US3003798A

US3003798A - Anchoring reinforcing cables or braids in well packers

Info

Publication number: US3003798A
Application number: US660210A
Authority: US
Inventors: Herman L Sandlin
Original assignee: Jersey Production Research Co
Current assignee: Jersey Production Research Co
Priority date: 1957-05-20
Filing date: 1957-05-20
Publication date: 1961-10-10
Anticipated expiration: 1978-10-10

Description

H. L. SANDLIN Filed May 20, 1957 INVENTOR. Herman L. Sendlin,

BY i

FIG.

Kul# 9.13.6'... .4, A7#

FIG. 4.

ATTORNEY.

Oct. l0, 1961 ANCHORING REINFORCING CABLES OR BRAIDS IN WELL PACKERS Unite States This invention relates to the connection of interftting metallic members and more particularly to the interconnection of strain-bearing members of a well packer.

In connection with the construction of well packers, it has been the practice to secure flexible packing members, such as cables or braids, to a pair of end plates by a clamping arrangement wherein the ilexible braid or cable is clamped against a rough, generally sharp-toothed surface on each end plate so that the teeth bite into the cable or braid and effectively lock thereto, Another arrangement that has been successful with cable reinforced packers has been to lace a cable back and forth between the end plates through bores drilled into the plates near the edges thereof. While both of the above-described arrangements have advantages, there are certain objectionable disadvantages attendant to their use. For example, in connection with lacing a cable back and forth between end plates, it has been found diflicult, if not impossible, to make the various cable loops of the same length. Therefore, the various sections of the cable will not carry the same load and will tend to break prematurely. With the tapered wedge arrangement the strength of the connection is not particularly great and many packer failures have been encountered.

Manifestly, it should be possible to anchor individual lengths of cable or a braid into recesses drilled or otherwise formed in the end plates. However, in the past this arrangement has not been particularly successful. Babbitt metal or Zinc has been used to anchor cables in bores, but Babbittmetal must be applied at such high temperatures (in the vicinity of 1l00 F.) that the heat causes the cables to lose their temper and, hence, to break easily under subsequent tension and flexing. While zinc may be applied at low temperatures, it lacks holding strengthy and inevitably fails under relatively light loads. The use of granulated particles to lock cables to a bore as described in U.S. Patents No. 1,827,297 to C. R. Moore, No. 2,149,209 to D. P. Dickie et al., and No. 2,038,535 to O. W. Bernizer, is precluded because of the impossibility of compressing the end plates of well packers as required by the teachings of the aforementioned patents.

Accordingly, it is one object of this invention to provide an improved method for interconnecting two members that effects a junction of great strength and that may be applied at low temperatures.

Another object is to provide a connection for intertting members that will not be eiected by temperatures in the vicinity of 350 F.

Still another object is to provide a cable-reinforced well packer wherein the cables may be madel to carry substantially the same load when the packer is sealing oli a section of a borehole.

Still another object is to provide a connection for the llexible metallic members of a well packer that will not ice adversely effect the strength of the flexible metallic members.

Other objects and features will become apparent upon consideration of the following detailed description of the invention when taken in connection with the accompanying drawings, wherein:

FIG. l is a front elevation, partially in cross-section, of a typical well packer that may be used in connection with this invention;

FIG. 2 is an enlarged sectional view of a portion of the well packer illustrated in FIG. l showing certain of the component parts o-f the cable anchor in greater detail;

FIG. 3 is a cross-sectional view taken along the line 3 3 of FiG. 2;

FIG. 4 is a sectional view somewhat similar to FIG. 1 illustrating another embodiment particularly adapted for anchoring a metallic sheath; and

FIG. 5 is a cross-sectional view taken along the line 5-5 of FIG. 4.

The well packer illustrated in FIG. l is in many respects similar to well packers that have been in use in the oil industry for many years. It is -to be understood that this particular well packer is shown for illustrative purposes only and that many other types of well packers can be utilized in accordance with the teachings of this invention, such as the packers illustrated in Patent 2,828,823, for Reinforced Iniiatable Packers, by W. D. lvlounce and assigned to the assignee of this invention. The packer shown in FIG. 1 includes a well pipe 1 to which is secured an end plate 3, the end plate threadingly engaging well pipe 1 and being secured against rotation by a set screw 5. An O-ring sealing member 6 is provided for the purpose of obtaining a fluid-tight seal against the relatively high pressures which must Vbe exerted to inate the packer. The lower end of end plate 3 is provided with a plurality of recesses or bores 10 which are tapped in order to provide a rough surface in each recess for purposes to be described below.

A second end plate 21 is adapted to slide on the outer surface of well pipe 1 below end plate 3.' End plate 21` is provided with an O-ring sealing member 25, and has a plurality of tapped recesses or bores similar to recesses l0. A plurality of cable members 9 (each comprising a plurality of spirally wound wires, as shown most perspicuously in FIG. 2) of approximately the same length

interconnect end plates

3 and 21, the ends of the cable members being inserted in the recesses or

lbores

10 and 23. The cable ends are secured to the recesses by apotting composition 11 Iwhich will be described in greater detail below. The cables 9 act as a support upon which is formed a sheath or seal of rubber or rubber-like material 7. A fluid passage-way 13 extending through well pipe 1 opens to the exterior of the well pipe within the sheath formed by cables 9 and rubber-like composition 7 so that uid pressure may be exerted on the interior of the sheath arrangement'to inflate the packer. Manifestly, the lower end plate 21 will slide up and down on the well pipe in accordance Iwith the pressure exerted on the interior surface of sheathr 7.

The cable ends are secured to the end plates 3 by lirst lling the recesses in the end plates with a particular type of slurry, the composition of which is described below, after tapping the interior of recess 10 to insure a rough surface therein. The cables are inserted in the recesses, and the end plates and cables are thereupon placed within an oven and baked for a period of at least 2 hours at a temperature of at least 200 C. Preferably, the potting slurry is allowed to air dry for 2 hours before the baking operation but this is not absolutely necessary. Thereafter, the rubber or rubber-like sheath 7 is formed on the cables.

The potting slurry above described comprises a resinous material, preferably an exoxy resin, a granular filler and a heat responsive polymerizing (or hardening) agent for the resin. In order to add viscosity to the mixture, silicon dioxide may be added thereto although this has been found to be not absolutely necessary.

Epoxy resins have been found to be particularly desirable for application in this invention as the molecules thereof have the property of adhering to the molecules of other materials to an extent greater than any other known resin. The granular ller should be of at least the same hardness as the hardness of the materials of the members which are to be joined together. If the granular filler is of a material substantially harder than the members to be joined together, it may not be necessary to roughen the surface of the recess. However, for well packer applications, a rough-surfaced recess is preferred. Suitable llers for this application have been found to be earborundum, corundum, and aluminum oxide (A1203).

The polymerizing or hardening agent should have the following properties: (1) it must form a slurry with the other constituents described above; (2) the slurry formed therewith should not harden by itself at ordinary room temperatures for a period of at least 2 hours; (3) it should be heat-responsive, i.e., the hardening of the slurry containing the agent should be substantially accelerated by the application of heat; and (4) the slurry formed therewith should have a heat distortion point, when hardened, above the curing temperature of rubber (350 F.). Suitable curing or hardening agents have been found to be chlorendic anhydride, pyrornellitic dianhydride, and a mixture, 60% of m-phenylenediamine and 40% of 4,4methylene dianiline. Suitable slurries for use with the present invention have been found to comprise:

100 parts by weight of resin 40-80 parts by weight of a granular filler 20-45 parts by Weight of the hardening agent A very specific composition that has been found to be particularly satisfactory is the following:

100 parts by weight of resin 60 parts by Weight of carborundum 2O parts by weight of pyromellitic dianhydride The granular fillers described above should be 20-40 mesh in size or approximately 2-4 mils in diameter. It is believed that the granular particles interlock with each other and with the surfaces of the members to be joined to effectively form a bond between the members themselves. Utilizing steel cables having a diameter of inch anchored to steel end plates, and subjecting the cables to gradually increasing tension, it has been found that the cables themselves will break before the bond between the cables and the end plates is alected.

It should be noted that the invention is not to be limited to the above-described packer connection utilizing cable means. In FIG. 4 there is illustrated a connection particularly adapted for use with braided socks such as described in the aforementioned patent application, Serial No. 520,424. In this construction the end plate comprises an inner section l5 and an outer section 16 screw threaded to form the recess a. The braided sheath 17 is inserted into the annular recess formed by the two sections 0f the end plate. The potting composition utilized in connection with the apparatus shown in FIGS. 4 and 5 is the same as that described in connection with the embodiment shown and described with reference to FIGS. l, 2 and 3. With the exception of the use of the braided sheath and the particular construction of the annular recess 10a, the well packer is the same as that shown in HG. 1.

Although the embodiments disclosed in the preceding specification are preferred, other modifications will be apparent to those skilled in the art which do not depart from the broadest aspects of the scope of the invention.

What is claimed is:

l. Apparatus for end-connecting rough-surfaced, metallic reinforcing means of a well packer, comprising: an annular end plate adapted to t around a drill pipe; recess means in the end plate adapted to receive the reinforcing means; the ratio of the diameter of the recess means to the diameter of the reinforcing means being between 1.2 to l and 1.35 to l; and potting means between the reinforcing means and the end plate comprising parts by weight of an epoxy resin, 40 to 80 parts by weight of a granular filler for said resin selected from the group consisting of carborundum, corundum, and A1203, and 20 to 4S parts by weight of a heat responsive hardening agent selected from the group consisting of chlorendic anhydride, pyromellitic dianhydride, and a compound formed by a mixture of 60% of m-phenylenediamine and 40% of 4,4methylene dianiline.

2. Apparatus for connecting together the ends of Well packer cables, comprising: an annular plate; a plurality of recesses in the plate corresponding in number to the number of cables to be connected; the ratio of the diameter of each recess to the diameter of the cable to be inserted therein being between 1.2 to l and 1.35 to l; and potting means in each recess for securing the cables to the plate comprising 100 parts by weight of an epoxy resin, 40 to 80 parts by weight of a granular ller for said resin selected from the group consisting of carborundum, corundum, and A1203, and 20 to 45 parts by weight of a heat responsive hardening agent selected from the group consisting of chlorendic anhydride, pyromellitic dianhydride, and a compound formed by a mixture of 60% of m-phenylenediamine and 40% of 4,4methylene dianiline.

3. A method of connecting a cable to a member compn'sing the following steps: drilling a rough-surfaced recess in said member having a diameter not more than 1.35 times the outer diameter of the cable; forming a potting material by mixing 100 parts by weight of an epoxy resin with between 20 to 45 parts by weight of a heat responsive hardening agent selected from the group consisting of chlorendic anhydride, pyromellitic dianhydride, and the compound formed by a mixture of 60% of m-phenylenediamine and 40% of 4,4'methylene dianiline, and with 40 to 80 parts by weight of a granular filler selected from the group consisting of carborundum and corundum; inserting the potting material into said recess with the cable so that said potting material lills the space between the cable and the surface of the recess; and heating said cable bore and potting material to a temperature of 350 F. for at least 2 hours.

4. A method of connecting a cable to a member having a bore for receiving said cable comprising the following steps: roughening the surfaces of the bore and the cable; forming a potting material by mixing 100 parts by weight of an epoxy resin with 40 to 8O parts by Weight of a granular ller selected from the group consisting of carborundum and corundum, and between 20 to 45 parts by weight of a heat responsive hardening agent selected from the group consisting of chlorendic anhydride, pyromellitic dianhydride, and the compound formed by a mixture of 60% of m-phenylenediarnine and 40% of 4,4- methylene dianiline; inserting the potting material and the cable into the bore so that the potting material fills the space in the bore around the cable; and heating the 5 cable, bore, and potting material to a temperature of at 2,643,722 least 350 F. for atleast 2 hours. 2,768,090 2,828,823 References Cited in the file of this patent UNITED STATES PATENTS 5 1,189,235 Brown July 4, 1916 571,662 1,283,574 Schuster et a1 Nov. 5, 1918 1,827,297 Moore Oct. 13, 1931 2,357,733 Guderian Sept. 5, 1944 2,379,990 Rembert :my 1o, 1945 10 pages ros-9 9. '1 2,528,933 Wiles Nov. 7, 1950 2,561,351 Fentress July 24, 1951 6 Lynes .Tune 20, 1953 Wittcoff Oct. 23, 1956 Mounce Apr. 1, 1958 FOREIGN PATENTS Canada n Mar. 3, 1959 OTHER REFERENCES Industrial Engineering Chemistry, July 1957, vol. 49,

Industrial and Engineering Chemistry, October 1956, vol. 48, No. 10 (Flame-and-JHeat Resistant Epoxy Resins).