US3291218A

US3291218A - Permanently set bridge plug

Info

Publication number: US3291218A
Application number: US345246A
Authority: US
Inventors: Maurice P Lebourg
Original assignee: Schlumberger Well Surveying Corp
Current assignee: Schlumberger Well Surveying Corp
Priority date: 1964-02-17
Filing date: 1964-02-17
Publication date: 1966-12-13
Anticipated expiration: 1983-12-13

Description

Dec. 13, 1966 M. P. LEBOURG 3,291,218

PERMANBNTLY SET BRIDGE PLUG Filed Feb. 17, 1964 Mao/me x Zeboury VINVENTOR.

Q I "A III M United States Patent 3,291,218 PERMANENTLY SET BRIDGE PLUG Maurice P. Lebourg, Houston, Tex., assignor to Schlumberger Well Surveying Corporation, Houston, Tex, a corporation of Texas Fiied Feb. 17, 1964, Ser. No. 345,246 5 Claims. (Cl. 166134) This invention relates to a bridge plug for use in a well bore, and more particularly, to a bridge plug designed to be set permanently in place within tubing or casing.

A bridge plug typically consists of a mandrel on which an elastomeric packing element is mounted between reversely directed, extendible slip elements on tapered expander elements, with the slip elements being held in an inoperative first position on the expander elements by shear pins, and a body lock which maintains these elements in an operative second position. Setting of such a bridge plug is conventionally accomplished by use of a setting tool which applies oppositely directed forces in such a manner that the packing element is expanded into sealing engagement and the slip elements are extended into anchoring engagement with a well casing to hold the set bridge plug in place.

In setting such typical bridge plugs with a conventional wireline setting tool, at least one of the slip members is usually extended against and dragged along the casing before the packing element has been completely set, which dragging can break some of the casing-engaging teeth on the slip members. Furthermore, with a wireline setting tool having a tension-stud release, it will be appreciated that such dragging can reduce the degree of expansion of the packing element should the additional drag cause the setting tool to release before the packing element is fully set.

As a bridge plug is being lowered into a cased well, it is not uncommon for an obstruction, such as an internal projection in the casing, to engage the lower slip and force the slip upwardly over the lower expander in such a manner that the lower slip at least slightly expands and perhaps even engages the casing. Heretofore, this particular hazard has often resulted in the premature setting, or at best a partial setting, of the bridge Plug which usually requires that the incorrectly located bridge plug be set in place, drilled out, and a new bridge plug again lowered with the hope that it will clear the obstruction and reach its desired depth without being inadvertently set.

With those bridge plugs having slip members frangibly connected together in a ring, upon fragmenting of the ring,

the slip segments are free to move independently of their companion segments. When such a bridge plug is used in an inclined well bore, it will lay against one side of the casing and, as the slip segments are being set, the segments at the opposite side are free to advance further along the expander before engaging than those initially resting against the casing. Thus, the bridge plug will remain eccentrically disposed which may prevent the packing element from sealing completely and uniformly around its periphery.

Moreover, since a bridge plug is conventionally arranged with its lower slips adapted to resist downward movement of the bridge plug and its upper slips being reversely directed to resist upward movement, well pressure acting on the cross-sectional area at the high-pressure end of the mandrel imposes a load thereon which is not effectively resisted by the slip at that end. Instead, this load is transmitted through the packing element to the slips at the opposite end and, accordingly, increases the radial loading of the packing element against the casing. If sufiicient, this added radial loading can bulge or split the casing.

Patented Dec. 13, 1956 ice It is, therefore, an object of the present invention to provide a reliable bridge plug which positively pack-off a well casing.

It is a further object of the present invention to provide a new and improved bridge plug so arranged that it will not be accidentally set whenever it encounters an obstruction within a well casing.

These and other objects of the present invention are obtained by a bridge plug which includes new and improved upper and lower anchoring elements.

The bridge plug of the present invention consists of a central mandrel carrying at each end thereof opposed anchor elements with each anchor element operatively disposed between an abutment member and a slidable expander member. An elastomeric packing element is disposed between and cooperatively engaged with the expander members in such a manner that the packing element will be expanded as the bridge plug is being set. Means are provided for locking the mandrel in position when the bridge plug is finally set.

Each of the new and improved anchor elements consists of a concavo-convex or hollowed, frusto-conically shaped wall-engaging member. These wall-engaging members are slidably mounted around a mandrel at each end of a packing element and oppositely directed in such a manner that upon application of longitudinally directed forces, the wall-engaging members will begin to flatten, which action will extend the outer periphery of the members radially and circumferentially into anchoring engagement with the casing wall. The yieldable wall-engaging members are designed to retain their initial frusto-conical configuration until a force of a predetermined magnitude is applied thereto. In addition to anchoring the bridge plug in position within a cased well bore, the wall-engaging members further act as anti-extrusion members after the packing element and outer periphery of the wall-engaging members are brought into wall-engaging contact to prevent the extrusion -or cold-flow of the elastomeric packing element from around the body of the bridge plug.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation together with further objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a bridge plug, partly in section, with the wall-engaging members of the present invention in their initial retracted position; and

FIG. 2 is a view showing the bridge plug of FIG, 1 as it appears when expanded to sealing in anchoring engagement within a well casing.

Turning now to FIG. 1, an embodiment is shown of a bridge plug 10 with portions thereof in section for purposes of greater clarity.

The mandrel 11 of the bridge plug 10 is an elongated, cylindrical member around which is slidably mounted an elastomeric packing sleeve or element 12. Oppositely directed lower and

upper expander members

13, 14 are slidably mounted around mandrel 11 at opposite ends of packing element 12, with the rearward faces 15, 16 of

expanders

13, 14 being flat and respectively engaged with oppositely directed, hollowed, frusto-conical lower and upper wall-engaging

members

17, 18. Lower and upper wall-engaging

members

17, 18, as will be later described in detail, are initially disposed with their outermost edges engaged around the fiat faces 15, 16 of the

expander members

13, 14 and their innermost edges engaged with oppositely directed lower and

upper abutment members

19, 20, respectively. The lowermost abutment member 19 rests against an upwardly facing shoulder 21 around the lower end of mandrel 11.

Abutment members 19, are generally cylindrical with each having reduced-

diameter hub portions

22, 23 received within the inner edges of the

anchor members

17, 18. The hub portions 22, 23 of the

abutment members

19, 20 ensure that the

anchor members

17, 18 remain engaged against the abutment members rather than riding loosely on the mandrel 11. Furthermore, as the mandrel travels upwardly during the setting operation, the upper hub 23 prevents the mandrel ratchet teeth 24 from catching on the inner edge of upper anchor member 18.

The upper abutment member 20 is of hardened steel to ensure that as the bridge plug is being set, the hub portion 23 will not be deformed under the substantial radial load applied thereon by the upper anchor member 18 as it is flattened and extended against the casing. It will be understood, of course, that should hub 23 deform, the mandrel could not travel smoothly through the upper abutment member 20.

Upper abutment member 20 has an upwardly directed and outwardly diverging tapered recess 25 which receives a complementarily tapered split-nut 26. Split-nut 26 has ratchet teeth 27 around its axial bore 28 cooperatively engaged with downwardly facing ratchet teeth 24 cut around the upper end of mandrel 11. A spring member 29 is operatively engaged between the upper end 30 of split-nut 26 and a snap ring 31, which is in turn held against a downwardly facing, circumferential shoulder 32 around the upper end of recess 25. Spring member 29 is preferably an assembly of two opposed springs with each spring consisting of a single flat ring having resilient projecting tabs which are interlocked with the tabs of the other spring. These springs, when nested together, make a compactly arranged spring member with oppositely directed flattened annular end surfaces.

The upper end of upper abutment member 20 has a reduced outer-diameter portion 33 providing an upwardly facing shoulder 34 and is sized and arranged for receiving the lower end of the outer sleeve or pushing member of a conventional setting tool (not shown). External threads 35 around the upper end of mandrel 11 are provided for coupling to the inner mandrel or pulling member of the setting tool. A reduced-diameter or necked portion 36 near the upper end of mandrel 11 is sized to fail whenever oppositely directed forces of a predetermined magnitude are applied in the well-known manner by the setting tool.

As seen in FIG. 1, the concavo-

convex anchor members

17, 18 are initially disposed in a frusto-conical configuration around the central axis of the mandrel 11 to provide an annular clearance around the bridge plug 10 when it is inserted into a well casing. The

anchor members

17, 18 are arranged to be longitudinally compressed or flattened between their respective abutment members and expander members so that, as illustrated in FIG. 2, when completely flattened, the outer edges of the anchor members will be extended into anchoring engagement with the inner wall of the casing.

The

anchor members

17, 18 consist of integrally formed, hollowed, concave-convex frusto-conically shaped members. Each of the wall-engaging members are identical and are disposed around mandrel 11 with their hollowed inner or

concave surfaces

37, 38 facing the opposite ends of packing element 12. The conical members are initially coaxially disposed at an acute angle to the central axis of the mandrel. The outer edges of the members are cut at an acute angle to the

inner faces

37, 38 of the members to provide a sharp corner as at 39, 40, for anchoring engagement with the wall of a casing.

Wallengaging members

17, 18 are preferably made of steel with the outer edge portions being selectively hardened to ensure that the

sharp edges

39, 40 will bite into a casing wall.

The inner edges 41, 42 of the apical portions of the wall-engaging

members

17, 18 are preferably beveled to provide a sharp corner for pivoting around the shoulder formed by the junction of

hubs

22, 23 with

abutment members

19, 20, respectively.

It has been found that the frusto-conical configuration will permit the anchor members to be engaged with the casing and withstand a longitudinally directed force against its apical portion of approximately one-fourth of the setting force required to flatten it into anchoring engagement with the casing Wall.

When the wall-engaging members are fully extended against casing 43, as illustrated in FIG. 2, wall-engaging 1

members

17, 18 will be imbedded into the casing as at 44, 45 to substantially fill the annular openings around the outer diameter of expander

members

13, 14. Thus, it will be appreciated that wall-

engaging members

17, 13 also effectively prevent the extrusion or cold-flow of the elastomeric packing element 12 after it has been sealingly engaged with the inner casing wall 43.

When the bridge plug 10 is to be operated, a conventional setting tool (not shown) is attached to the upper end of bridge plug 10. The pulling member or inner mandrel of the setting tool is threadedly attached to threads 35 at the upper end of mandrel 11 and the pushing member or outer sleeve of the setting tool is cooperatively engaged with upwardly facing shoulder 34 of upper abutment member 20.

When the bridge plug has been positioned for setting, the setting tool is operated in the conventional manner to pull mandrel 11 and lower abutment member 19 upwardly as the setting tool sleeve forces upper abutment member 20 downwardly.

As the

abutment members

19, 20 advance toward each other, it will be appreciated that gradually increasing, oppositely directed setting forces will be applied through the wall-engaging

members

17, 18 and

expander members

13, 14 against the opposite ends of packing element 12, which forces will begin foreshortening and displacing the packing element radially outwardly toward the casing wall.

As the setting forces increase, wall-engaging

members

17, 18 slowly yield which allows the

inner surfaces

37, 38 of the members to slide outwardly over the adjacent edges of the

expander members

13, 14 as the apical portions of the members are concurrently driven toward the

expanders

13, 14, which action begins to flatten the anchor members.

As the anchor members are being flattened, displacement of the packing element 12 continues until its outer ends are finally longitudinally displaced into the small annular voids remaining around the outer circumference of the

expander members

13, 14.

It will be appreciated that by varying the dimensions and material of the wall-engaging

members

13, 14, the strength of these mmebers can be regulated to require a predetermined force for flattening them completely. Thus, by properly correlating the degree of flattening of the anchor members to the corresponding amount of expansion of the packing element at a given magnitude of setting forces, the anchor members can be prevented from engaging the casing until the packing element has been completely displaced into sealing engagement.

When

anchor members

17, 18 have flattened sufiiciently, the

hardened edges

39, 40 of the members will first contact the casing and the continued travel of the

abutment members

19, 20 will subsequently flatten the wall-engaging members against the flat end surfaces 15, 16 of the opposing

expander members

13, 14 to drive the hardened edges of the wall-engaging members into the casing.

When the setting tool is actuated and as mandrel 11 first begins to travel upwardly, ratchet teeth 24 on the mandrel 11 will slide under ratchet teeth 27 on split-nut 26 to expand the split-nut. Accordingly, split-nut 26 is free to alternately expand and contract, and each time it expands, it will begin sliding relatively upwardly and outwardly along the tapered surface of tapered recess 25 within upper abutment member 20. As split-nut 26 begins to slide upwardly, however, spring member 29 is compressed and then expands to drive the split-nut inwardly and downwardly to force ratchet teeth 27 into engagement with the next group of ratchet teeth 24 around the mandrel. This alternate compression and expansion of spring member 29 tends to drive split-nut 26 downwardly while preventing any backlash or retrograde movement of the packing element. It will be appreciated, therefore, that split-nut 26 will be continuously driven over the lowermost ratchet teeth 24 of the mandrel that the nut can engage.

After the bridge plug has been completely set into anchoring and sealing engagement with the casing, the setting tool forces continue to increase until weakened portion 36 of mandrel 11 fails, as shown at 46, which failure will release the mandrel from the setting tool and allow the setting tool to be retrieved in the conventional manner. When bridge plug 13 is finally anchored and the setting tool disengaged, it will be appreciated that the bridge plug will effectively resist either upwardly or downwardly directed forces.

It should be noted that by properly sizing the anchor elements, they will withstand encounters with well bore obstructions which might tend to accidentally set the bridge plug. Moreover, since the anchor elements will not completely flatten until the packing element has been displaced against the casing, the

outer edges

39, 40 of the anchor members will not contact the casing until the bridge plug has nearly reached its minimum longitudinal dimension. Then, when the outer edges do engage the casing, the inner edges 41, 42 of each member effectively pivot around their respective outer edges as the anchor members are finally flattened. Thus, it will be appreciated that the wall-engaging edges of the anchor members are not dragged across the casing Wall but instead remain where they first engaged the casing.

With any bridge plug having an elastomeric packing element, it will be appreciated that a longitudinally directed force on the packing element will proportionately increase the radial loading of the element against the easing. Thus, when there is a pressure differential across a bridge plug, pressure is applied on the annular crosssectional area of the packing element which increases the radially directed loading against the casing. This pressure is also applied on the circular cross-section of the mandrel. With a conventionally arranged bridge plug, since any load on the mandrel is transmitted through the packing element to the slip member opposing forces acting in that direction, this latter pressure force further increases the loading against the casing.

It will be appreciated, however, that with a bridge plug arranged as shown and employing anchor members of the present invention, a load on the mandrel is not imposed on the packing element but is instead transmitted directly to the anchor members opposing forces acting in that direction. For example, an upwardly directed load on the mandrel is transmitted directly from the mandrel 11 and lower abutment member 19 into the lower anchor member 17 which is engaged against the casing in such a manner as to oppose upwardly directed forces. Similarly, a downwardly directed force is transmitted directly to the upper anchor member 18. Thus, once the bridge plug of the present invention is set, pressure forces acting on the mandrel will not be transmitted through the packing element which, consequently, reduces the likelihood that additional loading of the element might bulge or split the casing or perhaps crack the cement behind the casing.

Accordingly, it will be appreciated that a bridge plug constructed in accordance with the present invention will be suitable for high-pressure service in well conduits with the anchor members carrying most of the additional loads imposed thereby. Furthermore, the anchor members will expand uniformly to provide a uniform loading against the casing as well as ensure that the bridge plug is centralized within the casing. The anchor members of the 6 present invention will further ensure that elastomeric packing elements will not extrude from around the packer body.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is .claimed is:

1. In a packer device having a packing element operatively mounted around a mandrel where the packing element is adapted for expansion into sealing engagement within a well bore, the improvement comprising: an annular member slidably mounted around said mandrel and operatively engaged with an end of said packing element; integrally-formed, deformable annular anchor means slidably mounted around said mandrel -and initially coaxially disposed in a frusto-conical configuration around the central axis of said mandrel with the apical portion of said anchor means being directed away from said expander member and the base portion of said anchor means member being arranged for engagement with said expander member, said base portion having wall gripping portions; and means on said mandrel engaging said apical portion, for deforming said anchor means in response to relative longitudinal advancement of said engaging means toward said wall gripping portions of said expander member to expand said base portion into anchoring engagement with the wall of .a well conduit.

2. In a packer device having a packing element operatively mounted around a mandrel where the packing element is adapted for expansion into sealing engagement within a well bore, the improvement comprising: an annular' expander member slidably mounted around said mandrel and operatively engaged with an end of said packing element; integrally-formed deformable, annular anchor means slidably mounted around said mandrel and initially coaxially disposed in a frusto-conical configuration around the central axis of said mandrel with the apical portion of said anchor means being directed away from said expander member and the base portion of said anchor means being arranged for engagement with said ex pander member, said anchor means having a peripheral edge surface substantially parallel to said central axis to provide a sharp edge; and means on said mandrel engag ing said apical portion for deforming said anchor means in response to relative longitudinal advancement of said engaging means toward said expander member to expand said base portion whereby said sharp edge is extended to engage in a well conduit wall.

3. In a packer device having a packing element operatively mounted around a mandrel where the packing element is adapted for expansion into sealing engagement within a well bore, the improvement comprising: an annular expander member slidably mounted around said mandrel and operatively engaged with an end of said packing element; an integrally-formed annular anchor means for attaching the packer device to the wall of a well conduit, and anchor means being slidably mounted around said mandrel and initially coaxially disposed in a frustoconical configuration around the central axis of said mandrel with the apical portion of said anchor means being directed away from said expander member and the base portion of said anchor means being arranged for engagement with said expander member; and means on said mandrel for engaging said apical portion, said anchor means being deformable in response to concurrent application of oppositely-directed forces of a predetermined magnitude acting through said expander member and engaging means to expand said base portion into anchoring engagement with the well conduit wall.

4. In a packer device having a packing element operatively mounted around a mandrel where the packing element is adapted for expansion into sealing engagement within a well bore in response to forces of a predetermined magnitude, the improvement comprising: an annular expander member slidably mounted around said mandrel and operatively engaged with an end of said packing element; integrally-formed, deformable annular anchoring means slidably mounted around said mandrel and initially lcoaxially disposed in a frusto-conical configuration around the central axis of said mandrel with the apical portion of said anchor means being directed away from said expander member and the base portion of said anchor means being arranged for engagement with said expander member, said base portion having wall gripping portions, and means on said mandrel engaging said apical portion for deforming said anchor means in response to concurrent application of oppositely-directed forces of a predetermined magnitude at least equal to that of the forces required to expand said packing element acting through said expander member and means to expand said wall gripping portions of said base portion into anchoring engagement with a well conduit wall as said packing element is being expanded.

5. In a well tool, the combination comprising: a body; expander means slidably mounted on said body; annular anchor means disposed on said body extendible outwardly thereof for attaching the well tool to the wall of a well conduit, said anchor means being integrally formed in a generally frusto-conical shape to provide a base portion and an apical portion, said base portion adapted to engage said expander means; and means on said body engageable with said apical portion capable of relative movement toward said expander means, thereby to flatten said anchor means and expand said base portion into gripping engagement with the well conduit wall.

References Cited by the Examiner UNITED STATES PATENTS 1,804,619 4/1931 Humason 166-134 2,135,583 11/1938 Layne 277116.2 X 2,182,196 12/1939 Brown 166-134 X 3,068,942 12/1962 Brown 227-ll6.2 3,083,775 4/1963 Nielson et a1. 277-1l6.2 X

CHARLES E. OCONNELL, Primary Examiner.

J. A. LEPPINK, Assistant Examiner.

Claims

1. IN A PACKER DEVICE HAVING A PACKING ELEMENT OPERATIVELY MOUNTED AROUND A MANDREL WHERE THE PACKING ELEMENT IS ADAPTED FOR EXPANSION INTO SEALING ENGAGEMENT WITHIN A WELL BORE, THE IMPROVEMENT COMPRISING: AN ANNULAR MEMBER SLIDABLE MOUNTED AROUND SAID MANDREL AND OPERATIVELY ENGAGED WITH AN END OF SAID PACKING ELEMENT; INTEGRALLY-FORMED, DEFORMABLE ANNULAR ANCHOR MEANS SLIDABLY MOUNTED AROUND SAID MANDREL AND INITIALLY COAXIALLY DISPOSED IN A FRUSTO-CONICAL CONFIGURATION AROUND AND CENTRAL AXIS OF SAID MANDREL WITH THE APICAL PORTION OF SAID ANCHOR MEANS BEING DIRECTED AWAY FROM SAID EXPANDER MEMBER AND THE BASE PORTION OF SAID ANCHOR MEANS MEMBER BEING ARRANGED FOR ENGAGEMENT WITH SAID EXPANDER MEMBER, SAID BASE PORTION HAVING WALL GRIPPING PORTIONS; AND MEANS ON SAID MANDREL ENGAGING SAID APICAL PORTION, FOR DEFORMING SAID ANCHOR MEANS IN RESPONSE TO RELATIVE LONGITUDINAL ADVANCEMENT OF SAID ENGAGING MEANS TOWARD SAID WALL GRIPPING PORTIONS OF SAID EXPANDER MEMBER TO EXPAND SAID BASE PORTION INTO ANCHORING ENGAGEMENT WITH THE WALL OF A WELL CONDUIT.