WO2013045550A1

WO2013045550A1 - A punching tool

Info

Publication number: WO2013045550A1
Application number: PCT/EP2012/069084
Authority: WO
Inventors: Jørgen HALLUNDBAEK; Rasmus Sommer
Original assignee: Welltec A/S
Priority date: 2011-09-30
Filing date: 2012-09-27
Publication date: 2013-04-04
Also published as: EP2574721A1; CN103797212A; US20140374100A1; CA2848818A1; MX2014003023A; AU2012314450A1; BR112014005115A2; RU2014114427A; EP2761128A1

Abstract

The present invention relates to a punching tool for providing a hole or a dimple in a metal casing in a borehole. The punching tool comprises a tool body having an axial extension, and a punching unit connected with the tool body comprising : a fluid inlet, a punch movable between a retracted and a projected position and extending substantially radially in relation to the axial extension, and at least one hydraulic punch cylinder moving the punch between the retracted and the projected position. The present invention further relates to a method for providing a hole or a dimple in a metal casing downhole and to a method for installing a plug in an existing hole in the casing downhole.

Description

A PUNCHING TOOL

Field of the invention

The present invention relates to a punching tool for providing a hole or a dimple in a metal casing in a borehole. The present invention further relates to a method for providing a hole or a dimple in a metal casing downhole and to a method for installing a plug in an existing hole in the casing downhole.

Background art

When producing hydrocarbons from a well, the casing is most often perforated by means of detonations to provide holes in the casing for letting the formation fluid into the casing. However, using detonations for perforating is risky, and there is therefore an increasing demand for alternative methods for making such holes.

Perforations or holes in a casing may be used for various purposes, such as for injection purposes, for insertion of completion elements, e.g. valves after making the completion, or for allowing fluid to flow from the formation into the casing. There is thus a need for an apparatus and a method for providing perforations or holes without using detonation of charges.

Further, when a hole or perforations are to be used for injection purposes, e.g. for providing an annular seal in an annulus, determination of the exact position of the hole in relation to an injection apparatus is a difficult task. If the exact position cannot be established, a large section of the casing has to be sealed off to perform the injection. In this regard, one applied solution is to provide a seal downhole well below the injection hole and simply pressurise the entire well down to the seal to inject the fluid. Such an operation is cumbersome and requires a great amount of injection fluid, making it a cost-intensive operation.

Summary of the invention

It is an object of the present invention to wholly or partly overcome the above disadvantages and drawbacks of the prior art. More specifically, it is an object to provide a solution for providing holes in a casing without using detonation of charges.

The above objects, together with numerous other objects, advantages, and features, which will become evident from the below description, are accomplished by a solution in accordance with the present invention by a punching tool for providing a hole or a dimple in a metal casing in a borehole, comprising :

- a tool body having an axial extension, and

- a punching unit connected with the tool body, comprising :

- a bore provided in the tool body, extending substantially radially in relation to the axial extension,

- a fluid inlet in fluid communication with the bore, and

- a hydraulically activated punch arranged in the bore, being movable between a retracted and a projected position,

wherein the hydraulically activated punch is moved into the projected position by injecting a fluid into the bore through the fluid inlet.

The punching tool described above may further comprise two isolation devices circumferenting the tool body and arranged spaced apart in the axial extension on opposite sides of the punching unit, the isolation devices being expandable from the tool body in a radial direction, thereby providing zonal isolation of a section of the casing downhole, wherein the punching tool further comprises one or more injection nozzles for injecting a fluid into the section of the casing being isolated by the isolation devices, the injection nozzle being arranged between the isolation devices.

Hereby, when a section of the casing downhole has been isolated and a hole in the casing has been punched, a fluid may be injected into the section inside the casing isolated by the isolation devices to inflate an annular barrier arranged in fluid communication with the isolated section via the punched hole. The punching tool may thus be used for providing a hole in the casing downhole and subsequently for injecting a fluid though the hole. By using a tool having a punching unit arranged between a set of isolation devices, it is guaranteed that the hole in the casing is provided in the isolated section. Had the hole been punched by a first punching tool and the section of the casing been isolated by a second isolation and injection tool, great care would have to be taken to position the isolation and injection tools to secure that the hole punched was in fact in the isolated section of the casing. The punching tool may also be used for other injection purposes, such as for inflating a packer, for stimulating the pressure in inflatable packers or other types of annular barriers, for acid treatment of a formation outside a casing or for fracking purposes.

In one embodiment, the hydraulically activated punch may have a punching edge for providing a hole in a metal casing.

The punching tool described above may further comprise a pump arranged in association with the tool body, the pump being connected to the fluid inlet for supplying a hydraulic fluid to the bore to move the hydraulically activated punch into the projected position.

In an embodiment, the isolation devices may be constituted by inflatable packers being inflated and expanded from the tool body by the pump supplying a fluid to the inflatable packers.

Furthermore, the isolation devices may be inflatable packers, swellable packers, compression or cup packers, other downhole packers, retrieval packers or combinations thereof.

Additionally, the pump may be in fluid communication with the one or more injection nozzles, and the pump may be adapted to inject a fluid into the section of the casing being isolated by the isolation devices through the one or more injection nozzles.

The punching tool described above may further comprise an inlet fluidly connecting the pump with an annulus surrounding the punching tool, wherein the pump is adapted to draw fluid from the annulus and inject the fluid from the annulus through the one or more injection nozzles into the section of the casing being isolated by the isolation devices.

Moreover, the punching unit may comprise an abutment arranged circumferentially opposite the hydraulically activated punch around the tool body. In addition, part of the hydraulically activated punch may engage part of the abutment to control the radial movement between the retracted and the projected position of the hydraulically activated punch. Furthermore, one of the hydraulically activated punch and the abutment may comprise one or more radially extending guide elements, and the other of the hydraulically activated punch and the abutment may comprise one or more radially extending tracks being adapted to engage with the guide elements to control the radial movement between the retracted and the projected position of the hydraulically activated punch.

Also, the hydraulically activated punch and the abutment may define an expandable space. The punching unit may further comprise a piston and a spring which is compressed when the hydraulically activated punch is moved into the projected position.

Moreover, the hydraulically activated punch and the abutment may be arranged in a through-bore in the tool body.

In addition, sealing means may be arranged in grooves in the through-bore of the tool body to seal against the hydraulically activated punch, and/or the abutment may be arranged in the through-bore.

Such sealing means may be arranged in grooves in the hydraulically activated punch, the punch base part and/or the abutment to seal against the through- bore and the tool body. In an embodiment, the tool may comprise a plurality of punching units.

In another embodiment, the tool may comprise a plurality of punching units and a plurality of abutments. Furthermore, the piston may be movable in a hollow space defined by the hydraulically activated punch or a base part of the hydraulically activated punch, and the piston may be connected with the abutment through a piston rod. Additionally, the piston may be movable in a hollow space defined by the abutment, and the piston may be connected with the hydraulically activated punch through a piston rod. Also, one of the hydraulically activated punch and the abutment may be connected with the piston through a piston rod, and the other of the hydraulically activated punch and the abutment may have an end arranged inside the tool body, the end comprising a flange, and a spring may be arranged between the piston and the flange.

Further, a stop element may be arranged in connection with the hydraulically activated punch and the abutment to avoid separation of the hydraulically activated punch and the abutment. Also, the abutment may be fixedly connected with the tool body.

The abutment may project radially from the tool body.

In an embodiment, the stop element may be arranged in connection with the fluid inlet.

Furthermore, the fluid inlet may be connected with one or more fluid channels being in fluid communication with a pressure side of the piston. A distance between the retracted and a projected position of the punch may be 3 mm, preferably above 10 mm, most preferably above 20 mm, and more preferably above 100 mm.

Moreover, the punch may comprise a pointed surface adapted to rupture the metal casing during the movement of the hydraulically activated punch from the retracted to the projected position.

Additionally, the abutment may comprise a "curved" (convex) face which is adapted to abut an inner surface of a tubular metal casing during the punching.

Further, the abutment may comprise attachment elements so that the face of the abutment can be changed in relation to the inner surface of the metal casing. In an embodiment, the tool may comprise an electrical motor driving the pump.

In addition, the tool may comprise a fluid reservoir for containing a fluid for being injected into the bore to move the hydraulically activated punch into the projected position, a fluid reservoir for containing a fluid for being injected into the inflatable packers to inflate and expand the inflatable packers from the tool body, and/or a fluid reservoir for containing a fluid for being injected into the isolated section of the casing through the one or more injection nozzles. Moreover, the fluid reservoir may be one common fluid reservoir.

Furthermore, the hydraulically activated punch may be a punch adapted to provide a dimple in a metal casing. Additionally, the hydraulically activated punch may be a punch having rounded edges.

Also, the hydraulically activated punch may be a pin punch, a centre punch, a taper punch, a flat chisel, a cape chisel, a half-round nose chisel or a combination thereof.

Further, the hydraulically activated punch may be a punch adapted to install a plug in an existing hole in the casing downhole to seal the existing hole. Hereby, if an annular barrier or packer bursts, an inlet to such annular barrier or packer may be sealed off to avoid fluid from flowing from the casing and into the formation through the defect annular barrier or packer. Thus, by installing a plug in an inlet of the defect annular barrier or packer, the remaining annular barriers or packers may still be inflated by pressurising the well from the top or by pressurising a section of the well containing the defect annular barrier or packer.

Moreover, the punch may have a cavity in which the plug can be arranged.

In an embodiment, the hydraulically activated punch may be further adapted to hold on to the plug prior to installing the plug in the existing hole, to place the plug in the existing hole when the hydraulically activated punch is moved into a projected position, and to deform the plug when the hydraulically activated punch is moved into a fully projected position.

In addition, the cavity of the punch may have a circumferential projection or a plurality of projections matching a circumferential groove in the plug.

By having a projection matching the groove of the plug, the plug can be held in place before being inserted, and when the hole has been plugged, the plug is secured in the hole so that the force securing the plug in the hole is greater than a force enabling detachment of the plug from the punch. The plug is thus easily detached from the punch when the plug has been punched in the hole.

The present invention furthermore relates to a method for providing a hole or a dimple in a metal casing downhole, comprising the steps of:

- providing a punching tool as described above in the metal casing downhole,

- positioning the punching unit of the punching tool at a location where a hole or dimple is to be provided,

- positioning the abutment arranged circumferentially opposite the hydraulically activated punch around the tool body so that it abuts a casing wall at a position circumferentially opposite the hydraulically activated punch, and

- moving the hydraulically activated punch radially from a retracted position to a projected position so that a hole or dimple is provided in the metal casing by the hydraulically activated punch in its projected position. Furthermore, the hydraulically activated punch may be moved radially to provide a hole in the metal casing, the method further comprising the steps of expanding the isolation devices from the tool body in a radial direction, thereby providing zonal isolation of a section of the casing downhole, and injecting a fluid into the section of the casing being isolated by the isolation devices, thereby forcing a fluid through the hole provided in the casing.

Moreover, the hydraulically activated punch may be moved radially to provide a dimple in the metal casing, the method further comprising the step of arranging an electronic device in the dimple or hole, the electronic device comprising a radio-frequency identification (RFID) chip, a radio-frequency tag (RFT) and/or one or more sensors, such as a temperature sensor. Finally, the present invention relates to a method for installing a plug, such as a Lee-plug, in an existing hole in the casing downhole, the method comprising the steps of:

- providing a punching tool as described above in the casing downhole,

- positioning the punching unit of the punching tool at a location opposite the existing hole,

- positioning the abutment arranged circumferentially opposite the hydraulically activated punch around the tool body so that it abuts a casing wall at a position circumferentially opposite the hydraulically activated punch,

- moving the hydraulically activated punch radially from a retracted position to a projected position to place the plug in the existing hole, and

- moving the hydraulically activated punch to a fully projected position, thereby deforming the plug to secure the plug and seal the existing hole. In one embodiment, part of the plug may be plastically deformed.

Brief description of the drawings

The invention and its many advantages will be described in more detail below with reference to the accompanying schematic drawings, which for the purpose of illustration show some non-limiting embodiments and in which

Fig. 1 shows a punching tool in a casing, Fig. 2 shows a partly cross-sectional view of the punching tool,

Fig. 3 shows a partly cross-sectional view of another embodiment of the punching tool, Fig. 4 shows another embodiment of the punching tool in a casing,

Fig. 5 shows yet another embodiment of the punching tool in a casing, Fig. 6 shows yet another embodiment of the punching tool in a casing,

Fig. 7 shows a partly cross-sectional view of another embodiment of the punching tool along the axial extension of the tool, Fig. 8 shows a partly cross-sectional view of another embodiment of the punching tool along a radial extension of the tool perpendicular to the axial extension of the tool,

Fig. 9 shows a partly cross-sectional view of a punching tool for providing a dimple in a casing downhole,

Fig. 10 shows a cross-sectional view of a casing in which an electronic device has been secured in a dimple,

Fig. 11 shows a partly cross-sectional view of the punching tool comprising isolation devices for providing zonal isolation of a section of the casing, Fig. 12 shows a partly cross-sectional view of the punching tool comprising an injection nozzle for injecting a fluid into the isolated section of the casing, and

Fig. 13 shows a partly cross-sectional view of a punching tool comprising a hydraulically activated punch adapted to install a plug in an existing hole in a casing downhole.

All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.

Detailed description of the invention

Fig. 1 shows a punching tool 1 having just punched a hole 2a in a casing 3 in a borehole 4. The punching tool 1 comprises a tool body 5 having an axial extension 6, a punching unit 11 comprising a bore 27a provided in the tool body, and a hydraulically activated punch 9 which is movable between a retracted and a projected position to be able to punch out a piece 12 of a wall 13 of the casing 3 or to provide a dimple in a wall 13 of the casing 3. The hydraulically activated punch may also be used for applying a force to an object, such as a plug, downhole, e.g. to plug a hole in the casing. The hydraulically activated punch 9 is arranged in a bore 27a extending in a direction substantially radial in relation to the axial extension of the tool body, and a fluid inlet 26 in fluid communication with the bore is provided to enable injection of a fluid into the bore to activate the hydraulically activated punch. The punching unit further comprises an abutment 10 arranged circumferentially opposite the hydraulically activated punch around the tool body to abut the wall of the casing so that the force generated by injection of the fluid into the bore is applied to the hydraulically activated punch and exploited to move the hydraulically activated punch in the radial direction. The abutment is fixedly connected with the tool body.

In one embodiment, the punching tool further comprises two isolation devices 70 for providing zonal isolation of a section 75 of the casing and a plurality of injection nozzles 80 for injecting a fluid into the isolated section of the casing, as shown in Figs. 11-12. The isolation devices 70 circumferent the tool body and are positioned along the tool body on opposite sides of the punching unit, and are expandable from the tool body in a radial direction. When the isolation devices 70 are expanded, they isolate a section 75 of the casing, thereby providing zonal isolation. The isolation devices 70 may be constituted by inflatable packers, swellable packers, compression or cup packers, other downhole packers, retrieval packers, combinations thereof or any other means known to the skilled person for providing a seal between the inner wall of the casing and the tool body. The injection nozzles 80 are arranged between the isolation devices 70, allowing a fluid to be injected into the isolated section 75 of the casing through the injection nozzles.

The punching tool 1 is submerged into the well and is powered through a wireline 14 and connected with the tool through a cable head 15. The punching tool 1 comprises a motor 17 connected with the cable head 15 through an electronic section 16 and a pump 18 driven by the motor, which pump supplies a fluid under pressure to the bore 27a via the fluid inlet 26 to activate the hydraulically activated punch 9. In one embodiment, the pump is further in fluid communication with the isolation devices 70 constituted by inflatable packers. Accordingly, the inflatable packers are inflated and expanded from the tool body by the pump supplying a fluid to the inflatable packers. In a further embodiment, the pump is in fluid communication with the injection nozzle 80 via a conduit 83 extending in the axial extension of the punching tool, as indicated by the dotted lines in Fig. 11. The pump is further fluidly connected to an inlet 81 provided in the punching tool, whereby fluid may be drawn in by the pump from an annulus 82 surrounding the punching tool. The fluid drawn in from the annulus may subsequently be supplied to the injections nozzles 80 via the conduit 83 and injected into the isolated section of the casing. When a hole 2a is provided in the wall of the isolated section of the casing and fluid is continuously injected into that section, the fluid in the section will be displaced through the hole 2a, as shown in Fig. 12. The hole 2a, 2c may be an existing hole 2c or a hole 2a provided by the punching tool, and the casing may also have a plurality of holes through which the fluid can be injected.

In Fig. 2, the hydraulically activated punch 9 defines a hollow space 19a in which a piston 20 is arranged, enabling the hydraulically activated punch 9 to move from its retracted position to its projected position, thus functioning as a hydraulic punch cylinder. The hydraulically activated punch 9 moves inside an expandable space 31 primarily defined by the bore 27a. In one end, the hydraulically activated punch 9 has a punching edge 21a for providing a hole in a metal casing, and in the opposite end, a flange 22 extending towards a piston rod 23 of the piston is provided. Between the flange 22 and the piston, a spring 24 is arranged which is compressed when the hydraulically activated punch is in its projected position. In another embodiment, the end of the hydraulically activated punch extending from the tool body may alternatively be adapted to provide a dimple in a metal casing, as illustrated in Fig. 9. The hydraulically activated punch for providing a dimple in the metal casing may have a shape substantially similar to that of a pin punch, a centre punch, a taper punch, a flat chisel, a cape chisel, a half-round nose chisel, a combination thereof, or any other shape for providing a dimple known to the skilled person.

Further, in another embodiment, the hydraulically activated punch is adapted to install a plug 61 in an existing hole 2c in the casing, as shown in Fig. 13. The hydraulically activated punch is adapted to hold on to the plug prior to installation and to place the plug in the existing hole by moving the hydraulically activated punch into a projected position. After having placed the plug in the hole 2c, the plug may be deformed by further moving the hydraulically activated punch into a fully projected position, whereby the plug is secured in the hole and the hole is sealed. The plug may be any kind of plug suitable for sealing a hole in a casing downhole, such as a plug sold under the trade name Lee Plug by The Lee Company. What is special about the Lee Plug is that only a radial force is required to install the plug, and such a plug may thus be installed by the punching tool according to the present invention. After having plugged the hole, the hydraulically activated punch may be moved further radially from the tool body in an even further projected position, forcing the plug further outwards and deforming the casing wall so that the plug does not diminish the inner diameter of the casing. In this way, the plug plugs the hole and is used to provide a dimple in the casing wall.

The pump 18 illustrated by dotted lines in Fig. 2 provides fluid through fluid channels 25 into the expandable space 31 through inlets 26 in order to force the hydraulically activated punch radially outwards from the tool body 5. When the punching process is completed, the pump stops pumping fluid into the expandable space 31, and the fluid is forced back into the fluid channel 25 by the decompressing force of the spring 24. Sealing means 28 is arranged in grooves 29 in the bore 27a of the tool body to seal against the hydraulically activated punch 9.

By having a hydraulically activated punching tool, the punching force can be substantially increased compared to prior art mechanically operated solutions. Furthermore, tests have shown that the hole in the casing can be made with a higher degree of accuracy and that this cut is cleaner, leaving almost no burrs on the edges. The prior art solutions leave substantial burrs on the edges, hindering the insertion of a valve in the hole in a subsequent process. If the hole is made to open the casing to an inflow of well fluid, such as hydrocarbons, also called oil and/or gas, the burrs hinder an optimal inflow, causing a more turbulent flow before the hole at the burring side.

In Fig. 3, also the abutment 10 projects radially from the tool body 5, and it is therefore slidably arranged in a second bore 32 provided in the tool body. The abutment 10 is activated by injecting a fluid into the second bore 32, whereby the abutment 10 moves radially in relation to the axial extension. The abutment has a hollow space 33 in which a second piston 34 moves, thereby compressing a second spring 35 between the piston and a second flange 36 provided in one end of the abutment opposite an outer face of the abutment abutting the inner wall of the casing. The fluid is injected into the second bore 32 by the pump pumping a fluid into the expandable space 38 via second fluid channels 37 and through second inlets 39. One pump may thus supply fluid to move both the hydraulically activated punch 9 and the abutment 10, and the fluid channels 25, 37 supplying fluid to the hydraulically activated punch 9 and the abutment 10 may be one channel.

The punching tool 1 may comprise several punching units 11 punching holes in the casing in a predetermined pattern, as shown in Fig. 4. Thus, the punching tool can be used instead of a perforation gun, thereby avoiding the risky detonations downhole. As can be seen in Fig. 5, the punching tool 1 comprises second punching units l ib also arranged circumferentially opposite the first punching units 7 around the tool body 5. The second punching units have the same design as the first punching units 7 and function as abutments in relation to the first punching units 7. Similarly, the first punching units function as abutments to the second punching units l ib. The punching units shown in Fig. 5 are arranged with an angular spacing of 180°. As shown in Fig. 6, the punching tool 1 may further comprise third punching units 11c and fourth punching units (not shown) arranged opposite each other and between the first and second punching units. The third and fourth punching units have a design similar to that of the previously described punching units and function as abutments in relation to one another. Each of the punching units is thus arranged with an angular displacement of 90° along the circumference of the punching tool. Further, the third and fourth punching units are displaced in an axial direction of the punching tool in relation to the first and second punching units. The punching tool shown in Fig. 5 thus comprises 10 punching units spaced apart to optimise the tool length, and all the punching units may be supplied with fluid from the same pump through the same channel or through several channels.

In another embodiment shown in Fig. 7, the hydraulically activated punch and the abutment are arranged in a through-bore 27b. As shown, the abutment 10 and the hydraulically activated punch 9 engage one another, forming two common fluidly connected expandable spaces 31. The radial movement of the abutment and the hydraulically activated punch thus occurs by the abutment and the hydraulically activated punch moving radially away from each other. A piston 20 provided on a piston rod 23 is arranged in each of the expandable spaces 31, and the piston rods 23 are connected with the abutment 10 by screws 41. The hydraulically activated punch 9 is connected with a punch base part 42 defining part of each of the expandable spaces 31, and the punch base part 42 is again threadedly connected with two inserts 40. The pistons are movable within each of the expandable spaces 31. The inserts 40 each have a flange 22 which together with the piston compresses a spring 24 when the hydraulically activated punch and the abutment are projected from the tool body. The hydraulically activated punch 9 and the abutment 10 are forced away from each other by means of fluid pumped into the expandable space 31 through fluid channels 25 and is led into the expandable space through a circumferential groove 43 leading the fluid in through the inlet 26 and into a cylinder bore 44. Sealing means 28 are arranged in grooves 29 in the through-bore 27b in which the hydraulically activated punch and the abutment are arranged, preventing the fluid from escaping into the annulus 82 surrounding the tool.

In order to fasten the hydraulically activated punch 9 and the abutment 10 to each other, a hollow rod 45 functioning as a stop element is arranged penetrating both the hydraulically activated punch and the abutment. Both comprise an elongated opening allowing the hydraulically activated punch 9 and the abutment 10 to move in relation to the rod and each other. The rod is hollow to be able to lead the fluid and has openings for the fluid to enter, thus leading the fluid into the expandable space 31. The fluid inlet 26 is thus positioned in the centre of the punching unit.

In another embodiment shown in Fig. 8, the punching unit 11 is rotated 90 degrees compared to the punching unit shown in Fig. 8. Otherwise, the punching unit shown in Fig. 8 has substantially the same design as the punching unit of Fig. 7. In Fig. 8, the punching unit, however, has a fluid channel 46 in the punch base part 42 to lead the fluid from the hollow rod 45 to one end of each of the expandable spaces 31 so that the fluid is injected into the expandable spaces acting directly on the pistons. Hereby, the initial movement of the hydraulically activated punch 9 and the abutment 10 requires less fluid power.

In Figs. 7 and 8, part of the hydraulically activated punch 9 engages part of the abutment 10 to control the radial movement between the retracted and the projected position of the hydraulically activated punch 9. The abutment 10 has radially extending guide elements 50 engaging radially extending tracks 51 of the hydraulically activated punch 9. Hereby, the hydraulically activated punch 9 engages the abutment 10 on an outside thereof or vice versa so as to control the radial movement between the retracted and the projected position of the hydraulically activated punch 9. In Fig. 8, the sealing means 28 are arranged in grooves in the punch base part 42 and in the abutment to seal against the through-bore 27b and the tool body 5. The punching tool 1 is designed so that the distance between the retracted and the projected position of the hydraulically activated punch is above 5 mm, preferably above 10 mm, more preferably above 20 mm, and most preferably above 50 mm. However, this depends on the completion and the restrictions already present in the completion.

The punching tool may be used to punch only a small hole having a diameter smaller than that of the hydraulically activated punch, and thus, the hole is made by the tip of the hydraulically activated punch. When having a double-cased casing and when the inner casing is blocked in the bottom, it may be necessary to make small relief holes and even pump gas down through the outer casing in through the inner casing to force the fluid upwards. Such relief holes may also be necessary to even out the pressure between the casing and the annulus. When making relief holes, the piece of the casing is not separate from the rest of the casing and does not flow freely in the annulus.

The punching tool may have several abutments and one hydraulically activated punch, all of which are hydraulically activated so that the abutments are positioned on both sides of the hydraulically activated punch and are projected radially until the hydraulically activated punch presses against the inner wall of the casing. Subsequently, the hydraulically activated punch is activated and cuts its way into the casing wall without having to travel a certain length before reaching the inner casing wall. In this way, the hydraulically activated punch is capable of penetrating thicker casings than if it had to travel a certain length before reaching the inner casing wall.

The hydraulically activated punch may be any kind of punch, e.g. a punch comprising a pointed surface adapted to rupture the metal casing during the movement of the hydraulically activated punch from the retracted to the projected position.

As shown, the abutment has a curved and convex face which is adapted to abut an inner surface of a tubular metal casing during the punching. The abutment may comprise attachment elements so that the face of the abutment can be changed in relation to the inner surface of the metal casing. The abutment face may then change to a teethed surface or a similar design to better be able to fasten the tool while punching the hole.

The pump of the tool takes fluid in from the well through a filter, but the tool may instead comprise a fluid reservoir, or the fluid may be led from the surface through the wireline which is thus also a supply line. In the following, the use of the punching tool will be described in further detail. In Fig. 9, the punching tool comprises a hydraulically activated punch 9 for providing a dimple 2b in the casing downhole. When the punching tool has been inserted into the casing and the punching unit has been positioned at a location where a dimple is to be provided, the abutment 10 arranged circumferentially opposite the hydraulically activated punch is positioned so that it abuts the casing. Subsequently, the hydraulically activated punch is moved radially from the retracted position to the projected position so that a dimple is provided in the metal casing. When the dimple has been provided, the hydraulically activated punch is retracted into the tool body, and an electronic device 60 is secured in the dimple, as shown in Fig. 10. The electronic device may have various functionalities and may comprise a radio-frequency identification (RFID) chip, a radio-frequency tag (RFT), and/or one or more sensors, such as a temperature sensor. In Fig. 11, the punching tool comprises a hydraulically activated punch 9 for providing a hole 2a in the casing downhole. When the punching tool has been inserted into the casing and the punching unit has been positioned at a location where a hole is to be provided, the abutment 10 arranged circumferentially opposite the hydraulically activated punch is positioned so that it abuts the casing. The isolation devices 70 are also expanded from the tool body, thereby sealing off a section 75 of the casing. Subsequently, the hydraulically activated punch is moved radially from the retracted position to the projected position so that a hole 2a is provided in the metal casing. When the hole has been provided, the hydraulically activated punch is retracted into the tool body by the force exerted by the spring shown in the previously mentioned figures. The isolation devices 70 may also be expanded when the hole has been punched in the casing to seal off the section 75 of the casing. When the hole has been punched and the section of the casing has been isolated, a fluid is injected into the section of the casing being isolated by the isolation devices, as shown in Fig. 12. Thereby, the fluid present in the isolated section is forced through the hole 2a in the casing and into an annular barrier 90. The punching tool may thus be used for expanding the annular barrier or stimulating the pressure in the annular barrier, e.g. to expand the annular barrier even further. The punching tool may also be used for other injection purposes envisaged by the skilled person, such for inflating inflatable packers or other types of annular barriers, for flushing the annulus after insertion of the casing, for acid treatment of a formation outside a casing or for fracking purposes.

In Fig. 13, the punching tool comprises a hydraulically activated punch 9 for installing a plug 61 in an existing hole 2c in the casing. This functionality may be relevant if an annular barrier forming part of a series of annular barriers is defect. An annular barrier may be defect if for example the annular barrier have burst during inflation as shown in Fig. 13, or if the annular barrier is leaking for other reasons, and fluid injected into the well to inflate the series of annular barriers will thus flow through the defect annular barrier into the formation. Hereby, the series of annular barriers cannot be inflated as the required pressure cannot be reached by pressurising the well from the top or by pressurising a section of the well containing the defect annular barrier. However, by installing the plug 61 in the existing hole 2c constituting an inlet to the defect annular barrier, the defect annular barrier is sealed off and the remaining annular barriers may still be inflated.

In order to be able to install a plug in an existing hole 2c, the exact position of the existing hole must be known and the operator must be able to position the punching tool in the correct position to install the punch. To facilitate positioning of the punching tool, the casing in the vicinity of the annular barrier and the punching tool may be provided with associated marker tags 91 and marker tag identifications means 92. The marker tag 91 may be arranged on the casing and the marker tag identification means 92 may be arranged on the punching tool, or the other way around. The marker tag 91 may be a radio-frequency identification (RFID) chip, a radio-frequency tag (RFT) or any other device adapted to send or receive a signal known to the skilled person, and the marker tag identification means 92 may be any kind of sensor or receiver known to the skilled person for detecting the position of the marker tag 91 in relation to the punching tool. In one embodiment, the marker tag 91 and the marker tag identification means 92 may be replaced by mechanical positioning means, whereby the punching tool may latch onto the casing to ensure the correct position of the punching tool in relation to the existing hole 2c.

When the punching tool has been inserted into the casing and the punching unit has been positioned with the piston opposite the existing hole to be sealed, the abutment 10 arranged circumferentially opposite the hydraulically activated punch is positioned so that it abuts the casing. Subsequently, the hydraulically activated punch is moved radially from the retracted position to the projected position so that the plug is placed in the hole and the hole is sealed. The installation of the plug may require that a further radial force is applied to the plug, e.g. to plastically deform part of the plug. To apply a further radial force to the plug, the hydraulically activated punch may be moved to a fully projected position, thereby deforming the plug.

After having installed the plug in the existing hole 2c constituting the inlet to the defect annular barrier, the defect annular barrier is sealed off. Hereby the well may once again be pressurised to inflate the remaining annular barriers as the injected fluid does not escape through the defect annular barrier.

In another embodiment, the punching tool may comprise multiple punching units, wherein one or more punching units comprises a hydraulically activated punch adapted to provide a hole in the casing and one or more other punching units comprises a hydraulic activated punch adapted to install a plug. The punching tool may thus install a plug in an existing hole to seal off that hole as described above and provide a new hole adjacent to the hole sealed off. Alternatively, the punching tool may provide a new hole, enlarge an existing hole or trim a fracture in order to allow installation of a plug to seal off the existing hole or fracture.

By fluid or well fluid is meant any kind of fluid that may be present in oil or gas wells downhole, such as natural gas, oil, oil mud, crude oil, water, etc. By gas is meant any kind of gas composition present in a well, completion, or open hole, and by oil is meant any kind of oil composition, such as crude oil, an oil- containing fluid, etc. Gas, oil, and water fluids may thus all comprise other elements or substances than gas, oil, and/or water, respectively. By a casing is meant any kind of pipe, tubing, tubular, liner, string etc. used downhole in relation to oil or natural gas production.

In the event that the tools are not submergible all the way into the casing, a downhole tractor can be used to push the tools all the way into position in the well. A downhole tractor is any kind of driving tool capable of pushing or pulling tools in a well downhole, such as a Well Tractor®.

Although the invention has been described in the above in connection with preferred embodiments of the invention, it will be evident for a person skilled in the art that several modifications are conceivable without departing from the invention as defined by the following claims.

Claims

1. A punching tool (1) for providing a hole (2a) or a dimple (2b) in a metal casing (3) in a borehole (4), comprising :

- a tool body (5) having an axial extension (6), and

- a punching unit (11) connected with the tool body, comprising :

- a bore (27a) provided in the tool body, extending substantially radially in relation to the axial extension,

- a fluid inlet (26) in fluid communication with the bore, and

- a hydraulically activated punch (9) arranged in the bore, being movable between a retracted and a projected position,

2. A punching tool according to claim 1, further comprising two isolation devices (70) circumfe renting the tool body and arranged spaced apart in the axial extension on opposite sides of the punching unit, the isolation devices being expandable from the tool body in a radial direction, thereby providing zonal isolation of a section (75) of the casing downhole, and wherein the punching tool further comprises one or more injection nozzles (80) for injecting a fluid into the section of the casing being isolated by the isolation devices, the injection nozzle being arranged between the isolation devices.

3. A punching tool according to claim 2, further comprising a pump (18) arranged in association with the tool body, the pump being connected to the fluid inlet for supplying a hydraulic fluid to the bore to move the hydraulically activated punch into the projected position.

4. A punching tool according to claim 3, wherein the isolation devices are constituted by inflatable packers being inflated and expanded from the tool body by the pump supplying a fluid to the inflatable packers.

5. A punching tool according to claim 3 or 4, wherein the pump is in fluid communication with the one or more injection nozzles and the pump is adapted to inject a fluid into the section of the casing being isolated by the isolation devices through the one or more injection nozzles.

6. A punching tool according to claim 5, further comprising an inlet (81) fluidly connecting the pump with an annulus (82) surrounding the punching tool, wherein the pump is adapted to draw fluid from the annulus and inject the fluid from the annulus through the one or more injection nozzles into the section of the casing being isolated by the isolation devices.

7. A punching tool according to any of the preceding claims, wherein the punching unit comprises an abutment (10) arranged circumferentially opposite the hydraulically activated punch around the tool body.

8. A punching tool according to claim 7, wherein part of the hydraulically activated punch engages part of the abutment to control the radial movement between the retracted and the projected position of the hydraulically activated punch.

9. A punching tool according to claim 7 or 8, wherein one of the hydraulically activated punch and the abutment comprises one or more radially extending guide elements (50) and the other of the hydraulically activated punch and the abutment comprises one or more radially extending tracks (51) being adapted to engage with the guide elements to control the radial movement between the retracted and the projected position of the hydraulically activated punch.

10. A punching tool according to any of claims 7-9, wherein the hydraulically activated punch and the abutment define an expandable space (31).

11. A punching tool according to claim 10, wherein the punching unit further comprises a piston (20) and a spring (24) which is compressed when the hydraulically activated punch is moved into the projected position.

12. A punching tool according to any of the preceding claims, wherein the hydraulically activated punch and the abutment are arranged in a through-bore (27b) in the tool body.

13. A punching tool according to any of the preceding claims, wherein the tool comprises a plurality of punching units (11, l ib, 11c).

14. A punching tool according to any of the claims 11-13, wherein the piston is movable in a hollow space (19a, 19b) defined by the hydraulically activated punch or a base part (42) of the hydraulically activated punch, and wherein the piston is connected with the abutment through a piston rod (23).

15. A punching tool according to any of the claims 11-14, wherein one of the hydraulically activated punch and the abutment is connected with the piston through a piston rod (23) and the other of the hydraulically activated punch and the abutment has an end arranged inside the tool body, the end comprising a flange (22), and wherein a spring (24) is arranged between the piston and the flange.

16. A punching tool according to any of the preceding claims, wherein a stop element (45) is arranged in connection with the hydraulically activated punch and the abutment to avoid separation of the hydraulically activated punch and the abutment.

17. A punching tool according to claim 16, wherein the stop element is arranged in connection with the fluid inlet.

18. A punching tool according to any of the preceding claims, wherein the hydraulically activated punch is a punch adapted to provide a dimple in a metal casing.

19. A punching tool according to claim 18, wherein the hydraulically activated punch is a pin punch, a centre punch, a taper punch, a flat chisel, a cape chisel, a half-round nose chisel or a combination thereof.

20. A punching tool according to any of the preceding claims, wherein the hydraulically activated punch is a punch adapted to install a plug (61) in an existing hole (2c) in the casing downhole to seal the existing hole.

21. A punching tool according to claim 20, wherein the hydraulically activated punch is further adapted to hold on to the plug prior to installing the plug in the existing hole, to place the plug in the existing hole when the hydraulically activated punch is moved into a projected position, and to deform the plug when the hydraulically activated punch is moved into a fully projected position.

22. A method for providing a hole or a dimple in a metal casing downhole, comprising the steps of:

- providing a punching tool according to any of the claims 1-19 in the metal casing downhole,

- moving the hydraulically activated punch radially from a retracted position to a projected position so that a hole or dimple is provided in the metal casing by the hydraulically activated punch in its projected position.

23. A method according to claim 22, wherein the hydraulically activated punch is moved radially to provide a hole in the metal casing, the method further comprising the steps of:

- expanding the isolation devices from the tool body in a radial direction, thereby providing zonal isolation of a section (75) of the casing downhole, and

- injecting a fluid into the section of the casing being isolated by the isolation devices, thereby forcing a fluid through the hole provided in the casing.

24. A method according to claim 22, wherein the hydraulically activated punch is moved radially to provide a dimple in the metal casing, the method further comprising the step of:

- arranging an electronic device (60) in the dimple or hole, the electronic device comprising a radio-frequency identification (RFID) chip, a radio-frequency tag (RFT) and/or one or more sensors, such as a temperature sensor.

25. A method for installing a plug, such as a Lee-plug, in an existing hole in the casing downhole, the method comprising the steps of:

- providing a punching tool according to any of the claims 20-21 in the casing downhole,

- positioning the punching unit of the punching tool at a location opposite the existing hole, - positioning the abutment arranged circumferentially opposite the hydraulically activated punch around the tool body so that it abuts a casing wall at a position circumferentially opposite the hydraulically activated punch,

- moving the hydraulically activated punch to a fully projected position, thereby deforming the plug to secure the plug and seal the existing hole.