WO2014126481A2

WO2014126481A2 - A stabiliser and wear resisting band for rotating drilling equipment pipe and tool joints

Info

Publication number: WO2014126481A2
Application number: PCT/NZ2014/000014
Authority: WO
Inventors: Geoffrey Neil Murray; Gregory Douglas TROWBRIDGE; Steven Jeoffrey HOLLAND
Original assignee: Geoffrey Neil Murray; Trowbridge Gregory Douglas; Holland Steven Jeoffrey
Priority date: 2013-02-15
Filing date: 2014-02-14
Publication date: 2014-08-21
Also published as: WO2014126481A3

Abstract

A stabiliser or wear resisting band for drilling or casing drilling or running casing tubulars, comprising a cylindrical body formed in-situ by moulding around a pipe or tool joint, the body of the tool formed from a base material that can be one of an elastomer, semi-crystalline or amorphous polymer, a thermoset material, or a cross-linked material. Also, a method of forming a stabiliser or wear resisting band comprising the steps of placing a mould around a drill pipe tool joint, drill pipe or casing, heating the mould, processing the moulding base material in a high temperature melter, and delivering the moulding base material to the mould via a screw and/or ram arrangement, and a heated barrel or barrels, and/or an insulated line or lines.

Description

A STABILISER AND WEAR RESISTING BAND FOR ROTATING DRILLING EQUIPMENT PIPE AND TOOL JOINTS

FIELD OF THE INVENTION The present invention relates to a drilling and completion stabilisation and wear banding system for stabilising drilling and completion tubulars and equipment in a well bore for oil, gas, geothermal and other types of wells. More particularly, the present invention relates to a drilling and completion tubular stabilisation and wear banding system for reducing casing or tool joint wear or annular drilling and cementing fluid friction pressure.

BACKGROUND OF THE INVENTION

When drilling a well bore for oil, gas, geothermal or similar, there may be numerous problems. The types of problem encountered depend largely on the well geometry and the type of drilling fluid used. Examples of problems that may be encountered include, but are not limited to: high torque, high drag, casing wear, drill pipe body and drill pipe tool joint wear and heat checking, vibration, rotational stick-slip related high strain rate deformation and excessive annular drilling fluid friction pressure.

Currently, rotating drill pipe rubbers are used to help solve some of these problems. However, the use of these rubbers can exacerbate other problems. For example, if drill pipe rubbers are used to protect casing and drill pipe, their large diameter and bluff shape can severely hinder annular drilling fluid friction pressure. Non-rotating type drill pipe protectors are also used and are effective at reducing torque plus casing and drill pipe wear however they all impair hydraulic performance and tend to increase axial drag.

A process known as hardbanding can also be used to combat tool joint wear while reducing casing wear. Typically, hardbanding involves continuously depositing a metal alloy around the circumference of a tool. Although the use of metal alloy helps to overcome the disadvantages of using a softer material such as rubber, this application process generates significant heating of the tool joint area which can damage the internal plastic coating of the drill pipe or adversely affect its mechanical properties. A common component in the material used for hardbanding is tungsten carbide. The use of tungsten carbide in hardbanding generally increases casing wear. Another product that can be used is Enhanced Performance Drill Pipe. This has an external appearance somewhat like a metal Archimedes screw pump mounted on drill pipe. Although this product has generally better all-round performance, and particularly in regard to improving hydraulic performance, it is extremely expensive and is therefore not commonly used.

It is common and desirable for a drilling or operating contractor to reposition drilling tubulars within a drill string in order to distribute the fatigue conditions and/or down- hole integrity threatening chemicals a particular piece of drilling tubular is exposed to. Currently this can be difficult to achieve because the identification marks may be both difficult to locate, and are almost always hard to read.

Operating companies tend to prefer water-based drilling mud systems as they are cheaper, and also typically less damaging to hydrocarbon bearing rock than an oil- based system. However, in practice water based mud may not deliver the lubricity needed to successfully drill the well.

It is an object of the present invention to provide a drilling and completion tubular stabilisation system which goes some way to overcoming the abovementioned disadvantages or which at least provides the public or industry with a useful choice.

It is a further object of the present invention to provide a method of moulding a drilling and completion tubular stabilisation system in-situ which goes some way to overcoming the abovementioned disadvantages or which at least provides the public or industry with a useful choice.

It is a yet still further object of the present invention to provide a wear banding system which goes some way to overcoming the abovementioned disadvantages or which at least provides the public or industry with a useful choice. It is a yet still further object of the present invention to provide a method of moulding a wear banding system in situ which goes some way to overcoming the abovementioned disadvantages or which at least provides the public or industry with a useful choice.

SUMMARY OF THE INVENTION

In a first aspect, the invention may broadly be said to consist in a stabiliser or wear resisting band for drilling or casing drilling or running casing tubulars, comprising a cylindrical body formed in-situ by moulding around a pipe or tool joint, the body of the tool formed from a base material that can be one of an elastomer, semi-crystalline or amorphous polymer, a thermoset material, or a cross-linked material.

Preferably the selected base material may be any one of Nitrile Rubber, Silicon Rubber, Polyurethane, Polyethylene including high and ultra-high Molecular Weight Polyethylenes, Polyamides (Nylon) or a PEEK type material.

Preferably specialist fibres or powders are mixed with the base material before the in-situ forming.

Preferably the specialist fibres or powders are any one of Kevlar, glass or carbon fibre.

Preferably the specialist fibres or powders are nano-diamond and/or tourmaline and/or molybdenum disulfide.

Preferably the base material contains additives of the type that aid with the dissipation of static electricity. Preferably the base material is coloured by the addition of a coloured dye.

Preferably the stabiliser or wear resisting band has an outside diameter greater than the outside diameter of the connections between items in the string. Preferably the stabiliser or wear resisting band is a stabiliser with a plurality of standoff ribs arranged around and extending radially outwards from the cylindrical body. Preferably the ribs are aligned lengthways. Preferably the stand-off ribs taper down to merge with the diameter of the cylindrical body at each end.

Preferably the ribs are spiralled around the body. Alternatively the stabiliser or wear resisting band is a wear resisting band with a plurality of stand-off ribs arranged around and extending radially outwards from the cylindrical body.

Preferably the ribs run circumferentially around the outside of the wear resisting band.

Preferably the ribs are located so as to improve the strength of a weld line on the stabiliser. Preferably the stabiliser or wear resisting band has visual wear indicators.

In a second aspect, the invention may broadly be said to consist in a method of forming a stabiliser or wear resisting band comprising the steps of:

placing a mould around a drill pipe tool joint, drill pipe or casing;

heating the mould;

processing the moulding base material in a high temperature melter;

delivering the moulding base material to the mould via a screw and/or ram arrangement, and a heated barrel or barrels, and/or an insulated line or lines.

Preferably the method comprises the additional initial step of ensuring that the mould is adequately vented before heating the mould and delivering the moulding base material. Preferably the method comprises the additional step during delivery of the moulding base material of applying a vacuum to a vent or vents in the mould to aid the flow and placement of the stabiliser material.

Preferably the method comprises the additional initial step of choosing the base material from any one of Nitrile Rubber, Silicon Rubber, Polyurethane, Polyethylene including high and ultra-high Molecular Weight Polyethylenes, Polyamides (Nylon) or a PEEK type material.

Preferably the method comprises the additional initial step of mixing specialist fibres chosen from any one of Kevlar, glass or carbon fibre with the base material before the in-situ forming.

Preferably the method comprises the additional initial step of mixing specialist powders chosen from nano-diamond and/or molybdenum disulfide with the base material before the in-situ forming.

Preferably the method comprises the additional initial step of adding additives of the type that aid with the dissipation of static electricity to the base material. Preferably the method comprises the additional initial step of adding coloured dye to the base material.

Preferably the temperature of the mould and the base material is chosen such that the integrity of the internal plastic coating of the tubular is not affected.

Preferably the mould is chosen to have an internal profile such that the formed stabiliser or wear resisting band will have a plurality of stand-off ribs arranged around and extending radially outwards from the body of the stabiliser or wear resisting band.

Preferably the mould is chosen to have an internal profile such that the ribs are aligned lengthways. Preferably the mould is chosen to have an internal profile such that the ribs taper down to merge with the body of stabiliser or wear resisting band at each end.

Preferably the mould is chosen to have an internal profile such that the ribs are spiralled around the body.

Alternatively the mould is chosen to have an internal profile such that the ribs run circumferentially around the outside of the wear resisting band.

Preferably the mould is chosen to have an internal profile such that the ribs are located so as to improve the strength of a weld line on the stabiliser.

Preferably the mould is chosen to have an internal profile and is positioned such that the weld line is opposite the injection point. In a third aspect the invention may broadly be said to consist in a method of repairing or restoring a stabiliser or wear resisting band comprising the steps of:

placing a mould around a drill pipe tool joint, drill pipe or casing around or over the top of the existing stabiliser or wear resisting band;

heating the mould;

processing the moulding base material in a high temperature melter;

delivering the moulding base material to the mould via a screw and/or ram arrangement, and a heated barrel or barrels and/or an insulated line or lines.

Preferably the method comprises the additional initial step of ensuring that the mould is adequately vented before heating the mould and delivering the moulding base material.

Preferably the method comprises the additional step during delivery of the moulding base material of applying a vacuum to a vent or vents in the mould to aid the flow and placement of the stabiliser material.

Preferably the method comprises the additional initial step of choosing the base material from any one of Nitrile Rubber, Silicon Rubber, Polyurethane, Polyethylene including high and ultra-high Molecular Weight Po!yethylenes, Polyamides (Nylon) or a PEEK type material.

Preferably the method comprises the additional initial step of mixing specialist powders chosen from nano-diamond and/or tourmaline and/or molybdenum disulfide with the base material before the in-situ forming.

Preferably the method comprises the additional initial step of adding additives of the type that aid with the dissipation of static electricity to the base material.

Preferably the method comprises the additional initial step of adding coloured dye to the base material.

Preferably the temperature of the mould and the base material is chosen such that the integrity of the internal plastic coating of the tubular is not affected. In a fourth aspect the invention may broadly be said to consist in a method of forming a number of stabilisers or wear resisting bands on a drill pipe tool joint(s), drill pipe(s), or casing(s) to alter the first natural frequency, comprising the steps of: choosing the desired number of points of support;

placing a mould or moulds around drill pipe tool joint(s), drill pipe(s), or casing(s) around or over the top of the existing stabiliser or wear resisting band; heating the mould or moulds;

processing the moulding base material in a high temperature melter;

delivering the moulding base material to the mould or moulds via a screw and/or ram arrangement, and a heated barrel or barrels, and/or an insulated line or lines.

Preferably the stabilisers or wear resisting bands are positioned at irregular intervals. BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a side elevation of the stabiliser of the present invention, attached to a drill well tubular;

Figure 2 shows an end cross-sectional view of the stabiliser and tubular of figure 1 ; Figure 3 shows a perspective view of the stabiliser of the present invention;

Figure 4a shows a side elevation of a drill pipe tool joint with a first embodiment of wear band moulded in position on the tool joint; Figure 4b shows a side elevation of a drill pipe tool joint with a second embodiment of wear band moulded in position on the tool joint; and

Figure 5 shows an exploded perspective view of the wear band of figure 4 and a split mould for moulding the wear band onto the tool joint, the two halves of the split mould clamping together around the tool joint in use.

DETAILED DESCRIPTION OF THE INVENTION

The present invention uses specifically formulated engineering polymers as an alternative to hardbanding using metal alloys. These polymers generally exhibit lower wear rates while also significantly reducing friction, torque and drag. The use of engineering polymers also significantly reduces the potential for casing wear. In the present invention, the engineering polymers are applied to the pipes and tubulars using an in-situ application process. This process generates significantly less heat than hardbanding, and therefore damage to the drill pipe's internal plastic lining is minimised or totally eliminated. Moulding a wear band in-situ around a tubular or tool joint replaces the need to apply a welded metal hardband. The present invention has two preferred embodiments: a stabiliser, primarily for use on drilling tubulars, and a wear band, primarily for use at or close to tool joints for drill pipe, heavy weight drill pipe, drill collars and associated drilling tools. The present invention is applicable to both new and used tubulars. The stabiliser and wear band are described below.

Stabiliser

A preferred embodiment of stabiliser 1 is shown in figures 1 to 3. The stabiliser 1 has a generally cylindrical body, with a plurality of stand-off ribs or lubrication channels 3 arranged around the periphery and extending radially from the cylindrical body. The ribs are aligned to run lengthways along the body. In the preferred embodiment, the ribs 3 are slightly spiralled around the body as best shown in figure

1. In sectional elevation, the standoff ribs taper down to merge with the diameter of the cylindrical body at each end.

The stabiliser 1 shown in figures 1 and 2 is moulded in-situ around a drilling tubular

2. The stabiliser 1 is moulded onto a pre-prepared surface at any selected position along the length of the tubular 2. For casing drilling, drilling with casing, drilling with liner or simply running casing, the tubular may be a casing material rather than drill pipe.

As described above and shown in figure 3, the standoff blades are spiralled around the cylindrical body of the stabiliser 1. A different pitch or tightness of the spiral may be more suitable for different applications. For example, if a particular application or drilling situation requires a particular annular drilling velocity, (e.g. to enable some degree of pumping at typical drilling rotational speeds), then a stabiliser having suitably pitched blades can be created. The number of stabilisers installed per joint of pipe may also be altered to achieve the desired number of points of support wherein the more closely the pipe is supported, the higher will be the first natural frequency. Additionally, the stabilisers may be positioned at irregular spacings in order to halt the development of a various harmonics that may otherwise propagate in the drill string. Wear band

Two embodiments of drill pipe wear band are shown in figures 4a, 4b, and 5. The wear band is generally referred to as wear band 7 (7a in figure 4a, and 7b in figure 4b). Wear band 7 is preferably moulded in-situ around a tubular tool joint 6 on a drill pipe 5. In the preferred embodiment, the position at which the wear band 7 is to be moulded is prepared and machined to an appropriate uniform dimension below the tool joint surface and is of an appropriate uniform width. Alternatively, the wear band may be in situ moulded directly onto the upset portion of the drill pipe as shown in figure 6.

The wear band can have a uniform outer circumferential surface, as shown in figure 4a, or it can be profiled, as shown in the embodiment of figure 4b. In the embodiment shown in figure 4b, the outer surface has two stand-off ribs 9 arranged around and extending radially outwards from the cylindrical body. These ribs run circumferentially around the outside of the body, substantially perpendicular to the axis of the body, and the drill pipe when installed on the drill pipe. The mould is profiled to create the ribs 9, and this profiling assists with directing the fibre reinforced melt flow in order to improve the strength of the weld line opposite the injection point.

It should be noted that 'circumferentially around' in the context of this specification should be taken to mean perpendicular, as just described, or at an angle or circumferentially spiraled around the body. It is intended that to improve convenience and reduce pipe transportation costs, the stabilisers and wear bands will preferably be capable of being safely and efficiently installed on the drill site using self-contained equipment. This process is described below. The outside diameter of the standoff blades and tool joint protection wear bands is preferably formed so that their outside diameters are larger than the outside diameter of the connections between tubulars in the string, in order to provide positive stand-off and to enable washing over with wash-pipe should the tubular unintentionally be cemented in the wellbore. For casing drilling and casing running and cementing applications, the outside diameter will preferably be greater than the connection diameter in order to provide adequate standoff for cementing purposes.

Mould and material

The stabilisers and wear bands are formed in-situ by moulding around the pipe or tool joint using an in-situ mould 8. The mould is preferably of a low-pressure split type which clamps tightly to the drill pipe tool joint, drill pipe or casing. In the preferred embodiment, the moulds are split into two halves (8a and 8b) to enable installation around the pipe or tool joint. The moulds are heated to ensure that the moulded stabiliser material will flow properly and without risk of cold-shut. The mould and stabilizer material heating means may be electric induction, radio frequency, microwave, fluid gallery or other means. The moulding material is processed in a high temperature melter such as to deliver the stabiliser material in a highly fluid state to the casting mold via a screw arrangement or a ram arrangement, or both, and a heated barrel or barrels, or insulated lines or both. The mould is adequately vented and a vacuum may be pulled on the vent(s) to aid the flow and placement of the stabiliser material. The base material the stabiliser and wear band are moulded from may be an Elastomer or Semi-crystalline or Amorphous Polymer. The selected base material may, depending on the application, be any one of Nitrile Rubber, Silicon Rubber, Polyurethane, Polyethylene including high and ultra-high Molecular Weight Polyethylenes, Polyamides (Nylon) or a PEEK type material. Many other types of thermoset, cross-linked or other products may however be used. Surprisingly and counter-intuitively, it has been found that the use of these polymers provides a stabiliser or wear band that can withstand the conditions necessary for both drill pipe and casing application. The use of a polymer also provides a product that has improved performance over regular DP hard-banding.

To enhance the properties of the moulding material, and particularly the heat deflection temperature, it may be reinforced with a suitable type of fibre such as Kevlar, Glass or Carbon Fibre or similar. To enhance the abrasive life, reduce friction and improve the stiffness of the material, specialist materials such a nano-diamond, molybdenum disulfide, tourmaline or other powders may be added.

Furthermore, the base material may contain additives to aid with the dissipation of static electricity, thereby reducing the risk of sparks and reducing the build-up of magnetism in well or drilling tubulars.

Advantages

The stabiliser and wear band stabilise the drilling or completion tubulars. They also serve to reduce torque, drag, rotational and axial stick/slip and associated vibration. This is achieved primarily through the use of materials (as listed above) that have a low coefficient of friction. Various iterations of the device may replace tool joint hardbanding and enhance drilling tubular life. The preferred form of stabiliser as described above has spiraled ribs, which helps to reduce annular pressure drop, thereby reducing cuttings hold-down pressure and thereby improving rate of penetration. The device also reduces casing and/or drill pipe wear, open hole key- seating, differential sticking while lifting cuttings and thereby improving hole cleaning. The devices allow closer spaced points of drilling tubular support. This stiffens the drill string thereby delaying sinusoidal buckling and enabling tubular use with the string in greater compression than would otherwise be possible. The drillable (Polymer) positive stand-off also ensures that a drilling tubular can be washed over should it inadvertently become cemented into the wellbore.

Following a period of service, the standoff ribs or tool joint wear band will wear such that they are no longer effective. In the case of Semi-crystalline or Amorphous materials, the option may exist to over-mold the standoff ribs with new material although preferably the Polymer will be totally removed and replaced. For stabilisers and wear bands cast in thermoset or cross-linked materials, the old material will be removed and the surface buffed before the new material is applied.

The use of stabilisers on drill pipe can be used in conjunction with the applied wear bands or alternatively these can be used independently of each other. The stabiliser and wear resisting bands can be coloured to enable rapid and effective identification, thereby also making it easier to rotate drilling tubulars.

The invention as described above is effective in reducing all of the drilling problems listed in the prior art section above. It is also cost effective to use. Furthermore, should a piece of stabiliser fall off, it will not compromise the well as has been the case with other rotating and non-rotating equipment.

As outlined above, operating companies tend to prefer water-based drilling mud systems as they are cheaper, and also typically less damaging to hydrocarbon bearing rock than an oil-based system. However, in practice water based mud may not deliver the lubricity needed to successfully drill the well. The invention as described above effectively extends the use of water based drilling mud systems by reducing friction.

Claims

CLAIMS:

1. A stabiliser or wear resisting band for drilling or casing drilling or running casing tubulars, comprising a cylindrical body formed in-situ by moulding around a pipe or tool joint, the body of the tool formed from a base material that can be one of an elastomer, semi-crystalline or amorphous polymer, a thermoset material, or a cross-linked material.

2. A stabiliser or wear resisting band as claimed in claim 1 wherein the selected base material may be any one of Nitrile Rubber, Silicon Rubber, Polyurethane,

Polyethylene including high and ultra-high Molecular Weight Polyethylenes, Polyamides (Nylon) or a PEEK type material.

3. A stabiliser or wear resisting band as claimed in claim 1 or claim 2 wherein specialist fibres or powders are mixed with the base material before the in-situ forming.

4. A stabiliser or wear resisting band as claimed in claim 3 wherein the specialist fibres or powders are any one of Kevlar, glass or carbon fibre.

5. A stabiliser or wear resisting band as claimed in claim 3 or claim 4 wherein the specialist fibres or powders are nano-diamond and/or tourmaline and/or molybdenum disulfide.

6. A stabiliser or wear resisting band as claimed in any one of claims 3 to 5 wherein the base material contains additives of the type that aid with the dissipation of static electricity.

7. A stabiliser or wear resisting band as claimed in any one of claims 1 to 6 wherein the base material is coloured by the addition of a coloured dye.

8. A stabiliser or wear resisting band as claimed in any one of claims 1 to 7 wherein the stabiliser or wear resisting band has an outside diameter greater than the outside diameter of the connections between items in the string.

9. A stabiliser or wear resisting band as claimed in any one of claims 1 to 8 wherein the stabiliser or wear resisting band is a stabiliser with a plurality of stand-off ribs arranged around and extending radially outwards from the cylindrical body.

10. A stabiliser or wear resisting band as claimed in claim 9 wherein the ribs are aligned lengthways.

11. A stabiliser or wear resisting band as claimed in claim 10 wherein the standoff ribs taper down to merge with the diameter of the cylindrical body at each end.

12. A stabiliser or wear resisting band as claimed in claim 10 or claim 11 wherein the ribs are spiralled around the body.

13. A stabiliser or wear resisting band as claimed in any one of claims 1 to 8 wherein the stabiliser or wear resisting band is a wear resisting band with a plurality of stand-off ribs arranged around and extending radially outwards from the cylindrical body.

14. A stabiliser or wear resisting band as claimed in claim 13 wherein the ribs run circumferentially around the outside of the wear resisting band.

15. A stabiliser or wear resisting band as claimed in claim 14 wherein the ribs are located so as to improve the strength of a weld line on the stabiliser.

16. A stabiliser or wear resisting band as claimed in any one of claims 1 to 15 wherein the stabiliser or wear resisting band has visual wear indicators.

17. A method of forming a stabiliser or wear resisting band comprising the steps of:

placing a mould around a drill pipe tool joint, drill pipe or casing; heating the mould;

processing the moulding base material in a high temperature melter;

18. A method of forming a stabiliser or wear resisting band as claimed in claim 17 comprising the additional initial step of ensuring that the mould is adequately vented before heating the mould and delivering the moulding base material.

19. A method of forming a stabiliser or wear resisting band as claimed in claim 17 or claim 18 comprising the additional step during delivery of the moulding base material of applying a vacuum to a vent or vents in the mould to aid the flow and placement of the stabiliser material.

20. A method of forming a stabiliser or wear resisting band as claimed in any one of claims 17 to 19 comprising the additional initial step of choosing the base material from any one of Nitrite Rubber, Silicon Rubber, Polyurethane, Polyethylene including high and ultra-high Molecular Weight Polyethylenes, Polyamides (Nylon) or a PEEK type material.

21. A method of forming a stabiliser or wear resisting band as claimed in claim 20 comprising the additional initial step of mixing specialist fibres chosen from any one of Kevlar, glass or carbon fibre with the base material before the in-situ forming.

22. A method of forming a stabiliser or wear resisting band as claimed in claim 20 or claim 2 comprising the additional initial step of mixing specialist powders chosen from nano-diamond and/or molybdenum disulfide with the base material before the in-situ forming.

23. A method of forming a stabiliser or wear resisting band as claimed in any one of claims 20 to 22 comprising the additional initial step of adding additives of the type that aid with the dissipation of static electricity to the base material.

24. A method of forming a stabiliser or wear resisting band as claimed in any one of claims 20 to 23 comprising the additional initial step of adding coloured dye to the base material.

25. A method of forming a stabiliser or wear resisting band as claimed in any one of claims 17 to 24 wherein the temperature of the mould and the base material is chosen such that the integrity of the internal plastic coating of the tubular is not affected.

26. A method of forming a stabiliser or wear resisting band as claimed in any one of claims 17 to 24 wherein the mould is chosen to have an internal profile such that the formed stabiliser or wear resisting band will have a plurality of stand-off ribs arranged around and extending radially outwards from the body of the stabiliser or wear resisting band.

27. A method of forming a stabiliser or wear resisting band as claimed in claim 26 wherein the mould is chosen to have an internal profile such that the ribs are aligned lengthways.

28. A method of forming a stabiliser or wear resisting band as claimed claim 27 wherein the mould is chosen to have an internal profile such that the ribs taper down to merge with the body of stabiliser or wear resisting band at each end.

29. A method of forming a stabiliser or wear resisting band as claimed in claim 27 or claim 28 wherein the mould is chosen to have an internal profile such that the ribs are spiralled around the body.

30. A method of forming a stabiliser or wear resisting band as claimed in claim 26 wherein the mould is chosen to have an internal profile such that the ribs run circumferentially around the outside of the wear resisting band.

31. A method of forming a stabiliser or wear resisting band as claimed in claim 30 wherein the mould is chosen to have an internal profile such that the ribs are located so as to improve the strength of a weld line on the stabiliser.

32. A stabiliser or wear resisting band as claimed in claim 31 wherein the mould is chosen to have an internal profile and is positioned such that the weld line is opposite the injection point.

33. A method of repairing or restoring a stabiliser or wear resisting band comprising the steps of:

heating the mould;

processing the moulding base material in a high temperature melter;

34. A method of repairing or restoring a stabiliser or wear resisting band as claimed in claim 33 comprising the additional initial step of ensuring that the mould is adequately vented before heating the mould and delivering the moulding base material.

35. A method of repairing or restoring a stabiliser or wear resisting band as claimed in claim 25 or claim 26 comprising the additional step during delivery of the moulding base material of applying a vacuum to a vent or vents in the mould to aid the flow and placement of the stabiliser material.

36. A method of repairing or restoring a stabiliser or wear resisting band as claimed in any one of claims 33 to 35 comprising the additional initial step of choosing the base material from any one of Nitrite Rubber, Silicon Rubber, Polyurethane, Polyethylene including high and ultra-high Molecular Weight Polyethylenes, Polyamides (Nylon) or a PEEK type material.

37. A method of repairing or restoring a stabiliser or wear resisting band as claimed in claim 36 comprising the additional initial step of mixing specialist fibres chosen from any one of Kevlar, glass or carbon fibre with the base material before the in-situ forming.

38. A method of repairing or restoring a stabiliser or wear resisting band as claimed in claim 36 or claim 37 comprising the additional initial step of mixing specialist powders chosen from nano-diamond and/or tourmaline and/or molybdenum disulfide with the base material before the in-situ forming.

39. A method of repairing or restoring a stabiliser or wear resisting band as claimed in any one of claims 36 to 38 comprising the additional initial step of adding additives of the type that aid with the dissipation of static electricity to the base material.

40. A method of repairing or restoring a stabiliser or wear resisting band as claimed in any one of claims 36 to 39 comprising the additional initial step of adding coloured dye to the base material.

41. A method of repairing or restoring a stabiliser or wear resisting band as claimed in any one of claims 33 to 40 wherein the temperature of the mould and the base material is chosen such that the integrity of the internal plastic coating of the tubular is not affected.

42. A method of forming a number of stabilisers or wear resisting bands on a drill pipe tool joint(s), drill pipe(s), or casing(s) to alter the first natural frequency, comprising the steps of:

choosing the desired number of points of support;

processing the moulding base material in a high temperature melter;

43. A method of forming a number of stabilisers or wear resisting bands on a drill pipe tool joint(s), drill pipe(s), or casing(s) as claimed in claim 42 wherein the stabilisers or wear resisting bands are positioned at irregular intervals.

44. A stabiliser substantially as herein described with reference to figures 1 to 3.

45. A wear resisting band substantially as herein described with reference to figure 4a.

46. A wear resisting band substantially as herein described with reference to figure 4b.