated within a well bore, applies a relatively low setting force to an apparatus during the portion of the setting cycle when relatively low force is required and which applies relatively greater setting force when relatively greater force is required.

A similar, more specific object of the invention is to provide an apparatus for use within a well bore which, in response to a force remotely generated within the well bore, causes a movable apparatus setting or actuating member to move at a relatively rapid rate during the first portion of the setting cycle where a low setting force is required and to move at a relatively slower rate during a later portion of the setting cycle when greater setting force is required.

It is also an object of the invention to provide such apparatus which may be so configured as to have movable components exposed to the pressure of well bore fluids but which components may remain substantially pressure balanced and not adversely affected by such pressure.

A still further object of the invention is to provide a fluid, force transmitting coupling between components of a force transmitting mechanism which may be automatically `supplied from well bore fluids as the mechanism is lowered into a well bore.

In order to accomplish the foregoing objectives, there is presented through this invention an apparatus for use in a well bore which includes force generating means having actuating means and which is operable Within a well bore to move the actuating means. The apparatus may further include a mechanism to be actuated within the well bore. Force transmitting means included in the apparatus are operatively disposed between the actuating means and the mechanism to be actuated. The force transmitting means includes first means movable in response to movement of the actuating means and second means movable in response to movement of the first means and adapted to actuate the mechanism. Coupling means included in the force transmitting means operably connect the rst and second means. The coupling means is adapted to cause the second means to initially move at a first rate more rapid than the rate of movement of the first means and thereafter move at a second rate slower than the first rate. The second means, while moving at the second rate, transmits greater force to the mechanism than when moving at the first rate.

A particularly significant and independent aspect of the invention resides in the particular structure of a force transmitting means. This structure comprises first piston means and second piston means having at least first and second, fluid reactive, piston head areas. Coupling means operatively connecting these piston means comprise first cylinder means in which the first piston means is slidably received. The coupling means further includes second cylinder means in fluid communication with the first cylinder means and in which the second piston means is slidably received. The second cylinder means has a rst portion adapted to expose only the first, fluid reactive, piston head area of the second piston means to the pressure of fluid urged by the first piston means from the first cylinder means into the second cylinder means during one portion of the movement of the second piston means. The second cylinder means further includes a second portion which is adapted to expose both the first and second, fluid reactive, piston head areas of the second piston means to the pressure of fluid moved by the first piston means from the first cylinder means into the second cylinder means during another portion of the movement of the second piston means. Gne of the piston means is adapted to move in response to a force applied thereto within a well bore. The other of the piston means is adapted to transmit force to means to be actuated within the well bore.

In describing the invention reference will be made to a preferred embodiment shown in the drawings.

In the drawings:

FIGURE l provides a partially sectioned, schematic, vertical elevation view of an apparatus to be actuated within a well bore, which apparatus includes a setting portion, a force transmitting portion, and a radially expansible packer portion. FIGURE l illustrates the portions of the apparatus prior to the setting of the packer portion;

FIGURE 2 schematically illustrates the portions of the FIGURE l apparatus during the initial part of the setting of the packer portion;

FiGURE 3 schematically illustrates the disposition of the components of the FGURE l apparatus during the terminal part of the setting of the packer portion;

FIGURE 4 provides an enlarged, sectioned, vertical elevational View of operating components of the force transmitting portion of the apparatus shown in FIG- URE l;

FIGURE 5 is a cross sectional view of the FIGURE 4 assembly as viewed along the section line 5 5;

FIGURE 6 is a cross sectional view of the FIGURE 4 assembly as viewed along the section line 6 6;

FIGURE 7 is a cross sectional view of the FIGURE 4 assembly as viewed along the section line 7 7; and

FIGURE 8 is a fragmentary, schematic view of a portion of the FIGURE 4 assembly illustrating representative increments of movement of one annular piston corresponding to and resulting from increments of movement of another annular piston.

FIGURE 1 illustrates an apparatus which includes as its principal components a force generating or setting tool portion 1, a force transmitting portion 2, and a mechanism to be actuated, i.e., packer portion 3.

As illustrated in FIGURE l, the overall apparatus may 3 be supported within a well bore 4 by a cable 5 which extends to a hoist mechanism at the ground surface.

The schematically illustrated setting tool 1 includes a cylinder 6. This cylinder has an upper portion 6a which houses an explosive charge 7 and a lower portion 6b which houses a piston 3. A conventional, explosive charge igniting, electrical device 9 may be mounted in cylinder head c and actuated by an electrical signal transmitted through cable 5. The actuation of ignition device 9 causes the detonation of the explosive charge '7 which generates pressurized gas. This gas, in a well recognized fashion, will force piston S axially downwardly.

Packer portion 3, as schematically illustrated, may include upper slips 10, upper slip expanding blocks 11, lower slips 12, and lower slip expanding blocks 13. Slip expanding

blocks

11 and 13 may function as abutnients engaging the upper and lower ends, respectively, of a radially expansible, resilient, and annular packer assembly 14.

Slips 1t) and 12, expander

blocks

11 and 13, and the annular packer assembly 14 are slidably supported on a mandrel-like, central support 15. An enlarged end a of mandrel 15 provides an annular abutment surface 15b which engages the underside of the lower slips 12 as schematically shown.

As will be apparent, the imposition of converging forces on slips 1t) and 12 will tend -to cause these slips to move generally radially outwardly while -convering toward each other so as to engage the wall ofthe well bore 4. These forces will further tend to cause the radial expansion of the packer assembly 14 into sealing engagement with this well bore wall.

For purposes of illustration, mandrel 15 is shown as extending through the force transmitting portion 2 of the apparatus and as being connected wi-th the cylinder 6 of the setting tool 1.

Mandrel 15 is connected by an annular shoulder 16 to sleeve means 17. This sleeve means, which is coaxially related to mandrel 15, has an upwardly directed sleeve portion 13 extending from shoulder 16 and a downwardly directed sleeve portion 19 extending from shoulder 16.

As shown in FIGURES 4 and 5, sleeve portion 18 is of uniform inner diameter and is radially spaced from the uniform outer diametered mandrel 15 so as to define an upper or first, annular cylinder 20. An annular piston 21 is slidably received within the cylinder and may be connected by a cross-link 22 to a piston rod 23. Piston rod 23 extends downwardy from the setting tool piston 8. Cross-link 22 extends through longitudinal slots 15e and 15d in mandrel 15 so as to be axially or longitudinally slidable and to be able to transmit longitudinal downward movement of the piston 8 through the wall of mandrel 15 to the piston 21.

As shown in FIGURES 4 and 6, sleeve portion 19 includes an upper portion 24 of uniform inner diameter which is radially spaced from mandrel 15 so as to define an upper or first, annular portion 25 of a second or lower, annular cylinder 26. As shown in FIGURES 4 and 7, lower portion 27 of sleeve portion 19 has a uniform inner diameter exceeding the inner diameter `of sleeve portion 24. Sleeve portion 27 is radially spaced from mandrel 15 and is connected to sleeve portion 24 so as to define a second or lower portion 28 of second cylinder 26 which communicates with and defines an extension of the upper cylinder portion 25. In the illustrated arrangement, the inner diameter of sleeve portion 27 is the same as the inner diameter of sleeve portion 1S.

A series of circumferentially spaced, longitudinally extending passages 29, formed in shoulder 16, provide communication between the first cylinder 20 and the upper or first portion 25 of the second cylinder 26. FIGURE 5 illustrates a representative arrangement of these passages in cross section.

A second annular piston 3f? is slidably disposed in second cylinder 26. Piston 3f) includes an upper or first portion 31 which slidably and sealingly engages the upper if cylinder portion 25. Second piston 30 additionally includes a second or lower portion 32 which slidably and sealingly engages second portion 28 of second cylinder 26 and is connected with first piston portion 31.

With the cylinder 20, lpassages 29, and cylinder portion 25 above piston portion 31 filled with fluid, the

pistons

21 and 30 will be in fluid coupled, force transmitting relationship. Downward movement of the piston 21, caused by the explosively induced downward movement of the piston 8, will thus induce downward movement of the piston 31.

The axial length of second portion 28 of the lower cylinder 26 exceeds the axial length of the upper piston portion 31. Thus, the upper piston portion 31 of the second piston 3f) will leave the upper cylinder portion 25 and enter the lower cylinder portion 28 during the downward movement of the piston 30.

As will be apparent, the first portion 25 of second cylinder 26 exposes only the upper or first piston portion 31 to the pressure of fluid moved by the first piston 21 through the passages 29 into the cylinder portion 25 while the piston portion 31 remains in sealing engagement with the cylinder portion 25. When the piston portion 31 has moved axially downwardly out of the cylinder portion 25 and into the cylinder portion 28, both piston portion 31 and piston portion 32 are exposed to the pressure of fluid moved by the piston 21 through the passages 29 into the cylinder 26.

Piston 31 will have a fluid reactive, piston head area equal to its annular cross sectional area, i.e., the cross sectional area of the cylinder portion 25. Thus, with piston 31 in cylinder portion 25, the piston 30 will have an effective iiuid reactive area equal to the cross section of cylinder 20. Piston portion 32 will have an effective, fluid reactive, piston head area equal to its annular cross sectional area less the annular, cross sectional area of the piston portion 31. In other words, the effective liuid reactive, piston head area of the piston portion 32 will equal the cross sectional area of the annular space between the outer wall of the piston portion 31 and the inner wall of the sleeve portion 19. With piston 31 moved into cylinder portion 2S, the effective fluid reactive area of the piston 30 will -be equal to the cross sectional area of the piston portion 32, i.e. cylinder portion 28 which, of course, is equal to the combined, piston head areas of the

piston portions

31 and 32.

As shown in FIGURE 8, the initial movement of piston 21 through the increment X, caused by the explosively induced downward movement of the pist-on 8, piston rod 23, and cross-link 22, will result in movement of the piston 30 through a corresponding but larger increment Y. The ratio of increment Y to the increment X will be proportional to the ratio of the cross sectional area of the cylinder 20 to the cross sectional area of the cylinder portion 25.

After the piston 30 has moved downwardly a sufiicient degree so as to enable the piston portion 31 to leave the cylinder portion 25 and enter the cylinder portion 2S as shown in FIGURE 8, each increment of movement M of the piston 21 will be accompanied by a corresponding and equal increment of movement N of the piston 3f). These equal rates of piston movement in the illustrated embodiment result from the equal cross sectional areas of the annular cylinder 20 and annular cylinder portion 28.

An annular, sleeve-like portion 33 of piston 32 projects downwardly from piston 32 and terminates in an enlarged lower end 34. End 34 provides an annular abutment shoulder 34a which engages the upper end of the upper slips 1f). Abutment 34a moves downwardly, relatively to mandrel 15, in response to relatively downward movement of piston 8 so as to cause the previously noted packer setting convergence of the expander blocks 11 and 13 and the

slips

10 and 12. However, owing to the differences in effective, fluid reactive, piston head areas of the second piston 30 during the initial and terminal portions of the downward movement of this piston, the initial convergence of the

abutments

34a and 15b, as shown in FIG- URE 2, will occur at a relatively rapid rate with relatively low applied force while the terminal portion of this converging movement will occur at a relatively slow rate but with a greater relatively applied force. Thus, during the initial part of the packer setting, where little resistance to slip setting and packer expansion is encountered and where the packer components are most freely movable, the packer components are moved at an efficient, relatively fast rate with an attendant relatively low applied force. During the terminal part of the setting operation shown in FIGURE 3, where greater setting force is required, i.e. where it is necessary to expand the packer into tight fitting sealing engagement with a well bore wall, the packer components are moved with maximum applied force but at an attendant relatively slow rate.

As shown, annular piston 21 projects upwardly out of the upper open end of cylinder so as to extend upwardly away from the passages 29 and be subject to the pressure of well bore fluids surrounding the apparatus. Similarly, sleeve portion 33 of piston portion 32 projects downwardly out of the lower open end of cylinder 26 so as to project downwardly away from the passages 29 so that piston 3f) will also be subject to the pressure of well bore fluid surrounding the apparatus.

Where, as in the illustrated embodiment,

sleeve portions

18 and 19 are of uniform and the same diameter, the cross sectional areas of cylinder portions 2f) and 28 will be the same. In these instances the portions of the

pistons

21 and 39, which are subject to the pressure of well bore fluid, will have the same effective fluid reactive areas exposed to well bore fluids. As a result, the pressure of well bore fluid exerted on the upper and lower ends of the

pistons

21 and 30, respectively, will have a substantially counter-balancing effect on these fluid coupled pistons. While the difference in elevation of the

pistons

21 and 30 will provide some net, upward force resulting from the hydrostatic pressure of the well bore fluids. this upward force will 'be of relatively minor consequence.

Prior to describing the overall mode of operation of the apparatus, specic structural details of the force transmitting apparatus portion 2 which are not illustrated in FIGURE l should be discussed with reference to FIG- URE 4.

FIGURE 4 illustrates a representative manner in which the sleeve means 17 may be associated with the mandrel 15 so as to provide the

annular cylinders

20 and 26.

As shown in FIGURE 4, sleeve 17 is provided with the radially inwardly directed, annular shoulder 16. Shoulder 16 has an internally threaded coupling portion 35 which is threadably engaged with an externally threaded coupling portion 36 formed on mandrel 15. An annular, radially outwardly projecting mandrel shoulder 27 provides an abutment surface against which the lower edge of the shoulder 16 may come to rest, and thus be secured. As illustrated, the passages 29 may extend below the shoulder 16 and partially into the wall of the body of the mandrel 15 so as to terminate in communication with an annular opening 38 which defines the uppermost portion of the upper portion of the lower annular cylinder 26.

In order to insure that the

pistons

21 and 30 remain in fluid coupled relationship and are not adversely influenced by the pressure of well bore fluids surrounding the apparatus, check valve means are incorporated in the apparatus. Such check valve means are adapted to allow well bore fluids to flow into each of the cylinders 2f) and 26 and are further adapted to prevent an outflow of fluid from these cylinders.

As shown in FIGURE 4, in the preferred embodiment of the force transmitting mechanism 2, the check valve means comprise first and

second check valves

39 and 49 which comprise portions, respectively, of the

pistons

21 and 30.

As shown in FIGURE 4, check valve 39 comprises an annular support ring 41 to which is secured, by conven tional means, a generally annular and resilient, flexible seal 42. Seal 42 may be fabricated of resilient material such as rubber or neoprene. Seal 42 includes a cylindrical portion 42a which is secured to the supporting ring 41 and a free-lip portion 42b having a generally downwardly converging, frustoconical configuration. As illustrated, the lip portion 42h wipingly and sealingly engages the outer surface -of the mandrel 15. Support ring 41 may be secured in an annular notched portion 43 on the lower end of piston 21 by conventional fastening means Ilot shown.

As illustrated, valve 39 is so mounted that the cylindrical portion 42a of flexible seal 42 is slightly radially spaced from the outer periphery of the mandrel 15. As will be further noted by reference to FIGURE 4, the inner surface of the piston 21 may be substantially aligned with the inner surfaces of the seal portion 42a and the supporting ring 41 so as to define an annular channel 44 which is sealed from the cylinder 29 below the head of piston 21 only by the lip portion 42!) of the flexible seal 42. One or more radially extending ports 45 may be provided which intersect the wall of the annular piston 21 so as to communicate with the passage 44. In this fashion, a circuit of fluid communication between the cylinder 20 and the exterior of the mechanism 2 is provided, with flow through this passage being controlled by the check valve functioning, seal lip portion 42h. As will be appreciated, with the downwardly converging frustoconical configuration of the seal lip portion 42h, fluid will be prevented from flowing out of the cylinder 20 by the seal lip 42b while fluid from the exterior of the tool may flow into the interior of the `cylinder 2f! when the pressure of the well bore fluid exceeds that of the coupling fluid contained within the cylinder 20. It will be apparent, of course, that fluid which enters the cylinder 2f) may also flow through the passages 29 so as to fill the upper portion 25 of the lower cylinder 26 if necessary.

Lower check valve 40 is structurally and functionally similar to upper check valve 39 and includes an annular support ring 46 and an annular, flexible and resilient seal 47 which may be fabricated from material such as rubber or neoprene. Seal 47 includes a cylindrical portion 47a which is secured to support ring 46 and an upwardly diverging, `free lip portion 47b which extends from the top of the seal portion 47a into wiping and sealing engagement with the inner wall of the sleeve portion 27.

As illustrated, the cylindrical seal portion 47a, the periphery of the mounting ring 46, and the periphery of the annular cylinder portion 32 are spaced radially inwardly from the inner wall of the sleeve portion 27 so as to define an annular passageway 48 which is adapted to communicate with the cylinder portion 28 above the piston 32. Fluid flow through this passageway is controlled by the seal lip portion 47h. Passageway 48 communicates with the exterior of the mechanism, i.e. with well bore fluid, through passageway means such as the illustrated space 49 between the lower edge of the sleeve portion 27 and the top of the enlarged sleeve portion 34. As will be appreciated, the upwardly diverging character of the seal lip 47b will serve to prevent the flow of fluid out of the cylinder portion 28 while allowing well bore fluid from the exterior of the apparatus to flow through the passage 48 into the cylinder portion 28.

With the check valve arrangement heretofore described, the apparatus may be lowered into a fluid filled well ybore without any `coupling fluid being initially contained within the

cylinders

26 and 26. Upon being immersed in the Well bore fluid, these cylinders will automatically fill in response to the pressure differentials existing across the seal lip portions 42h and 4711. This check valve arrangement also insures that the cylinder cavities will remain constantly fully filled so that there will always exist an effective, pressure transmitting fluid coupling between the

pistons

21 and 30.

In describing a preferred apparatus embodiment, several advantages of the invention have been demonstrated.

A foremost advantage of the invention resides in the manner in which the force transmitting mechanism causes the setting components of an apparatus to move relatively rapidly and with relatively low applied force when the apparatus offers relatively low resistance to setting and the setting components of the apparatus are most freely movable. An especially significant facet of the invention involves the manner in which the force transmitting mechanism automatically causes apparatus setting components to under a change in rate of movement, accompanied by a change in rate of applied force, so that while apparatus components are least freely movable and offer the greatest resistance to setting, they are moved at a relatively' low speed but with relatively great applied force.

Another significant aspect of the invention involves the manner in which the check valves associated with the tWo pistons of the force transmitting mechanism enables the apparatus to be lowered into a iiuid filled well bore even though not containing coupling liuid. Once immersed in the fiuid, with there being a sufficient diierence in pressure between the well bore fluids and the cylinder interiors efiective to open the check valves, well bore fiuid will automatically flow into and till the cylinders. This check valve arrangement will also insure that the cylinders will remain filled throughout the operation of the apparatus so that the pistons of the force transmitting mechanism will remain constantly in fluid coupled relationship.

An additional noteworthy aspect of the invention involves the manner in which the two piston of the force transmitting mechanism may be exposed to the well bore fluids but remain substantially pressure balanced.

It is also apparent that the force transmitting mechanism, While characterized by overall structural simplicity, Will also be characterized by operational reliability.

While the invention has been described with reference to a preferred embodiment, it will be apparent that the utility of the force transmitting mechanism is not limited to the setting Of the illustrated packer embodiment. It will also be apparent that the invention is not limited to the illustrated dimensional relationships of the various piston and cylinder components of the force transmitting mechanisms, to the illustrated piston, cylinder, configurations and seal to the use of a multi-stepped piston having two reactive areas, or to the use of the specically illustrated check valves.

In describing the invention, various apparatus elements, normally multi-component in character, have been shown as unitary assemblies so as to avoid structural complexity which might obscure the invention.

Those skilled in the art and familiar with the disclosure of the invention may well recognize additions, deletions, substitutions and modifications which would be within the purview of the invention as defined in the appended claims.

I claim:

1. An apparatus for use in a well bore, said apparatus comprising:

force generating means including an actuating means and operable within a well bore to move said actuating means;

a mechanism to be actuated within said well bore; and

force transmitting means operatively disposed between said actuating means and said mechanism and including first means movable in response to movement of said actuating means, second means movable in response to -movement of said rst means and adapted to actuate said mechanism, and coupling means operably connecting said first and second means and Iadapted to cause said second means to initially move at a first rate more rap-id than the rate of movement of said first means and thereafter move at a second rate slower than said first rate, said second means While moving at said second rate transmitting greater force to said mechanism than when moving at said first rate.

Cil

2. An apparatus as described in claim 1: wherein said actuating means comprises actuating piston means; wherein said force generating means includes cylinder means housing said actuating piston means, and explosive means contained within said cylinder means and adapted to generate gas within said cylinder means so as to move said actuating piston means; wherein said mechanism includes radially expansible packer means, and axially movable abutment means adapted to axially compress said packer means to effect the radial expansion thereof: wherein said first means of said force transmitting means comprises first piston means: wherein said second means of said force transmitting means comprises second piston means having first and second, fiuid reactive, piston head areas; and wherein said coupling means includes first cylinder means in which said first piston means is slidably received, second cylinder means in fiuid communication with said first cylinder means and in which said second piston means is slidably received, said second cylinder means having a first portion adapted to expose only said first fiuid reactive, piston head area of said second piston means to the pressure of fluid urged by said first piston `means from said first cylinder means into said second cylinder means during the initial move- Kment of said second piston means, and said second cylinder means further having a second portion adapted to expose both the first and second, fiuid reactive, piston head areas of said second piston means to the pressure of tluid moved by said first piston means from said first cylinder means into said second cylinder means during the terminal movement of said second piston means. 3. An apparatus -as described in claim 2 including: first check valve means adapted to prevent fiuid fiow out of said first cylinder means but allow well bore fiuid surrounding said apparatus to fiow into said first cylinder means; and second check Valve means adapted to prevent fiuid ow out of said second cylinder means but allow well bore fiuid surrounding said apparatus to fiow into said second cylinder means. 4. A force transmitting mechanism for use in a well bore, said mechanism comprising:

first piston means; second piston means having at least first and second,

fluid reactive, piston head areas; first cylinder means in which said first piston means is slidably received; second cylinder means in tiuid Communication with said first cylinder means and in which said second piston means is slidably received; said second cylinder means having a first portion adapted to expose only said first fiuid reactive, piston head area of said second piston means to the pressure of uid urged by said first piston means from said first cylinder means into said second cylinder means during one portion of the movement of said second piston means; and said second cylinder means further having a second portion adapted to expose both the first and second, fiuid reactive, piston head areas of said second piston means to the pressure of fluid moved by said rst piston means from said first cylinder means into said second cylinder means during another portion of the movement of said second piston means; one of said piston means being adapted to move in response to a force applied thereto within a well bore; the other of said piston means being adapted to trans- -mit force to means to be actuated within said well bore. 5. A mechanism as described in claim l including: first check valve means adapted to prevent Fluid flow out of said first cylinder means but allow well bore Huid surrounding said mechanism to ow into said rst cylinder means; and second check valve means adapted to prevent uid ow out of said second cylinder means but allow well bore uid surrounding said mechanism to How into said second cylinder means. 6. A force transmitting mechanism for use in a well bore, said mechanism comprising:

mandrel means; sleeve means having portions radially spaced from said mandrel means to define with said mandrel means, in consecutive, axially spaced relationship,

first, annular cylinder means, and second, annular cylinder means; passage means providing7 fluid communication between said rst `and second cylinder means; rst, annular piston means axially slidable in said first,

annular cylinder means; and second, annular piston means axially slidable in said second, annular cylinder means; said second, annular cylinder means having a iirst, annular portion facing and communicating with said passage means, and a second, annular portion having a cross sectional area exceeding that of said first, annular portion and defining an extension of said second, annular portion leading away from said passage means; and said second, annular piston means having a first, annular portion slidable within said nrst, annular portion of said second, annular cylinder means in substantially sealing engagement therewith, and a second, annular portion slidable within said sec- 0nd annular portion of said second, annular cylinder means in substantially sealing engagement therewith, the axial length of said first, annuar portion of said second, annular piston means being such that, prior to the end of the axial movement of said second, annular piston means away from said passae means, said rst, annular portion of said second, annular piston means leaves said first, annular portion of said second, annular cylinder means and enters said second, annular portion of said second, annular cylinder means;

said first, annular piston means being adapted to move in response to a force applied thereto within a well bore;

said second, annular piston means being adapted to transmit force to means to be actuated within said well bore.

7. A mechanism as described in claim 6:

wherein said rst, annular piston means has a portion projecting out of said rst annular `cylinder means, extending in one direction away from said passage means, and subject to the pressure of well bore fluid surrounding said mechanism;

wherein said second portion of said second annular piston means has a portion projecting out of said second portion of said second, annular cylinder means, extending in a direction opposite to said one direction away 'from said passage means, and subject to the pressure of well bore fluid surrounding said mechanism; and

wherein the cross sectional area of said rst, annular cylinder means is substantially the same as the cross sectional area of the second portion of said second, annular cylinder means.

S. A mechanism as described in claim 7:

wherein said first, annular piston means includes rst, annular flexible seal means disposed in slidable and sealing engagement with said first, annular cylinder means and adapted to allow well bore fluid surrounding said mechanism to flow into said rst cylinder means and further adapted to prevent a flow of fluid out of said first cylinder means; and

wherein said second portion of said second, annular piston means includes seco-nd, annular exible seal means slidably and sealing engaging said second portion of said second, annular cylinder means and adapted to allow well bore fluid surrounding said lmechanism to ow into said second, annular cylinder means and further adapted to prevent -a ow of fluid out of said second cylinder means.

References Cited by the Examiner UNTED STATES PATENTS 2,881,841 4/1959 Page 166-212 3,l38,207 6/1964 Peppers 166-63 3,193,013 7/1965 Whiteside 166-63 3,266,575 8/1966 Owen 166-63 CHARLES E. OCONNELL, Primary Examinez'.

I. A. LEPPNK, Assistant Examiner'.

Claims

1. AN APPARATUS FOR USE IN A WELL BORE, SAID APPARATUS COMPRISING: FORCE GENERATING MEANS INCLUDING AN ACTUATING MEANS AND OPERABLE WITHIN A WELL BORE TO MOVE SAID ACTUATING MEANS; A MECHANISM TO BE ACTUATED WITHIN SAID WELL BORE; AND FORCE TRANSMITTING MEANS OPERATIVELY DISPOSED BETWEEN SAID ACTUATING MEANS AND SAID MECHANISM AND INCLUDING FIRST MEANS MOVABLE IN RESPONSE TO MOVEMENT OF SAID ACTUATING MEANS, SECOND MEANS MOVABLE IN RESPONSE TO MOVEMENT OF SAID FIRST MEANS AND ADAPTED TO ACTUATE SAID MECHANISM, AND COUPLING MEANS OPERABLY CONNECTING SAID FIRST AND SECOND MEANS AND ADAPTED TO CAUSE SAID SECOND MEANS TO INITIALLY MOVE AT A FIRST RATE MORE RAPID THAN THE RATE OF MOVEMENT OF SAID FIRST MEANS AND THEREAFTER MOVE AT A SECOND RATE SLOWER THAN SAID FIRST RATE, SAID SECOND MEANS WHILE MOVING AT SAID SECOND RATE TRANSMITTING GREATER FORCE TO SAID MECHANISM THAN WHEN MOVING AT SAID FIRST RATE.