US3467182A

US3467182A - Retrievable well packer

Info

Publication number: US3467182A
Application number: US703947A
Authority: US
Inventors: James W Kisling
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 J. w. KISLING m 3,467,182

RETRIEVABLE WELL PACKER Filed Feb. 8, 1968 4 Sheets-Sheet 1 JAMES W. KISLING 111 FIG. /8

FIG. m hi; ATTORNEYS J. w. KISLING Ill RETRIEVABLE WELL PACKER Sept. 16, 1969 4 Sheets-Sheet 2 Filed Feb. 8. 1968 w w m a M IN VI LIN"! Y 1R JAMES W. K'SLING m his ATTORNEYS 4 4 m 4 2 2 8 48 6 I 6 kA 1 1 3 z 4 w fl Q \N M'Wl i; 0 w. 7 a IO P 1969 J. w. KISLING m 3,47,12

REIRI EVABLE WELL PACKER Filed Feb. 8, 1968 4 Sheets-Sheet 5 his ATTORNEYS United States Patent 3,467,182 RETRIEVABLE WELL PACKER James W. Kisling III, Houston, Tex., assignor to Schlumberger Technology Corporation, Houston, Tex., a corporation of Texas Filed Feb. 8, 1968, Ser. No. 703,947 Int. Cl. E21h 33/129, 23/06 US. Cl. 166-121 24 Claims ABSTRACT OF 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 comprises a body, packing elements for packing on the annulus and an anchoring structure in the form of a single expander and a set of coacting slips mounted for movement toward and away from each other and longitudinally of the body 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 relative to the slips and expand the slips, the friction drag associated with the slips precludes movement of the slips and aifords relative movement between the expander and slips to engage the slips in anchoring engagement with the well bore wall. Under pressure conditions tending to move the tool in the opposite direction, namely, to move the slips, the expander is forced toward the slips by differential pressure acting on a fluid chamber of variable volume, one wall formation of which is an element on the expander and constitutes a moving wall of the chamber. Accordingly, differential pressure between the inside and outside of the chamber causes the expander to be moved toward and under the slips to wedge the slips into gripping engagement with the well bore wall. The tool further includes a control mechanism for maintaing 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.

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 fracturing, acidizing, squeeze cemeting, testing and other 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 off 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 comunicating 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 ice 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.

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 sufiicient 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 diiferential 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 the 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 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 afforded. 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 limits 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 each is engaged with the slips or expander, respectively.

The tool further includes packing elements, preferably of the cup-type which engage and 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 bore wall and impede the movement of the expander and slip structure, respectively, through the well bore. 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, and is operable to permit movement between the expander and slips toward each other so that the slips are expanded outwardly into gripping engagement with the well bore wall. The control mechanism is, desirably, operably solely by longitudinal movements, so that the tool can be used with a wire line, as well as with tubing, and comprises a control element which selectively (a) prevents movement of the expander relative to the body, (b) prevents movement of the slips relative to the body, or (c) permits the slips, expander and body to move relative to each other 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 body and moved relative to the slips, the slips are impeded from moving in the well bore with the body by the friction drag elements associated with them, thereby afiording relative movement between the expander and the slips so that the slips are forced outwardly into anchoring engagement with the casing. Movement of the body in the other direction so that the abutment associated with the slips engages the slips and causes them to move toward the expander similarly moves the slips into gripping engagement with the well bore wall, 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 well bore wall, the expander is relatively free to move inasmuch as the only impediment to its movement is provided by the friction drag elements. Accordingly, an important element of the invention is the provision of a fluid pressure system for urging the expander toward the slips when the body tends to move in a direction urging the slips toward the expander. In other words, the well tool includes a fluid pressure arrangement by which the expander is forced under the slips to engage them more firmly with the well bore wall when the body of the tool is subjected to the forces tending to move it in a direction counter to the taper of the expander surfaces. I

More particularly, the fluid pressure arrangement comprises a fluid chamber of variable volume defined by formations on the body and on the expander, a part of the formation on the expander constituting a moving wall of the chamber. The interior of the chamber communicates with one of the pressure zones in the well bore on one side of the packing, while the exterior of the chamber communicates with the pressurezone on the other side of the packing.

The anchoring mechanism in the well tool according to the invention has the important advantage over similar types of tools of providing engagement of the single set of slipsor equivalent anchoring elements with the well casing, regardless of the direction of forces tending to move the tool in the conduit. Accordingly there is no shifting of the point where the tool is anchored to the well conduit wall. Moreover, the slips remain in engagement with the conduit throughout any stage in which the tool is not subjected to any forces tending to move it, such as the nul stage occurring when the pressure conditions in the well are changing from a higher pressure 4 above the tool to a higher pressure below the tool. Accordingly, the opportunity for the tool to move any substantial distance in the well bore, beyond the relatively small shifting movement of the body relative to the anchoring structure, is sharply reduced. The inclusion of only one expander and one set of slips in the well tool of the invention also reduces the number of parts, the complexity of the construction, and the costs of manufacture, assembly and maintenance.

Another advantage of tools constructed according to the invention is their capability of being used with a wire line, i.e., cable, as well as with tubing. In some operations, a tubing string is not needed, and since running tubing is considerably more time-consuming and costly than running wire line, considerable savings are aflForded by a wire line tool.

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-elevationa1 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 ofthe type that can be lowered into a well conduit using a suitable coupling tool, released from the coupling tool ata desired location, and, upon any pressure differential in the well, anchors to the conduit wall against movement in eitherdirection and seals off the conduit against the passage of well fluids in either direction across 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 casing 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 as 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. A major length-wise part of the bore 14 is defined by the internal lsjuiface of a sleeve 23, the purpose of which is described e ow.

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 2-8 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. 1A

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

valves

28 and 30 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 conduit.

Mounted near the upper end of the body, just below the

valve cavities

24 and 26, are two cup-type packer elements, specifically an upper 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, and 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 suffices 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.

At the lower end of the tool (FIG. 1B, for example) is an anchoring structure which is composed of an expander member, designated generally by the reference numeral 44, and a series of circumferentially spacedapart 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, is 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 abutments or shoulder formations (e.g., 60) on the body in the region radially inwardly of the expander surface portion 50.

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 60 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 control 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 which the tool is moved through the well. The coupling device may be of various types, such as a suitable I-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) is a flange 74, 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 mandrel 70 is shiftable longitudinally of the body to the extent afforded by the lost motion available by virtue of the slot 76 in the mandrel and the slots 80 in the body.

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 causes it to seek its lowermost position relative to the tool body, thereby, as shown in FIGS. 1A and 1B, causing the mandrel 70 to engage the upper edge of the cross-piece 78 and in turn causing the lower edges of the cross-piece 78 to engage the lower edges of the slots 80 in the tool body. In the meantime, the flange 74 at 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 fluid 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 through the cross-piece 78 by engagement of the lower edges at the extreme ends of the cross bar 78 with the upper edges of the slip mounting member 62 (see FIG. 1B) which in turn acts through the abutment 68; the slip structure 68 is therefore pushed by the cross-piece to its lowermost position on the tool with the lower end of the housing 62 in engagement with the abutment 68 on the tool body. The tool body may also be pushed down through the casing by direct engagement of the lower end of the coupling tool with the top end of the body.

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 retreivable bridge plug is to be set has been reached, the coupling tool is detached from the fitting 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 elements 30 on the flange 74 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 the lower valve seat 38. Accordingly, the upward passage of well fluids through the tool bore 14 is terminated. The upper valve 28 is also urged closed by its spring 32 into seating engagement on the upper valve seat 34. In 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, 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. In other words, the control mandrel 70 has assumed a neutral position relative to the tool body. Because the cross-piece 78 is freely movable, movement of the expander and slip structure relative. toward each other can take place 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 new 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 fluids 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 in this instance causes the abutment 58 to engage the upper end of the expander structure 44 and pushes the expander down. Meanwhile, the slip structure 48 is supported against downward movement in 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. Consequently, the slips are 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 easing 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 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 swabbing the casing above, 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 keeps 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 bore 82 on the expander sleeve which is in sliding relation to and is sealed by an O-ring 83 with a flange forma tion 84 on the body. The bore 82 defines in part, a fluid chamber 85 which is further defined by the end face 86 of the flange 84, a face 88 at the upper end of the bore 82 and the part 89 of the outer wall of the tool body 12 facing the inner surface of the bore 82. The interior of the fluid chamber 85 communicates with the portion of the casing above the upper packer 40 through an annular passageway '90 defined by the internal surface of the body 12 and the sleeve 23 (referred to above) installed within the body. A series of circumferentially spaced-apart holes 94 through the body 12 near the lower end of the passageway and similar holes 96 through the upper end of the passageway communicate the passageway with the fluid chamber 85 and with the upper part of the well above the packer, respectively. Consequently, the interior of the chamber is at substantially the same fluid pressure as the zone of the well above the packers.

(It may be mentioned at this point that the passageway 90 may take various forms, such as a series of longitudinal holes formed in the body and moreover that the upper end of the passage may communicate with the space between the two

packer elements

40 and 42, inasmuch as the annular space between the packer cups 40 and 42 tends to be at substantially the same pressure as that zone of the well above or below the tool which is at the lower pressure.)

Inasmuch as the two

packer elements

40 and 42 are located above the fluid chamber 85, the well fluids surrounding the chamber are at the higher pressure of the zone below the packer elements. Accordingly, there is a differential pressure existing between the interior and exterior of the chamber 85 which creates a net force downwardly on the expander structure 44, the pressure difference acting on the upper end of the expander sleeve which constitutes a moving wall or piston. As the differential pressure across the tool increases, the pressure differential between the interior and exterior of the fluid chamber 85.similarly increases, thereby increasing the magnitude of the downward force of the expander structure 44 and more firmly forcing the expander downwardly along the slips so that the slips are correspondingly more tightly wedged against the casing in gripping engagement. Therefore, the tool is firmly anchored against upward movement in the well bore.

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 outside of the fluid chamber 83 than the pressure inside 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 85 is higher than the pressure outside so that the eifect of pressure conditions on the fluid chamber 85 are such that the expander structure 44 is forced upwardly relative to the body. Actually, this condition 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 flange 74 engages the lower valve element 30 and pushes it against the spring to unseat it and permit any higher pressure below the tool to equalize. The coupling is then raised to correspondingly pull up on the control mandrel, the upward movement of the control mandrel 70 engaging the flange 74 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 by pulling the control mandrel 70 up. This brings the lower end of the slot 76 at the lower end of the mandrel into engagement with the lower edge of the cross-piece 78 and moves the crosspiece 78 upwardly so that its upper edge engages (1) the upper edge of the slot 80 in the body and (2) the lower end of the expander structure 44. With further upward movement, the expander and body are pulled upwardly relative to the slips, thereby withdrawing them from gripping 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 cross-piece 78 with the upper edge of the slot 80 and the lower edge of the expander structure moving them as a unit while the slip assembly 48 remains in a relatively downward 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 by the abutment 68. The upper bypass valve 28 is held open by the shoulder 74 on the control bar so that well fluids above the tool can pass downwardly through the bypass passage 14 through the tool and downand 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 able 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, 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 fluids in either direction therethrough between zones above and below the tool, slip means mounted on the body for shifting movement thereon longitudinally outwardly into anchoring engagement with the "well conduit, an expander mounted for longitudinal movement relative to the body and to the slip means to urge the slip means into anchoring engagement with the conduit, fluid pressure means coupled to the expander and responsive to differential pressure between the said zones 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 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 ofi? the passage to prevent communication of well fluids between the said zones.

3. A well tool according to claim 1 wherein the con trol 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 of the expander through the conduit.

4. A well tool according to claim 1 wherein the fluid pressure means includes a fluid chamber of variable volume defined by formations associated with the body and the expander.

5. A well tool according to claim 4 wherein the formations associated with the expander include a wall formation movable with the expander constituting a moving wall of the fluid chamber.

6. A well tool according to claim 4 wherein the interior of the chamber communicates with one of said zones of the well and the exterior of the chamber communicates with the other of said zones.

7. 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.

8. A well tool according to claim 7 wherein the control means 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 mean in selected positions relative to each other.

9. A well tool according to claim 8 wherein the elements include a coupling member carried by the longitudinally shiftable member for relative longitudinal movement thereon between limit positions and having portions 1 1 selectively engageable with the body, expander and slip means.

10. A well tool comprising a body adapted to be lowered into a well conduit, packing means on the body for sealing the annular space between the body and the well conduit against passage of well fluids in either direction therethrough between zones above and below the tool, an expander mounted on the body for movement longitudinally of the body, an abutment on the body engageable with the expander to restrict the extent of movement of the expander relative to the body, slip means mounted on the body for movement longitudinally of the body and relatively along the expander thereby selectively to be urged outwardly into 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 relative to the body, friction drag means associated with the expander and engageable with the well conduit to impede movement of the expander through the conduit, friction drag means associated with the slip means and engageable with the well conduit to impede movement of the slip means through the conduit, fluid pressure means coacting between the body and expander and responsive to a differential pressure between the said zone to force the expander toward the slip means to urge the slip means in to anchoring engagement with the well conduit, and control 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.

11. A well tool according to claim further comprising a passage through the body and communicating the parts of the well bore above and below the packing means with each other, and valve means in the passage for selectively closing off the passage to prevent communication of well fluids between the said parts.

12. A well tool according to claim 11 wherein the valve means is coupled to and operated by the control means.

13. A well tool according to claim 10 wherein the fluid pressure means includes a fluid chamber of variable volume defined by formations associated with the body and the expander.

14. A well tool according to claim 13 wherein a formation associated with the expander constitutes a moving wall of the fluid chamber.

15. A well tool according to claim 13 wherein the interior of the chamber communicates with one of the said zones and the exterior of the chamber communicates with the other of said zones.

16. A well tool according to claim 10 wherein the packing means includes a cup-type upper packer element engageable with the well bore to hold pressure from above, and a cup-type lower packer element engageable with the well bore to hold pressure from below.

17. A well tool according to claim 16 wherein the fluid pressure means includes a fluid chamber defined by formations associated with the body and formations associated with the expander including a wall element movable with the expander and constituting a movable wall of the chamber.

18. A well tool accordng to claim 17 wherein the upper and lower packer elements are both positioned on the body at a portion thereof on one side of the fluid chamber, whereby the exterior of the chamber is exposed to a part of the well on one side of the packer elements, and further comprising passage means through the tool body and communicating the interior of the chamber with the part of the well bore on the opposite side of at least one of the packer elements.

19. A well tool comprising a body adapted to be lowered into a well conduit, a cup-type upper packer element on 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 on the body for sealing the annular space between the body and the well conduitagainst the passage of fluid upwardly therethrough, an expander having downwardly and inwardly inclined surfaces and mounted on the body for movement longitudinally of the body, a first 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 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 and engageable with the well conduit to impede movement of the expander through the well bore, friction drag means associated with the slip means and engageable with the well bore 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 fluid chamber of variable volume defined by formations on the body and formations associated with the expander including a portion constituting a moving wall of the chamber, the exterior of the chamber communicating with a part of the well on one side of the lower packer element and the interior of the chamber communicating with a part of the well on the opposite side of the lower packing element form the first part, 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 and permit the slip means to become engaged with the conduit.

20. A well tool according to claim 19 wherein the upper and lower packer elements are both mounted on the body in positions above the fluid chamber, whereby the exterior of the chamber communicates with the part of the well below the lower packer, and further comprising passage means communicating the interior of the fluid chamber with a part of the well above the lower packer element.

21. A well tool according to claim 19 further comprising a passage through the body and communicating parts of the well above and below the upper and lower packing elements with each other, and valve means in the passage for selectively closing off the passage to prevent passage of Well fluids between the said parts through the passage.

22. A well tool according claim 19 wherein the control means includes a member shiftable longitudinally of the body and elements coupled to the member and selectively engageabe 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.

23. A well tool according to claim 22 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.

24. A well tool according to claim 22 further comprising a passage through the body and communicating parts of the well above and below the packer elements with each other, the passage including a bore in the tool body receiving the control member, and valve means in the passage for selectively closing the passage to prevent passage of Well fluids therethrough, the valve means including valve elements engageable with and shiftable by formations on the longitudinal control member.

References Cited UNITED STATES PATENTS Baker et al. 166-121 Baker et a1 166120 X Evans 166121 X Chenoweth 166121 Young 166-420 Scott 16612l Conrad 166133 X Chenoweth 166120 US. Cl. X.R.

$2,3 3? UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3 ,467 ,182 Dated September 16 1969 Inventor) J. W. Kisling III It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

T- Column 11, line 25, "zone" should be zones Column 12, line 46, "to enable relative movement of the slip means and expander" has been omitted after "expander";

In the list of references, the date of U. S. patent No. 2,698,663 should be "1/1955" (January, 1955) SIGNED AND SEALED MAY 121970 Attest:

Edward M. Fletchenlr. Attenting Officer WIILIAM L SOHUYLER. flomissioner of Paten