US2619374A

US2619374A - Overshot

Info

Publication number: US2619374A
Application number: US77076A
Authority: US
Inventors: Vernon D Davidson
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-02-18
Filing date: 1949-02-18
Publication date: 1952-11-25
Anticipated expiration: 1969-11-25

Description

Nov. 25, 1952 v. D. DAVIDSON 2,619,374

OVERSHOT Filed Feb. 18, 1949 VERNON D. DAVIDbDN INVENTOR. FIg I BY M A TTORNE YS Patented Nov. 25, 1952 UNITED STATES 2,619,374 TENT OFFICE OVERSHOT Vernon 1). Davidson, Corpus Christi, Tex. Application February 18, 1949, Serial No. 77,076

1 Claim. 1

The invention relates to an overshot.

In the drilling of wells by the rotary method it is not uncommon for a drill pine to twist off or to become stuck in the well bore. It is then necessary to retrieve the pipe from the bore before drilling operations can be resumed.

It is, therefore, an o'biect of the instant invention to provide a tool for engaging and removing a stuck pipe or fish in a well bore.

Another object of the invention is to provide an overshot for en aging a stuck pipe in a well bore, which overshot is provided with spring fingers for engaging a tapered area on the stuck fish.

Another obiect of the invention is to provide in an overshot for engaging a ta ered area of a stuck pipe in a well bore s ring fingers which are provided with threaded means for engaging the taper on the stuck pi e, the taper of such threaded means being different from the taper on the engaged pipe so that the overshot may be released or disengaged from the stuck pipe by rotation to travel the threaded means up on the threaded area to release the overshot.

Other and further obiects and advantages of the invention will become more readily a arent from a consideration of the following description and drawings, wherein:

The figure is a vertical sectional view illustrating a stuck pipe in elevation in a well bore with the overshot portion of the tool engaged on the taper of such stuck pipe;

Generally. when a pipe becomes stuck in a well bore it is preferable to remove the pine by engaging a tool with the pipe and exerting an upward pull thereon.

The tool compri ing a form of the invention is illustrated in the figure and is shown in the figure as comprising a housing 2 with an overshot 3 slidably but non-rotatably mounted therein. To this end there is provided in the housin 2 a bolt 3' engaged in the longitudinal slot 4 of the overshot 3. The lower end 5 of the overshot 3 is provided with a plurality of s ring fingers B. These spring fingers are adapted to expand around the enlarged portion 1 of the pi e as it is being lowered downwardly into the well bore, as indicated by the dotted line at 1'.

Upon contact with the ta ered area of a tool joint as illustrated at 9, the fin ers 6 spring inwardlv, whereupon the threaded means I 6 engage with the tapered area 9 on the stuck pipe or fish ll. Upon reaching the desired elevation on the stuck pipe at which it will be attempted to remove such pipe from the well bore, an upward pull may be exerted on the housing 2 to effect relative movement between housing 2 and the overshot 3.

A tapered shoulder 13 in the housing 2 abuts against the taper l4 on the overshot 3, whereupon such overshot becomes seated in the housing 2. A continued upward pull on the housing 2 is transmitted through the overshot to the fish ll, whereupon it may become disengaged and pulled from the well bore. The tapers l3 and l4 c0- operate to efiect a locking action between the annular threaded means If) on the inner periphery 'of the spring finger 6 and the tapered area 9 of the fish.

If, however, for any reason the fish II will not dislodge from the well bore, it is desirable to release the overshot therefrom so as to remove the tool from the well. To this end it is to be noted that the taper of the annular threaded means 18 is somewhat different from the taper of the unthreaded area 9. This is more clearly illustrated by the line 15, which shows the taper of the threaded means I!) as being difierent from the taper on the area 9 of the pipe joint. In this manner when a combined upward pull and rotation is imparted to the housing 2, the threaded means 10 will travel up on the tapered area 9 and eventually release the fingers 6 from engagement with such tapered area. The spring fingers 6 will then expand to con-form to the enlarged portion 1 of the tool joint on the stuck pipe I I The overshot tool may then be removed from the well.

Broadly, the invention contemplates a releas able overshot.

What is claimed is:

A pulling tool for pulling a stuck pipe having a downwardly and inwardly tapered area thereon from a well bore comprising, a housing to telescope over such stuck pipe, an overshot rotatable with said housing and slidable therein, spaced radial elongated spring pulling fingers integrally formed on said overshot, a threaded area internally disposed on the pipe contacting surface of said pulling fingers, said threaded area being of different taper than said tapered area on said stuck pipe and formed to project inwardly relative to the maximum diameter of said ta ered area, and inclined surfaces on adjacent portions of said fingers and said housing cooperating so that the upper threads of said pulling fingers engage said tapered area of said stuck pipe to pull said pipe upwardly upon a straight upward pull of said housing, and upon failure of said straight pull the difierence of the taper of said threads enabling said overshot to travel on said tapered area of said pipe by a combined upward pull and rotation of said housing.

VERNON D. DAVIDSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,123,615 Stewart Jan. 5, 1915 1,625,392 Reilly et a1 Apr. 19, 1927 1,693,789 LeBus Dec. 4, 1928 1,728,781 Cameron Sept. 17, 1929 1,785,152 Stone et a1. Dec. 16, 1930 2,069,593 Reed Feb. 2, 1937