WO2014207085A1

WO2014207085A1 - Patch setting tool

Info

Publication number: WO2014207085A1
Application number: PCT/EP2014/063478
Authority: WO
Inventors: Hans Plessing; Lars Staehr; Ricardo Reves VASQUES
Original assignee: Welltec A/S
Priority date: 2013-06-27
Filing date: 2014-06-26
Publication date: 2014-12-31
Also published as: WO2014207086A1

Abstract

The present invention relates to a patch setting tool for sealing off an opening in a weak part of a casing in a well, comprising a tool body having a fluid channel, an outer face and a tool axis, the tubular patch surrounding part of the tool body and having a first end part, a second end part and an intermediate part intermediate the first and second end parts, the first and second end parts of the tubular patch abutting the outer face of the tool body and hence defining a space between the intermediate part and the tool body, wherein the intermediate part has a thickness which is smaller than that of the first and second end parts, and an aperture of the tool body being in fluid communication with the fluid channel faces the intermediate part, so that when pressurised fluid is forced out of the aperture into the space, the intermediate part is expanded.

Description

PATCH SETTING TOOL

Field of the invention

The present invention relates to a tubular patch adapted to surround a part of a tool body downhole and to a patch setting tool for sealing off an opening in a weak part of a casing in a well. Furthermore, the invention relates to a downhole patch setting system and a patch setting method.

Background art In the past, many attempts have been made to set patches downhole to seal off openings in casings or liners by using expandable cones which are pulled through the patches in order to expand the patches to press against the inner surface of the casings. Since the cone and the patch have to pass some restrictions downhole, the cone has to be expandable. However, the attempts made have shown it to be very difficult to make a workable solution using an expandable cone. This is due to the fact that an expandable cone has mechanically movable parts which may get stuck, which prevents the cone from expanding and subsequently being retracted properly. In other situations, there is a need for sealing off a production zone in an openhole part of a well. Most wells are at least partly cased and a tool for setting such patch arrangement therefore needs to enter through the cased, more narrow part, and subsequently the tool needs to be able set the patch arrangement in the openhole part of the well which has a substantially larger diameter than the cased part. For this purpose many attempts have been made to make a highly expandable cone. However, none of the prior art cones are able to enter the cased part and expand a patch in an openhole part of the well having approximately twice the diameter of the casing. 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 an improved patch setting tool which has fewer mechanically movable parts than the prior art tools. 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 patch setting tool for sealing off an opening in a weak part of a casing in a well, comprising :

- a tool body having a fluid channel, an outer face and a tool axis,

- the tubular patch surrounding part of the tool body and having a first end part, a second end part and an intermediate part intermediate the first and second end parts, the first and second end parts of the tubular patch abutting the outer face of the tool body and hence defining a space between the intermediate part and the tool body,

wherein the intermediate part has a thickness which is smaller than that of the first and second end parts, and an aperture of the tool body being in fluid communication with the fluid channel faces the intermediate part, so that when pressurised fluid is forced out of the aperture into the space, the intermediate part is expanded.

Additionally, the intermediate part may be made of a material different from that of the first and second end parts. A patch setting tool may further comprise an acid container for removing the first and second end parts of the patch by means of the acid.

The tubular patch may have a transport position in which the tubular patch has an unexpanded diameter, and an expanded position in which the tubular patch has an expanded diameter, wherein the first sealing element in the transport position is arranged side-by-side with the first end part along the tool axis in a non-overlapping manner, and the second sealing element in the transport position may be arranged side-by-side with the second end part along the tool axis in a non-overlapping manner.

The patch setting tool as described above may further comprise a pushing part arranged in a first end of the tool body and movable in relation to a tool housing for pushing the first sealing element along the first inclined surface of the first end part. Also, the patch setting tool as described above may comprise the tool further comprising a stop arranged in a second end of the tool body, and the second sealing element may be arranged between the stop and the second end part.

Moreover, the pushing part may be slidably arranged in relation to the tool body and the stop for pushing the first sealing element along the first inclined surface of the first end part and for pushing the second sealing element along the second inclined surface of the second end part.

In an embodiment, the patch setting tool may further comprise a pump for pressurising a fluid.

Furthermore, a release element may be arranged at a predetermined distance from the first and second end parts of the tubular patch, and the release element may be arranged in a radial bore in the tool body, and part of the release element may extend from the outer face of the tool body so as to prevent one of the end parts of the tool body from moving past the release element.

Also, a second piston may be arranged in the fluid channel in the tool body, the second piston having a cavity for receiving the release element when the second piston is in a second position, providing the cavity opposite the release element.

In another embodiment, the patch setting tool may further comprise sealing elements arranged between the first and second end parts and the tool body.

In yet another embodiment, the patch setting tool may further comprising a holding means for holding the patch on the tool body.

Furthermore, the holding means may comprise a stop for preventing the patch from moving axially in one direction, wherein the holding means further comprises a retractable retainer unit.

The stop may be part of the tool body, e.g. the tool body having an increased diameter.

Moreover, the retainer unit may comprise a cylinder and a piston dividing the cylinder into a first chamber part and a second chamber part, wherein the first chamber part is fluidly connected with the fluid channel and the piston has a projection part engaging an indentation in the patch.

In addition, a spring may be arranged in the first chamber part.

Also, the retainer unit may comprise a breakable element arranged in the second chamber part for maintaining the projection part in engagement with the indentation. Further, a valve may be arranged in the fluid channel upstream of the first chamber part.

Additionally, the valve may be activated at a certain differential pressure. Furthermore, the sealing elements may comprise a split ring-shaped retaining element.

Also, the stop may be retractable. Moreover, the stop may be axially movable in relation to the tool body.

The patch setting tool may further comprise a milling bit and an anchoring section having projectable anchors. Also, the patch setting tool as described above may further comprise a cutting tool having at least one extendable cutting arm for at least partly removing the first and second end parts.

In an embodiment, the milling bit may be axially movable and rotatable in relation to the tool body.

The tool may further comprise a driving unit, such as a downhole tractor, for propelling the tool forward in the well. Finally, the tool may comprise a plurality of patches. The patches may in the transport position be arranged side-by-side. Also, the present invention relates to a tubular patch adapted to surround a part of a tool body patch setting tool according to any of the preceding claims, comprising

- a first end part,

- a second end part, and

- an intermediate part intermediate the first and second end parts,

wherein the intermediate part has a thickness which is smaller than that of the first and second parts, so that when pressurised fluid is forced towards the intermediate part, the intermediate part is expanded, and

wherein the intermediate part is made of a material different from that of the first and second end parts.

The tubular patch may be adapted to seal off an openhole production zone in a borehole, and the first and the second end parts may taper away from the intermediate part, forming a first and a second inclined surface, and a first sealing element may be arranged sliding onto the first inclined surface and a second sealing element may be arranged sliding onto the second inclined surface for sealing against an inner wall of the borehole. A tubular patch according to the present invention may be a sealing arrangement for sealing off a production zone in an openhole part of a well.

Moreover, the first and second end parts may have a sleeve part with a thickness which is substantially the same as the thickness of the intermediate part.

Furthermore, the tubular patch may be made of metal.

Also, the first and second sealing elements may be arranged at a distance from each other.

Additionally, the intermediate part may have an inner diameter which is larger than that of the first and second end parts.

Further, the intermediate part may have a thickness which is less than 60% of the thickness of the first and second end parts, preferably less than 50% of the thickness of the first and second end parts. The intermediate part may be made mainly of metal.

Also, the second end part may have an indentation. In addition, the intermediate part may have an outer face, and a patch sealing element may be arranged on the outer face.

Further, the end of the first and second end parts may taper towards the intermediate part.

Moreover, the intermediate part may be connected to the first and second end parts by means of friction welding.

Furthermore, the intermediate part may be made of a material which is more elastic than a material of the first and second parts.

Also, the first and second end parts may be made of material which is acid- dissolvable. Additionally, the material of the first and second end parts may be aluminium.

Finally, the material of the first and second end parts may be composite steel, plastic, reinforced plastic, fiber glass and/or carbon. In addition, the first and second end parts may be made of a material which is less ductile than that of the intermediate part.

The present invention furthermore relates to a downhole patch setting system comprising a patch setting tool as described above and a casing having an opening or a weak part.

Finally, the present invention relates to a patch setting method for setting a tubular patch as described above, using the patch setting tool as described above, the method comprising the steps of:

- inserting the patch setting tool into a casing in a well,

- positioning an intermediate part of the patch opposite an opening in the casing to be sealed off or opposite a weak part of the casing, - pressurising a fluid,

- letting the pressurised fluid through the aperture in the tool to expand the intermediate part by means of the pressurised fluid so that the intermediate part abuts the casing and seals off an opening or weak part,

- moving the tool away from the patch, and

- removing first and second end parts of the patch.

In the patch setting method as described above, before the step of letting the pressurised fluid through the aperture, the first and the second sealing elements may be pushed onto the inclined surfaces by means of the pushing element.

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 cross-sectional view of a patch setting tool in an unexpanded condition of a patch,

Fig. 2 shows the patch setting tool of Fig. 1 in which the patch has been expanded,

Fig. 3 shows the patch setting tool of Fig. 1 in which the patch has been released from the tool,

Fig. 4 shows the patch of Fig. 1 in which the tool has been removed from the patch, Fig. 5 shows milling bits which are about to remove part of the patch,

Fig. 6 shows a cross-sectional view of a patch sealing off an opening in a casing, Fig. 7 shows several patches set in turn to seal off openings in the casing,

Fig. 8 shows a patch setting tool in a partly cased well, Fig. 9 shows a cross-sectional view of part of the patch setting tool,

Fig. 10A shows a cross-sectional view of part of the tubular patch in its unexpanded condition,

Fig. 10B shows a cross-sectional view of part of the tubular patch in its unexpanded condition with the first and second sealing elements pushed onto the outer face of the tubular patch, Fig. IOC shows a cross-sectional view of part of the tubular patch in its expanded condition,

Fig. 11 shows a patch setting tool having a cutting tool, and Fig. 12 shows a tubular patch in its expanded condition sealing off a production zone.

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 patch setting tool 1 for sealing off an opening 2, such as a leak, in a casing 3 or a weak part of the casing 3 in a well 4. The tool comprises a tool body 5 having a fluid channel 11 extending within the tool body and in fluid communication with an aperture 10 in an outer face 30 of the tool body. The tool 1 has a tubular patch 6 surrounding part of the tool body 5. The patch 6 has a first end part 7, a second end part 8 and an intermediate part 9 intermediate the first and second end parts. The intermediate part 9 has a thickness t, which is smaller than a thickness t_e of the first and second end parts 7, 8. The aperture 10 of the fluid channel 11 faces the intermediate part 9, meaning that when pressurised fluid is forced out of the aperture, the intermediate part is expanded as the pressurised fluid fills up a space 32 between the intermediate part and the outer face 30 of the tool body 5. The space 32 increases as the intermediate part 9 is expanded to abut the casing and thus seal the opening or leak in the casing or strengthen a weak part of the casing. As can be seen in Fig. 1, the intermediate part 9 has an inner diameter ID, which is larger than an inner diameter ID_e of the first and second end parts 7, 8. Sealing elements 14 are arranged between the first and second end parts 7, 8 of the patch 6 and the tool body 5, so that the space 32 is sealed off and can be pressurised. The intermediate part 9 is fastened to the first and second end parts 7, 8, and as the pressurised fluid pressurises the patch 6 from within, only the intermediate part of the patch is expanded, as shown in Fig. 2. The first and second end parts 7, 8 have a substantial thickness compared to the intermediate part 9 to ensure that only the intermediate part is expanded and that the end parts are able to maintain the seals provided by the sealing elements 14. Thus, the intermediate part 9 may have a thickness which is less than 60% of the thickness of the first and second end parts, preferably less than 50% of the thickness of the first and second end parts. As shown in Fig. 1, the patch setting tool 1 comprises a pump 12 for pressurising the fluid in order to expand part of the patch 6. The pump 12 may also be arranged at the surface to pressurise the casing 3 from within and further into the tool body 5 or down through a drill pipe connected to the tool. The patch 6 is maintained around the tool body 5 as the tool 1 is submerged into the well 4 by means of a holding means 15 for holding the patch on the tool body. In one end of the patch 6, the holding means 15 comprises a stop 16 for preventing the patch from moving axially in a first direction, and in the other end of patch, the holding means further comprises a retractable retainer unit 17 retaining the patch in a direction opposite the first direction. The holding means is in one end the tool body having an increased diameter defining the stop.

When the patch 6 has been expanded as shown in Fig. 2, the holding means 15 releases the patch, as shown in Fig. 3, and then, the tool 1 can be retracted from the patch, leaving the patch in the well opposite the openings 2 to be sealed off, as shown Fig. 4. Subsequently, the first and second end parts 7, 8 of the patch are removed, either by milling, as shown in Fig. 5, or by acid, leaving the intermediate part as the final patch, as shown in Fig. 6.

As shown in Figs. 1-3, the retractable retainer unit 17 comprises a cylinder 18 and a piston 19 movable within the cylinder and dividing the cylinder into a first chamber part 20 and second chamber part 21. The cylinder is arranged in a radial direction in relation to an axial direction of the tool, and thus the piston moves radially in relation to the patch. The first end part 7 of the patch defines the end wall of the cylinder and thus defines the end face of the second chamber part. The first chamber part 20 is fluidly connected with the fluid channel 11, so that the pressurised fluid can enter the first chamber part. The piston 19 has a projection part 22 engaging an indentation 23 in the second part of the patch 6 for holding the patch in the axial direction. The patch 6 is slid onto the tool body 5 over the projection part 22, and as the patch reaches the stop 16, the projection part engages the indentation 23, thereby preventing the patch from moving axially along the tool body as the tool 1 is submerged into the well 4 and also during expansion of the intermediate part 9.

A spring 24 is arranged in the first chamber part 20, forcing the piston 19 and the projection part 22 out of engagement with the indentation 23, thus helping the fluid move the piston to release the patch 6 from the tool body 5, as shown in Fig. 3.

The retractable retainer unit 17 comprises a breakable element 36, such as a shear pin, arranged in the second chamber part 21 for maintaining the projection part 22 in engagement with the indentation 23, as shown in Figs. 1 and 2. A valve 31 may be arranged in the fluid channel 11 upstream of the first chamber part 20. The valve 31 is activated at a certain differential pressure occurring when the space 32 has been pressurised and the intermediate part 9 has been expanded. Then, the pressure is built up even further and the valve 31 opens and lets the fluid into the first chamber part 20. As the pressure builds up in the first chamber part, then at a certain predetermined pressure on the breakable element 36, the breakable element 36 breaks and the piston 19 moves past the breakable element 36, disengaging the projection part 22 from the indentation 23. The sealing elements 14 may be any kind of seal and may comprise a split ring- shaped retaining element arranged in a groove in the tool body 5 between first and second circumferential edges, and the split ring-shaped retaining element has several windings so that when the patch 6 is expanded, the split ring-shaped retaining element partly unwinds. In this way, the sealing elements 14 are able to compensate for a slight movement of the first and second end parts 7, 8, should such movements occur. Furthermore, the split ring functions as a back-up for the sealing element. In Figs. 1-3, the stop 16 is fixed. However, in another embodiment, the stop is retractable into the tool body 5 so that the tool body can pass a set patch 6 and move further into the casing 3. In this way, the patch setting tool may be reused for setting several patches in one run, as shown in Fig. 7, and the milling bits 33 shown in Fig. 5 may also be moved to remove the first and second end parts 7, 8 in the same run. In Fig. 5, the patch setting tool further comprises an anchoring section 34 having projectable anchors 35 for fixating the patch in relation to the milling bit during the removal of the first and second end parts. The milling bits 33 are axially movable and rotatable in relation to the tool body to be able to remove the end parts.

As can be seen in Figs. 1-6, the intermediate part 9 has an outer face 26, and a patch sealing element 25 is arranged on the outer face 26 of the patch. In order to ease the expansion of the intermediate part 9 and to ensure that the intermediate part fully expands, the end of the first and second end parts tapers towards the intermediate part. In this way, the tapering parts of the first and second end parts become thinner as the intermediate part 9 is expanded.

As mentioned, the intermediate part 9 is connected to the first and second end parts and this connection may be performed by means of frictional welding. The ends of the parts are forced to abut each other, and the parts are rotated in relation to each other. A rotating pin between the parts may also be used. Thus, the intermediate part 9 can be made of a material which is more elastic than a material of the first and second parts. The first and second end parts may be made of material which is acid-dissolvable, i.e. almost any metal, and preferably aluminium. The first and second end parts may also be made of stainless steel, composite steel, plastic, reinforced plastic, fiber glass and/or carbon.

To ease the expansion, the intermediate part 9 may be made of a material different from that of the first and second end parts. The material of the intermediate part may be more elastic.

The invention further relates to a downhole patch setting system 100 comprising the patch setting tool 1 and a casing 3 having an opening 2 or a weak part.

The patch is set by inserting the patch setting tool into the casing in a well, and the intermediate part 9 of the patch is positioned opposite the aperture to be sealed or opposite the weak part. Then, the fluid is pressurised, and the pressurised fluid is let through the aperture to expand the intermediate part by means of the pressurised fluid, so that the intermediate part abuts the casing for sealing off the opening 2 or the weak part. Subsequently, the tool is moved away from the patch, and the first and second end parts of the patch are removed, either by milling the ends out or by injecting acid into the casing.

As shown in Fig. 7, several patches may be set by using the patch setting tool. A first intermediate part of the first patch extends in a straight line, and the second intermediate part of a second patch partly rests upon the first patch, so that the sealing elements of the patch seal on the inner face of the first patch. Similarly, the third intermediate part of a third patch rests against the second patch and seals to the inner face of the second patch. In this way, a larger region in the axial extension of the casing 3 can be sealed off, which is especially useful when sealing off a longer perforation zone. In Fig. 7, all the first and second end parts of the first, second and third patch have been removed.

In Fig. 8, the setting tool 1 is connected and powered through a wireline 43. The setting tool is operated from surface or may be programmed to be self-operable by means of a driving unit, such as a downhole tractor (not shown). The setting tool uses pressurised fluid for expanding the patch 6, which is provided by a pump 12 driven by a motor 45 and an electronic section 46. The tool 1 further comprises a fluid control section 47 to control the pressurisation of the patch 6. As can be seen, the patch setting tool 1 has the tubular patch 6 and the tubular patch is shown in its transport position in which the tubular patch has an unexpanded diameter d_u In the transport position, the first sealing element 29 is arranged side-by-side with the first end part 7 along the tool axis in a non- overlapping manner, and the second sealing element 30 in the transport position is arranged side-by-side with the second end part 8 along the tool axis in a non- overlapping manner.

The patch setting tool 1 further comprises a pushing part 38 arranged in a first end 57 of the tool body for pushing the first sealing element 29 along the first inclined surface 27 of the first end part 7, and for pushing the second sealing element 30 onto the second inclined surface 28, so that the first sealing element 29 surrounds the first end part 7 of the tubular patch 6 and the second sealing element 30 surrounds the second end part 8. Subsequently, the tubular patch is expanded having an expanded diameter d_e (shown in Fig. 12) which is larger than the unexpanded diameter, the expanded and unexpanded diameters here being the outer diameters of the patch. An expanded tubular patch is shown in Fig. 12 in which the patch is expanded to its expanded diameter d_e.

In Fig. 9, the patch setting tool 1 is shown having a pushing part 38 slidably arranged in relation to the tool body and having a stop 41 in the end of the tool body. Fig. 9 shows a part of the setting tool in cross-section in which the tubular patch 6 is shown before the sealing elements 29, 30 are to be pushed onto the end parts. The pushing part 38 is movable along the tool axis for pressing towards the first sealing element 29 and for arranging the first sealing element on the outer face of the first end part 7. The piston is arranged circumferenting the tool body 5 and is forced towards the second end 24 of the tool body 5 by means of pressurised fluid in a second fluid channel 56. The pressurised fluid in the second fluid channel is indicated by the encircled number "1", and the pressurised fluid flowing in the other fluid channel for expanding the tubular patch is indicated by the encircled number "2". The pushing part 38 has a flange 53a abutting the sealing element and the tool body, so that fluid from the second fluid channel 56 is pressed into an expandable space 55 between a flange 54 of the tool body and the flange 53a.

When the pushing part 38 slides, the pushing part pushes the first sealing element 29 along the first inclined surface 27 of the first end part 7, and by pushing further towards the stop 41, the second sealing element 30 is pushed along the second inclined surface 28 of the second end part 8. The pushing part 38 is movable in relation to a tool housing 39 for pushing the first sealing element along the first inclined surface of the first end part. The second sealing element 30 is arranged between the stop 41 and the second end part 8, so that when the pushing part is moved, the second end part 8 is squeezed under the second sealing element 30 until it reaches the stop. The second sealing element, when seen in cross-section, has a projection part 71 having an inner diameter which is smaller than the outer diameter of the tool body. When forcing the second sealing element onto the second end part, the tip of the second end part squeezes the projecting part 71, so that the projecting part departs/separates from the remaining second sealing element. The stop thus presses against the second sealing element when the pushing part acts, and both the first and second sealing elements are arranged on the outside of the first and second end parts, respectively, as shown in Fig . 10B.

Subsequently, the direction of the pressurised fluid is changed to flow in the other fluid channel indicated by the encircled number "2" for expanding the tubular patch is and the patch 6 is expanded as shown in Fig. IOC.

As can be seen in Fig . 10A, the first and second end pa rts 7, 8 have a sleeve part 72a, 72b having a thickness which is substantially the same as the intermediate part, and part of the first and second end part has a thickness which is substantially thicker than the intermediate part so as to seal the space 37. The first and second end parts may be made of a material which is less ductile than that of the intermediate part, so that when the patch is expa nded, the intermediate pa rt is kept more straight and thus capable of forming part of the sealing arrangement shown in Fig . 12, which arrangement seals off a production zone in an openhole part of the well . If the intermediate part is made of the same ductile material as the end parts, the intermediate part would bulge during expansion and hence the sealing properties between the sealing elements and the intermediate part would be compromised . In another embod iment, the intermediate part has a thickness which is thicker than the thickness of the sleeve parts of the first and second end parts.

In Fig . 10A, the patch setting tool 1 comprises a release element 51 arranged at a predetermined distance Xi from the first and second end parts of the tubular patch 6. The release element 51 is arranged in a radial bore 52 in the tool body 5 and part of the release element extends from the outer face 44 of the tool body so as to prevent one of the end parts 7, 8 of the tubula r patch from moving past the release element and thus ensures that the second sealing element 30 is pushed onto the second end part 8. The predetermined dista nce Xi in Fig . 10A is the same as the distance from the pushing part 38 to the first end part 7 as shown in Fig . 9. In this way, it is ensured that both the first sealing element 29 and the second sealing element 30 a re pushed onto the first end part and the second end part of the tubular patch 6 when the pushing pa rt 38 pushes the first seling element onto the first end part 7. In order to release the release element 51 of Fig . 10A, a second piston 53 is arranged in the fluid channel 11 in the tool body. The second piston has a cavity 54 for receiving part of the release element when the second piston is in a second position, in which the second piston 53 is moved by the pressurised fluid breaking the release element, e.g. a shear pin, arranging the cavity opposite the release element, so that the remaining part of the release element drops into the cavity and no longer extends from the outer face 44 of the tool body. Hereby, the tool body and the stop can be retracted from the tubular patch due to the fact that the outer diameter of the stop is almost equal to the outer diameter of the tool body 5 as can be seen in Fig. 9.

In Fig. 11, the setting tool 1 further comprises a cutting tool 61 having an extendable cutting arm 62. By rotating the arm, the cutting arm is able to cut away part of the first and second end parts, hence decreasing the inner diameter of the patch, so that only the intermediate part 9 and the first and second sealing elements 29, 30 are present to form the sealing patch of a production zone in an openhole shown in Fig. 12. The cutting tool may also be a hole saw circumferenting a fastening means. The fastening means is expandable to abut the first end part and secondly the second end part to be able to cut into the patch.

The invention furthermore relates to a patch setting method for setting the tubular patch, using the patch setting tool. The method comprises the steps of inserting the patch setting tool into a casing in a well and positioning the intermediate part of the patch opposite the aperture to be sealed off or opposite a weak part. Then fluid is pressurised and let through the aperture to expand the intermediate part by means of the pressurised fluid, so that the intermediate part abuts the casing and seals off the opening or weak part. Subsequently, the tool is moved away from the patch and the first and second end parts of the patch are removed.

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 tool is not submergible all the way into the casing, a driving unit, such as a downhole tractor can be used to push the tool all the way into position in the well. The downhole tractor may have projectable arms having wheels, wherein the wheels contact the inner surface of the casing for propelling the tractor and the tool forward in the casing. 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 patch setting tool (1) for sealing off an opening (2) in a weak part of a casing (3) in a well (4), comprising :

- a tool body (5) having a fluid channel (11), an outer face (44) and a tool axis, - the tubular patch (6) surrounding part of the tool body and having a first end part (7), a second end part (8) and an intermediate part (9) intermediate the first and second end parts, the first and second end parts of the tubular patch abutting the outer face of the tool body and hence defining a space (37) between the intermediate part and the tool body (5),

wherein the intermediate part has a thickness which is smaller than that of the first and second end parts, and an aperture (10) of the tool body being in fluid communication with the fluid channel faces the intermediate part, so that when pressurised fluid is forced out of the aperture into the space, the intermediate part is expanded.

2. A patch setting tool (1) according to claim 1, wherein the tubular patch has a transport position in which the tubular patch has an unexpanded diameter (d_u), and an expanded position in which the tubular patch has an expanded diameter (d_e), wherein the first sealing element in the transport position is arranged side- by-side with the first end part along the tool axis in a non-overlapping manner, and the second sealing element in the transport position is arranged side-by-side with the second end part along the tool axis in a non-overlapping manner.

3. A patch setting tool (1) according to claim 1 or 2, further comprising a pushing part (38) arranged in a first end of the tool body and movable in relation to a tool housing (39) for pushing the first sealing element along the first inclined surface of the first end part.

4. A patch setting tool (1) according to any of the preceding claims, further comprising the tool further comprising a stop (41) arranged in a second end of the tool body, and the second sealing element is arranged between the stop and the second end part.

5. A patch setting tool (1) according to claim 3 or 4, wherein the pushing part is slidably arranged in relation to the tool body and the stop for pushing the first sealing element along the first inclined surface of the first end part and for pushing the second sealing element along the second inclined surface of the second end part.

6. A patch setting tool (1) according to any of claims 1-5, further comprising a pump (12) for pressurising the fluid.

7. A patch setting tool (1) according to any of claims 1-6, wherein a release element (51) is arranged at a predetermined distance from the first and second end parts of the tubular patch, and the release element is arranged in a radial bore (52) in the tool body, and part of the release element extends from the outer face of the tool body so as to prevent one of the end parts of the tool body from moving past the release element.

8. A patch setting tool (1) according to claim 7, wherein a second piston (53) is arranged in the fluid channel in the tool body, the second piston having a cavity (54) for receiving the release element when the second piston is in a second position, providing the cavity opposite the release element.

9. A patch setting tool (1) according to any of claims 1-8, further comprising a holding means (15) for holding the patch on the tool body.

10. A patch setting tool (1) according to claim 9, wherein the holding means comprises a stop (16) for preventing the patch from moving axially in one direction, wherein the holding means further comprises a retractable retainer unit (17).

11. A patch setting tool (1) according to claim 10, wherein the retainer unit comprises a cylinder (18) and a piston (19) dividing the cylinder into a first chamber part (20) and a second chamber part (21), wherein the first chamber part is fluidly connected with the fluid channel and the piston has a projection part (22) engaging an indentation (23) in the patch.

12. A patch setting tool (1) according to claim 10 or 11, wherein the retainer unit comprises a breakable element (36) arranged in the second chamber part for maintaining the projection part in engagement with the indentation.

13. A patch setting tool (1) according to any of claims 1-12, further comprising a milling bit (33) and an anchoring section (34) having projectable anchors (35).

14. A patch setting tool (1) according to any of claims 1-13, further comprising a cutting tool (61) having at least one extendable cutting arm (62) for at least partly removing the first and second end parts.

15. A downhole patch setting system (100) comprising a patch setting tool according to any of claims 1-14 and a casing (3) having an opening (2) or a weak part.

16. A tubular patch (6) adapted to surround a part of a tool body (5) patch setting tool (1) according to any of the preceding claims, comprising

- a first end part (7),

- a second end part (8), and

- an intermediate part (9) intermediate the first and second end parts,

wherein the intermediate part has a thickness (t,) which is smaller than that of the first and second parts, so that when pressurised fluid is forced towards the intermediate part, the intermediate part is expanded, and

17. A tubular patch according to claim 16, wherein the tubular patch is adapted to seal off an openhole production zone in a borehole, and wherein the first and the second end parts taper away from the intermediate part, forming a first and a second inclined surface (27, 28), and a first sealing element (29) is arranged sliding onto the first inclined surface and a second sealing element (30) is arranged sliding onto the second inclined surface for sealing against an inner wall (4a) of the borehole.

18. A tubular patch according to claim 16 or 17, wherein the first and second end parts have a sleeve part with a thickness which is substantially the same as the thickness of the intermediate part.

19. A tubular patch according to any of the preceding claims, wherein the tubular patch is made of metal.

20. A tubular patch according to claim 19, wherein the first and second sealing elements are arranged at a distance from each other.

21. A tubular patch according to any of the preceding claims, wherein the intermediate part has an inner diameter (ID,) which is larger than that of the first and second end parts.

22. A tubular patch according to any of the preceding claims, wherein the intermediate part has a thickness which is less than 60% of the thickness of the first and second end parts, preferably less than 50% of the thickness of the first and second end parts.

23. A tubular patch according to any of the preceding claims, wherein the intermediate part is made mainly of metal.

24. A tubular patch according to any of the preceding claims, wherein the first and second end parts are made of a material which is less ductile than that of the intermediate part.

25. A patch setting method for setting a tubular patch (6) according to any of claims 16-24, using the patch setting tool (1) according to any of claims 1-15, the method comprising the steps of:

- inserting the patch setting tool into a casing in a well,

- positioning the intermediate part of the patch opposite an opening (2) in the casing to be sealed off or opposite a weak part of the casing,

- pressurising a fluid,

- letting the pressurised fluid through the aperture in the tool to expand the intermediate part by means of the pressurised fluid so that the intermediate part abuts the casing and seals off the opening (2) or weak part,

- moving the tool away from the patch, and

- removing the first and second end parts of the patch.

26. A patch setting method according to claim 25, wherein before the step of letting the pressurised fluid through the aperture, first and the second sealing elements are pushed onto the inclined surfaces by means of the pushing element.