US2976076A

US2976076A - Releasing overshot

Info

Publication number: US2976076A
Application number: US721500A
Authority: US
Inventors: David L Farley
Original assignee: Halliburton Co
Current assignee: Halliburton Co
Priority date: 1958-03-14
Filing date: 1958-03-14
Publication date: 1961-03-21
Anticipated expiration: 1978-03-21

Description

'March 21, 1961 D, L, FARLEY 2,976,076

RELEASING OVERSI-IOT Filed March 14, 1958 l I i f 26// I7 25//7 /J\\l8 I x 2o /IB Flai F162 F165 I INVENTOR.

David L. Farley ATTORNEY United Statesv Patent O RELEASING OVERSHOT David L. Farley, Duncan, Okla., assigner to Halliburton Company, a corporation of Delaware Filed Mar. 14, 1958, Ser. No. 721,500

1 Claim. (Cl. 294-4102) This invention relates to an oil well device and more particularly to what is known as an overshot for removing objects Ifrom oil wells in a fishing operation.

Overshots are well-known devices for retrieving objects from oil wells. Ordinarily, such overshots are lowered into an oil well on either a wire line or on tubing or drill pipe and surround and latch on to the object or fish to be removed, the grapple having spring fingers of some sort to assist in making the coupling.

The overshot `of the present invention has similar mechanisms, but it is especially designed to release from the fish when desired, as in the case where the fish is stuck and cannot be removed and it is necessary to remove the overshot fro-rn the well without pulling the fish.

The overshot of the present invention is composed basically of a locking spring and a releasing mechanism. The locking spring consists of a cylindrical part split into several sections which act as fingers. When the fingers are spread over the neck of the fish, the inner shoulders of the fingers normally hook below the top of the fishing neck so that when upward force is exerted on the overshot, this force is transferred to the fish. The overshot can be released by jarring downwardly upon the locking spring and the housing which contains it. Within the housing there is la releasing sleeve held in inactive position `during normal operation of the tool, and provided with a snap ring and two shear pins. Downward jarring shears these pinsso that the housing can then slide downwardly and cause the snap ring to secure the releasing sleeve in -a higher position in the housing. Then, when an upward yforce is exerted on the overshot, the releasing sleeve comes in contact with the lower end of the locking spring, thus, spreadingy the fingers and allo-wing the overshot to pull off from the fishing neck.

It will -thus be seen that an object of the invention is to provide a releasing overshot which can be lowered into a .well in such a condition that it will serve as a grapple and impart upward pull or upward jarring action upon a fish but which may be caused to releasefrom the fish upon downward jar being delivered to it.

Other objects and advantages reside in certain novel features of the arrangement and construction of parts, Vas will be apparent from the following description taken in connection with the accompanying drawing in which:

Figure l is a view in side elevation of an assembly of jars, releasable overshot, and fish, such as `may be used inan oil well;

Figure 2 is a view in vertical quarter cross section of the releasing overshot of Figure l, the view illustrating the position of the parts when the overshot is first brought into grapple posit-ion with a fish; v

Figure 3 is a vertical quarter cross-sectional view similar to that of Figure 2 but illustrating Athe position of the parts where an upward pull is being exerted on the fish or when an upward jar Vblow is being delivered to the fish;

Figure 4 is a view in vertical `cross section of the retrievable overshot similarto that of Figures 2 and 3 but illustrating the position of the parts after a downward ICC jarring blow has been delivered to shear the pins but before the fingers of the locking spring have been disengaged from the leek of the fish; and

Figure 5 is a view of the releasing overshot in vertical quarter cross section similar to Figures 2, 3, and 4 but illustrating the positionvof `the parts after the overshot is released from the neck of the fish.

Referring to the drawing in detail and first to the general assembly of Figure 1it will be seen that a cable 10 is there illustrated as supporting a conventional twoway jar 11 which is, in turn, connected to a releasing overshot 12 connected to a fishing neck L13 of a fish 14.

The novelty of the present invention resides in the general assembly illustrated and more particularly in the details of construction of the releasing overshot which is contained within the housing 12.

Figures 2, 3, 4, and 5 are all similar and illustrate the sequence of operation of the releasing overshot as well as the details of construction of the various parts.

As shown in Figures 2, 3, 4, and 5, the housing 12 is provided with a threaded coupling 16, at its upper end. The housing 12 is a hollow cylinder but is provided with a number of -grooves and lands on its interior. Near its upper end it is provided with a land 15 of circular shape which serves as a guide for the locking spring 23. Some distance below the land 15, there is a second circular land 17 which also serves as a guide, and beneath this land 17 there is a groove y18, the purpose of which will be apparent :from the description hereinafter.

There are two shear pins 19 employed in the overshot, these 'being fitted into suitable sockets in the housing 12, as illustrated in Figures 2 and 3, and arranged 180 degrees apart. For purposes of assembly, the sockets for the pins 19 may be provided with externally removable caps, -but these have not been illustrated in the drawing for reasons of clarity.

There is also provided in the overshot assembly a split snap ring 20. This is mounted in a groove on the releasing sleeve 26 and serves to lock the sleeve in its upper position in the housing 12, as described hereinafter, once the pins 19 have sheared. As shown in Figures 2 and 3, this snap ring 20 is held compressed by the lower portion of the housing 12. When it is raised sufiiciently within the housing 12, it snaps outwardly into the groove 18, as illustrated in Figures 4 and 5.

The neck 13 of the fish 14 is provided at its upper end with an enlarged head orrlatch portion 21 suitably tapered as illustrated.

For normal operation in making connection with the head 21, there is a locking spring consisting of a cylinder of spring steel having a ring portion 23 and depending fingers 24 terminating at the lower end in catches 25. Thus, when the overshot 'is lowered into the well, the

fingers 24 move outwardly radially and then inwardly to' clasp the fish beneath the head 21. l' The locking spring is so mounted as to have a certain amount of play within the cylinder 12 in that it can slide upward-ly and downwardly between the top of the housing 1-2 and the upper land 15. This locking spring is more or less of conventional design and need not be described furtherl here.

The important -feature of the invention resides in the provision of mechanism for spreading the fingers 24 outwardly and holding them in an outwardly or expanded position should it be desired to release the overshot from the fish. To this end a releasing sleeve 26 is mounted in the lower portion of the housing 12 and held in place therein by the shear pins 19. So long as the pins 19 are not sheared, the releasing sleeve is held stationary with respect to the sleeve 12 and occupies the inactive posit-ionv shown in Figures 2 and3 with respect thereto. When the 'pins 19 are sheared,.the sleeve 26 can then move upwardly with respect to the housing 12 and occupy thepositions of Figures 4 and 5, the split ring 2t) serving to limit the amount of travel of the sleeve 26 with respect to the housing 12 as the ring 20 enters the groove 1S.

The upper surface of the sleeve 26 is provided with a tapered cam surface 27. The purpose of this surface 27 is to engage the lower edges of the catches 25 and force them outwardly when pulling upwardly on `the cable and housing 12.

With the above mechanism, it will be clear that the overshot mechanism, consisting of the housing 12 and the parts mounted in it, may be lowered into a well until the locking spring engages and grapples a suitable shing neck, such as illustrated in Figure 2. In normal operation an upward pull may then be taken on housing 12, and the upward pull may be transmitted by the land 15 to the locking ring and iish. Any number of upward jar blows can then be delivered by the jar 11 to the fish through the spring lingers 24 and catches 25.

Assume, however, that the fish cannot be moved or that for any other reason it is desired to release the overshot from the fish, the upward pull is discontinued and a downward jar blow is delivered b v the jar 11 to the housing 12. Such downward blow will cause the parts to take the position shown in Figure 4. 1n this position, the sleeve 26 is resting upon the sh and the downward stress of the jar blows has been taken by the jar pins 19 so that they have sheared. As soon as the pins 19 shear, there can be relative movement between the housing 12 and the sleeve 26 so that the ring 2G snaps into the groove 18 and holds the sleeve 26 in its upper position in the housing 12. After this has happened, upward pull upon the overshot will cause the cam surface 27 to engage the catches and spread the spring iingers 25a outwardly so that the catches 25 can be moved upwardly past the head 21 and the overshot removed from the ,well without engagement with the tish 13.

While only one embodiment of the invention has been shown and described herein, it is obvious that various changes may be made in the arrangementand construction of the parts yWithout departing from the spirit of the invention or the scope of the annexed claim.

I claim:

A releasing overshot for use in removing a fish from a well or the like, comprising a cylindrical housing, a locking spring within said housing and having a sh engaging catch depending therefrom, a releasing sleeve Within said housing beneath said catch, said catch and said releasing sleeve having opposed surfaces eifective to positively cam said catch to a fish releasing position upon movement of said releasing sleeve relatively toward said catch, releasable retaining means for holding said releasing sleeve in a lower inoperative position in said housing and out ot" engagement with said catch, said retaining means being releasable upon forcible downward movement of said housing relative to said releasing sleeve to position said releasing sleeve in an upper operative position in said housing, and a latch between said releasing sleeve and said housing for holding said releasing sleeve in said upper position in said housing after said forcible upward movement therein, said opposed surfaces engaging in said upper position of said releasing sleeve to positively cam said catch to a sh releasing position whereby the overshot maybe removed from the well without the tish.

References Cited in the tile of this patent UNITED STATES PATENTS 2,281,389 Shaffer Apr. 28, 1942 2,605,131 Marshall et al July 29, 1952 2,745,693 McGill May 15, 1956 2,872,238 Dailin Feb. 3, 1959