Constant Strain Jar

Abstract

A jar for removing a fish from a well, in which a piston is moved in a chamber and then released to allow the hydrostatic pressure of fluid in the well to move the piston against an anvil. Such a jar in which the piston is repeatedly shifted in response to rotation of the running in string of pipe.

Description

BACKGROUND OF THE INVENTION

In the drilling and completion or treatment of wells, such as oil and/or gas wells, as well as in the production of wells, it sometimes occurs that a so-called "fish" must be removed from the well. For example, if the drill pipe should become stuck during a drilling operation, it may be necessary to remove the pipe above the stuck point from the well, and then perform a fishing operation to remove the stuck pipe. It sometimes is necessary or desirable to remove a stuck casing or liner from a well, and the casing or liner is another example of a fish.

Fishing tools for performing such tasks are well known and include a variety of spears or grabs and overshots adapted to grip the upper end of the fish or stuck pipe. When the pipe or fish is engaged by the gripping device, it is the practice to apply a jarring force to the pipe to attempt to free the same. Conventionally such jarring devices or jars are so constructed that they are capable of applying a jarring force, but the jarring force is applied independently of the application of an upward strain on the fish.

SUMMARY OF THE INVENTION

The present invention involves the provision of a tool for removing a fish from a well bore by applying a constant upward strain on the fish while applying a jarring force to the tool and to the fish.

More particularly the invention employs the force derived from the column of liquid in the well to provide the jarring force. In this connection, the jar includes a piston in a chamber which is sealed off to prevent entry of fluid from the well bore, and an anvil adapted to be struck by the piston, means being provided to effect movement of the piston away from the anvil and to allow opposite movement of the piston responsive to the hydrostatic well fluid pressure.

Movement of the piston away from the anvil is effected by camming means which operate in response to rotation of the string of pipe by which the jar is run into the well.

The jarring tool is combined with an anchor or device adapted to engage and grip the fish. More particularly in the adaptation of the invention herein disclosed, the anchor includes anchor slips expansible into gripping engagement with the fish, but releasable therefrom when desired.

An object of the invention is to provide a fishing tool operable to apply repetitive jarring forces to a stuck object or fish in a well bore while a constant strain is maintained on the fish tending to move the same.

Another object is to provide such a jarring tool which is easy to operate, rugged, durable, and easy to maintain.

Other objects and advantages of the invention will be apparent to those skilled in the art from the following detailed description of an illustrative embodiment, and the novel features of the invention will be defined in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1a and 1b together constitute a view partly in elevation and partly in longitudinal section, showing a jar embodying the invention and being run into a stuck pipe, FIG. 1b being a downward continuation of FIG. 1a;

FIG. 2 is a view in transverse section, as taken on the line 2-2 of FIG. 1b;

FIG. 3 is a view in transverse section, as taken on the line 3-3 of FIG. 1b;

FIG. 4 is an enlarged fragmentary detail view in section illustrating the releasable latch for the anchor embraced by the line 4 in FIG. 1a;

FIGS. 5a and 5b together constitute a view corresponding to FIGS. 1a and 1b, showing the tool anchored in a fish and with the hammer piston shifted downwardly; and

FIG. 6 is a view corresponding to FIG. 4, but showing the latch released.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As seen in the drawings, the present jarring tool may be incorporated in a suitable tool assembly comprising an anchor section A and a jar section J respectively shown in FIGS. 1a and 1b. In the illustrative embodiment the tool assembly constitutes a spear adapted to be speared into the upper end of the stuck object, pipe or fish F, herein illustrated as a well liner which is disposed in a well bore 10 extending downwardly from a larger bore 11 in which a casing C has been set. It will be understood that the invention may also be incorporated in a so-called overshot for engaging other types of fish or stuck objects.

The tool includes a mandrel 20 at the upper end of which is a female joint part or threaded box 21 which is adapted to receive the externally threaded pin at the lower end of a string S of running in pipe such as drill pipe, whereby the tool is manipulated as will be hereinafter more fully described.

This mandrel 20 constitutes a support for the tool assembly, comprising, in the anchor portion A, a friction drag device including a sleeve 23 which is disposed about the mandrel 20 for relative rotational and longitudinal movement. Carried by the sleeve 23 are a number of circumferentially spaced bow springs 24 which are arched outwardly so as to engage the fish F when the tool is speared into the fish. At the upper end of the sleeve 23 is a stop collar 24 having circumferentially spaced stop lugs 26 projecting therefrom to engage the upper end of the fish or liner F. The collar 25 may be of any desired axial extent so as to locate the stops 26 in the desired spaced relation above the bow springs 24 to allow the tool to extend more or less into the fish F.

At its lower end, the sleeve 23 has a collar 27 for supporting a number of slip units 28 for movements between retracted positions and radially expanded anchoring positions. The collar 27 is provided with laterally opening T-slots 29 and the upper ends of the slip units 28 are provided with T-heads 30 slidable in the slots 29, but holding the slip units against longitudinal movement relative to the friction drag means.

The slip units 28 also include elongated slip bodies 31 having wickers or teeth 31a spaced therealong and adapted to bite into an inside wall of a pipe such as the pipe F when the slips are expanded from their normally retracted positions. In order to expand the slips they are provided on their inner faces with a series of longitudinally spaced cam surfaces 32 extending upwardly at angles and engageable by expander surfaces 33 which are correspondingly spaced longitudinally along a slip supporting sleeve or expander member 34. This sleeve or expander 34 is disposed about the body or mandrel 20. At its upper end, the expander or sleeve 34 abuts with a shoulder 35 on the mandrel 20 and the slip units 28 are preferably interconnected with the expander 34 by the usual dovetail connection at 36.

Means are provided for normally holding the mandrel or body 20 and the slip units 28 in the positions shown in FIG. 1a, with the slip units retracted, and such means is best seen in FIG. 4. The drag spring supporting collar 27 is provided with a radial hole 37 in which is reciprocably disposed a ratchet or control button 38. A leaf spring 39 biases the button 38 inwardly to effect engagement of downwardly facing ratchet teeth 40 on the button with an upwardly facing thread 41 on the mandrel 20. When the button 38 is engaged with the mandrel thread as seen in FIG. 4, the mandrel 20 and slip units 28 are held in the relative position shown in FIG. 1a, with the slip units retracted and the mandrel 20 held in fixed relation to the anchor assembly by coengaged shoulders at 42 formed by the cone sleeve 34 and the slip units 28, the engagement of the cone sleeve 34 with the shoulder 35, and the coengaged teeth 40 on the button 38 and thread 41 on the mandrel 20. However, rotation of the mandrel 20 will effect threaded movement of the mandrel thread 41 through the button 38 with resultant upward movement of the mandrel relative to the drag springs 24 and the slip units 28 (see FIG. 6), whereby the cone or expander surfaces on the cone sleeve will force the slip units 28 outwardly to the anchored positions of FIG. 5a. In this condition, the anchor A is adapted to grip the fish F and allow the application of an upward pull or strain to the running-in string S.

The jarring tool J is supported on the lower portion of the mandrel 20 and includes a sleeve 50 forming with the mandrel 20 an annular chamber 51. This sleeve 50 has an upper portion 52 having a suitable packing 53 forming a seal with the mandrel 20. Within the chamber 51 is an annular flange 54 formed on or otherwise made a part of the mandrel 20, the cylinder sleeve 50 being slidable along the outer circular surface of the flange 54. Above the flange 54 is a bearing 54a which seats on the flange 54 and supports the cylinder sleeve 50. Below the flange 54 is the upper end 55 of a hammer sleeve 56, the end 55 extending into the chamber 51 and the lower end of the cylinder sleeve 50 having a skirt 57 provided with a suitable packing 58 forming a seal with the outer cylindrical surface 59 of the upper end 55 of the hammer sleeve 56. At its lower end, the hammer sleeve 56 is provided with another suitable packing 56a forming a seal with the outer surface of the mandrel 20.

It is now apparent that the seals 52, 56a and 58 seal the chamber 51 against the entry of fluid when the tool is lowered into the well and that the pressure in the chamber 51 is essentially atmospheric. Thus hydrostatic pressure in the well bore acting over the annular area X, FIG. 1b, provides a force tending to move the hammer sleeve 56 upwardly.

This structure is availed of to produce the jarring force to remove the fish F by moving the hammer sleeve 56 downwardly and then allowing it freedom of upward movement responsive to hydrostatic pressure. To accomplish this, the hammer sleeve 56 and the cylinder sleeve 50 are provided with ratchetlike cam elements respectively designated 60 and 61 adapted to effect downward movement of the hammer sleeve 56 responsive to relative rotation of the latter and the cylinder sleeve 50, and alternately to allow upward movement of the hammer sleeve when axial faces 62 and 63 of the cam elements 60 and 61 are brought to positions of coplanar relationship.

In order to effect such relative rotation of the cylinder and hammer sleeves 50 and 56, the cylinder sleeve 50 is keyed to the cone member 34, as best seen in FIG. 2, and the hammer sleeve 56 is keyed to the mandrel 20, as best seen in FIG. 3.

Referring to FIG. 2, it will be seen that the portion 52 of the cylinder sleeve 50 and the lower extremity of the cone or expander sleeve 34 have splines 64 interconnecting the same so that the expander member 34 will hold the cylinder sleeve 50 against rotation, but upward movement of the cylinder sleeve 50 is permitted during anchoring of the tool in the fish F, as previously described. The hammer sleeve 56 is caused to rotate with the mandrel 20 by a key 65 provided on the mandrel and projecting into a keyway 66 extending axially in the hammer sleeve 56, whereby the hammer sleeve is free for reciprocation on the mandrel 20.

At the lower end of the mandrel 20 is a centralizer or guide shoe 70 having radially projecting wings 71 engageable with the inner wall of the fish F to centralize the lower portion of the tool assembly, thereby preventing contact between the hammer sleeve 56 and the fish F. Thus, such contact cannot interfere with freedom of movement of the hammer sleeve.

If desired, a plug 72 may be employed in the lower end of the mandrel to preclude entry of well fluids, but such a plug may be pumped out if desired. Alternatively, a circulation shoe may be employed including a back flow preventing valve.

In the use of the tool it is run into the well and landed on the fish F. Rotation of the running in string S will then move the mandrel thread 41 from the latch thread 40 as the mandrel moves upwardly. When the latch 38 is released, the mandrel is pulled upwardly to effect expansion of the slip units 28, the flange 54 on the mandrel engaging the bearing 54a and the cylinder sleeve 50 moving upwardly on splines 64 until the cylinder sleeve shoulders with the cone or expander sleeve 34. Upward movement of the slip units 28 is resisted by the drag springs 24, and further upward movement of the mandrel then effects upward movement of the expander sleeve 34 with respect to the slip units 28 and the latter are expanded to hold the assembly fast with respect to the fish F.

Thereupon, the mandrel is pulled upwardly and rotated to effect repetitive downward movements of the hammer sleeve 56 by the ratchet cams 60 and 61 and upward hammer blows of the hammer sleeve on the flange 54, the hammer forces being transmitted through the cylinder sleeve 50 to the cone or expander sleeve 34 and thence to the slips 28 and the fish F, whereby to apply the constant upstrain on the fish, combined with rapid and repetitive hammer or jarring blows.

While the specific details of an illustrative embodiment have been herein shown and described, changes and alterations may be resorted to without departing from the spirit of the invention.

Claims

I claim:

1. A jarring tool for removing a fish from a well bore, comprising: a mandrel adapted to be connected to a running-in string of pipe, anchor means on said mandrel for anchoring said mandrel with respect to said fish, and jarring means carried by said mandrel including impact means for applying a repetitive impact force to said fish responsive to rotation of said mandrel, said impact means comprising an annular hammer piston reciprocable on said mandrel, a cylinder sleeve disposed about said mandrel and defining with said mandrel an atmospheric chamber in which one end of said hammer piston is disposed, said piston having a portion projecting from said chamber and exposed to the hydrostatic pressure of fluid in the well bore, said cylinder sleeve including a portion engageable with said anchor means, and means for repetitively moving said piston away from said anchor means in said chamber.

2. A jarring tool as defined in claim 1, said means for repetitively moving said piston away from said anchor means in said chamber including ratchetting cam means on said piston and rotatable with said mandrel.

3. A jarring tool as defined in claim 1, said means for repetitively moving said piston away from said anchor means in said chamber including ratchetting cam means on said cylinder sleeve and said hammer piston, means for holding said cylinder sleeve against rotation with respect to said fish and means for affecting rotation of said hammer piston responsive to rotation of said mandrel, said ratchetting cam means including cam lugs extending about said cylinder sleeve and said hammer piston, said cam lugs having axially extended surfaces for allowing instantaneous movement of said hammer piston to effect a jarring force upon said rotation of said hammer piston.

4. A jarring tool as defined in claim 1, and including centering means on said mandrel for centering said hammer piston with respect to the well bore.

5. A jarring tool as defined in claim 1, wherein said anchor means includes anchor elements engageable with said fish, and cam means for forcing said anchor elements into engagement with said fish responsive to the application of an upward strain to said running in string.

6. A jarring tool as defined in claim 1, wherein said anchor means includes anchor elements engageable with said fish, cam means for forcing said anchor elements into engagement with said fish responsive to the application of an upward strain to said running-in string, and releasable means for normally latching said mandrel and said anchor means against operation.

7. A jarring tool for removing a fish from a well bore comprising: a mandrel adapted to be connected to a running-in string of pipe, anchor means on said mandrel engageable with the fish including slip elements carried by said mandrel, said mandrel having expander means thereon for actuating said slip elements into gripping engagement with said fish responsive to upward movement of said mandrel, a cylinder sleeve engaged with said expander means, said mandrel extending through said cylinder sleeve and having an annular Anvil slidable in said cylinder sleeve, an annular hammer piston axially shiftable on said body and having an end disposed in said cylinder sleeve, the other end of said hammer piston being exposed to the hydrostatic pressure of fluid in the well, and cam means on said mandrel and said hammer piston for repetitively forcing said hammer piston axially away from said anvil and allowing pressure-responsive hammer blows of said hammer piston on said anvil responsive to rotation of said mandrel relative to said hammer piston.

8. A jarring tool for removing a fish from a well bore, comprising, in combination, anchor means adapted to be connected to a running-in string of pipe and engageable with said fish and including anchor elements expansible into engagement with said fish, expander means responsive to an upward strain on said running-in string to expand said anchor means, and hydrostatic fluid pressure-operated hammer means for applying a jarring force to said expander means upon rotation of said running-in string while said upward strain continues.