Tool for severing or assisting in the severing of a conduit

Abstract

A tool for severing a conduit includes a housing defining a void that encircles a conduit to be severed. There is at least one propellant source located within the housing. Upon ignition by an ignition mechanism, the propellant source deflagrates, creating at least one stream of combustion products. The combustion products flow out of the tool through at least one void access and into the void. The void access channels the combustion products towards the conduit. The stream of combustion products combines with a modifying material to sever or assist in severing the conduit. A method of severing a conduit using the tool is provided.

Claims

1. A tool for severing or assisting in the severing of a conduit, the tool comprising: a housing defining a void, the void arranged, in use, to at least partially encircle a conduit; an at least one propellant source located within the housing; an at least one void access providing fluid communication from the interior of the housing to the void, the at least one void access having an inlet and an outlet, the at least one void access inlet being in fluid communication with the housing and the at least one void access outlet being in fluid communication with the housing void; an ignition mechanism for igniting the at least one propellant source; and an at least one modifying material; wherein, upon ignition, the at least one propellant source deflagrates, creating an at least one stream of combustion products including propellant gas, the at least one stream of combustion products flowing out of the tool through the at least one void access in to the void, the at least one void access channelling the at least one stream of combustion products towards the conduit, the at least one stream of combustion products combining with the at least one modifying material to sever or assist in severing the conduit.

2. A tool according to claim 1, wherein the housing void is a housing throughbore, the housing throughbore, in use, encircling a conduit.

3. A tool according to claim 1, wherein the at least one stream of combustion products heats the conduit to a temperature sufficient to soften the conduit, and the modifying material impinges on at least a portion of the conduit, transferring energy to the conduit to be manipulated, thereby forcibly displacing or moving the conduit portion.

4. A tool according to claim 1, wherein there are a plurality of void accesses.

5. A tool according to claim 4, wherein the plurality of void accesses is arranged in an array.

6. A tool according to claim 5, wherein each of the plurality of void accesses in the array of void accesses has a focal point the same distance from the void longitudinal axis as every other void access in the array.

7. A tool according to claim 1, wherein a stream of combustion products and modifying material flows through each void access or array of void accesses in a sequence.

8. A tool according to claim 1, wherein the at least one void access is defined by a housing wall.

9. A tool according to claim 8, wherein the at least one void access is an aperture in the housing wall, the aperture having a sidewall.

10. A tool according to claim 9, wherein the aperture sidewall channels the stream of combustion products and/or the/each modifying material.

11. A tool according to claim 1, wherein the tool includes an at least one carrier, the/each void access being mounted to the/each carrier.

12. A tool according to claim 11, wherein the/each carrier is movable between a retracted position and a deployed position.

13. A tool according to claim 12, wherein in the deployed position the/each carrier is adjacent to the conduit.

14. A tool according to claim 11, wherein the carrier comprises rams movable in a plane perpendicular to a tool longitudinal axis.

15. A tool according to claim 11, wherein the carrier comprises rollers configured to rotate into engagement with the conduit.

16. A tool according to claim 15, wherein the rollers defines a recess for receiving the conduit.

17. A tool according to claim 1, wherein the at least one modifying material includes solid particles.

18. A tool according to claim 1, wherein the at least one modifying material contains liquid droplets.

19. A tool according to claim 1, wherein at least one modifying material is included within the propellant source.

20. A tool according to claim 1, wherein at least one modifying material is a metal.

21. A tool according to claim 20, wherein the metal at least partially melts as the/each propellant source deflagrates.

22. A tool according to claim 20 wherein the metal at least partially oxidises.

23. A tool according to claim 1, wherein at least one modifying material is formed by the at least partial deflagration of the propellant source.

24. A tool according to claim 1, wherein at least one modifying material is formed separately from the deflagration of the propellant source.

25. A tool according to claim 1, wherein at least one modifying material is present in the tool prior to ignition of the propellant source.

26. A tool according to claim 1, wherein at least one modifying material is introduced into the stream of combustion products.

27. A tool according to claim 1, wherein at least one modifying material is mechanically or forcibly introduced into the propellant gas and/or the stream of combustion products.

28. A tool according to claim 1, wherein the tool includes a positioning mechanism for positioning a conduit, in use, with respect to the/each void access.

29. A tool according to claim 28, wherein the positioning mechanism centres the conduit with respect to the void.

30. A tool according to claim 28, wherein the positioning mechanism comprises a plurality of positioning devices, each device being configured to engage the conduit.

31. A tool according to claim 28, wherein the positioning mechanism centres the conduit with respect to a longitudinal axis of the void defined by the housing.

32. A tool according to claim 1, wherein the/each void access is movable with respect to the conduit to a position where the severing action of the/each stream of combustion products and modifying material is optimised.

33. A tool according to claim 1, wherein the tool is configured, within a fluid filled environment, to locally purge the medium between the void accesses and the conduit, and replace this medium with a medium of lower density.

34. A tool according to claim 33, wherein the medium of lower density is a gas.

35. A tool according to claim 34, wherein the tool produces the gas through propellant deflagration.

36. A tool according to claim 34, wherein the gas is used to displace the fluid in the vicinity of the tool.

37. A tool according to claim 1, wherein the tool further includes a sealing mechanism.

38. A tool according to claim 37, wherein the sealing mechanism is adapted to form a seal to isolate a section of the conduit.

39. A tool according to claim 37, wherein the sealing mechanism is a packer or sealing element above and/or below the housing.

40. A tool according to claim 1, wherein the tool comprises a restraining or fastening mechanism to restrict relative movement between the tool and the conduit.

41. A tool according to claim 40, wherein the restraining or fastening mechanism forms a seal on the conduit to assist in, at least partially, confining the stream of combustion products and modifying material to a stationary conduit location.

42. A tool according to claim 1, wherein the tool is configured to impart additional forces onto the conduit, from those applied by the at least one stream of combustion products and/or the at least one modifying material.

43. A tool according to claim 42, wherein the tool applies torsion, tension or bending to the conduit.

44. A tool according to claim 1, wherein the at least one stream of combustion products and/or the at least one modifying material applies torsion or tension or bending to the conduit.

45. A tool according to claim 1, wherein the tool is configured to rotate the/each stream of combustion products in a vortex.

46. A tool according to claim 1, wherein the tool comprises a shearing mechanism configured to seal a wellbore.

47. A tool according to claim 1, wherein the tool comprises a scraping mechanism to scrape away molten or softened conduit material.

48. A tool according to claim 1, wherein there is a plurality of propellant sources.

49. A tool according to claim 48, wherein where there is the plurality of propellant sources, each propellant source deflagrates separately.

50. A tool according to claim 49, wherein where there is the plurality of propellant sources, at least some of the propellant sources are ignited in a sequence.

51. A tool according to claim 1, wherein the at least one propellant source and, in some embodiments the associated ignition mechanism, is thermally insulated from well temperatures and/or potentially high temperatures from the stream of combustion products and/or modifying material.

52. A tool according to claim 1, wherein additional energy can be imparted to the at least one stream of combustion products and/or the at least one modifying material by ionisation.

53. A tool according to claim 52, wherein the at least one stream of combustion products and/or the at least one modifying material is at least partially ionised by at least part of the at least one stream of combustion products and/or the at least one modifying material coming into contact with an electrical arc.

54. A tool according to claim 52, wherein the at least one stream of combustion products and/or the at least one modifying material is ionised by passing through an induction coil.

55. A tool according to claim 52, wherein additional energy can be imparted to the at least one stream of combustion products and/or the at least one modifying material by passing at least a portion of the stream of combustion products and/or the modifying material through a magnetic field and/or electric field.

56. A tool according to claim 52, wherein additional energy can be imparted to the at least one stream of combustion products and/or the at least one modifying material by passing at least a portion of the stream of combustion products and/or the modifying material through microwave radiation.

57. A tool according to claim 52, wherein additional energy can be imparted to the at least one stream of combustion products and/or the at least one modifying material by raising its temperature.

58. A method of severing or assisting in the severing of a conduit, the method comprising the steps of: providing a tool having a housing, the housing defining a void, the void at least partially encircling a conduit to be severed; igniting an at least one propellant source located within the housing, the at least one propellant source upon deflagration creates an at least one stream of combustion products including propellant gas, the at least one stream of combustion products flowing out of the tool through an at least one void access providing fluid communication from the interior of the housing to the void, the at least one void access channelling the at least one stream of combustion products towards the conduit, the at least one of combustion products containing and/or combining with at least one modifying material to sever or assist in severing the conduit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the present invention will now be described with reference to the accompanying drawings in which:

(2) FIG. 1 is, a schematic of an oilwell incorporating a tool for severing or assisting in the severing of a conduit according to a first embodiment of the present invention;

(3) FIG. 2 is a section of the tool of FIG. 1;

(4) FIGS. 3 to 5 are sections of the tool of FIG. 1 in operation;

(5) FIG. 6 is a section of a tool for severing or assisting in the severing of a conduit according to a second embodiment of the present invention

(6) FIGS. 7 and 8 are sections of part of the tool of FIG. 6 in operation;

(7) FIG. 9 is a section of a tool for severing or assisting in the severing of a conduit according to a third embodiment of the present invention;

(8) FIGS. 10 to 13 are sections of part of the tool of FIG. 9 in operation;

(9) FIG. 14 shows a section of a tool according to another embodiment of the invention;

(10) FIG. 14A shows a detail of the tool of FIG. 14; and

(11) FIG. 15 shows a section of a tool similar to that of FIG. 6 but including a scraper.

DETAILED DESCRIPTION OF THE DRAWINGS

(12) Reference is first made to FIG. 1, a schematic of an oil well generally indicated by reference numeral 5, incorporating a tool 10 for severing or assisting in the severing of a conduit 12 according to a first embodiment of the present invention.

(13) The tool 10 is part of a well string 14 providing fluid communication between a reservoir 16 and a rig 18. The primary components of the conduit 14 are a riser 20, the tool 10 and a wellbore 22 lined with a casing 24.

(14) The rig 18 floats on the sea 26 and receives hydrocarbons from the reservoir 16 which flow into the well string 14, as indicated by the arrow 28, and particularly into the conduit 12, towards surface.

(15) Referring now to FIG. 2, a section of the tool 10, the tool 10 is an integral part of the blowout preventer (BOP) and comprises a housing 30 defining a void 32. The void 32 is a through bore 34 fully encircling the conduit 12. Located within the housing 30 is a first propellant source 36 and a second propellant source 38.

(16) A housing internal wall 40 defines a first circumferential void access 42 having an inlet 44 in fluid communication with a housing interior 46 and an outlet 48 in fluid communication with the through bore 34. Similarly the housing internal wall 40 defines a second circumferential void access 50 with an inlet 52 and an outlet 54, the second circumferential void access 50 providing fluid communication between the housing interior 46 and the through bore 34.

(17) The tool 10 further comprises a first shear ram 58 and a second shear ram 60, the purpose of which will be discussed in due course, and an ignition mechanism 56 for igniting the first and second propellant sources, 36, 38.

(18) The tool 10 is activated in a well control emergency in which it is necessary to seal the wellbore 22 by closing the shear rams 58, 60. This requires severance of the conduit 12.

(19) The propellant sources 36, 38 are potassium perchlorate. Upon ignition by the ignition mechanism 56, the propellant sources 36, 38 deflagrate, forming a hot gas of combustion products which, due to the confines of the housing 12, is highly pressurised. The propellant sources 36,38 further comprise a modifying material in the form of a metal, in this case silver (not visible) embedded in the potassium perchlorate. The deflagration process heats the silver until the silver becomes molten.

(20) The highly pressurised combustion products produced by the deflagration of the potassium perchlorate flows away from the propellant sources 36, 38 at great velocity as a stream of combustion products carrying with it the molten silver modifying material.

(21) The streams of combustion gases carrying the molten silver modifying material can be seen with reference to FIG. 3, a section of the tool 10 showing the beginning of the process of severing a conduit 12.

(22) The propellant sources 36, 38 have been ignited by the ignition mechanism 56 and the propellant sources 36, 38 have released a first stream and a second stream of combustion products 62, 64 containing the molten silver modifying material.

(23) The streams of combustion products 62, 64 flow towards, and impinge on, the housing internal wall 40. Part of the streams of combustion products, 62, 64 flow through the first and second circumferential void accesses 42, 50 and impact on the conduit 12.

(24) The gas within the streams of combustion products 62, 64 heat the conduit 12 and the modifying material melts the conduit 12. As the conduit melts, the streams of combustion products 62,64 move the molten material away revealing and further melting conduit material. Through this process, conduit 12 is severed or at the very least softened by the streams of combustion products 62, 64 containing the modifying material in the form of molten silver.

(25) As shown in FIG. 4, the streams of combustion products 62, 64 containing the molten silver modifying material, work through the conduit 12 until, as shown in FIG. 5 the first and second propellant sources 36, 38 have been fully deflagrated, the conduit 12 has been severed and the shear rams 58, 60 can close sealing the through bore 34.

(26) Reference is now made to FIG. 6, a section of one side of a tool 110 according to a second embodiment of the present invention.

(27) The tool 110 is similar in many ways to the tool 10 of the first embodiment and rather than repeat the structural similarities, the primary differences will be highlighted.

(28) The tool 110 has a single circumferential void access 142 defined by the housing internal wall 140. The circumferential void access 142 has a seal sleeve 166 covering the circumferential void access 142 to prevent ingress of well fluids from the through bore 134 into the housing interior 146.

(29) There are three propellant sources 168, 170, 172 shown in FIG. 6. The upper and lower sources 168, 172 produce a gas, the purpose of which will be discussed in due course. The middle propellant source 170 is of similar construction to the propellants 36, 38 of the first embodiment, and produces a similar effect.

(30) The tool 110 further comprises a positioning mechanism 173 in the form of a plurality of arms, of which one is visible in FIG. 6. These arms are pressed against the conduit 112 to bring the conduit into the optimum position for severance.

(31) The operation of the tool 110 will now be described. To give the propellant 170 the best environment in which to sever the conduit 112, it is it is desirable to remove any well fluids in the through bore 134.

(32) Referring to FIG. 7, the conduit has been positioned in the optimum position with respect to the tool 110 by the positioning mechanism 173. Once positioned, the upper and lower gas producing propellant sources 168, 172 are ignited by the ignition mechanism (not visible) creating a flow of high pressure combustion gas 174. This pressurises the seal sleeve 166 (not shown in FIG. 7) until the seal sleeve 166 ruptures and the gas 174 escapes through the void access 142 into the through bore 134, driving well fluids away from the propellant source stream of combustion products and modifying material (shown in FIG. 8).

(33) Referring to FIG. 8, a potassium perchlorate propellant 170 is then ignited by an ignition mechanism (not visible) and a stream of combustion products carrying a modifying material 164, in this case garnet, flows towards the conduit 112. The high pressure combustion gas 174 formed from the deflagration of the upper and lower gas producing propellant sources 168, 172 channels the stream of combustion products 164 towards the target. On impact with the conduit 112, the garnet modifying material is in solid form and removes material from the conduit 112 by abrasion.

(34) The use of the combustion gas 174 reduces friction between the stream of combustion products carrying a modifying material 164 and the housing wall 140 around the void access 142. This maximises the energy of the stream of combustion products 164, thereby increasing the efficiency of the severing of the conduit 112.

(35) FIG. 9 shows a third embodiment of a tool 210 for severing through a conduit 212. In this case the tool 210 is fitted to the outside of a tubular 276 through which the conduit 212 passes. The conduit 212 has an increased diameter portion 278 which, in essence, is a non-shearable object in that the increased diameter portion 278 is too thick for a conventional BOP to sever using conventional shear rams.

(36) The tool 210 utilises three potassium perchlorate propellant sources 268, 270, 272, each propellant source being associated with a void access 280, 282, 284, each void access 280, 282, 284 being arranged to channel a stream of combustion products and a molten silver modifying material (not shown in this Figure but discussed in due course) towards a different focal point, progressively an increasing distance away from the tool 210.

(37) The tool 210 further comprises an ignition mechanism 238 and a first and second barrier 286, 288. The barriers 286, 288 prevent one propellant source 268, 270, 272 igniting an adjacent propellant source 268, 270, 272 as will be shown.

(38) The operation of the tool 210 will now be described with reference to FIG. 10.

(39) As shown in FIG. 10, the first propellant source 270 has been ignited by the ignition mechanism 238 and a first stream of combustion products and modifying material 290 flows through the first void access 280, first piercing the tubular 276 and then moving material from the conduit increased diameter portion 278.

(40) Referring to FIG. 11, the first propellant source 270 has completed deflagration and the flame transfers up a first fuse 292 inside the second barrier 288 to the second propellant source 272 which deflagrates producing a second stream of combustion products and modifying material 294 which flows through the second void access 282, first piercing the tubular 276 and then moving material from the conduit increased diameter portion 278. It will be noted that the focal point of this second stream of combustion products and modifying material 294 is deeper into the conduit increased diameter portion 278.

(41) Referring to FIG. 12, the second propellant source 272 has completed deflagration and the flame transfers up a second fuse 296 inside the ignition mechanism 238 to the third propellant source 268 which deflagrates producing a third stream of combustion products and modifying material 298 which flows through the third void access 284, first piercing the tubular 276 and then moving material from the conduit increased diameter portion 278. It will be noted that the focal point of this third stream of combustion products and modifying material 298 is deeper again into the conduit increased diameter portion 278.

(42) Finally referring to FIG. 13, upon completion of the deflagration of the third propellant source 268, the conduit 212 is severed.

(43) FIG. 14 shows a section of a tool 310 in a view similar to that of the tool shown in FIG. 2. Like parts are numbered the same as in FIG. 2. In this embodiment pistons 390 can be used to drive moveable carriers 392 towards each other (direction shown by arrows A); or away from each other. The carriers 392 mount void accesses 42 and 50. Carriers 392 also mount rollers 394 that are configured to rotate into engagement with the conduit 12. As shown in perspective detail view FIG. 14A the rollers 394 include recesses 398 for receiving a conduit 12.

(44) Also shown in FIG. 14 are energy providers 396 for imparting additional energy into the streams of combustion products and/or the modifying material employed. Thus, energy providers 396 may be electric arc generators, induction coils, or other mechanisms for generating a magnetic field and/or electric field. Alternatively, energy providers 396 may be microwave generators, providing microwave radiation to the combustion products and/or modifying material.

(45) FIG. 15 shows the tool 110 of FIG. 6 but fitted with a scraper 199. Scraper 199 is moveable in the direction of arrow S to scrape away molten or softened material from conduit 112 in use of tool 110.

(46) Various modifications and improvements may be made to the above described embodiments without departing from the scope of the invention. For example, although the tool is described integrated into a blow out preventer (BOP), to form an integral part of the BOP, the tool may be positioned adjacent a BOP. In other embodiments it can be used with other suitable well control equipment, for example a rigless/riserless well intervention system or in other locations such as with a riser or as part of a downhole completion.

(47) When used with a riser, the tool may form an integral part of the riser. In some embodiments the tool may sever the riser itself in an emergency, including all the control lines and other equipment items. For this functionality it may also include a sealing mechanism to seal off the riser itself and prevent a spill of the fluids in the riser to sea.

(48) Similarly, when integrated into a downhole completion to form an integral part of the downhole completion the tool may also include a sealing mechanism to seal off the well itself to prevent fluids travelling up the wellbore to surface.

(49) In all of these locations the tool may act as the primary method for severing shearable and/or non-shearable items that may be passing through the tool void.