CUTTING DEVICE SAFETY VALVE, METHOD AND USES FOR SEVERING A PIPE-STRING-RELATED OBJECT IN A SAFETY VALVE FOR A WELL |
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| 申请号 | EP12785067.5 | 申请日 | 2012-05-16 | 公开(公告)号 | EP2710218B1 | 公开(公告)日 | 2016-12-07 |
| 申请人 | Smart Installations As; | 发明人 | BIRKELAND, Petter; | ||||
| 摘要 | |||||||
| 权利要求 | |||||||
| 说明书全文 | The invention concerns a cutting device for a safety valve, a safety valve for a well, a method for severing a pipe-string-related object in a safety valve and also three uses for severing a pipe-string-related object located in a through bore in a safety valve for a well. Such a safety valve may be comprised of a blowout preventer ("BOP"), for example a blowout preventer for drilling a well. The safety valve may also be comprised of a Christmas tree for a completed well, for example a production well, injection well, geothermal well or a water well. In this context, the well may be comprised of an underwater well, for example a subsea well, or a surface well. The background of the invention relates to the so-called Macondo-blowout, which was initiated in April, 2010. The blowout originated from a BP-operated oil well located in ca. 1500 meter deep water in the Gulf of Mexico. Following a preceding explosion on a floating drilling rig ("Deepwater Horizon") connected to the oil well, attempts were made to sever an associated oil pipe extending through a blowout preventer placed on the seabed above the oil well. High pressure from flowing oil in the oil pipe caused the pipe to bend and displace to a non-centric position within the through bore (pipe interior) of the blowout preventer. Among other things, this blowout preventer was provided with a so-called blind shear ram designed for severing a steel pipe and also for subsequent sealing of the bore through the blowout preventer. The shear ram, however, was not designed for severing a non-centric pipe in the blowout preventer. This resulted in incomplete severing and sealing of the bore of the blowout preventer, whereby oil at high pressure leaked out for a long time thereafter. There are a number of publications, including patent publications, relating to various aspects of well safety valves and cutting devices associated therewith. The closest prior art appears to be represented by the following patent publications:
The following patent publications are also mentioned as examples of cutting devices for such well safety valves:
Common to all of these publications is that they concern cutting devices based on mechanical cutting principles, the cutting devices of which are generally structured for cutting of well pipes. Pipe strings used in wells may also comprise various objects being far more massively structured than that of ordinary well pipes incorporated in such pipe strings. For example, said pipe-string-related objects may comprise various tools and equipment connected to such pipe strings. Moreover, pipe strings comprising pipes having a particularly large material thickness, for example so-called drill collars used in bottomhole assemblies (BHA) for drill strings, may be used. Upon using known cutting devices for well safety valves, it may prove far more cumbersome and even impossible, in an emergency, to sever such tools, equipment and thickened well pipes than that of severing ordinary well pipes. The principal object of the invention is to remedy or reduce at least one disadvantage of the prior art, or at least to provide a useful alternative to the prior art. Another object of the invention is to be able to sever, in a well safety valve, pipestring-related objects being more massively structured than that of ordinary well pipes. A further object of the invention is to be able to sever, in a well safety valve, pipestring-related objects being non-centrically positioned within the through bore of the safety valve. The objects are achieved by virtue of features disclosed in the subsequent claims. According to a first aspect of the invention, a cutting device is provided for severing a pipe-string-related object in a safety valve for a well, wherein the cutting device is structured for incorporation in the safety valve, and wherein the cutting device comprises a housing having a through bore structured for passing said object therethrough. The distinctive characteristic of the cutting device is that it comprises at least one induction coil device disposed in said housing, and around at least a portion of the bore of the housing;
In context of a hydrocarbon well, heating by means of such an induction coil device may involve danger of explosion and/or danger of fire. This, however, may only occur if air/oxygen is supplied to the cutting device in the course of heating. Such a situation will not exist under water or in the event that the particular well is not producing hydrocarbons. If said course of heating is carried out above water, and in context of a hydrocarbon well, danger of explosion and/or danger of fire may be avoided by enclosing, or enveloping, the present cutting device in a non-flammable means which ensures that air/oxygen is not supplied in the course of heating. For example, such a non-flammable means may be comprised of an air-tight receptacle enclosing the cutting device and being filled with e.g. water or a non-flammable gas, for example nitrogen, carbon dioxide and/or an inert gas. When required, it is even conceivable to envelope the cutting device in such a gas being supplied from a suitable gas supply arrangement associated with the cutting device. As mentioned, said pipe-string-related object in the safety valve may comprise a relatively massively structured object, for example various tools and equipment connected to a pipe string extending through a through bore in said housing. As such, the object may comprise a well tool, for example a measuring instrument, a well valve, an actuator, a pumping device or similar. Oftentimes, but not always, such objects have a tubular design. The object may also be comprised of a typical tubular object. As such, the object may comprise an ordinary well pipe per se, for example a casing, a production tubing, an injection pipe, a drill pipe, a drill collar or similar. For heating of said object, the at least one induction coil device may also be structured for connection to an electric power supply network on an associated instal-lation, for example on a platform or a vessel, possibly on a remote host facility onshore or offshore. As an alternative or addition, the induction coil device may be structured for connection to one or more batteries, for example a battery pack, for supply of electric power to the induction coil device. Further, the induction coil device may comprise one or more induction coil devices disposed, for example incorporated in a cavity, in said housing, and around a longitudinal portion and/or circumferential portion of the bore of the housing. For example, two opposite induction coil devices incorporated each in a respective opposite cavity in the housing may thus be used. In this context, a heat-insulating portion, for example an asbestos-containing and/or ceramic-containing portion, may be disposed between the induction coil devices and the surrounding material (goods) of the housing. By so doing, the induction coil devices may possibly heat and melt said object until being severed, but without the surrounding material of the housing being weakened or melt-ing at the same time. According to a first embodiment, the cutting device may also comprise at least one pipe ram disposed in said housing, and below the induction coil device;
By so doing, the pipe ram may be activated and caused to enclose a lower part of the object upon having severed, by means of the induction coil device, an overlying portion thereof from a lower part of the object. According to an alternative, second embodiment, the cutting device may also comprise at least one shear ram disposed in said housing and in vicinity of the induction coil device for cooperation therewith;
By disposing at least one shear ram in vicinity of the induction coil device and also activating said shear ram upon having heated the object sufficiently, by means of the induction coil device, to weaken the object structurally, the shear ram and the induction coil device will cooperate and, hence, will contribute to a faster severing of the object than that of pure inductive severing of the object. For this reason, this second embodiment of the cutting device is also well suited for severing relatively massive objects in the bore of the housing. In context of this second embodiment, the at least one shear ram may be disposed below and/or above the induction coil device. According to this second embodiment, the cutting device may also comprise at least one pipe ram disposed in said housing, and below the shear ram;
By so doing, the pipe ram may be activated and caused to enclose a lower part of the object upon having severed, by means of the induction coil device and possibly also said shear ram, an overlying portion thereof from a lower part of the object. Further, said induction coil device may be structured so as to be radially movable relative to said bore. By so doing, the distance between the induction coil device and the object may be adjusted and, hence, may be adapted to the particular object in the bore. In this context, the induction coil device may be connected to a suitable moving device, for example a suitable actuator, a hydraulic piston-and-cylinder arrangement or similar, which is connected to or incorporated in the housing. Such an adjustment possibility renders possible to position the induction coil device at an optimum distance from the object, thereby rendering possible to carry out the most efficient and fast heating of the object when required. Yet further, the at least one induction coil device may also be structured so as to be replaceable, thereby allowing the induction coil device to be readily removed from the housing for repair or replacement. As such, the induction coil device may be releasably connected to the housing and possibly may be released and withdrawn from the housing, for example from the outside of the housing. The cutting device may also be formed as at least one module structured for incorporation in said safety valve. By so doing, one module may be readily replaced with a corresponding module, if desirable or required. According to a second aspect of the invention, a safety valve for a well is provided, wherein the safety valve is structured for severing a pipe-string-related object in the safety valve, and wherein the safety valve comprises the cutting device according to the first aspect of the invention. The distinctive characteristic of the safety valve is that The induction coil device is connected to the at least one electric power source for supply of electric power for said heating. In context of a hydrocarbon well, heating by means of such an induction coil device may, as mentioned, involve danger of explosion and/or danger of fire. This, however, may only occur if air/oxygen is supplied to the cutting device in the course of heating. Such a situation will not exist under water or in the event that the particular well is not producing hydrocarbons. If said course of heating is carried out above water, and in context of a hydrocarbon well, danger of explosion and/or danger of fire may be avoided by enclosing, or enveloping, the present cutting device in a non-flammable means which ensures that air/oxygen is not supplied in the course of heating. For example, such a non-flammable means may be comprised of an air-tight receptacle enclosing at least the particular portion of the safety valve and being filled with e.g. water or a non-flammable gas, for example nitrogen, carbon dioxide and/or an inert gas. When required, it is even conceivable to envelope the safety valve, or the particular portion thereof, in such a gas being supplied from a suitable gas supply arrangement associated with the safety valve. Furthermore, all comments regarding relevant features of the cutting device according to the first aspect of the invention also apply to the safety valve according to this second aspect of the invention. According to a first embodiment of the safety valve, it may also comprise at least one pipe ram disposed in said housing, and below the induction coil device;
By so doing, the pipe ram may be activated and caused to enclose a lower part of the object upon having severed, by means of the induction coil device, an overlying portion thereof from a lower part of the object. According to an alternative, second embodiment of the safety valve, it may also comprise at least one shear ram disposed in said housing and in vicinity of the induction coil device for cooperation therewith;
By disposing at least one shear ram in vicinity of the induction coil device and also activating said shear ram upon having heated the object sufficiently, by means of the induction coil device, to weaken the object structurally, the shear ram and the induction coil device will cooperate and, hence, will contribute to a faster severing of the object than that of pure inductive severing of the object. For this reason, this second embodiment of the cutting device is also well suited for severing relatively massive objects in the bore of the housing. In context of this second embodiment of the safety valve, the at least one shear ram may be disposed below and/or above the induction coil device. According to this second embodiment of the safety valve, it may also comprise at least one pipe ram disposed in said housing, and below the shear ram;
By so doing, the pipe ram may be activated and caused to enclose a lower part of the object upon having severed, by means of the induction coil device and possibly also said shear ram, an overlying portion thereof from a lower part of the object. Moreover, said power source for the shear ram and/or the pipe ram may comprise at least one hydraulic power source, for example a hydraulic power pack. Further, the induction coil device may be structured so as to be radially movable relative to said bore. By so doing, the distance between the induction coil device and the object may be adjusted and, hence, may be adapted to the particular object in the bore. In this context, the induction coil device may be connected to a suitable moving device, for example a suitable actuator, a hydraulic piston-and-cylinder arrangement or similar, which is connected to or incorporated in the housing. Such an adjustment possibility renders possible to position the induction coil device at an optimum distance from the object, thereby rendering possible to carry out the most efficient and fast heating of the object when required. Yet further, the at least one induction coil device may also be structured so as to be replaceable, thereby allowing the induction coil device to be readily removed from the housing for repair or replacement. As such, the induction coil device may be releasably connected to the housing and possibly may be released and withdrawn from the housing, for example from the outside of the housing. Furthermore, at least said induction coil device may be incorporated as a module in the safety valve. By so doing, one module may be readily replaced with a corresponding module, if desirable or required. The safety valve may also comprise at least one shut-off valve for said bore, wherein the shut-off valve is disposed above the induction coil device. By so doing, the bore of the safety valve may be shut off upon severing and withdrawing an upper part of the object. For example, said shut-off valve may comprise a ball valve. Further, the object may be comprised of a tubular object, for example a well pipe or a well tool. Yet further, the safety valve may be comprised of a blowout preventer ("BOP"), or of a Christmas tree. According to a third aspect of the invention, a method is provided for severing a pipe-string-related object in a safety valve for a well, wherein the safety valve comprises a housing having a through bore structured for passing the object therethrough. The distinctive characteristic of the method is that it comprises the following steps:
Further, the present method may also comprise the following steps:
All comments from the above-mentioned cutting device and safety valve according to the first and second aspects of the invention also apply to the present method. Further, and according to a fourth aspect of the invention, a use of a cutting device according to the first aspect of the invention is provided for severing a pipe-string-related object in a safety valve for a well. Yet further, and according to a fifth aspect of the invention, a use of a safety valve according to the second aspect of the invention is provided for severing a pipe-string-related object in the safety valve. Finally, and according to a sixth aspect of the invention, a use of a method according to the third aspect of the invention is provided for severing a pipe-string-related object in a safety valve for a well. Hereinafter, a non-limiting exemplary embodiment of a safety valve for a well will be shown, wherein the safety valve is formed according to the second aspect of the invention. This well safety valve comprises a cutting device according to the first aspect of the invention. This exemplary embodiment describes a preferred embodiment depicted in the accompanying drawings, where:
As mentioned, the figures are very schematic and only show details and equipment being essential to the understanding of the invention. Further, the figures are much distorted with respect to the relative dimensions of details and components shown in the figures. The figures are also very simplified with respect to the shape and richness of detail of such details and components. Hereinafter, equal, equivalent or corresponding details in the figures will be denoted substantially with the same reference numerals. Figure A1 shows a vertical section through a safety valve according to the invention. In this embodiment, the safety valve is comprised of a blowout preventer 2, i.e. a socalled "BOP", for a subsea well 4. The blowout preventer 2 is mounted on top of a wellhead 6 placed on a seabed 8. Further, the blowout preventer 2 is connected to, and is controlled from, an installation (not shown) on the surface (not shown). The blowout preventer 2 receives control signals, hydraulic power and electric power from said installation. The blowout preventer 2 comprises a massive housing 10 having a through bore 12 connected to the well 4. Yet further, Figure A1 shows a well pipe 14, for example a drill string or a production tubing, conducted through the bore 12 in the housing 10 of the blowout preventer 2. In addition, the blowout preventer 2 comprises a cutting device 16 according to the invention. In this embodiment, the cutting device 16 is incorporated as a module 18 in the blowout preventer 2, the module 18 being shown only as a dashed section window in Figure A1. This exemplary embodiment is meant to illustrate the manner in which the well pipe 14 may be severed both quickly and efficiently by means of the cutting device 16 in the blowout preventer 2. Accordingly, the cutting device 16 comprises an induction coil device 20 disposed in a peripheral groove 22 in an annular area 24 of the housing 10, wherein the area 24 is located around the bore 12. This annular area 24 of the housing 10 also comprises a heat-insulating portion (not shown) formed from a heat-resistant material, for example asbestos or ceramics. Further, the groove 22 and the induction coil device 20 are directed inwards in the direction of the bore 12. For supply and control of electric power when required, the induction coil device 20 is connected to electric wires 26 conducted through the wall of the housing 10, the wires of which are connected, via a suitable cable (not shown), to said installation. As an alternative or addition, the electric power supply may comprise a battery pack (not shown) disposed on, or in vicinity of, the blowout preventer 2. Yet further, the induction coil device 20 is structured for cutting-promoting heating, hence thermal structural weakening, of (in this case) the well pipe 10 when located vis-à-vis the induction coil device 20. In this embodiment, the cutting device 16 also comprises a shear ram 28 disposed immediately below the induction coil device 20. The shear ram 28 comprises two opposite cutting knives 30a and 30b disposed each in a radially movable manner in a respective opposite cylinder housing 32a and 32b in the massive housing 10 (material goods) of the blowout preventer 2. As shown in Figures A2-A4, the shear ram 28 is disposed in immediate vicinity of the induction coil device 20, thereby allowing it to cooperate with the induction coil device 20 during severing of the well pipe 14. Each cutting knife 30a, 30b is connected to a hydraulic piston-and-cylinder arrangement (not shown) disposed in each cylinder housing 32a, 32b. For control and supply of hydraulic power when required, and via suitable hydraulic lines (not shown), each piston-and-cylinder arrangement is connected to said installation. As an alternative or addition, the hydraulic power supply may comprise at least one hydraulic power supply unit/-pack (not shown) disposed on, or in vicinity of, the blowout preventer 2. Yet further, the shear ram 28 is structured for optional activation and mechanical cutting of the well pipe 10 when located vis-à-vis the shear ram 28 which, accordingly, is placed in immediate vicinity of the induction coil device 20. In inactive position, each of the opposite cutting knives 30a, 30b of the shear ram 28 are disposed within a respective recess 34 in the wall of the housing 10 surrounding the bore 12 in the blow-out preventer 2, as shown in Figures A1, A2, A4 and B2. In active position, however, the cutting knives 30a, 30b are pushed out from their recesses 34 and are disposed with their knife blades and knife edges toward each other at the centre of the bore 12, as shown in Figures A3 and B3. In this embodiment, the rectilinear knife blades of the cutting knives 30a, 30b have a width exceeding the outer diameter of the well pipe 14 (cf. Figure B3), whereby the cutting knives 30a, 30b may sever the complete well pipe 14 when required. Each cutting knife 30a, 30b also has a relatively pointy and V-shaped knife edge aligned, in the horizontal plane, with the opposite knife edge, as shown in Figure A3. Moreover, other knife blade configurations and/or knife edge configurations may be used. In this respect, there are many examples to be found from known cutting devices for well safety valves; cf. the above-mentioned patent publications. Further, opposite cutting knives having knife blades formed in a complementary manner with respect to each other may be used, for example. Opposite cutting knives having knife blades formed in a non-complementary manner with respect to each other may also be used, for example V-shaped knife blades directed toward each other. Further, and as an addition or alternative, opposite cutting knives displaced parallel to each other may be used, hence cutting/clipping off the particular pipe-string-related object, for example the well pipe 14. In this embodiment, the blowout preventer 2 also comprises several pipe rams 36 disposed in the massive housing 10, and below the shear ram 28. These pipe rams 36 are structured for optional activation and enclosing of the well pipe 14 when located vis-à-vis the pipe rams 36. Also these pipe rams 36 are connected, via suitable hydraulic lines (not shown), to said installation and a possible hydraulic power supply unit/-pack (not shown) on/at the blowout preventer 2 for control and supply of hydraulic power when required. The blowout preventer 2 also comprises at least one shut-off valve (not shown), for example a ball valve, for the bore 12 in the massive housing 10. Said shut-off valve is disposed above the cutting device 16, thereby allowing the bore 12 to be shut off upon severing and withdrawing an upper part 38 of the well pipe 14, whereas a lower part 40 of the well pipe 14 will be located below the cutting device 16. Hereinafter, severing the well pipe 14 by means of the present cutting device 16 will be described in further detail. When severing the well pipe 14 by means of this cutting device 16 is required, at first the induction coil device 20 is activated and heats the well pipe 14 until it is significantly weakened structurally via the heating. This heating step is shown in Figure A2. Upon sufficient heating and structural weakening of the well pipe 14, a hydraulic piston (not shown) in each of the opposite cylinder housings 32a, 32b is then activated and drives the opposite cutting knives 30a, 30b against each other and through the heated, structurally weakened well pipe 14 until the cutting knives 30a, 30b abut each other and sever the well pipe 14 into said upper part 38 and lower part 40. This cutting step is shown in Figures A3 and B3. Then the cutting knives 30a, 30b may be withdrawn toward their respective cylinder housings 32a, 32b, as shown in Figure A4, and the upper part 38 of the well pipe 14 is pulled out of the bore 12 and the blowout preventer 2. Finally, said shut-off valve (not shown) in the blowout preventer 2 may be closed, thereby closing the blowout preventer 2 completely. During the mechanical severing of the well pipe 14, the induction coil device 20 may become damaged completely or partially. This is shown in Figure B3. In this embodiment, however, the induction coil device 20 is structured so as to be replaceable (not shown), thereby allowing the induction coil device 20 to be readily removed from the housing 10 for repair or replacement. |
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