FIELD OF THE INVENTION

The present invention relates to a fishing tool. In some embodiments, the invention is directed to a fishing tool for use in gas and oil drill bores, although the scope of the invention is not necessarily limited thereto.

BACKGROUND

Gas and oil exploration requires the testing of drill bores into coal and oil seams. This is normally achieved by a drill rig drilling to depths down to 6km. A purpose built testing truck will then take data samples at varying depths with what is known as a set of tools on the end of a communication wire. The tool is lowered into the drill bore by the winch truck and data is collected. In some instances the tool can become lodged in the drill bore by the bore caving in or other unforseen problems. When a tool is trapped in the drill bore it becomes known as a 'fish'. The cable that attaches the tool to the winch is often not able to take the high loads required to free the fish and therefore a special fishing tool is required to retrieve the fish. This fishing tool is usually attached to a drill pipe and lowered into the drill hole with a drill rig.

Existing fishing tools are complex and usually have a lot of moving parts to be able to adequately connect to the fish. A problem with existing fishing tools is that well bores are usually filled with water and have high amounts of large particles and mud, which can contaminate the fishing tools and prevent the parts from functioning properly. This can result in the fishing tool having to be retrieved multiple times to be cleaned before it catches the fish.

Another disadvantage with existing fishing tools is that they are large and heavy due to the number of parts that they contain.

It is an aim of the invention to provide a fishing tool which overcomes or ameliorates one or more of the disadvantages or problems described above, or which at least provides the consumer with a useful choice. It will be clearly understood that any reference herein to background material or information, or to a prior publication, does not constitute an admission that any material, information or publication forms part of the common general knowledge in the art, or is otherwise admissible prior art, whether in Australia or in any other country.

DESCRIPTION OF THE INVENTION

In one aspect, the present invention provides a fishing tool for attaching to a head section of an object, the fishing tool comprising a tool body having at least one opening, a collet accessible through one of the at least one opening of the tool body, the collet being adapted to expand and contract to allow the head section to at least partially pass there through whereupon the collet holds the head section, and an attachment means on the tool body to attach to a support.

In one embodiment, the fishing tool may include a mouth, part which is adapted to guide the head section to the collet. The mouth section may be located about an opening of the tool body. The mouth part may be attached to the tool body. Alternatively the mouth section may be part of the tool body. The mouth part preferably has a conical shaped opening. Alternatively the mouth part may have a tapered opening or the like to guide the head section. The mouth part may have a wire slot, slit and/or the like to allow a wire and/or the like to pass into the mouth part. Reference to wire herein can also refer to communication wire, cable, string, rope, thread, cord, conduit, chain, fibre, strap, tape, tether, ribbon or the like. Alternatively, the mouth part may be made of a plurality of parts, such that it can be assembled around a wire.

In another embodiment, the tool body has a wire slot, slit and/or the like to enable a wire or the like to pass into the tool body. Alternatively, the tool body may be made from a single part or may be made from a plurality of parts. Additionally, the tool body may be adapted to be assembled around a wire. The tool body may be adapted to be attached to an attachment part. Alternatively the attachment part may be part of the tool body. Normally the tool body has an opening for a wire to exit the tool body. The tool body may have at least one wire guide roller adapted to guide a wire through the tool body. Normally the tool body is cylindrically shaped. Alternatively, the tool body may be a non cylindrical support structure.

In one embodiment, the attachment part may have at least one wire guide roller adapted to guide a wire. The attachment part may have an opening that corresponds with an opening on the tool body. The attachment part may be adapted to attach to a support. The attachment part may include an attachment means such as a threaded opening, adapted to attach to a support. The support may be a drill pipe, wire, other equipment or the like. Normally the attachment part does not have a wire slot. Alternatively the attachment part may have a wire slot.

In one embodiment, the collet may contain segments to allow the collet to expand and contract. Alternatively, the material of the collet may allow expansion and contraction without the need for segments. The collet may be made of elastic, flexible and/or resilient material or the like. The collet may be a single part. The collet may have a wire slot, slit and/or the like to allow a wire or the like to pass into the collet. Alternatively the collet may have two or more parts that can be assembled around a Wire. The collet may have a thick walled section to provide sufficient strength for the fishing tool to retrieve an object. The collet may have a thin walled section to provide sufficient flexibility for the collet to allow a head section or the like to pass therethrough. The collet may be supported by a collet support. When used, the collet support provides the collet with additional support, as the thin walled section of the collet may not have enough strength to enable the fishing tool to retrieve an object. Part of the thick walled section would normally be in contact with the collet support when retrieving an object, such that a substantial part of at least one of the forces acting on the collet is transferred to the collet support. The collet would normally fit partially over the collet support with the collet base in contact with the collet support base. To avoid stress concentrations the collet may be provided with stress reducing cutouts. The collet and/or collet support is normally attached to the fishing tool through engagement of the tool body with the mouth part, holding the collet and/or collet support between the tool body and the mouth part. The tool body and/or the mouth part may have a shoulder which is adapted to retain part of the collet and/or collet support. Alternatively, the collet and/or collet support may be attached to another part of the fishing tool. In one embodiment, the collet support may have a wire slot, slit and/or the like to allow a wire or the like to pass into the collet support. Alternatively the collet support may have two or more parts that can be assembled around a wire. Normally the collet support will have a flanged collet support base. A collet support may also be called a support collar. Normally the collet support will have a collet support face which engages with part of the thick walled section of the collet.

In another embodiment, the fishing tool may be made from multiple components. Alternatively the fishing tool can be made from one piece. Normally the fishing tool is substantially cylindrical in shape. The fishing tool may be provided with at least one wire slot and/or slit and/or may be adapted to be at least partially assembled around a wire. The benefit of this is that a wire can be passed into the fishing tool without having to be threaded through the fishing tool, this is especially useful as the wire will not need to be cut or unwound from a spool to be threaded through the fishing tool. The fishing tool may have at least 1 wire guide roller to prevent damage to the wire and/or the fishing tool as the wire passes through the fishing tool.

In one embodiment, the head section of an object may be frustum shaped. The head section may be shaped such that the collet at least partially contracts once the head section has at least partially passed through the collet. The head section may be shaped to be retained by the collet. The head section may have a groove, lip, shoulder, flange, neck section, expansion, and/or the like to be retained by collet. Normally the head section has an attachment means to attach to an object. Alternatively the head section may be part of an object. The head section may have an opening to allow a wire to attach to an object. Alternatively a wire may attach directly to the head section. The head section may have a wire slot, slit and/or the like to allow a wire to be passed into the head section. The object that the head section is attached to may be a tool trapped in a drill bore. Alternatively the object may be any type of object, device, vehicle, material and/or the like which needs to be retrieved and/or attached to. In another embodiment, the fishing tool may attach to a head section without requiring a wire to be passed through the fishing tool. Once an object has been retrieved, the head section may be removed from the fishing tool by disassembling the fishing tool. A head section may also be removed from the fishing tool by pushing the head section through the fishing tool. Alternatively the collet may be forced open using a tool, thus allowing the head section to pass back through the collet.

Normally, the present invention may be used in oil and/or gas bores to retrieve fish. Alternatively, the present invention may be used in underwater retrieval, retrieval of equipment from confined spaces, and/or may be used in a situation where an object has to be retrieved and/or attached to.

The present invention also extends to a collet suitable for use in a fishing tool. Accordingly, in another aspect, the present invention provides a collet for use in a fishing tool, the collet comprising an expandable region for allowing passage of a head section and/or a fish therethrough, and a collet support, the collet support supporting the expandable region.

The collet may comprise a thick wall region and a thin wall region, the thin wall region allowing the expandable part of the collet to expand as a head section and/or a fish passes therethrough. The thick wall region may be supported on the collet support such that the thick wall region and the collet support bear a substantial portion of any longitudinal compressive force applied to the collet.

Some benefits of the fishing tool of at least some embodiments of the present invention include the following:

1. Reduced costs;

2. Reduced size and weight;

3. Less moving parts; .

4. Construction simplification;

5. Ease of assembly; and

6. Ability to operate under most conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a section view of a fishing tool showing the collet in the open position.

Figure 2 is a detailed section view of a fish and of a collet in the open position. Figure 3 is a section view of a fishing tool showing a collet in the closed position.

Figure 4 is a detailed section view of a fish and of a collet in the closed position.

Figure 5 is a detailed view of a collet in the open position.

Figure 6 is a detailed view of a collet in the closed position.

Figure 7 is a view of a fishing tool showing the cable slot.

Figure 8 is a view of a fishing tool showing the wire guide rollers

Figure 9 is an unassembled view of the bottom part of the fishing tool showing the collet assembly.

DETAILED DESCRIPTION OF THE DRAWINGS

Figure 1 shows a fishing tool 10 and a fish 50. Figure 2 shows a collet 30, collet support 38 and a fish 50. With reference to Figures 1 and 2, the fishing tool 10 has a tool body 12 which is attached to an attachment part 14 and a mouth part 16. The collet base 42 and the collet support base 44 of the collet 30 and collet support 38 respectively, are held in place between the tool body 12 and the mouth part 16. The fishing tool 10 is usually attached to a drill pipe(not shown) by engagement with the threaded opening 20 of the attachment part 14. The fishing tool 10 includes wire guide rollers 18 which help guide a communication wire 58 through the fishing tool 10. In use, the fishing tool 10 is lowered down to a fish 50 which is to be retrieved.

The fish 50 comprises a tool 52, a head section 56 and is connected to a communication wire 58. The fish 50 is guided through a conical opening in mouth part 16 as the tool 10 is lowered. The head section 56 of fish 50 has an opening 60 to allow a communication wire 58 to be attached to the tool 52. A threaded bore 62 attaches to a threaded section 54 of tool 52 of fish 50.

As the fishing tool 10 is lowered, the head section 56 of fish 50 passes through the collet 30, expanding the collet 30 as it passes therethrough. Figures 1 and 2 show the collet 30 in an exaggerated expanded condition for diagrammatic purpose. The collet 30 would normally be in contact with the head section 56 in this position. The thin wall section 34 of the collet 30 allows the collet 30 to expand easily with minimal force required for this expansion.

Figure 3 shows a fishing tool 10 and a fish 50, with the collet 30 in the closed position. Figure 4 shows a collet 30, collet support 38 and a fish 50 with the collet 30 in the closed position. With reference to Figures 3 and 4, once the lip 68 of the head section 56 of the fish 50 passes through the collet 30, the collet 30 contracts to the closed position and contacts the neck section 64 of the head section 56. The fishing tool 10 can now be raised to retrieve the fish 50. The head section 56 of the fish 50 is captive due to the top of the collet 30 being contained by the groove 66 and lip 68 of the head section 56. In the closed position, the thick wall section 32 of the collet is in contact with the collet support face 40 (which can also be clearly seen in figure 2). In this position the thick wall section 32 of the collet is supported by the collet support 38 and the collet 30 is capable of withstanding more force than the collet 30 could withstand if it had to rely solely on the thin wall section 34. In particular, a longitudinally directed compressive force (which occurs when the fishing tool has engaged with the fish as shown in figure 3 and the fishing tool is raised to withdraw the fishing tool and the fish from the bore hole) results in thick wall section 32 of the collet bearing upon collet support 34, effectively providing a thick wall section to resist the force. ^' '

Figure 5 shows a collet 30 having six collet segments 36, each collet segment 36 has a thick wall section 32 and a thin wall section 34. The collet 30 also has stress reducing cutouts 46 to reduce the stress experienced by the collet 30 through expansion and contraction. The collet 30 and collet support 38 (not shown) are both divided in two sections (not shown) so that the collet and collet support 38 (not shown) can be placed around a wire (not shown) without needing to thread the wire through the collet 30.

Figure 6 shows the collet 30 of Figure 5 in the closed position to which it is naturally biased. Figure 7 shows the outside of the fishing tool 10. The connecting members 70 and screws 72 attach the attachment part 14 and the mouth part 16 to the tool body 12. The cable slots 74, 76 in the tool body 12 and the mouth part 16 allow the fishing tool 10 to be assembled around a wire (not shown) such that the wire can pass through the fishing tool 10 without needing to be threaded through the fishing tool 10.

Figure 8 shows the outside of the fishing tool 10. The wire (not shown) can be passed between the two wire guide rollers 18 before the attachment part 14 is attached to the tool body 12.

Figure shows the tool body 12, the mouth part 16, the collet 30, the collet support 38, the connecting member 70 and the screws 72. The shoulder 78 of the mouth part 16 supports the collet support 38 and the collet 30 once they are in place. The cable slot 76 allows a wire (not shown) to pass to the inside of the mouth part 16. The collet support 38 and the collet 30 would also be assembled around the wire, the wire would then be passed through the cable slot 74 (not shown) and over the wire guide 18 (not shown) on the tool body 12, the fishing tool would then be assembled and ready for use. Once the fish (not shown) has been retrieved, the fishing tool would be disassembled to remove the captive fish.

The foregoing embodiments are illustrative only of the principles of the invention, and various modifications and changes will readily occur to those skilled in the art. The invention is capable of being practiced and carried out in various ways and in other embodiments. It is also to be understood that the terminology employed herein is for the purpose of description and srumld not be regarded as limiting.

In the present specification and claims (if any), the word "comprising" and its derivatives including "comprises" and "comprise" include each of the stated integers but does not exclude the inclusion of one or more further integers.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations. In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims (if any) appropriately interpreted by those skilled in the art.