US3467183A

US3467183A - Retrievable well packer

Info

Publication number: US3467183A
Application number: US703946A
Authority: US
Inventors: David E Young
Original assignee: Schlumberger Technology Corp
Current assignee: Schlumberger Technology Corp
Priority date: 1968-02-08
Filing date: 1968-02-08
Publication date: 1969-09-16
Anticipated expiration: 1986-09-16

Description

Sept. 16, 1969 D. E. YOUNG RETRIEVABLE WELL PACKER his ATTORNEYS Sept. 16, 1969 D. E. YouNG 3,467,183

RETRIEVABLE WELL PACKER Sept. 16, 1969 D. E. YouNG RETRIEVABLE WELL PACKER 4 Shees--Sheei 3 Filed Feb. 8. 1968 DAVID E. YOUNG m' 7 l Z Z .wrom/frs his Sept. 16, 1969 D. E. YOUNG 3,467,183

RETRIEVABLE WELL PACKER Filed Feb. 8. 19758 y 4 Sheets-Sheet 4 '022 (0l ,OZ I04 o onIIIIHHIlHI' 94 84 l 90 l 62 48 74a f 64 ll4 l A 5 4 F ZZ lm/lfwm/e. DAVID e. YOUNG 52 m' m M 44 E 'tiff ,l

4A his v,arrof/VEYS United States Patent O U.S. Cl. 166-121 17 Claims ABSTRACT F THE DISCLOSURE A well tool, according to the exemplary embodiments, is of a type adapted to be anchored in a well conduit against both upward and downward movement and cornprises a body, packing elements for packing off the annulus and an anchoring structure in the form of a single expander and a set of coacting slips mounted for movement longitudinally yof the body toward and away from each other between limit positions. The expander and slips are both equipped with friction drag blocks which engage the conduit wall and impede their movement through the well. Upon a fluid pressure condition which tends to move the well tool body in a direction to move the expander towards the slips, the friction drag associated with the slips precludes movement of the slips and aiords relative movement between the expander and slips so as to engage the slips in anchoring engagement with the well conduit. Under pressure conditions tending to move the tool in the opposite direction, namely, to move the slips toward the expander, the expander is forced toward the slips by a higher pressure acting in a uid chamber of variable volume, one wall formation of which is an element on lthe expander and constitutes a moving wall of the chamber. Accordingly, the higher pressure within the chamber than the pressure outside causes the expander to be moved toward and under the slips to wedge the slips into anchoring engagement with ythe well bore wall. The tool further includes a control mechanism for maintaining the slips and expander in inactivated condition when the tool is run into or retrieved from the well and for releasing the expander from engagement with the slips to release the tool for movement in the well, a fluid passage for bypassing fluids through the tool when it is moved in the well, and valving in the passage for bridging the conduit.

BACKGROUND OF THE INVENTION This invention relates to a well tool of the type that is adapted to be lowered into a well conduit, anchored in the well conduit against both upward and downward movement, released from and moved in the conduit and ultimately retrieved.

In many operations performed in a well, such as fracrturing, acidizing, squeeze cementing, testing and vother remedial, stimulation and production operations, various forms of well tools of the type that can be anchored to a well conduit are employed. For example, certain operations employ a lower tool, commonly known as a bridge plug, to seal or pack olf fully the entire cross-section of the well or an upper tool or so-called well packer to isolate an annular space between the casing and a tubing string communicating the well surface with a zone below the packer from the remainder of the well, or both of these tools. Various forms of bridge plugs and packers having been proposed and used for these operations. Many of the tools are of the so-called retrievable type which are capable of being lowered into the well bore, manipulated to anchor them to the well casing or other well conduit, released after use, and moved to another location or retrieved from the Well.

"ice

The anchoring mechanisms used in some retrievable tools of the type that are anchored to the Well bore in a manner which precludes movement of the tool in either direction employ two sets of slips, each of which is associated with an expander. In one form of such tools, the expanders are spaced from each other and are tapered inwardly toward each other, the slips being located between the expanders and the spacing between the expanders being suicient to afford movement of the slips relative to the expanders. The upper expander and upper set of slips coact to anchor the tool against downward movement, while the lower expander and lower set of slips coact to anchor the tool against upward movement in the Well bore. Associated with the `two sets of slips are friction drag elements that engage the well bore wall and impede the movement of the slips relative to the expanders, and an appropriate control mechanism is provided to either maintain the slips in a de-activated position relative to the two expanders or to permit movement of the slips relative to the expanders so that the tool may become anchored in the well. The tools of this type involve selective operation of the slips, only one set of slips being engaged at any given time, depending -upon whether the tool is anchored against downward movement or upward movement.

In many operations the pressure differential across the tool may shift and thereby require that one set of slips and the expander associated with that set be released from anchoring engagement with the well bore wall and ythe other set of slips and the associated expander be engaged to anchor the tool against movement in the other direction. The shifting of the anchoring function from one set of slips to the other requires the tool body to move longitudinally in the well bore and also involves, in the course of shifting,A a stage or period at which neither set of slips is anchored to the well bore wall and in which opportunity for movement of the entire tool a substantial distance up or down the well is aorded. In many instances it is important that the tool be located and remain relatively precisely at a predetermined level in the well, `and movement of the well tool =upon a change in pressure conditions can have serious consequences.

Summary of the invention There is provided, in accordance with the invention, a retrievable well tool which includes an anchoring structure of the type adapted to anchor the tool against both upward and downward movement in the well, the anchoring mechanism having but one set of slips and an expander which coact to anchor the tool against both upward and downward movement and remain set in anchored engagement regardless of a shift in pressure conditions that changes the direction in which the slips are holding. The expander and slips `are both mounted for movement longitudinally on a tool body which includes abutments that engage the expander and slips and limit the extent of their movement away from each other as well as transmit forces and motion from the body to them. The abutments are located so that the expander and slips are in inactive relation, with the slips withdrawn from engagement with the well conduit, when they are engaged with the slips and expander, respectively.

The tool further includes packing elements, preferably of the cup-type which engage land seal the annulus between the tool and conduit. Associated with the expander and the slips are friction drags, such as spring-loaded friction drag blocks, which engage the well conduit and impede the movement of the expander and slip structure, respectively, through the conduit. A control mechanism maintains the slips and expander in inactive positions when the tool is being run into, moved in, or retrieved from the well, is operable to permit movement between the eX- pander and slips toward each other so that the slips are expanded outwardly into gripping engagement with the well conduit. The control mechanism is, desirably, operable solely by longitudinal movements, so that the tool can be used with a wire line, as well as with tubing, and comprises control elements which selectively (a) prevent movement of the expander relative to the body, (b) prevent movement of the slips relative to the body, or (c) permit the slips, expander and body to move relative to eachother so that the slips can become anchored to the conduit.

Upon movement of the tool body in a direction to cause the expander to be engaged by the corresponding abutment and moved toward the slips, the slips are impeded from moving in the conduit with the body by the friction drag element, thereby effecting relative movement between the expander and the slips so that the slips rare forced outwardly into anchoring engagement with the conduit. Movement of the body in the other direction so that the abutment associated with the slips engages the slips and causes them to move tow-ard the expander similarly moves the slips into gripping engagement with the well conduit, the expander being impeded from moving with the body and slips by the friction drag elements associated with it. However, even when the slips engage the conduit, the expander is relatively free to move inasmuch as the only impediment to its movement is provided by the friction drag elements, and the slips may thus slide along the conduit and the tool shift out of position. Accordingly, the tool of the invention further includes a fluid pressure system for urging the expander toward the slips when the body and slips are subjected to pressure conditions forcing them toward the expander.

In the foregoing respects the well tool of the invention is similar to that disclosed in the copending application of James W. Kisling III, Ser. No. 703,947, filed concurrently herewith, and assigned to the same assignee as this application. The tool of this invention, however, embodies certain distinct features and improvements.

More particularly, the fluid pressure arrangement in a tool according to the present invention comprises a fluid chamber of variable volume defined by formations on the body and associated with the expander, a part of the expander formation constituting a moving wall of the chamber, and the interior of the chamber communicates with the higher pressure zone in the well bore on the side of the packing which holds against pressure tending to move the body and slips toward the expander, while the exterior of the chamber communicates with the lower pressure zone on the other side of the packing. The higher pressure within the chamber shifts the expander toward the slips to urge them into firm anchoring engagement with the (conduit.

In the tool -according to the invention the control mechanism preferably includes a longitudinally shiftable control mandrel carried in a passage through the body, a sleeve member slidable on an external surface of the body between limit positions established by spaced-apart labutments on the body, and a cross bar coupled to the mandrel, extending out through openings in the body and coupled to the sleeve member. The sleeve member is sealed to the body so that well fluids cannot communicate between the body passage and the annulus between the body and conduit. In one position, the sleeve engages the body and expander to prevent relative movement between them, while in another position the sleeve engages and prevents relative movement of the body 4and slips. In the intermediate or neutral position, the sleeve permits relative movement of the body, slips and expander so that they can shift relative to each other and provide the coaction between the expander and slips that affords anchoring engagement of the slips with the conduit,

In a preferred emobdiment the tool further includes 4a valve arrangement which selectively closes off communication of well fluids through the body passage, thus rendering the tool a retrievable bridge plug. The valve arrangement desirably is composed of upper and lower one-way valves operable selectively to close ott passage of well fluids in either direction. The valves are controlled by the control mandrel. As a further feature, communication between `the part of the passage between the valves and the part of the annulus (between the body and well conduit) between the two packer elements is provided, thereby allowing well fluids to ow from passage into the space between the packer elements. This ensures that the uid pressure in the annulus between the packers does not drop below the ambient well pressure as the tool is moved through the well, which would, if it occurred, force the packer elements tightly into engagement with the conduit and considerably accelerate wearing of the packer elements.

Description of the drawings For a better understanding of the invention, reference may be made to the following description of an exemplary embodiment, taken in conjunction with the figures of the accompanying drawings, in which:

FIGS. 1A and 1B, taken together end-to-end in that order, make up a half-sectional, half-elevational side view of the tool, the tool being shown in its configuration when it is being moved downwardly through the well conduit;

FIGS. 2A and 2B, taken together end-to-end in that order, make up a half-elevational, half-sectional side view of the tool, showing it anchored against downward movement in the well conduit;

FIG. 3 is a half-elevational, half-sectional side view of the major portion of the tool, showing it anchored against upward movement in the conduit; and

FIGS. 4A and 4B, taken together end-to-end in that order, make up a half-elevational, half-sectional side view of the tool in its configuration `when it is being moved upwardly through the conduit.

Description of exemplary embodiment The embodiment of the well tool illustrated in the drawings and described below is a retrievable bridge plug of the type that can be lowered into a well conduit using a suitable coupling tool, released from the coupling tool at a desired location, and, upon any pressure differential in the well, anchors to the conduit wall against movement in either direction and seals olf the conduit against the passage of well uids in either direction 4across the tool.

The retrievable bridge plug, in the form illustrated in the drawings, is designed for use in a cased well, a portion of the well c-asing being illustrated in the drawings and being designated generally by the reference numeral 10, but `a similar tool can be used in other well conduits, such yas tubing. The retrievable bridge plug includes an elongated body 12, which will generally be made up of a number of sections joined together by threaded or other appropriate forms of connections. For simplification, the several sections making up the body 12 are not depicted in the drawing. A central bore 14 extends substantially the entire length of the body 12 and is communicated by a series of circumferentially spaced ports 16 formed in a head section 18 of the body with the portion of the casing above the tool and is communicated through similar ports 20 in a bottom section 22 of the body with the part of the casing below the tool.

Adjacent the upper end of the housing bore 14 are two

valve housing cavities

24 and 26, each of which contains a spring-loaded

bypass valve element

28 and 30, respectively. The upper valve 28 is urged downwardly by a spring 32 into engagement with a seat 34 formed on the body, while the lower valve 30 is urged upwardly by a spring 36 into engagement with -a seat 38. In FIGS. lA

and 1B, the valves are shown in their open positions in which they afford the passage of Well fluids from below the tool through the ports 20, upwardly through the central bore 14, past the

halves

28 and 50` and out into the zone of the well above the tool through the ports 16. As described below, the bypass valves are kept open as the tool is moved downwardly or upwardly in the conduit, but are forced closed by the

springs

32 and 36 when the tool is released from the coupling tool used to move it in the cond-uit.

Mounted near the upper end of the body is an upper cup-type packer element 40 which is constructed and is mounted on the tool such that it stops fluid passage through the annulus between the tool and casing in a downward direction, i.e., holds pressure from above. At the lower end of the body is a lower packer element 42 which holds pressure from below. The

packer elements

40 and 42 may be of any appropriate specific design, many of which are well known to those skilled in the art, and therefore the details of their construction and installation on the tool need not be described here. It suices to say that a portion of the outer perimeter of each of the

packer elements

40 or 42 engages the inner surface of the well casing and is sealed to the tool body in a manner forming a seal against the passage of fluids through the annulus in a direction against the concave side of the cup part.

Between the two packer elements is an anchoring structure which is composed of an expander member, designated generally by the reference numeral 44, and a series of circumferentially spaced-apart slips 46 forming a part of a slip structure designated generally by the reference numeral 48. The expander member 44 includes downwardly and inwardly tapering expander surfaces 50 at its lower end, one such surface for each slip 46, and a sleeve portion 52 extending upwardly from the expander surface portion. A series of circumferentially spaced-apart friction drag shoes or blocks 54, each of which is urged outwardly into engagement with the casing by springs 56, are carried by the sleeve portion 52. The expander member 44 is mounted for longitudinal movement on the body 12, but the upward movement of the expander member relative to the body is limited by an abutment 58 on the body which engages the upper end of the sleeve portion 52, and an abutment 59 which engages an inturned flange formation 60 on the lower end of the expander.

The slip structure 48 includes the slips 46, a housing or mounting member 62 which is slidable on the body and a series of spring-loaded friction drag blocks 64. In the embodiment illustrated in the drawings, the slips 46 are of the type which dove-tail with the expanders by appropriate rib and groove formations on the slips and the expander, and they are linked to the mounting member 62 by links or so-called reins 66. The extent of downward movement of the slip structure 48 on the body is limited by an abutment 68 on the body which engages the lower end of the slip mounting member 62.

The

abutments

58 and 59 associated with the expander and the abutment 68 associated with the slip structure 48 are spaced widely enough apart so that the slips remain retracted inwardly from the well casing, by virtue of the slips being relatively widely separated longitudinally from the expander, when the expander and slip structures engage the respective abutments.

The retrievable bridge plug is controlled by a control mechanism which includes a vcontrol mandrel 70 extending from above the top of the body 12 down through the central bore 14 through the tool body to a point near the bottom of the body. At the upper end of the control mandrel 70 is a fitting 72 which is complementary to and coacts with a releasable coupling device (not shown) by whichthe'tol is moved through the well. The coupling device may be of various types, such as a suitable J-slot coupling, and may be of the type that is used with either a wire line (cable) or a tubing string by which the tool is run into, manipulated in and removed from the well.

Between the two valve elements 28 and 30 (which, it should be mentioned, are ring-like members surrounding and sealed to the mandrel) are

flanges

74a and 74b, and at the lower end of the mandrel 70 is an elongated slot 76 which receives a cross-piece 78 that extends across the bore 14 and protrudes out through elongated slots 80 formed in the body. The outer ends of the cross-piece 78 are received in slots or grooves 82 formed in a sleeve member 84 which surrounds the body and is slidable on the body between limit positions established by the abutment 59 on the body above the sleeve member and by an abutment 88 below the sleeve member. The sleeve member 84 further includes an outwardly extending flange portion 90 which is received in an elongated annular recess 92 formed in the inner surface of the slip mounting member 62, the flange 90 being movable longitudinally in the recess 92 between

shoulders

94 and 96 constituting the upper and lower extremeties of the recess 92. The sleeve is sealed to the outer surface of the body above and below the slots 80 (in all positions of the sleeve member 84) by

seals

97 and 98 so that fluid communication between the body passage 14 and the annulus between the tool and the conduit is precluded.

The tool is moved downwardly in the well by pushing down on the control mandrel 70, through the medium of the coupling tool and pipe, or by weights associated with the coupling tool when wire line is used. A downward force on the mandrel 70 pushes down on the cross-piece 78, thereby, as shown in FIGS. 1A and 1B, engaging the lower end of the sleeve 84 with the lower abutment 88 on the tool body and engaging the lower end of the flange 90 on the sleeve with the shoulder 96 on the slip housing 62. In the meantime, the flange 74b near the upper end of the mandrel engages the top of the lower bypass valve element 30, thus unseating it and permitting well fluids to pass upwardly through the bore 14 in the body. The pressure of the iluid created as the tool moves down forces the upper valve element 28 to open against its spring 32 and bypass the fluid through the bore and out through the ports 16.

The downward force on the control mandrel 78 is transmitted to the tool body 12 and slip structure 48 through the sleeve 84, and `the body and the slip structure are therefore pushed downwardly through the casing together as a unit. The body 12 resists downward movement by virtue of the frictional engagement between the friction drag elements 54 on the expander structure 44 with the well bore casing, thereby causing the expander structure to assume a supporting position for the body by engagement of its upper end with the abutment 58 on the body and at the same time maintaining itself separated from the slips. In addition, the

packing elements

40 and 42 provide additional support for the tool against downward movement into the well. Consequently, the tool supports itself in the casing and must be pushed down. The configuration of the tool when it is being moved downwardly in the casing is illustrated in FIGS. 1A and 1B.

When the desired location at which the retrievable bridge plug is to be set has been reached, the coupling tool is detached from the titting 72 at the upper end of the control mandrel 70 or, at least, the control mandrel is otherwise appropriately released from downward force. When this occurs, the spring 36 acting through the valve element 30 on the flange 74b of the control mandrel 70 pushes the mandrel upwardly relative to the body and at the same time causes the lower valve 30 to engage and lseat on the lower valve seat 38. Accordingly, the upward passage of well fluids through the tool bore or passage 14 is terminated. The upper valve 28 is also urged closed by its spring 32 into seating engagement on the upper valve seat 34. The conjunction with the sealing action of the

packer elements

40 and 42, the closing of the

bypass valves

28 and 30 blocks the passage of well fluids in either direction between the portions of the well above and below the bridge plug or, in other words, bridges the casing.

Upon movement of the control mandrel 70 upwardly relative to the body, as described in the preceding paragraph, the slot 76 at its lower end assumes a position generally aligned with the slots 80 in the body so that the cross-piece 78 is freely movable through the two

slots

76 and 80, and the sleeve 84 is similarly free to move. Accordingly, the control mandrel 70, cross-piece 78, and sleeve are in a neutral condition in which they permit movement of the expander and slip structure relatively toward each other at any time that a force on the tool body in either direction exceeds the resisting force of the friction drag blocks 54 or 64 plus other forces, such as the frictional forces of the packer elements, which are then resisting the movement.

More particularly, inasmuch as the tool now constitutes an obstruction or bridge against the passage of well fluids in either direction across it, it acts as a piston in the casing and responds to the existence of any forces due to a differential between the pressures of the well fluids in the casing above and below the tool by tending to move upwardly or downwardly toward the lower pressure zone. For example, if a higher pressure is created in the zone of the well above the tool, such as by pumping iluids down the casing or a tubing string, the differential pressure may and usually does (depending on the magnitude of the differential) create a net downward force on the tool tending to move it downwardly through the casing. The downward movement of the tool body brings the abutment 58 into engagement with the upper end of the expander structure 44 and pushes the expander down. Meanwhile, the slip structure 48 is supported against downward movement with the other parts of the tool by frictional engagement of the drag blocks 64 with the casing wall. Consequently, the expander structure 44 is shifted downwardly relative to the slip structure 48, thereby causing relative sliding movement between the tapered surfaces of the slips and expander, and the slips are therefore forced outwardly into anchoring engagement with the well casing. After the relatively small downward shifting of the tool required to wedge the slips outwardly so that they grip and hold the casing, the tool is precluded from moving further down the casing and is anchored against downward movement. The configuration of the tool when it is anchored against downward movement, in other words when it is anchored and sealed against a higher pressure in fluids above the tool than below, is illustrated in FIGS. 2A and 2B.

Starting again with the retrievable bridge plug in the neutral position described above, that is, referring back to the point at which the tool was initially uncoupled from the coupling device and the control mandrel 70, cross-piece 78, and sleeve 84 assumed a neutral position, the creation of a higher pressure below the tool than above, such as higher pressure created by a producing formation below the tool or by a swabbing operation in the casing above the tool, similarly results in anchoring the tool against movement in the well, in this case against upward movement (see FIG. 3). The differential pressure across the tool creates forces on the tool body tending to move it upwardly through the 'well (the piston effect), thus engaging the abutment 68 adjacent the lower end of the tool body 12 with the lower end of the slip structure mounting sleeve 62 and pushing the slip structure 48 upwardly with the body. Meanwhile, the friction drag blocks 54 on the expander member 44 keep the expander member from moving up with the remaining parts of the tool, thereby affording relative movement of the slips upwardly along the expander surface 50 and consequently causing them to be forced outwardly into engagement with the well casing. When the slips engage the well casing, their upward movement with the tool is somewhat restricted; however, the structure as described thus far provides resistance against upward movement of the expander with the slips only by the friction forces of the expander drag blocks 56. In this regard, once the slips engage the casing wall, their further upward movement is impeded, not by firmly biting into the casing by wedging action but by relatively light outward force at this point. Firm anchoring engagement is not certain to occur and the slips and expander may drag up along the casing wall. This problem does not arise when the expander is pushed down under the slips, as in the normal setting against pressure from above the tool or as provided for in the further structural and functional features of the tool described below.

A downward force on the expander toward the slips is provided by a fluid pressure arrangement, thereby wedging the slips out into firm anchoring engagement with the casing. The fluid pressure system includes an internal recess on the expander sleeve which is in sliding relation to and is sealed by an O-ring 101 with a flange formation 102 on the body. The recess 100 defines, in part, a fluid chamber 104 (see FIG. 3) which is further defined by the lower face 106 of the flange 102, awall 108 constituting the lower end of the recess 100 and a portion 110 of the outer wall of the tool body 12 facing the inner surface of the recess 100. The interior of the fluid chamber 104 communicates with the bypass passage 14 of the body through one or more radial ports 112. Inasmuch as the passage 14 is communicated to the zone of the well below the tool (the higher pressure zone at this point) the interior of the chamber is at substantially the same higher pressure as the zone of the well below the lower packer. The exterior of the chamber 104, however, is located in the annulus between the tool and casing above the lower packer element 42, the annulus at this point being at a fluid pressure substantially the same as the lower pressure zone above the tool (i.e., above the upper packer element 40), inasmuch as any higher pressure in the annulus can relatively easily bleed oft across the upper packer 40 in an upward direction because of the construction of the packer. In addition, the portion of the annulus between the upper and lower packers is communicated by one or more openings or ports 114 (see FIG. 1A) formed through the body and located between the two

valve elements

28 and 30, thus permitting any substantially higher pressure in the annulus between the packer elements to bleed off through upper valve element 28 and the upper ports 16 to the zone of the well above the tool. Y

The ports 114 also serve the important function of preventing the portion of the annulus between the packer elements from assuming a lower pressure than either of the zones of the well above and below the packer elements as the tool is moved either upwardly or downwardly through the casing. If that portion of the annulus between the packer elements were to drop to a substantially lower pressure than the ambient pressure in the well fluid, it is apparent that the packer elements would be subjected to a differential pressure which would tend to engage them more firmly with the well casing so that they would drag excessively and would be worn at an accelerated rate.

In view of the higher pressure within the chamber 104 than outside of it, there is created a net force due to the pressure differential that acts on the end wall 108 of the recess 100 in the expander and urges the expander downwardly relative to the body 12 and along the slips 46 and forces the slips outwardly into firm anchoring engagement with the well casing. As the differential pressure across the tool increases, the pressure differential between the interior and exterior of the chamber 104 similarly increases, thereby increasing the magnitude of downward,

force on the expander structure 44 so that the slips are correspondingly more tightly wedged against the casing in anchoring engagement. Therefore, the tool is firmly anchored against upward movement in the casing.

Assuming that the tool is anchored against movement in one direction, say against downward movement as depicted in FIGS. 2A and 2B, a shift in the pressure conditions so that the higher pressure shifts from above the tool to below the tool tends to shift the body upwardly. Before the change in pressure conditions, the slips are firmly engaged with the well casing, and as the pressure difference shifts, the expander and slips remain engaged and act essentially as a unit on the tool which is anchored to the wall casing. The slight movement of the tool body that occurs can take place relatively freely, inasmuch as it is impeded only by the frictional engagement between the packer elements and the casing (plus the weight of the tool). Accordingly, the body of the tool shifts relative to the anchoring structures from the position illustrated in FIGS. 2A and 2B into the position illustrated in FIG. 3. Just as in the case when the tool initially sets against higher pressure from below, the creation of a higher pressure inside of the uid chamber 104 than the pressure outside the chamber creates a downward force on the expander and keeps the slips firmly engaged.

The reverse of the situation described in the preceding paragraph occurs when the tool is initially anchored against upward movement against a higher well fluid pressure below the tool and the higher pressure shifts to the zone above the tool. Beginning with the tool in the configuration illustrated in FIG. 3, a higher pressure above the tool causes the body to move downwardly, such shifting being relatively free as described above, thereby shifting the body so that the upper abutment 58 on the body engages the expander structure 44 and transmits the forces due to differential pressure through the expander and into the slips to wedge them firmly into anchoring engagement with the casing. With the shift in pressure, the fluid pressure inside the fluid chamber 104 is lower than the pressure outside so that the effect of pressure conditions on the fiuid chamber 104 are such that the expander structure 44 is pushed upwardly relative to the body. Actually, the same end result is inherently produced by the downward movement of the body which engages the abutment 58 with the expander structure, and the pressure conditions obtaining in the fluid pressure arrangement are of minor consequence.

After the completion of operations employing the retrievable bridge plug at a given location in the well conduit, the bridge plug can be released and moved to another location for further operations or can be retrieved from the well bore. To release the bridge plug, the coupling tool (not shown) is lowered and reconnected to the fitting 72 at the upper end of the control mandrel 70. To ensure that the pressures below and above the tool are substantially equalized, the coupling tool is lowered to correspondingly push down on the control mandrel 70 so that the lower valve-operating flange 74b engages the lower valve element 30 and pushes it against the spring 36 to unseat it and permit any higher pressure below the tool to equalize. The coupling tool is then raised correspondingly to pull up on the control mandrel, the upward movement of the control mandrel 70 engaging the upper ange 74a with the upper valve element 28 and unseating it to allow a higher pressure above the tool to equalize with the pressure below it.

The bridge plug is released (see FIGS. 4A and 4B) by pulling the control mandrel 70 up. This brings the lower end of the slot 76 at the lower end of the mandrel 4into engagement with the lower edge of lthe cross-piece 78 and moves the cross-piece 78 upwardly so that it pulls up on the sleeve 84. The upper end of the sleeve engages and pushes up on the expander through the flange 60, and also on =body 12 through the abutment 59 which is engaged by the flange 60. With further upward movement, the expander and body are pulled upwardly relative to the slips, thereby withdrawing the slips from gripping 10 engagement with the casing and releasing the bridge plug from anchored position in the well casing. At this point, the bridge plug is in the configuration depicted in FIGS. 4A and 4B.

The bridge plug can now be moved upwardly in the casing in the configuration illustrated in FIGS. 4A and 4B, the upward pull on the control bar 70 engaging the sleeve 84 with the expander and body, as above, and moving them as a unit while the slip assembly 48 remains in a relatively downwardly position on the tool body by virtue of its weight and the friction forces developed by the drag blocks 64. The lower end of the slip mounting sleeve 62 is engaged and pushed upwardly through the casing by the abutment 68. The upper 4bypass valve 28 is held open by the iiange 74a on the control mandrel 70 so that well fluids above the tool can pass downwardly through the bypass passage 14 through the tool and down and out through the lower ports 20.

On the other hand, downward movement of the tool can be accomplished in the manner described above with the tool in the configuration illustrated in FIGS. 1A and 1B. Should it be desired to employ the bridge plug at another location in the well, it can be released 'from the coupling tool and reset in the casing in precisely the manner that has been previously described.

The above-described embodiment of the invention is intended to be merely exemplary, and those skilled in the art will be a-ble to make numerous variations and modifications of it without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as defined in the appended claims.

I claim:

1. A well tool comprising a body adapted to be lowered into a well conduit, slip means mounted on the body for shifting movement outwardly into anchoring engagement with the well conduit, an expander mounted on the body for longitudinal shifting movement relative to the body and to the slip means to urge the slip means into anchoring engagement with the conduit, a first cuptype packer element mounted on the body adjacent the end of the slip means remote from the expander and facing in a direction to seal the annular space between the tool and the well conduit and to hold pressure tending to move the body and slip means toward the expander, a second cup-type packer element mounted on the body and facing in a direction to seal the annular space between the tool and the well conduit and hold pressure tending to move the body and expander toward the slip means, fluid pressure means coupled to the expander and responsive to a higher pressure in the zone of the well in which pressure is held by the first packer element for forcing the expander toward the slip means to urge the slip means into anchoring engagement with the well conduit, and control means for selectively preventing or permitting relative movement of the body, expander and slip means.

2. A well tool according to claim 1 `wherein the control means includes means for selectively (a) preventing movement of the slip means relative to the body, (b) preventing movement of the expander relative to the body, or (c) enabling relative movement between the body, slip means and expander to permit the expander to urge the slip means into anchoring engagement with the well conduit.

3. A well tool according to claim 1 further comprising a passage through the body communicating the parts of the well bore above and below the packing means with each other, and valve means in the passage and operable by the control means to selectively close ol the passage to prevent communication of well fluids between the said zones.

4. A well tool according to claim 1 wherein the fluid pressure means includes a fluid chamber o'f variable volume defined by formations associated with the body and the expander, the formation associated with the expander including a wall formation movable with the eX- pander and constituting a moving wall of the iluid chamber.

5. A well tool according to claim 4 wherein the interior of the chamber communicates with the said zone of the Well in which pressure is held by the iirst packer element, and the exterior of the chamber communicates with a zone of the well on the opposite side of the first packer element from the aforementioned zone.

6. A well tool according to claim 1 further comprising a passage through the body communicating the parts of the well bore above and below the packer elements with each other, an upper one-way valve element in the passage and operable to selectively close off the passage communication of well uids downwardly through the tool and lower one-way valve element in the passage and operable to selectively close off the passage to prevent communication of well uids in an upward direction through the passage.

7. A well tool according to claim 6 further comprising means communicating the part of the passage between the valve elements with the portion of the annular space between the tool and well conduit between the packer elements.

8. A well tool according to claim 1 wherein the control means includes friction drag means associated with the slip means and engageable with the well conduit to impede movement of the slip means through the conduit and friction drag means associated with the expander to impede movement ofthe expander through the conduit.

9. A well tool according to claim 8 wherein the control means further includes a member shiftable longitudinally of the body and elements coupled to the member and selectively engageable in different positions of the member relative to the body with the body, expander, and slip means to maintain the body, expander and slip means in selected positions relative to each other.

10. A well tool according to claim 9 wherein the elements include a coupling member carried by the longitudinally shiftable member for relative longitudinal movement thereon between limit positions and having portions selectively engageable with the body, expander and slip means.

11. A well tool according to claim 9 wherein the coupling elements include a sleeve member mounted on the exterior of the 'body for movement on the body between spaced-apart limit positions and having formations thereon selectively engageable with the slip means and expander at the respective limit positions of movement along the body selectively to preclude movement of the slip means and expander, respectively, relative to the body.

12. A well tool according to claim 11 further comprising seal means between the sleeve member and body.

13. A well tool comprising a body adapted to be lowered into a well conduit, cup-type packing means on the body engaging the conduit to seal the annular space between the tool and the well conduit against passage of well lluids in either direction therethrough, slip means mounted on the body for shifting movement outwardly into anchoring engagement with the well conduit, an expander mounted on the body for shifting movement relative to the slip means to urge the slip means into anchoring engagement with the well conduit, the slip means and expander being mounted on the body between the packing means, a passage through the body communicating the zones above and below the packing means with each other, valve means in the passage for selectively preventing passage of well lluids in either direction through the body passage, fluid pressure means coupled to the expander and responsive to a higher pressure in the zone of the well bore in which pressure is held by one of the packer means for forcing the expander toward the slip means to urge the slip means into anchoring engagement with the well conduit, and control means for selectively preventing or permitting relative movement of the body expander and slip means, the control means including a member shiftable longitudinally of the body, a sleeve member mounted on and surrounding the body and slidable on the body between a first limit position in which it engages the body and expander to preclude relative movement of the body and expander and a second limit position in which it engages the body and slip means to preclude relative movement of the Vbody and slip means, an element coupling the longitudinally shiftable member to the sleeve member for movement of the sleeve member with the longitudinally shiftable member, the coupling element extending through openings in the body, and seal means between the sleeve and body to present communication of well uid from the passage into the annular space between the body and conduit through the openings.

14. A well tool according to claim 13 wherein the body includes spaced-apart abutments engageable by the sleeve member and affording predetermined limited sliding movement of the sleeve on the body.

15. A well tool according to claim 14 further comprising a formation on the expander engageable with one of the said abutments on the body and engageable by the sleeve when the sleeve is in one position whereby engagement between the sleeve and abutment is through the expander formation.

16. Awell tool according to the claim 14 further comprising a formation on the sleeve member, spaced abutments on the slip means engageable by the sleeve member formation, the abutments on the slip means affording limited predetermined movement of the sleeve member relative to the slip means.

17. A lwell tool comprising a body adapted to be lowered into a well conduit, a cup-type upper packer element adjacent the upper end of the body for sealing the annular space `between the body and the well conduit against passage of well fluids in a downward direction therethrough, a cup-type lower packer element adjacent the lower end of the body for sealing the annular space between the body and the well conduit against the passage of well fluids upwardly therethrough, an expander member having downwardly and inwardly inclined expander surfaces and mounted on the body between the packer elements for movement longitudinally of the body, a rst abutment on the body engageable with the expander to restrict the extent of movement of the expander upwardly along the body, slip means including slip elements having inclined surfaces complementary to and engageable by the expander inclined surfaces, the slip means being mounted on the body below the expander and above the lower packer element for movement longitudinally and laterally of the body and positioned to be engaged by the expander and to be moved relatively therealong thereby selectively to be forced outwardly into anchoring engagement with the well conduit, a second abutment on the body engageable with the slip means to restrict the extent of movement of the slip means downwardly along the body, friction drag means associated with the expander member and engageable with the Well conduit to impede movement of the expander member through the well conduit, friction drag means associated with the slip means and engageable with the well conduit to impede movement of the slip means through the well conduit, fluid pressure means coacting between the body and expander and operable upon pressure conditions in the well tending to push the body in an upward direction in the well for forcing the expander toward the slip means to force the slips into anchoring engagement with the well bore, the fluid pressure means including a lluid chamber of variable volume defined by formations associated with the body and formations associated with the expander member including a portion on the expander member constituting a moving wall of the chamber, the exterior of the chamber communicating with the annulus between the tool and the conduit above the lower packer element and the interior of the chamber communicating with a part of the well below the lower packing element, and control means movable on the body for engagement in a first position with the body and slip means to prevent movement of the slip means relative to the body and for engagement in a second position with the body and expander to prevent movement of the expander relative to the body and for disengagement in a third position from the body, slip means and expander to enable relative movement of the slip means and expander and permit the slip means to become engaged with the conduit.

References Cited UNITED STATES PATENTS Otis 166-121 X Brown 166-121 Baker et al. l66-135 Evans 166-121 X Chenoweth 166--121 Young 166--120 Scott 166-121 Conrad 166-133 X Chenoweth 166-120 U.S. Cl. X.R.