Sucker rod fishing tool

Abstract

A fishing tool for fishing sucker rods from a subterranean well. The tool is a top piece, a barrel piece and bottom piece that all thread together. One or more extender sections are added by unthreading the top piece from the barrel piece and threading the extender sections therebetween to effectively lengthen the barrel piece and increase its functionality. The bottom piece retains a curved cast metal slip movable within grooves milled internally into the body. A lower end of a side opening provided in the barrel piece is level with an upper shoulder of the slip when the slip is at its lowest position. Optionally, the bottom piece can be replaced with a bell, lip guide, mill shoe, or other types of tools and the top piece can be replaced by a prior art fishing tool or other tools.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a fishing tool for fishing sucker rods, tubing, pipe, pumps, plungers, plugs, tubing stops, packers, tools, anchors, obstructions, etc. from downhole in a subterranean well, such as but not limited to an oil producing, gas producing, injection or disposal well. More specifically, the fishing tool of the present invention is strong enough to retrieve up to 12,000 feet of rod at once, is designed to reduce stress on the tool so that it can be reused multiple times, is serviceable because it can be disassembled and repaired in the field, and is versatile since it can be combined with bells, adapters and other existing types of rod fishing equipment and accessories to successfully retrieve a wide range of items from subterranean wells. One or more extension pieces can be added to the body of the fishing tool to effectively lengthen the tool and thereby increase its functionality.[0003]2. Des...

AI Technical Summary

Benefits of technology

[0021]The barrel piece of the body is constructed of hollow tube stock. The barrel piece is provided with female threads on its top end for securing the barrel piece to the male threads provided on the bottom end of the top piece and provided with female threads on its bottom end for securing the barrel piece to the bottom piece. Internally the barrel is machined to provide two parallel, longitudinally oriented grooves in which the slip is movably retained within the barrel. The slip is inserted into the barrel with ears of the slip inserting in the longitudinal grooves before the bottom piece of the body is secured to the barrel piece so that the bottom piece then captures the slip within the barrel portion when the bottom piece is attached to the barrel piece. Because the bottom piece secures the slip within the barrel, in order to replace the slip, the bottom piece is unthreaded from the barrel piece and then the slip can readily be removed from the barrel and replaced, if desired.

[0024]However, the normal configuration is to have a bottom piece attached at the bottom end of the barrel piece. The bottom piece is also constructed of hollow tube stock. The top end of the bottom piece is provided with male threads for engaging the female threads provided on the bottom end of the barrel piece in order to secure the bottom piece to the barrel piece. The bottom end of the bottom piece is enlarged externally to help in centering the tool within the tubing and is beveled internally to aid in feeding rod into the barrel of the tool.

[0025]Optionally, the bottom piece can be replaced by one of several sizes of existing bells. The bell can either be threaded directly onto the female threads provided on the bottom end of the barrel piece if the bell is provided with male threads that are compatible therewith, or alternately, can be secured to the barrel piece with an appropriate adaptor. The bell serves to guide the tool through larger size pipe interiors such as larger tubing sizes or production casing. The bell serves to guide the parted rod into the tool and allows the tool to stay centered in the pipe.

[0026]The slip is in a half moon shape, with its externally facing wall convex in shape and its internally facing wall concave in shape. Two ears are provided on the external surface of the slip for movable engagement with the longitudinal grooves provided internally within the barrel, as previously described. The bottom edge of the slip is beveled on its internally face in a half moon configuration to provide for smooth engagement of the slip with the rod as the rod enters the tool and pushes the slip upward. The top end of the slip is provided with a square shoulder against which an expanded surface of the rod or other item to be pulled will engage the slip as the tool is raised, as will be further described herein.

[0027]An optional slip can be employed instead of the standard slip. The optional slip is provided with a serrated or toothed shoulder on its top end instead of a square shoulder. The purpose of the teeth or serrations is to resist rotational slippage of the caught rod. The teeth are milled into a standard slip and are added to allow the tool to more easily be backed-off from downhole. Also, the teeth allow the tool to be more easily used when a rod on / off tool must be unlatched from downhole.

Problems solved by technology

One problem with the socket type tools is that they are designed to catch only on specific shaped items and therefore are limited in the types of items with which they can interlock.

This often results in the several different sizes of sockets having to be run into the well before the proper socket size can be found.

This is expensive in terms of time and manpower to try again and again to get the proper socket size for the specific situation.

Furthermore the sockets have a tendency of slipping open when hardened, hard lined, brass, out of round or worn couplings are being fished.

Lastly, the sockets generally last for only one or two uses and become worn easily.

One problem with the biter type tools is that they are attempting to bite into a hard surface and therefore can slip.

Furthermore the teeth on the slips generally only last for one or two uses before becoming worn off.

Also, the tool is limited on the sizes of rods it can catch, limited on where it can catch the rod.

The tool can become wedged and therefore limits the amount of pressure that this tool can exert when pulling an item from a well.

The prior art mousetrap tools have several problems.

First, because this type of tool is welded together, the barrel of this type of tool is weak and cannot withstand large lateral strains such as those imposed on it when the slip and the item being pulled are wedge between the walls of the barrel.

Also, the top of this type of tool is also welded to the barrel portion and this creates another weak area where the tool will break.

A further problem with this type of tool is that the side opening provided in the barrel of the tool is located above the shoulder of the slip, causing the item to create a sideways pull and torque moment on the tool as the item is pulled.

This torque moment imposes stress on the tool that causes the barrel of the tool to split open and fail.

Still a further problem with this tool is that it cannot be made in the sizes that are needed in the field.

The geometry of the tool makes the walls too thin to hold the weight and tension of the rod string being pulled from the well.

A further problem with the tool is the way in which the slip is retained within the barrel of the tool.

The problem with these shoulders is that they can become bent and can prevent the slip from moving up and down within the barrel of the tool.

When this happens, the tool is unable to attach to a rod and cannot fish rod out of the well.

Because the shoulders of prior art tools are either welded within the tool or formed as an integral part of the barrel of the tool, once they become damaged, they cannot be economically repaired or replaced.

This results in the tool no longer being functional and the tool must then be discarded.

Still a further problem with prior art fishing tools is that because their body is a fixed length and their bodies cannot be lengthened, they are unable to catch certain types of breaks, such as rod breaks where the broken length of rod exceeds the length of the body of the fishing tool, thus making it impossible for the fishing tool to be lowered sufficiently around the broken rod for the fishing tool to engage one of the protrusions on the well string which can be gripped by the slip of the fishing tool.

There are no tools within the industry today that can catch fiberglass sucker rods or successfully catch polished rods that break in the body.

Fiberglass sucker rods will simply tear if biter type tools are used and also sometimes fiberglass rods will flare out slightly at the end of the break, making it difficult for the rod body to fit into a biter type tool.

Therefore they are hardened to prevent wear which makes them very difficult to fish with biter type tools.

Because of all these weaknesses in this tool, it generally will only be a single use tool and it can only pull approximately 5,000 pounds of force without breaking.

Further, this tool will catch hard lined couplings, fiberglass, worn or out of round couplings.

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