US2939534A

US2939534A - Sealed telescopic connection

Info

Publication number: US2939534A
Application number: US577325A
Authority: US
Inventors: Allen Herbert
Original assignee: Cameron Iron Works Inc
Current assignee: Cooper Industries LLC
Priority date: 1956-04-10
Filing date: 1956-04-10
Publication date: 1960-06-07
Anticipated expiration: 1977-06-07

Description

June 7, 1960 H. ALLEN 2,939,534

SEALED TELESCOPIC CONNECTION Filed April 10, 1956 f IN VENTOR.

United States Patent SEALED TELESCOPIC CONNECTION Herbert Allen, Houston, Tex., assignor to Cameron Iron Works, Inc., Houston, Tex., a corporation of Texas Filed Apr. 10, 1956, Ser. No. 577,325

2 Claimsv (Cl. 166-86) This invention relates to a novel sealed connection between a pair of telescopically arranged members; and, more particularly to such a connection in which the seal is formed as the members are threadedly made up with one another. 1

In the completion and reworking of oil and gas wells, it is frequently necessary to pass a variety of tools into the well tubing through passages in the wellhead equipment from which the tubing is suspended. Obviously, it is desired to keep the tubing and Wellhead size to a minimum by having the minimum inside diameter of the tubing and the passages approximate the maximum outside diameter of such tools as closely as possible.

One of the more commonoperations in well completion and reworking is the location of a valve fixedly within a passage in the wellhead above the tubing to prevent the flow of production upwardly therethrough. A connection of the general type contemplated by this invention is especially useful in this connection for it permits the valve to be sealed and fixedly located within the passage as it is extended axially therethrough. Thus, it has been proposed to form this sealed joint by means of complementary shoulders on the valve and wellhead passage which are adapted to be brought into abutment to form a metal-to-metal seal as the valve is threadedly made up within the wellhead. In such a case, the outer diameter of the valve at the shoulder necessitates that the minimum inside diameter through the upper portion of the wellhead passage be correspondingly larger than the minimum inside diameter of the well tubing, and thus the maximum out-side diameter of the tool.

An object of this invention is to provide an improved telescopic sealed connection of this general type in which the maximum outside diameter of the male member need only exceed the minimum inside diameter of the female member by approximately the depth of the threads by which they are made up with one another.

Another object is to provide a sealed telescopic connection of the character described in the foregoing object in which a desired degree of pressure may be applied to the sealing part between the male and female members.

A further object which is pertinent particularly to the environment above-mentioned is to provide an improved connection between a back-pressure valve and a wellhead member in which the valve is to be telescopically received, which connection is so constructed that the passage in the wellhead member through which the valve is extended need not be appreciably greater than that of the well tubing below the wellhead.

Other objects, advantages and features of this invention will be apparent to one skilled in the art upon a consideration of the written specification, the attached claims and the annexed drawings.

In the drawings, wherein like reference characters are used throughout to designate like parts:

Fig. 1 is a view, partly in section, of a dual string of well tubing suspended by hangers within the wellhead, and with a back-pressure valve shown fixedly and seal- 2,939,534 1C6 Patented June 7, 196,

ably located within one hanger by means of the connection of the present invention;

Fig. 2 is an enlarged sectional view of a part of the connection as the valve is being made up Within the hanger, but prior to formation of the seal therebetween; and

Fig. 3 is a view similar to Fig. 2, but upon an additional making up of the valve within the hanger to form the seal therebetween.

Referring now particularly to the drawings, there is shown in Fig. 1 a wellhead which includes a tubing head and another wellhead member 11, which, as shown in Fig. 1, is a valve, as will be described hereinafter. The member 11 is connected above the tubing head by means of circumferentially spaced apart bolts 12 and sealed with respect thereto by an annular ring 13 compressed tightly between oppositely disposed grooves 14 and 14a in the member 11 and tubing head 10, respectively. Suspended by hangers 15 Within the tubing head are a pair of parallel well tubings 16 which are adapted to extend to production zones within the well and are of a minimum, inside diameter to accommodate the passage of tools therethrough. As fully described in my copending application, Serial No. 545,079, filed November 4, 1955, and entitled Pipe Hanging Apparatus, and now issued as Patent No. 2,794,505, each of the tubing hangers 15 is supported from and sealed with respect to the tubing head 10. In the particular embodiment shown in the drawings, the wellhead member 11 is, as previously noted, a valve. However, in an earlier stage of the completion process, a blowout preventer is connected above the head and the hangers are run through the preventer and into supported position by means of handling joints of tubing. The handling joints are then removed and the preventer is replaced by the master valve 11 which has passages 17 formed therein above each of the hangers. When the -hangers have been landed, the strings are removed through the preventer, and the preventer is removed from the head and replaced by a completion valve. Inasmuch as the other details of this Wellhead installation are not pertinent to the present invention, and are fully disclosed in the above-mentioned copending application, further reference thereto will not be made.

The opening through each of the hangers 15 is provided with a threaded portion 18 for connection with a back pressure valve or similar member 19. During the completion process the back pressure valve is lowered with the hanger through the preventer and then removed therefrom through the passage 17 in the completion valve 11 when the well is to be brought in. Preferably, the minimum inside diameter of the passage through the valve 11 is larger than the minimum inside diameter of the opening through the hanger, which is defined by the inside or extremities of the threads 18, by only an amount approximating the depth of such threads so as to accommodate passage of the maximum outside diameter of the body of the valve 19. The maximum diameter is defined by the outermost portion or extremities of threads 20 on the valve body for mating with threaded portion 18 of the opening through the hanger 15 to telescopically connect the valve within the opening through the hanger. It will be appreciated that the maximum size of tool which may be passed through the hanger and into the well tubing 16 is limited by the minimum inside diameter of the hanger defined by threaded portion 18, such that the minimum inside diameter of the passage through the completion valve will be somewhat larger than that of the well tubing=16. However, in accordance with the present invention, and as will be appreciated from the description to follow, this excess need only be approximately the depth of the threads by which the valve and hanger are connected together.

The back-pressure valve 19 is made up of a valve body 20a upon the outer diameter of which are disposed the threads 20, and a passageway 21 through the body having an annular seat 22 formed upon an intermediate portion thereof. A valve member 23 is movable within the passage between seated and unseated positions with respect to the valve seat 22 for closing and opening the flow passage 21, respectively. More particularly, the valve member 23 is provided with a stem 24 guided Within an opening 25 on the lower end of the valve body, and is urged to a normally closed position by means of a coil spring 26 disposed between the body and the head of the valve member. Thus, when disposed as shown within the hanger 15, the valve 19 serves to shut off production flow upwardly through tubing 16.

As is common in the art, the valve is moved into and out of its fixed position within hanger by means of a stinger or similar tool which depresses the valve memher to hold it in an open position. For this purpose, the upper end of the valve body may be provided with slots 27 to accommodate parts of the stinger by means of which a rotary movement may be imparted to the valve body for making up the threads with the threaded portion 18 on the passage through the hanger. Also, as can be seen from Fig. 1, the lower end of the valve body is of a spider construction to define the opening while at the same time permitting the freedom of flow therepast.

Although the connection of the present invention will be described in detail below in connection with the aforesaid valve and wellhead, and even though it, in fact, has particular utility in such an environment, it should be understood that it is contemplated that the connection may have other applications, and the terms of the claims should not be limited to the illustrated environment.

With reference now particularly to Figs. 2 and 3, the connection of the present invention includes a seal ring 27 of flowable material, such as rubber or a suitable plastic, disposed annularly of one of the valve body 20a and hanger 15 for confinement therebetween and deformation by the threads of the other of the valve body and hanger into sealing engagement therebetween as such members are made up with one another. Thus, the seal ring 27 is disposed in the path of the leading threads of said other member as the two members are made up with one another, so that the flowable material of the ring will be displaced and thus distorted in the manner described. In accordance with the present invention, these threads bear such a relation to the ring that the latter is first deformed as the members reach one stage of being made up and then the internal pressure of the confined seal ring is increased to a desired extent as the members are further made up with one another.

More particularly, the seal ring 27 is disposed annularly between the two telescoping members for confinement between a shoulder 28a on one member and the aforementioned threads on the other member. As shown in the drawings, the ring 27 substantially fills a groove 27a about the valve body between the threads 20 and one end of a cylindrical surface on the valve body at the other side of the ring, said cylindrical surface and seal ring being of an outer diameter substantially no greater than the outer portions of the threads 20, but at the same time disposable closely adjacent inner diameter of a cylindrical surface 18a of the opening through the hanger 15, which inner diameter substantially equals that of the root of threads 18 so as to prevent the flow of the ring therepast.

As shown, the threads are preferably of a relatively shallow flat-crested type so as to maintain the inside diameter of the wellhead passage at a minimum while at the same time providing a maximum of displacement of the flowable material of the ring per unit of axial movement of the threads on the hanger relative to the ring. In this manner, the threads may easily bear such a cross-sectional area relative to that of the seal ring 4 so that the ring, as previously mentioned, is first distorted into sealing engagement with the cylindrical surface 18a of the hanger opening between the shoulder 28a forming part of the groove 27a on 'the end of the cylindrical surface 28 and the uppermost thread of the threads 18, such that its internal pressure may then be increased to a desired degree upon further making up of the valve within the hanger. Although the seal ring is shown to be of a substantially rectangular cross-section, it may be of an O-ring shape or any other desired cross-sectional shape having the desired relationship to the threads. Furthermore, of course, it is desired that the seal ring not project too far beyond the outer diameter of the valve body so that it will not be damaged in any way in passing through the passage 17 and hanger 15.

It will be appreciated that the straight-type threads illustrated are preferred inasmuch as they permit a great flexibility in the accomplishment of desired pressure upon the seal ring as there is no limit to axial movement between the threads. Also, it is preferred that the seal ring 27 be carried by the valve as this facilitates removal and replacement thereof, when desired.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

The invention having been described, what is claimed is:

1. A sealed telescopic connection, comprising a first member having threads and a substantially cylindrical surface whose diameter substantially equals that of the thread roots, a second member having threads for mating with the threads of the first member and a substantially cylindrical surface of very nearly the same diameter as the cylindrical surface of the first member for disposal closely adjacent the cylindrical surface of the first member, an annular groove in the second member intermediate the threads and an end of the cylindrical surface thereof, and an annular deformable sealing ring substantially filling the groove and having a diameter substantially the same as that of the cylindrical surface of said second member, the cylindrical surface of the first member being opposite the sealing ring and cylindrical surface of the second member, as the leading threads of the first member engage with the scaling ring during making up of the members with one another, confining the sealing ring for deformation into sealing engagement between the first and second members and permitting the internal pressure of the confined sealing ring to be increased to a desired degree upon continued making up of said members.

2. A wellhead assembly, comprising a tubing head, a wellhead member connected to the upper end of the tubing head, a tubing hanger supported within the tubing head for suspending tubing therefrom and having an opening therethrough which includes a threaded portion and a substantially cylindrical surface whose diameter substantially equals that of the thread roots, means defining a flow passage through the wellhead member in alignment with the opening through the tubing hanger, a back pressure valve comprising a body having threads thereon for connection with the threaded portion of the opening through the hanger and a substantially cylindrical surface of very nearly the same diameter as the cylindrical surface of the hanger opening for disposal closely adjacent the cylindrical surface of the hanger opening, an annular groove in the valve body intermediate the threaded portion and an end of the cylindrical surface thereof, and an annular deformable sealing ring substantially filling the groove and having a diameter substantially the same as the cylindrical surface of the valve body, the cylindrical surface of the hanger opening being opposite the sealing ring and cylindrical surface of the valve body as the leading threads on the hanger opening engage with the sealing ring during connection of the valve with the hanger, confining the sealing ring for deformation into 10 sealing engagement between the hanger opening and valve body and permitting the internal pressure of the confined sealing ring to be increased to a desired degree upon continued making up of the valve within the hanger, and

5 passage of the valve therethrough.

References Cited in the file of'this patent UNITED STATES PATENTS 2,148,327 Smith et al Feb. 21, 1939 2,246,436 Downey June 17, 1941 2,413,878 Maky Jan. 7, 1947 2,469,074 Mueller May 3, 1949 2,794,505 Allen June 4, 1957