WO2014074754A2

WO2014074754A2 - External catch fishing tool

Info

Publication number: WO2014074754A2
Application number: PCT/US2013/069014
Authority: WO
Inventors: James R. Streater, Jr.; Daniel Hernandez; Filiberto Garcia
Original assignee: National Oilwell Varco, L.P.
Priority date: 2012-11-07
Filing date: 2013-11-07
Publication date: 2014-05-15
Also published as: GB201508100D0; WO2014074754A3; CA2890648C; GB2523022B; GB2523022A; CA2890648A1

Abstract

An external catch fishing tool, or an overshot having a grapple control that has at least one gap to allow the grapple control to be more compliant and to reduce the contact force between the grapple key and the grapple control during fishing operations. The grapple control may also include a bridge or a plurality of bridges of reduced thickness. Alternate embodiments of the grapple control may include two or more gaps and support bands with or without bridges. Additional embodiment so the grapple control include a backup ring to help eliminate misalignment of the grapple control with the support shoulder of the overshot guide.

Description

EXTERNAL CATCH FISHING TOOL

FIELD OF THE INVENTION

[oooi] The present invention relates generally to external catch fishing tools or overshot tools utilized in fishing operations to recover an object from a wellbore. More particularly, the present invention relates to modifications to grapples and grapple controls that would prevent mechanical failure of the tools.

BACKGROUND OF THE INVENTION

[0002] External catch fishing tools are used to engage, seal against and retrieve tubing, drill pipe, casing coupling, tool joint, casing or other similar fish that have been twisted-off, stuck or lost in a borehole drilled through the Earth's crest. External catch fishing tools are capable of withstanding heavy pulling, torsion, and jarring strains without damage to the fishing tools or the fish.

[0003] Increasing the range of the outside diameter of the fish that can be caught with a given fishing tool may reduce the number of attempts necessary for a successful fishing operation, and thus may reduce costs for retrieving the fish. Examples of fishing tools that can be used over an increased range of the outside diameter of the fish are described in U.S. Patent Application Publication. No. 2011/0114317 titled "Assembly and Method for Wide Catch Overshot" and in PCT/US2010/056848 which published WO2011/060423.

[0004] A basic assembly for an external fishing tool includes a top sub, a bowl, a standard guide, a grapple (either a basket grapple or a spiral grapple) and grapple controls as shown in Figure 1. A grapple control usually includes a key, and grooves. In some embodiments, the spiral grapple also comprises a key that engages a corresponding grot

diameter of the grapple control. After engaging a fish with a spiral grapple, and the spiral grapple moves down the bowl, sometimes causing a large contact force between the grapple key and the grapple control. An excessive level of contact force may cause the system to fail. There is, therefore, a need for an overshot tool in which mechanical failure of its components upon high contact force is eliminated or delayed.

SUMMARY OF THE INVENTION

[0005] The present invention provides assemblies and methods comprising a grapple control to make it more compliant and to reduce the contact force between the grapple key and the grapple control. A more compliant grapple control allows it to withstand higher levels of contact forces during fishing operations and reduces or eliminates equipment failure.

[0006] In an exemplary embodiment, the present invention provides for assemblies and methods that allow the reduced failure of the grapple, its control, or the key by including a gap in the grapple control to make it more compliant and to reduce the contact force between the key of the grapple and the grapple control. The gap maybe of varying width and angle relative to the axis and outer diameter surface of the grapple control.

[0007] In another exemplary embodiment, the present invention provides assemblies and methods having a grapple control with a gap and a bridge that is sized to reduce the stress level in the grapple control a the gap closes. The bridge may be of varying thickness and may span an arc of varying sizes. It may be located diametrically opposite of the gap. In some embodiments, the grapple control comprises multiple bridges.

[0008] In further exemplary embodiments, the present invention provides for assemblies with grapple controls that comprise two or more gaps and support bands with or without bridges. [0009] In additional exemplary embodiments, the assemblies according

invention include a grapple control with a backup ring between the grapple control and the guide of the overcatch tool. The backup ring helps eliminate misalignment of the grapple control with the support shoulder of the guide. The contact plane between the backup ring and the grapple control may be angled. In further embodiments, a contact surface between the backup ring and the grapple control comprises a plurality of segments at different angles. That is the grapple control (or the backup ring) may comprise at least two segments that have contact with the backup ring (or with the grapple control respectively) at different angles, [ooio] The present invention provides for a fishing method comprising engaging a fish into a spiral grapple, allowing the spiral grapple to move down a bowl, transmitting torque between the spiral grapple and the bowl using a grapple control, and deforming the grapple control with the spiral grapple.

BRIEF DESCRIPTION OF THE DRAWINGS

[ooii] The present disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features may not be drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

loon] FIG. 1 is a view of a fishing tool according to one or more aspects of the present disclosure.

[0013] FIG. 2 is a view of a portion of the fishing tool shown in FIG. 1.

[0014] FIG. 3 is a view of a spiral grapple control and back-up ring according to one or more aspects of the present disclosure. [0015] FIG. 4 is a view of a portion of the spiral grapple control and back- FIG. 3.

[0016] FIG. 5 is a view of a stress reducing, deflecting spiral grapple control according to one or more aspects of the present disclosure.

[0017] FIG. 6 is another view of the stress reducing, deflecting spiral grapple control shown in FIG. 5.

DETAILED DESCRIPTION

[0018] It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact.

[0019] FIG. 1 is a cross sectional view of an external catch fishing tool 10. The fishing tool 10 may be lowered in a borehole drilled through the Earth's crest at the end of a drill string (not shown) connected to the fishing tool 10 at an upper end 50 thereof. The fishing tool 10 is to be engaged with a fish (not shown) at a lower end 55 thereof. During the engagement with the fish, the fishing tool 10 is rotated clockwise and lowered, expanding gripping parts provided inside the fishing tool 10 and allowing the fish to enter the fishing tool 10. After the fish is engaged, rotation is ceased and an upward pull force is exerted on th causing the gripping parts inside the fishing tool 10 to contract and the fishing tool 10 to grip the fish firmly. For releasing the fish, a sharp downward acceleration releases the contraction of the gripping parts on the fish, breaking the grip. Thereafter, the fishing tool 10 is rotated clockwise and slowly elevated, screwing the gripping parts off the fish. The fact that the fishing tool 10 is operated clockwise for engaging and releasing the fish may reduce the risks encountered when rotating the drill string counterclockwise.

[0020] In the example of FIG. 1, the fishing tool 10 comprises three external parts: a top sub 15, a bowl 25, and a guide 45. The bowl 25 includes a helically tapered spiral section in its inside diameter. The fishing tool 10 may be dressed with either of two sets of gripping parts, either a spiral grapple or a basket grapple, depending on whether the fish to be caught is near maximum catch size. For example, if the fish diameter is near the maximum catch, a spiral grapple 30 and grapple control 35 may be used. The spiral grapple 30 is formed as a left- hand helix with a tapered exterior that conforms to the helically tapered section in the inside diameter of the bowl 25. The inner diameter of the spiral grapple 30 is usually provided_with wickers (not shown) for engagement with the fish.

loon] Referring to the sectional views of FIGs. 1 and 2, the grapple control 35 allows the spiral grapple 30 to move up and down in the bowl 25 during operation of the fishing tool 10 while simultaneously transmitting torque from the spiral grapple 30 to the bowl 25. In this example, the spiral grapple 30 comprises a key 32 that engages a corresponding groove 39 on the outer diameter of the grapple control 35. In addition, the grapple control 35 comprises a key 37 that engages the outer diameter of the spiral grapple 30. Keys 32 and 37 engage and may slide along a longitudinal groove on the inner diameter of the bowl 25 (not shown). The back up ring in Figures 1 and 2 is similar to the one shown in Figure 4. [0022] After engaging the fish with the spiral grapple 30, the spiral grappli

the bowl 25, the tapers along the grapple outer diameter slide along the ones along the bowl inner diameter, in some cases over a large distance. As a result, the key 32 of the grapple 30 compresses axially towards the inner diameter of the tool. The key 32 may come into contact with and press against the surface of the groove 39 on the grapple control 35. Also, as a substantially large upward pull force is exerted on the fishing tool 10, and the spiral grapple 30 bites into the fish, the spiral grapple 30 moves even further down the bowl 25, possibly increasing the contact force between the key 32 and the grapple control 35. An excessive level of contact force may cause the spiral grapple 30, the key 32, the grapple control 35, or the bowl 25 to fail.

[0023] As best shown in perspective and top views of FIGs. 5 and 6, respectively, the ring portion of the grapple control 35 is provided with a gap 65 to make the grapple control 35 more compliant and reduce the contact force between the key 32 and the grapple control 35. The gap 65 may be located and sized to promote the deflection of the grapple control 35 as the key 32 presses on the surface of the groove 39. The gap 65 may also be located and sized to close without causing the two ends on either sides of the gap 65 to overlap. For example, the gap may be between about 90 degrees and 135 degrees apart from the groove 39. In addition, a bridge 60 having a reduced thickness is provided on the grapple control 35. The bridge 60 may be located and sized to reduce the stress level in the grapple control 35 as the gap 65 closes. For example, the thickness at the bridge may be reduced by at least one half of the thickness in the rest of the grapple control 35. The bridge may span an arc of varying sizes. For example, the bridge may span an arc of about 10 degrees. The bridge 60 may be essentially opposite the gap 65 with respect to a diameter line passing through the groove 39.

[0024] The gap 65 may be of varying width and angle relative to the axis and outer diameter surface of the grapple control 35. The gap 65 may be located and sized to allow the grapple control 35 to deform under any load it may be subjected to, including by th portion of the spiral grapple 30. Depending on its width, the gap 65 may close completely or partially. While the angular position of the gap 65 relative to the groove 39 is variable, the angular position is preferably selected such that as the grapple control 35 is compressed, the cut faces across the gap 65 do not hinder sliding of the grapple control 35 into the bowl 25, or proper engagement of the spiral grapple 30 with the fish.

[0025] The compression of the grapple control 60 may be attenuated with the addition of multiple bridges similar to bridge 60. The locations of the bridges and the quantity of material machined out of the grapple control may be selected to reduce the stress level or obtain a suitable deformed shape of the grapple control. Other embodiments of the present disclosure also include a grapple control with two or more gaps and support bands, and may not include bridges. In yet other embodiments of the present disclosure, the grapple control may be provided with alternate upward and downward cuts which may also make the grapple control more compliant without machining bridges.

[0026] As shown in perspective and sectional views of FIGs. 3 and 4, respectively, a backup ring 40 may be provided at the base of the grapple control so that it is situated between the grapple control 35 and the guide 45 to give the grapple control 35 a face on which to slide. The backup ring 40 may have a bevel 44 that enables the fish to enter the fishing tool easily. The backup ring 40 may further facilitate the deflection of the grapple control 35 by eliminating the misalignment of the grapple control 35 with a support shoulder provided by the guide 45. Indeed, the backup ring 40 has a flat, smooth face 42 that pairs with a corresponding flat, smooth face of the grapple control 35. This face to face contact may allow relative movement, sliding for example, between the grapple control 35 and the backup ring 40 as the grapple control 35 is being deformed. While a flat face to face contact is shown in FIG. 4, the contact plane between the backup ring 40 and the grapple control 35 may be angled, for example to affect the load needed to deform the grapple the contact surface between the backup ring 40 and the grapple control 35 may be comprised of several segments at different angles, for example to maintain the grapple control 35 centered or to insure its even deflection. That is the grapple control (or the backup ring) may comprise at least two segments that have contact with the backup ring (or with the grapple control respectively) at different angles. The backup ring may also be omitted if the guide 45 provides a flat face for the grapple control to slide upon.

[002₇] By providing the gap 65 and the bridge 60 to allow the grapple control 35 to deflect when the key 32 of the spiral grapple 30 contacts the grapple control 35, mechanical failure of the spiral grapple 30, the key 32, the grapple control 35, or the bowl 25 may be delayed or eliminated. Indeed, as the fishing tool 10 is pulled and the spiral grapple 30 slides down in the bowl 25, the key 32 may first come into contact with the outer surface of the grapple control 35. Then, as the pulling load on the fishing tool increases, the grapple control 35 may deflect without excessive resistance, partially closing the gap 65. The deflection of the grapple control 35 may reduce the stress level in the area of contact between the key 32 and the grapple control 35, at least until the gap 65 is completely closed.

[0028] In view of all of the above and the figures, those skilled in the art should readily recognize that the present disclosure introduces a fishing tool comprising a spiral grapple and a grapple control each having a key for sliding engagement with a bowl groove, wherein a cut is provided on the grapple control. The grapple control may further include a bridge of reduced thickness.

[0029] The present disclosure also introduces a fishing method comprising engaging a fish into a spiral grapple, allowing the spiral grapple to move down a bowl, transmitting torque between the spiral grapple and the bowl using a grapple control, and deforming the grapple control with the spiral grapple. [0030] The foregoing outlines features of several embodiments so that those

may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure.

Claims

Claims What Is Claimed Is:

1. An overshot comprising:

a bowl having a bore therethrough;

a spiral grapple placed inside the bore of the bowl, the grapple comprising a grapple key; a grapple control comprising at least one gap; and

a guide.

2. The overshot of claim 1, wherein the grapple control further comprises at least one bridge wherein the bridge has a reduced thickness as compared to the thickness of the grapple control..

3. The overshot of claim 1, wherein the grapple control further comprises a support band.

4. The overshot of claim 1, wherein the grapple control further comprises a backup ring between the grapple control and the guide of the overshot.

5. The overshot of claim 4, wherein a plane of contact between the backup ring and the grapple control is angled.

6. An improved overshot comprising a bowl, a spiral grapple, a grapple control and a guide, wherein the improvement comprises at least one gap in the grapple control.

7. The improved overshot of claim 6, wherein the improvement further comprises a bridge in the grapple control, wherein the bridge has a reduced thickness as compared to the thickness of the grapple control.

8. The improved overshot of claim 6, wherein the improvement further comprises a backup ring on the base of the grapple control.

9. The improved overshot of claim 8, wherein a plane of contact between the backup ring and the grapple control is angled.

10. The improved overshot of claim 8 , wherein a contact surface between the backup ring and the grapple control comprises a plurality of segments, wherein the plane of contact between the backup ring and the grapple control for at least two segments are at different angles relative to one another.

11. The improved overshot of claim 6, wherein the improvement further comprises at least one support band in the grapple control.

12. A fishing method comprising the steps of:

engaging a fish into a spiral grapple,

allowing the spiral grapple to move down a bowl,

transmitting torque between the spiral grapple and the bowl using a grapple control, and deforming the grapple control with the spiral grapple.