DOWNHOLE TOOL WITH FUEL SYSTEM

Abstract

A tool (1) for manipulating a material, includes a body (4) defining a chamber (6). At least one source (8) of a pressurised fuel and oxidant mixture (9) or of a monopropellant is in communication with a chamber via an injector device. At least one mechanism (18) for igniting the fuel and oxidant mixture or for initiating decomposition of the monopropellant is provided. Upon ignition of the fuel and oxidant mixture or initiation of the decomposition of the monopropellant, a combustion jet (20) or a decomposition product jet is formed in the chamber which, in use, flows out through a nozzle outlet (28) towards, and into engagement with, a material to be manipulated. Methods of using the tool (1) and fuel and oxidant compositions suitable for use in the tool are also described.

Claims

1. A tool for manipulating a material, the tool comprising: a body defining a chamber; at least one source of a pressurised fuel and oxidant mixture, or of a pressurised monopropellant, in fluid communication with the chamber via an injector device; at least one nozzle, each nozzle having an inlet and an outlet, the inlet being in fluid communication with the chamber; and at least one mechanism for igniting the fuel and oxidant mixture, or for initiating decomposition of the monopropellant; wherein, upon ignition of the fuel and oxidant mixture, or initiating decomposition of the monopropellant, a combustion jet or a decomposition product jet is formed in the chamber which, in use, flows out of the tool through each nozzle outlet towards, and into engagement with, a material to be manipulated.

2. The tool of claim 1, wherein the tool comprises the at least one source of a pressurised fuel and oxidant mixture.

3. The tool of claim 1, wherein the tool is configured for use downhole.

4. The tool of claim 1 wherein the combustion jet or combustion jets emanate from the tool in a radially outwards 360 degree direction.

5. The tool of claim 1 further comprising a cooling system.

6. The tool of claim 2, wherein the fuel and oxidant mixture is provided as a single composition including both fuel and oxidant.

7. The tool of claim 2, wherein fuel and oxidant are provided separately to be mixed either before or at the point of ignition.

8. The tool of claim 1 wherein gas pressure is employed to drive at least one of the fuel, the oxidant, the fuel and oxidant mixture, or the monopropellant into the chamber.

9. The tool of claim 1 wherein the fuel, the oxidant, the fuel and oxidant mixture, or the monopropellant is a gel composition.

10. The tool of claim 2, wherein the fuel comprises an ionic liquid including a quaternary ammonium salt.

11. The tool of claim 2, wherein the fuel comprises a solution including a quaternary ammonium salt.

12. The tool of claim 2, wherein the fuel comprises at least one of: a nitro alkane, an alkyl nitrate, or mixtures thereof; a hydrocarbon; and an alcohol.

13. The tool of claim 6 wherein the fuel and oxidant mixture comprises one of: a) an ionic liquid including a quaternary ammonium salt; and a nitrate, chlorate, chromate, dinitramide or perchlorate salt, or mixtures thereof; b) an alcohol; and a nitrate, chlorate, chromate, dinitramide or perchlorate salt, or mixtures thereof; and c) a nitroalkane, a nitroalkene, an alkyl nitrate, or mixtures thereof; and a nitrate, chlorate, chromate, dinitramide or perchlorate salt, or mixtures thereof.

14. The tool of claim 13 wherein the fuel and oxidant composition further comprises: particles of at least one selected from the group consisting of: aluminium, beryllium, iron, zirconium, magnesium, boron, boron carbide and alloys thereof.

15. A method of manipulating a material, the method comprising: deploying a tool according to claim 1 into the proximity of a target material; and operating the tool to produce a combustion jet or a decomposition product jet that engages the target material.

16. The method of claim 15 wherein the tool is a downhole tool and the tool is moved axially within a tubular to remove a selected length of tubular.

17. The method of claim 15 wherein the tool is a downhole tool and the tool is operated to perforate a tubular at a selected location or locations and is then moved to perforate the tubular at a further selected location or locations.

18. The method of claim 15 wherein the tool is rotated in use so as to direct the combustion jet or the decomposition product jet in different directions around the location of the tool.

19. A fuel and oxidant mixture comprising an ionic liquid including a quaternary ammonium salt or a mixture of quaternary ammonium salts.

20. The fuel and oxidant mixture of claim 19 comprising a nitrate, chlorate, chromate, dinitramide or perchlorate salt, or mixtures thereof as oxidant.

21. The fuel and oxidant mixture of claim 20 comprising: from 50 to 70% by weight of a quaternary ammonium salt ionic liquid; from 5 to 25% by weight of a nitrate, chlorate, chromate, dinitramide or perchlorate salt, or mixtures thereof; from 5 to 25% by weight of at least one metal selected from the group consisting of aluminium, magnesium, and alloys of aluminium and magnesium; from 0 to 20% by weight of an alcohol; and optionally from 0.15 to 10% by weight of a gelling agent.

22. A fuel and oxidant mixture comprising an alcohol and a nitrate, chlorate, chromate, dinitramide or perchlorate salt, or mixtures thereof as oxidant.

23. The fuel and oxidant mixture of claim 22 comprising: from 30 to 50% by weight of an alcohol; from 35 to 55% by weight of a nitrate, chlorate, chromate, dinitramide or perchlorate salt, or mixtures thereof; from 5 to 25% by weight of at least one metal selected from the group consisting of aluminium, magnesium, and alloys of aluminium and magnesium; and optionally from 0.15 to 10% by weight of a gelling agent.

24. A fuel and oxidant mixture comprising a nitroalkane, a nitroalkene, an alkyl nitrate or mixtures thereof; and a nitrate, chlorate, chromate, dinitramide or perchlorate salt, or mixtures thereof as oxidant.

25. The fuel and oxidant mixture of claim 24 comprising: from 50 to 70% by weight of a nitroalkane, a nitroalkene, an alkyl nitrate or mixtures thereof; from 0 to 20% by weight of an alcohol; from 5 to 25% by weight of at least one metal selected from the group consisting of aluminium, magnesium, and alloys of aluminium and magnesium; from 10 to 30% by weight of a nitrate, chlorate, chromate, dinitramide or perchlorate salt, or mixtures thereof; and optionally from 0.15 to 10% by weight of a gelling agent.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0088] FIG. 1 shows an exemplary tool 1 for perforating a tubular in schematic cross section;

[0089] FIG. 2 shows an exemplary tool for severing a tubular in a schematic, partially dismantled perspective and cross section view;

[0090] FIG. 2A shows a cross section of the nozzle arrangement of the tool of FIG. 2;

[0091] FIG. 3 shows a nozzle arrangement; and

[0092] FIG. 4 shows another nozzle arrangement.

DETAILED DESCRIPTION OF THE DRAWINGS

[0093] FIG. 1 shows an exemplary tool 1 in schematic cross section. The tool 1 is downhole in an oil or gas well. Connection 2 to surface includes control signal wiring. The tool 1 has a generally cylindrical body 4 including a chamber 6. Within the chamber 6 is a fuel source, a cylinder 8 in this example. Cylinder 8 contains a gel fuel and oxidant mixture 9, pressurised by a charge of nitrogen gas contained within.

[0094] A signal sent via the connection to surface 2 operates the control module 10 which commands opening of valve 12, releasing the gel fuel and oxidant mixture 9 into injector head 14. The mixture 9 is sprayed through injector head nozzles 16 into chamber 6 as a finely divided spray. Ignitor 18 provides an electrical discharge that ignites mixture 9 to form a combustion jet suggested by arrows 20. The combustion jet pressurises the chamber 6 and is deflected by deflector 22 towards the inlets 24 of nozzles 26 that are closed by fusible material 28. The heat and pressure from the combustion jet removes the fusible material 24, allowing the combustion jet 20 to escape the chamber 6 via the outlets 28 of nozzles 26 as a plurality of directed combustion jets. As suggested by broad arrows 20a, the combustion jet can then attack and perforate the walls of a tubular 30

[0095] The use of the combustion jet 20, provided by the fuel and oxidant mixture 9 allows a well-controlled attack on the target material (wall of tubular 30 in this example).

[0096] FIG. 2 shows a downhole tool 1 with like parts numbered the same as in the tool of FIG. 1.

[0097] The tool 1 is shown in two parts in FIG. 2. Tool part 1A is shown in perspective with part of the wall of body 4 shown in ghost to allow viewing of the interior. Tool part 1B is shown in perspective cross section to allow viewing of the interior of the chamber 6 and related parts. In use the two parts 1A and 1B form a single generally cylindrical body 4.

[0098] In this example there are separate cylinders 32 and 34 containing an oxidant composition and a fuel composition respectively. Control module 10 commands operation of valving at injector head 14, allowing pressurised fuel and oxidant compositions to enter and be mixed. The mixed fuel and oxidant compositions are ignited by an ignition mechanism (not shown in this figure) as they leave injector head 14 via injector head nozzles 16. This produces a combustion jet in the chamber 6.

[0099] Chamber 6 includes a support rod 36 that mounts an end cap 38 of the chamber 6. End cap 38 includes a domed deflector 40 (see cross section FIG. 2A). End cap 38 seals to the rest of chamber 6 by an ‘O’ ring seal 42 at join 43.

[0100] The pressure produced in chamber 6 by the combustion jet (arrows 20) acts to slide end cap 38 along support rod 36 as suggested by arrows 44. Movement is prevented until the pressure in chamber 6 exceeds that required to break stop 46 mounted on rod 36 (FIG. 2). This allows end cap 38 to move until stopped by nut 48 at the extreme end of rod 36. Thus, an annular gap i.e. a nozzle, is opened around the body 4 of the tool at the previously sealed join 43. The combustion jet in the chamber can exit the annular gap, aided by deflection from the domed surface 40. This produces a circular disc combustion jet directed more or less orthogonally from the tool (arrows 46 in FIG. 2A).

[0101] If desired the end cap 38 may be provided with a supply of additional material for injection into the combustion jet. For example, a suspension of aluminium particles in liquid may be provided in a container (not shown) in end cap 38 and dispensed via nozzles exiting from domed surface 40.

[0102] FIG. 3 shows schematically an end of a tool 1 that is cylindrical and includes a plurality of nozzles 26 that extend circumferentially around the tool. A plurality of combustion jets exiting from nozzles 26 can provide an effect similar to that of the tool of FIGS. 2 i.e. a (generally) circular disc of overlapping combustion jets directed more or less orthogonally from the tool.

[0103] FIG. 4 shows schematically an end of a tool 1 that is cylindrical and includes a plurality of nozzles 26 that are of the convergent-divergent type as found in aerospace rocket engines. Such a design may be employed for perforation work downhole.