US 3158378 A
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United States Patent 3,158,378 0lt iPt3 SHE BACK-U? RING STRUCTURE Glenn L. Leomis, R0. Box 728, Pasadena, Tex. Filed Feb. '2, 1962, er. No. 179,538 Claims. (til. 277-198) The present invention relates to a packing structure for use in forming a seal between a rod-like element and a surrounding wml of a well pipe or the like and, more particularly, to a packing structure incorporating an improved composite back-up ring for preventing cold end flow of a packer when the packer is set against the wall of a well pipe and then subjected to high internal pressures.
The packing structures of the present invention is preferably intended for use in a device for testing well pipe or the like for leaks, but it may also be used with other well equipment when it is desired to set a packer in the Well pipe and the packer is subsequently subjected to extreme pressures. A typical testing device for which the packing structure of the present invention is preferably used is disclosed in my copending United States application Serial No. 170,711, filed February 2, 1962, and entitled Testing Tool for Well Pipe or the Like and filed concurrently herewith. The subject matter of the testing tool disclosed in the aforementioned copending application is incorporated by reference herein for that purpose.
In recent years, the flow tubing for oil or gas wells or the like has been made with an internal plastic lining. The plastic lining which is usually coated on the interior of the pipe provides protection to the metal pipe from the corrosive action caused by acids and other fluids flowed therethrough; The plastic lining of the sections of pipe is quite fragile and may be easily damaged if contacted by a well tool having a harder surface than the lining. In my aforementioned copending application, there is dis closed completely a well tool suitably coated on its ex terior surfaces with a material as soft as or softer than the lining so as to protect the lining as the well tool is inserted into the pipe.
The back-up rings heretofore used in association with resilient packers to prevent cold flow of the packer under extreme pressure conditions have been made from arcuate metallic segments which were simultaneously expanded into engagement with the wall of the pipe when the packer was expanded. Such a back-up ring is disclosed in my copending application Serial Number 754,197, now Patent No. 3,038,542, filed August 11, 1958, and entitled Tester Apparatus for Oil Wells or the Like. It has been found that the engagement of the metallic segments of the expansible segmental back-up ring with the plastic lining when the same are expanded by the annular pressure exerted by the packer immediately crushes the lining in the pipe and thus, when the well tool is removed, the effectiveness of the lining has been materially reduced as the pipe can be subjected to corrosive action at this point.
An important object of the present invention is to provide a packer back-up ring structure comprising an expansible segmental back-up ring composed of arcuate metallic segments having a covering of non-metallic material on their outer peripheral surface.
Another object of the present invention is to provide an expansible packer back-up ring having outer peripheral surfaces made from a non-metallic material which will not damage the plastic lining of a well pipe when engag ing the same, the back-up ring being providedwith arcuate metal segments for sustainingthe thrust exerted by the packers when the packers are caused to cold flow by application of extreme pressures thereto.
Ancillary to the preceding object, it is a further object of the present invention to provide an expansible packer back-up ring comprised of outer arcuate non-metallic ele- 3,158,378 Patented Nov. 24, 1964 ments for engaging well pipe wall and inner metallic segments fixed thereto, the metallic segments sustaining the forces necessary to cause expansion of the ring.
Still another object of the present invention is to pro vide an expansible packer back-up ring comprised of a plurality of metallic segments having replaceable nonmetmlic coverings over their outer peripheral surfaces.
Sections of well pipe are now made with threaded male and female ends which are thickened over the normal wall thickness. By providing such an arrangement, it is no longer necessary to use a collar in attaching two sections of well pipe together. However, the newly designed well pipe with the thickened end portions have a decreased internal diameter at their point of connection due to the internal upset caused by its male and female ends. Consequently, in order that well tools utilizing packers may pass through the internal upset, the well tools must be made of a decreased diameter and thus the packer backup rings have to be capable of accommodating a greater expansion tolerance than heretofore necessary.
Ancillary to the above, it is another important object of the present invention to prouide an expansible segmental back-up ring capable of having a greater tolerance of expansion than heretofore realized and then returned to its original retracted position.
The foregoing and other objects and advantages of the present invention will appear more fully in the following specification, claims and drawings in which:
FIGURE 1 is a fragmentary vertical section through a portion of well pipe and illustrating the packing structure of the present invention utilized on a testing device being lowered into the well pipe, the testing device being shown partly in section and partly in elevation;
FIGURE 2 is a view similar to FIGURE 1 but illustrat- I being shown in elevation and the well pipe being omitted for the purpose of clarity;
FIGURE 4 is a perspective view having a portion broken away and illustrating the expansible packer backup ring of the present invention; and
FIGURE 5 is a fragmentary longitudinal sectional view through a modified form of expansible packer back-up ring.
Referring now to the drawings wherein like character and reference numerals represent like or similar parts, the packer back-up ring structure of the present invention is illustrated utilized on the lower end of a testing device generally designated by the numeral 1%. The testing device 16 is of the type disclosed in my aforementioned pending applications and generally includes an elongated tester body having spaced packers mounted thereon and adapted to be expanded into engagement with the walls of a well pipe 12 or the like. The testing device it) is provided with suitable fluid passages for supplying hydraulic fluid under pressure to pistons acting against the packers, the pistons compressing the packers longitudinally and thus expanding them transversely so that they form sealing engagement with the well pipe 12 todefine a sealed. off section of well pipe to be tested.
The testing tool 10 is also provided with suit-able pres-- of Well pipe or' the well pipe wall itself may be tested by such a fluid pressure method. After the well pipe has been tested, the pressure on the hydraulic fluid in the testing tool is relieved and the packers are relaxed so in the well pipe to provide for a subsequent test. The
testing procedure briefly described above is disclosed in detail in my aforementioned pending application entitled Testing Tool for Well Pipe or the Like as well as in my prior United States Patent No. 2,731,827, issued 3 an. 24, 1956.
Referring now in detail to FIGURES l and 2, the well pipe 12; is of the type having a protective lining C made of a plastic material such as an epoxy resin or the like. The packing structure of the present invention generally designated by the numeral 14 is carried on the elongated body of the testing device ll) which may be considered for the purposes of this description as a rod-like element 16. Packing structure 14- includes a substantially cylindrical resilient packer 18 made of an elastomeric material such as iubber, synthetic rubber or the like, a piston element 20 and a back-up ring structure 22. The piston 20 abuts one end of the packer and may be moved longitudinally toward the packer by application of hydraulic fluid under pressure to the interior of the same. The rod-like element 16 is provided with an abutment portion or nose end 24 and the back-up ring structure 22 is interposed between the abutment portion 24 and the end of the packer l8 opposite the end abutting the piston 2 It will now be understood that when the piston 29 is extended or moved downwardly from the position 05' FIGURE 1 to the position of FIGURE 2, the packer 18 is compressed longitudinally against the back-up ring structure 22 and simultaneously expanded transversely into sealing engagement with the wall of the flow tubing 01 well pipe 12.
Since the resilient packer 18 is made of an elastomeric material, it will not damage the plastic lining C of the well pipe when it engages the same. As shown in FI URES l and 2, the exposed portions of the testing evice including the piston 2t and the rod-like element in with its abutment portion 24 are coated with a non-metallic material M as soft as or softer than the plastic lining C of the pipe. This feature of the well tool is disclosed in detail in my aforementioned application entitled Testing Tool for Well Pipe or the Like.
The back-up ring structure 22 includes an expansible segmental back-up ring 26 positioned intermediate a pair at 34. The expansible segmental ring 26 has each of its ends provided with an annular inverted cone-shaped surface 36 which cooperate with and are complementary to the cone-shaped surfaces 34 of ring elements '23 and 39. It will now be apparent that when the piston 29 moves downwardly from the position shown in FIGURE 1, it
is effectively working against the abutment portion 24 in that it compresses the packer l8 and causes the same to expand transversely, the packer in turn pushing the ring element 2%; toward the ring element 30. A wedging action occurs as the cone surfaces 34 of ring elements 28 and 3d push against the inverted cone surfaces 36 of the segmental back-up ring 26, thus causing uniform expansion of the back-up ring 26 radially outwardlyuntil it engages the wall of the well pipe 12, as shown in FIG- URE 2. When the back-up ring 26 is expanded, it prevents longitudinal extrusion of the packerwhen the packer is subjected to extreme pressures.
The expansible segmental back-up ring 26 is composed of a plurality of arcuate metallic segments 33 retained in .a retracted position by a pair of endless elastomeric retaining bands 40 and 42 and a plurality of non-metallic arc'uate covering elements 44, each being secured to one of the segments 38 by means of a brass screw 46. In-
part of the cone-shaped surface 36 of the ring. Further,
the segments 38 are provided on their outer curved periph- I eral surface 52; with spaced annular undercut shoulders 43 and a pair of circumferentia-lly extending grooves 56). The grooves 50 receive the O-ring retaining bands 40 and and maintain them in longitudinal spaced relationship I which are received in the undercut shoulders 48 of the metallic segments 38 when the non-metallic elements 44 are fixedly secured thereto. By such an arrangement, the thrust exerted on the end of the expansible packing ring by the cold flow of the packer is transferred to and sustained by the metallic segments 33 rather than entirely by the covering element 44. 7
It will be noted from FIGURE 4 that the ends of each of the non-metallic elements 34 are tapered inwardly, as indicated at 36", and thus when the elements 44 are assembled on the arcuate metallic segments 38 they form a continuation of the tapered surfaces 36' to define the inverted conical-shaped end surfaces 36.
Each of the non-metallic covering elements 44 is fixedly secured to one of the metallic segments 33 by the brass screw 46. The brass screw 4-6 has its head countersunk below the peripheral curved surface 52 of the element 44 so that it will not contact the wall of the well pipe when the ring is expanded. By utilizing a screw to attach the non-metallic elements 44 to the arcuate segments 38, the non-metallic elements 44 may be replaced when they become worn or damaged.
The non-metallic elements 44 are preferably made from a resin impregnated fiber such as phenolic impregnated Fiberglas or the like. However, they may be made from an elastomeric material such as rubber, synthetic rubber or the like or they may be made from a plastic material such as'polyurethane. By providing covering elements 44 for each of the arcuate segments 38, it will now be appreciated that when the back-up ring is expanded and contacts the wall of the Well pipe 12, it will not than age the lining or coating C. Also, by providing elastomeric endless retainer bands 40 and .42, circumscribing the metallic segments 38 and interposed between the same and the non-metallic covering elements 44, the expansible ring can be expanded from its retracted position a greater distance than previous back-up rings utilizingsnap rings or coil springs. Interposing the retaining bands 40 and 42 between the metallic segments and the non-metallic segments 44 protects the bands from exposure to fluids within the well as well as providing a simple means of assembling the ring 26 as a unit. Further, utilization of wedging means, such as the rings 28 and 30 on both ends of the ring 26, provides for a greater expansion tolerance which will be uniform over the entire range of expansion.
FIGURE 5 illustrates a slight modification of the backup ring of the present invention in that the metallic segments 33 are provided with a single enlarged groove 50 which receives aresilient endless retainer band 40' that is rectangular in cross-section. In this modification of the invention, the screw 46 extends through the outer covering element 44 and an aperture 4%)" provided in the band 40', the screw being threaded into the metallic segment 38'.
i Although the metallic segments 38 and the non-metallic covering elements 44 have been illustrated in simple arcuate form whereby they abut on their respective radial faces, 'it will be understood by'those skilled in'the' art, the expansible back-up ring of the present invention may incorporate the overlapping feature of the segments disclosed in the back-up ring of my copending application Serially Numbered 754,197 without departing from the spirit of the present invention. a
While the invention has been primarily disclosed in relation to its preferred use with a packing structure of a testing tool for oil and gas well flow tubing, it is, of course, within the scope of the present invention that the improved expansible back-up ring could be used with a packer in flow tubing or casing whenever it is desired to form a seal between any rod-like element of a well tube and the wall of the tubing or casing. Therefore, the terminology used in this specification is for the purpose of description and not for limitation as the scope of the invention is defined in the claims.
What is claimed is:
1. A composite expansible back-up ring for use with a resilient packer set in a plastic lined well pipe or the like, said back-up ring comprising: a plurality of arcuate metalllc segments; a plurality of non-metallic arcuate shaped elements, each of said non-metallic elements covering the entire exterior surface of each of said metallic segments; means for attaching each of said non-metallic elements to one of said metallic segments; and resilient means circumscribing said arcuate metallic segments and interposed between the same and said non-metallic arcuateshaped elements for retaining them in a retracted position as a unit.
2. The composite expansible back-up ring of claim 1 wherein each of said non-metallic arcuate shaped elements is made from a resin impregnated fabric.
3. The composite expansible back-up ring of claim 1 wherein each of said non-metallic arcuate shaped elements is made of an elastomeric material.
4. The composite expansible back-up ring of claim 1 wherein each of said non-metallic arcuate shaped elements is made of a plastic material.
5. The composite expansible back-up ring of claim 1 wherein said resilient means circumscribing said segments is an endless retainer band made of an elastomeric material.
6. The composite expansible back-up ring of claim 1 wherein said means for attaching each of said non-metallic elements to said metallic elements includes at least one screw extending inwardly through one of the non-metallic elements and threaded into one of the metallic segments,
each screw having its head countersunk below the exterior peripheral surface of the non-metallic elements.
7. A composite expansible back-up ring for use with a resilient packer set in a plastic lined well pipe or the like, said back-up ring comprising: a plurality of arcuate metallic segments; means circumscribing said segments for retaining them in a retracted position as a unit; said means including at least one groove in the exterior peripheral surface of each of said segments, the grooves in each of said segments defining an annular peripheral groove about the segments when the segments are arranged as a unit and at least one resilient retainer band carried in the annular peripheral groove; and a plurality of arcuate shaped non-metallic covering elements, each of said covering elements being fixedly secured to the exterior peripheral surface and entirely covering the exterior peripheral surface of one of said metallic segments, said band being interposed entirely between the metallic segments and the non-metallic covering elements when the same are retracted as a unit.
8. The composite expansible back-up ring of claim 7 wherein said resilient retainer band is rectangular in cros -section and wherein each of said non-metallic covering elements are fixedly secured to the respective metallic segments by at least one screw extending through the element and the band and threaded into the respective metallic segment, the screw having its head countersunk beneath the exterior surface of the non-metallic element.
9. The composite expansible back-up ring of claim 7 wherein opposite ends of the back-up ring defined by the arcuate metallic segments and arcuate shaped nonmetallic covering elements are each tapered to provide inverted conical surfaces.
10. A composite back-up ring of claim 7 wherein said resilient retainer band is an O-ring.
References Cited in the file of this patent UNITED STATES PATENTS 1,53 6,025 Lamb et al. Apr. 28, 1925 1,861,614 Schweitzer June 7, 1932 2,555,647 King June 5, 1951