US3389917A - Effective seal forming device - Google Patents

Description

June 25, 1968 c 3 ET AL 3,389,917

EFFECTIVE SEAL FORMING DEVICE 2 Sheets-Sheet 1 Filed June 22, 1966 0 l I. v {a 3 x56 g Cw 0; ix; plum Mm .Jm 1. 6 a w M b n 3 L w/ v 4 ATTORNEY June 25, 1968 MCGILL ET AL 3,389,917

EFFECTIVE SEAL FORMING DEVICE Filed June 22, 1966 2 Sheets-Sheet 2 flan/0rd 1. Ma 6/// /Vam6v' 6. J/wf/f, a}:

INVENTORS BY/JM /f? ATTORNEY United States Patent "ice 3,389,917 EFFECTIVE SEAL FORMING DEVICE Howard L. McGill and Homer G. Smith, Jr., Houston,

Tex., assignors to Schlumberger. Technology Corporation, Houston, Tex., a corporation of Texas Filed June 22, 1966, Ser. No. 559,465 Claims. (Cl. 277-63) ABSTRACT OF THE DISCLOSURE An anti-extrusion system for a well tool packing element comprising an annular member having slots extending from alternate end surfaces of said member to points adjacent alternate opposite end surfaces to divide said member into a plurality of segments having interconnected end portions, the interconnected end portions adjacent said packing element engaging said packing element to prevent extrusion of said packing element past said segments under pressure.

This invention relates generally to well tools, and more particularly to means for providing an effective seal in a well conduit. 3

For packing-off or plugging a well conduit, a well tool usually includes a pliant, elastomer packing element carried around a mandrel. When positioned within the well conduit, the packing element of the well tool functions to seal off the annular space between the mandrel and the surrounding wall of the well conduit. The packing element is normally supported against any substantial longitudinal movement relative to the mandrel by an annular shoulder or abutment extending outwardly of the mandrel.

In order that the well tool be freely shiftable within the well conduit prior to the effecting of a seal, a clearance space is provided between the outer surfaces of the well tool and the wall of the well conduit. Under the influence of compression forces, high pressures and temperatures, or any combination of these factors, the elastomer packing element may attempt to flow or extrude through the clearance space, resulting in deformation of the packing element and possible failure of the seal. Furthermore, if the well tool is to be subsequently retrieved from the well conduit, that portion of the packing element which has been forced into annular clearance space can cause the well tool to become anchored within the well conduit so that retrieval is either impossible or exceedingly difficut.

Accordingly, it is an object of the present invention to provide a new and improved sealing device for a Well tool which effectively overcomes one or more of the foregoing difficulties. I

Another object of the present invention is to provide a new and improved well tool with a packing element arrangement to minimize cold flow or extrusion of the packing element through adjacent clearance spaces.

These and other objects are attained in a well tool by providing the well tool with a resilient ring-like device which is selectively expandable from-a normally retracted position to form a solid bridge for the clearance space between the well tool and a well conduit. More specifically, the well tool body has an outwardly extending shoulder which supports an expandable and contractible annular member. The annular member is formed of longitudinally extending segments with a resilient interconnection between the segments. Means movable relative to the shoulder and the annular member are provided for expanding the annular member outwardly of the body. The annular member, when expanded, substantially closes the clearance space between the shoulder and a well conduit.

The invention has other objects and advantages which 3,389,917 Patented June 25, 1968 will become more apparent from the consideration of the following disclosure. Various embodiments thereof are shown in the accompanying drawings, which, in conjunction with the following detailed description, will illustrate the general principles of the invention. In the drawings:

FIGURE 1 is an elevational view of one embodiment of the present invention in connection with a well tool positioned within a well conduit;

FIGURE 2 is an enlarged partial cross-sectional view of a portion of the apparatus shown in FIGURE 1 to illustrate the principles of the present invention;

FIGURE 3 is a cross-sectional view of an expandable and contractible annular member in accordance with the present invention;

FIGURE 4 is a fragmentary view which illustrates the operation of the embodiment of the invention shown in FIGURES 1-3;

FIGURE 5 is a longitudinal view, partially in section, of an alternative embodiment of the present invention; and

FIGURE 6 is a cross-sectional view of the annular member of the alternative embodiment of FIGURE 5.

Referring now to FIG. 1, the invention is shown in connection with a bridge plug 10 (only partially illustrated) which would be positioned within a well conduit 11 where the conduit 11 extends upwardly to the earths surface. On the bridge plug are two oppositely facing cup-type packer elements 17, 18 attached to an operating mandrel 12 at a location adjacent to the top of a housing 13. The packer elements are responsive to pressure differentials from either direction across the bridge plug 10 which provide forces on the operating mandrel 12 tending to move the mandrel relative to the housing 13. On the bridge plug 10 is a friction anchor 14 circumferentially spaced about the housing. Movement of the mandrel relative to the anchor 14 increases the holding force of the anchor within the well conduit 11. The details of the bridge plug 10 which are not essential to the present invention are fully set forth in the patent application of James W. Kisling III, Ser. No. 482,009, now Patent No. 3,305,022, filed July 9, 1965, for Well Packing Apparatus. From the standpoint of the present invention, cups 17 and 18 are provided with an anti-extrusion device 26 which can be embodied on other types of packers and plugs aside from the specific bridge plug referred to above.

Referring now to FIG. 2, apparatus embodying the principles of the present invention includes a tubular mandrel or body 20 which may be, for example, the operating mandrel of the bridge plug shown in FIG. 1. Disposed around a reduced diameter portion 21 of the body 20 are the upper 17 and the lower 18 packing elements commonly known as swab cups. The inner end of each packing element is bonded or otherwise secured within annular recesses 22, 23 in expander members 24, 25 which are slidably received on the body. Disposed around the body 20 intermediate the packing elements is an expandable and contractible annular member 26 having an inwardly extending flange 27 received between an outwardly extending flange 28 of the reduced body portion 21 and a nut member 30 threadedly secured to the reduced body portion.

The annular member 26 has upper and lower inner inclined surfaces 31, 32 which diverge outwardly of the body 20, the surfaces complementarily engage inwardly converging surfaces 33, 34 on the upper and lower expander members 24, 25, respectively, so that longitudinal movement of either of the expander members is translated to outward movement of the annular member 26. Suitable sealing elements 35, 36 fluidly seal between the expanders 24, 25 and the reduced body portion 21. The lower end of the upper expander member 24 and the upper end of the lower expander member 25 are initially spaced a distance away from the nut member 30 and the outwardly extending flange 28, respectively, to permit limited longitudinal movement of the expander members relative to both the body 20 and the annular member 26.

The annular member 26 is made radially expansible and contractible by providing alternating series of radially cut slots 40, 41 extending from the ends of the annular member to points defined by radial holes 42 intermediate the ends of the annular member. The slots, in effect, divide the annular member into a plurality of circumferentially spaced longitudinally extended segments 43 which are interconnected by portions 44 between each segment to form a one-piece member. The member 26 is made of a steel or any other suitable material which has sufficient resilience to permit expansion when outward pressure is exerted on the inner inclined surfaces 33, 34 by the expander members 24, 25. When the outward pressure is relieved by movement of an expander member away from the annular member, the member should possess suflicient resilience to return toward its original position. The annular member is held against longitudinal movement relative to the body 29 by the engagement of the inwardly extending flange 27 between the outwardly extending flange 28 and the nut member 30 on the reduced body portion 21.

It Will be appreciated that as the annular member 26 expands outwardly, the slots 40, 41 will be widened. In order to prevent any cold fiow or extrusion of the packing elements into the slots, a plurality of plate members are positioned around the inclined surfaces of the annular member as shown in detail in FIG. 3. The plate members function to span or bridge the slots to keep the slots closed at all times. Each plate member 50 has a longitudinal portion 51 which extends across adjacent slots 40, 41, a tab portion 52 which extends into a radial hole 42 in the member 26 to fasten the plate member in place, and a radially outwardly extending flange portion 53 which extends across the end faces of the annular member. Each plate member 50 is made to have sufficient circumferential width whereby it will extend across adjacent slots 40, 41 when the annular member is expanded outwardly into engagement with the wall of the well conduit.

In operation of the apparatus illustrated in FIGS. 1-4 of the drawings, the well tool is positioned Within a well conduit. The outer surfaces of the packer elements 17, 18 are sized to normally engage the well conduit walls and the outer surface of the annular member 26 is spaced from the inner wall of the conduit in its contracted condition to provide a suflicient clearance space S therebetween. When a fluid pressure differential is developed in a downward direction across the packer elements of the well tool, the

upper packer element 17 will shift downwardly relative to the body 20, thereby moving the upper expander 24 downwardly as shown in FIG. 4. Downward movement of the upper expander 24 is translated to outward movement of the annular member 26 due to the interengagement of the inclined surfaces 31, 33. The annular member 26 will expand to substantially fill the annular clearance space between the member and the conduit wall and prevent the packer element 17 from cold flowing or extruding thereinto. The plate members 50 bridge the slots in the annular member adjacent the packer element so that the packer will not extrude into the slot spaces.

Conversely, an upwardly acting pressure differential across the packer elements of the well tool will activate the lower packer element 18 and expander 25 to expand the annular member 26 into the clearance space. Movement of the expanders away from the member will allow it to contract inwardly and return to its original shape so that ample clearance is again provided to permit shifting the well tool within the well conduit 11.

From the foregoing description, it should be appreciated that the slope of the inclined surfaces and construction of member 26 can be arranged to obtain uniform radial expansion. It is, of course, obvious to dovetail the connection between the member 26 and expanders 24, 25.

With particular reference to the alternative embodiment of the invention as shown in FIG. 5, a tubular body 60, which may be, for example, a part of a bridge plug of the type shown in the Composite Catalog of Oilfield Equipment and Services, 19661967, page 2898, has an enlarged portion 61 to provide a downwardly facing shoulder 62. A lower compression sleeve 63 is slidably received on the body for longitudinal movement relative thereto. An elastomer packing device 64 isvdisposed around the body 60 intermediate the shoulder 62 and the compression sleeve 63.

The upper and lower ends of the packing device 64 are bonded or otherwise secured within annular recesses 65, 66 in upper and lower expander members 67, 68, respectively. The expanders are slidably received on the body 60 and have inwardly converging surfaces 69, 70 which complementarily engage outwardly diverging inner surfaces on upper and lower annular members 71, 72. The annular members are made radially expansible and contractible by providing alternating series of radially cut slots as shown in FIG. 6, the slots extending from the ends of the members to points defined by radial holes 73 intermediate the length of the member in a manner similar to the slot configuration shown in FIG. 2. Similarly to the embodiment shown in FIG. 2, the slots divide the ring members into a plurality of longitudinal segments 74 with connecting portions 75 between each segment so that the members are uniformly expansible responsive to outward pressures exerted thereon by the expanders 67, 68.

A plurality of plate members 76 are positioned around the inner inclined surfaces of each ring member, the plate member functioning to bridge the slot gaps or spaces to prevent cold fiow or extrusion at the packer device into the spaces when the annular members are expanded outwardly. Each plate member 76 has a longitudinal portion 77 and a fastening tab 78 which engages in one of the holes 73. The plate members 79 which serve to span the slot spaces extending to the ends of expandable members adjacent the packing device, have flange portions 80 which extend outwardly over the member end surfaces.

Referring now to the operation of the alternative embodiment shown in FIGS. 5, 6, the well tool is positioned in-a well bore and the part operated to cause upward movement of the compression sleeve 63 relative to the body 60, thereby subjecting the packing device 64 to compressive forces for expanding the packing device outwardly into sealing engagement with the wall of the well conduit 11. As this expansion takes place, the expanders 67, 68 move relative to the annular members 71, 72 and exert outward pressure thereon to expand the annular members and substantially close the annular clearance space S adjacent both ends of the packing device.

It will be appreciated that as the ring members expand, the widths of the slots increase. However, the plate members 76 act to bridge the slot spaces at all times so that the packer element cannot extrude thereinto.

It will now be apparent that a new and improved sealing apparatus has been disclosed which provides an effective seal Within a well conduit and which prevents cold flow or extrusion of an elastomer packing element. It will be understood that although the invention is especially suited for retrievable well tools, it is not confined to the specific type of well tool described in the above-mentioned patent application, but can be used generally for preventing cold flow or extrusion of an elastomer packing element through the annular clearance space around a well tool and adjacent a packing element.

It will be understood that various changes and modifications may be made in the details of the embodiments shown without departing from the inventive concept, and it is intended that the appended claims cover all such changes and modifications.

We claim:

1. In a well tool, the combination comprising: a body; upper and lower packing devices disposed about said body and mounted for limited longitudinal movement relative to said body; an expansible and contractible annular member intermediate said packing devices; means cooperable between said body and said annular member for holding said annular member immovable longitudinally of said body While permitting radial movement thereof outwardly of said body; and expander means intermediate said packing devices and said annular member operable in response to longitudinal movement of said packing devices relative to said body for expanding said annular member radially outwardly of said body.

2. In a well tool: a body member; normally retracted anti-extrusion means disposed about said body member, said anti-extrusion means being a one-piece annular member having longitudinally cut slots extending from one end surface to points adjacent the opposite end surface in an alternating manner to divide said annular member into a plurality of segments which can be expanded outwardly, said segments having upper and lower inner inclined surfaces; upper and lower expander means cooperable with said inclined surfaces for expanding said segments outwardly; and packing means slidable on said body member and cooperable with one of said expander means for expanding said segments outwardly to positions where said segments engage said packing means to prevent extrusion of said packing means past said segments under pressure.

3. The well tool of claim 2 further including means between said segments for closing the spaces between said segments which are adjacent said packing means when said segments are expanded outwardly.

4. An anti-extrusion system for a well tool packing element comprising: an annular member having longitudinally cut slots extending from one end surface to points adjacent an opposite end surface to divide said annular member into a plurality of segments with adjacent segments having interconnected end portions, said segments being expansible to positions where alternate ones of said interconnected end portions engage said packing element to prevent extrusion of said packing element under pressure, said interconnected end portions also providing resilient means between said segments to enable expansion and also contraction of said segments relative to a well conduit wall.

5. An anti-extrusion system of claim 4 further including means between said alternate ones of said interconnected end portions for bridging the spaces therebetween When said segments are expanded to prevent flow of said packing into said spaces.

References Cited UNITED STATES PATENTS 2,672,199 3/1954 McKenna 166-202 X 2,714,931 8/1955 Bouvier 166135 X 2,743,780 5/1956 Brown 166-202 X 2,767,795 10/1956 Bush 166202 X 2,884,070 4/1959 Potts 166121 2,972,379 2/1961 Brown 166-202 X 3,181,614 5/1965 Brown 166-134 X 3,298,440 1/1967 Current 166135 X DAVID H. BROWN, Primary Examiner.

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