Patent Description:
Annular barriers are mounted as part of a cased well with the aim of isolating a production zone from other zones which are producing an excessive amount of water. Some of these barriers have an expandable metal sleeve which is fastened to the well tubular metal structure by means of welding or crimping. However, sometimes such fastening is not successful, for example in wells having a very varying hole diameter, such as washouts, where the expandable metal sleeve may have to be expanded to a larger extent than such connections are able to withstand without jeopardising the sealing ability of the annular barrier.

<CIT> discloses a packer for a wellbore comprising a central tubular element covered by a deformable peripheral sleeve, where fluid is injected inside the tubular element under pressure in order to form said sleeve and to apply it to the walls of the wellbore, and where the deformable sleeve is made out of metal, and the inner wall of the sleeve comprises at least one annular chamber that extends over at least one part of the surface of the sleeve and communicates with the inside of the packer via an orifice.

Furthermore, fastening the expandable metal sleeve by means of welding or crimping is time-consuming, not easily done and almost impossible to do on site.

It is an object of the present invention to wholly or partly overcome the above disadvantages and drawbacks of prior art. More specifically, it is an object to provide an improved annular barrier which is easier to mount to the well tubular metal structure and/or which is capable of withstanding a high level of expansion without jeopardising the sealing ability of the annular barrier, especially at the connection of the expandable metal sleeve to the well tubular metal structure.

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 an annular barrier for providing zonal isolation in an annulus downhole between a well tubular metal structure and another well tubular metal structure or a wall of a borehole, the annular barrier having an axial extension and comprising:.

wherein the tubular metal part bulges radially outwards in relation to the axial extension, forming at least one circumferential projection engaging the groove, thus providing a connection of the expandable metal sleeve to the tubular metal part.

In one aspect, the second end part is slidably connected with the tubular metal part.

In another aspect, the second end part is fixedly connected with the tubular metal part by means of a bite connection.

In yet another aspect, the second end part is fixedly connected with the tubular metal part by welding, crimping or a similar connection method.

In addition, the projection may have a projection height which varies along the circumference of the tubular metal part.

Moreover, the projection may have a round cross-sectional shape at least along the axial extension.

Furthermore, the projection may be provided by means of an expander tool.

Also, the tubular metal part may comprise an indentation in the inner part face opposite the projection.

Additionally, the annular barrier may comprise a sealing element arranged in the groove.

Further, the expandable metal sleeve may comprise several grooves, and the tubular metal part may comprise a corresponding number of projections.

Moreover, one of the grooves may be fluidly connected with a channel for the measurement of pressure as the tubular metal part bulges into the groove.

In addition, the connection between the expandable metal sleeve and the tubular metal part may be verified during mounting of the expandable metal sleeve to the tubular metal part.

Furthermore, the tubular metal part may comprise an expansion opening for allowing fluid to enter in order to expand the expandable metal sleeve.

Also, the annular barrier may comprise a valve arranged in the expansion opening or at least in fluid communication with the expansion opening for controlling the flow of fluid from within the tubular metal part/well tubular metal structure to the expandable space.

Additionally, each end part of the expandable metal sleeve may comprise grooves, the tubular metal part comprising a corresponding number of projections, and each projection engaging one of the grooves.

Further, the expandable metal sleeve may have an intermediate part between the end parts, the intermediate part having a smaller thickness than that of the end pa rts.

Moreover, the tubular metal part may have a first thickness and a second thickness at the projection, which second thickness may be substantially the same as the first thickness.

In addition, the second thickness may be substantially uniform at the projection since some thinning occurs during the bulging of the tubular metal part.

Furthermore, the present invention relates to a downhole system comprising the annular barrier and a well tubular metal structure, where the tubular metal part of the annular barrier is mounted as part of the well tubular metal structure.

The present invention also relates to a mounting method for mounting an expandable metal sleeve of an annular barrier to the tubular metal part, comprising:.

Finally, the expander tool may expand radially outwards until a sealing element in the groove is compressed.

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> shows an annular barrier <NUM> for providing zonal isolation in an annulus <NUM> downhole between a well tubular metal structure <NUM> and another well tubular metal structure 3b (as shown in <FIG>) or a wall <NUM> of a borehole <NUM>. The annular barrier has an axial extension L and comprises a tubular metal part <NUM> having an inner part face <NUM> and an outer part face <NUM>. The tubular metal part is mounted as part of the well tubular metal structure <NUM>. The annular barrier further comprises an expandable metal sleeve <NUM> surrounding the tubular metal part, forming an expandable space <NUM> between the tubular metal part and the expandable metal sleeve. The expandable metal sleeve <NUM> is configured to be expanded in a well downhole from a first outer diameter D1 to a second outer diameter D2 in order to abut against the wall of the borehole, as indicated by the dotted line. The expandable metal sleeve <NUM> has a first end part <NUM>, a second end part <NUM> and an outer face <NUM>. The end parts comprise two circumferential grooves <NUM> facing the outer part face, the tubular metal part bulging radially outwards in relation to the axial extension, forming two circumferential projections <NUM>, each engaging one of the grooves and providing a mechanical connection of the expandable metal sleeve to the tubular metal part, i.e. mechanically connecting the expandable metal sleeve and the tubular metal part. The tubular metal part comprises an indentation <NUM> in the inner part face <NUM> opposite each projection <NUM>.

The connection between the expandable metal sleeve <NUM> and the tubular metal part <NUM> is thus easily made by pressing from within the tubular metal part by means of an expander tool until the tubular metal part forms projections when bulging into the grooves, making indentations on the inner part face <NUM>. Each projection <NUM> has a round cross-sectional shape at least along the axial extension.

By forcing part of the tubular metal part into grooves of the expandable metal sleeve, the expandable metal sleeve is fastened to the tubular metal part in a simple manner which does not alter the material properties as seen in prior art in relation to welding or crimping. Furthermore, fastening is easier to reproduce than welding. Moreover, such press connection is substantially cheaper to use for mounting of the expandable metal sleeve to the tubular metal part as this solution is less time-consuming than welding.

As shown in <FIG>, the annular barrier <NUM> comprises an expansion opening <NUM> in the tubular metal part for allowing fluid to enter in order to expand the expandable metal sleeve <NUM>. The annular barrier further comprises a valve <NUM> arranged in the expansion opening or at least in fluid communication with the expansion opening for controlling the flow of fluid from within the tubular metal part/well tubular metal structure to the expandable space. The valve may also be arranged in connection with one of the ends of the expandable metal sleeve, even though not shown.

<FIG> shows the annular barrier <NUM> further comprising a sealing element <NUM> arranged in each groove so that the sealing elements <NUM> are squeezed when the projections bulge into the grooves, providing a seal between the expandable metal sleeve and the tubular metal part. The tubular metal part <NUM> has a first thickness t1 and a second thickness t2 at the projection <NUM>, which second thickness is substantially the same as the first thickness. By "substantially the same" is meant that the second thickness is substantially the same, i.e. a uniform thickness since some thinning occurs during the bulging of the tubular metal part. Each end part <NUM>, <NUM> of the expandable metal sleeve <NUM> comprises grooves <NUM>, and the tubular metal part <NUM> comprises a corresponding number of projections <NUM>, each projection engaging one of the grooves.

The expandable metal sleeve <NUM> has an intermediate part <NUM> extending from the first end part to the second end part, i.e. between the end parts, and the intermediate part has a smaller thickness than that of the end parts.

In <FIG>, the expandable metal sleeve comprises three grooves <NUM> - 14A, 14B and 14C - wherein the tubular metal part comprises a corresponding number of projections <NUM> - 15A, 15B and 15C. One of the grooves is fluidly connected with a channel <NUM> for the measurement of pressure as the tubular metal part bulges into the groove during the mounting of the expandable metal sleeve <NUM> to the tubular metal part <NUM>. In this way, the connection between the expandable metal sleeve and the tubular metal part can be verified during mounting of the expandable metal sleeve to the tubular metal part, while the two other grooves and projections provide the sealing ability between the expandable metal sleeve and the tubular metal part, as shown in <FIG>.

As shown in <FIG>, the projection <NUM> is provided by means of an expander tool <NUM>, and the projection has a projection height H (shown in <FIG>) which may vary along the circumference of the tubular metal part <NUM>. The expander tool <NUM> expands by projecting outwards a plurality of radially moving parts <NUM> having spikes <NUM>, and when expanding the parts <NUM>, a small gap is formed between two adjacent parts <NUM>, and thus the projection height may slightly vary, corresponding to the small gaps.

The expandable metal sleeve <NUM> is fastened in one end by pressing from within the tubular metal part by means of an expander tool until the tubular metal part forms projections when bulging into the grooves, making indentations on the inner part face <NUM>. In the other end, the expandable metal sleeve may be fastened by means of a bite connection as shown in <FIG> or another way of fastening, or it may be made as a sliding end, i.e. sliding in relation to the tubular metal part. As shown in <FIG>, the first end of the expandable metal sleeve has a first part 54A of a mechanical connection <NUM> being a thread <NUM>. The first end of the expandable metal sleeve is connected to the tubular metal part by means of a bite connection <NUM>. The bite connection <NUM> comprises a cutting ring <NUM> comprising an outer ring face <NUM> having an inclined face <NUM> and an inner ring face <NUM> having a first cutting edge <NUM> configured to cut into the outer part face of the tubular metal part. The bite connection <NUM> further comprises a connection ring <NUM> with a second part 54B of the mechanical connection <NUM> being a thread <NUM> engaging the thread of the expandable metal sleeve so that when rotating the connection ring, the inclined face <NUM> slides along a tapering face <NUM> of the expandable metal sleeve, pressing the first cutting edge into the outer part face and fastening the expandable metal sleeve <NUM> to the tubular metal part <NUM>. By forcing the cutting ring into the outer part face of the tubular metal part, the expandable metal sleeve is fastened to the tubular metal part in a simple manner which does not alter the material properties as seen in prior art in relation to welding or crimping. Furthermore, fastening is easier to reproduce than welding. Moreover, a bite connection is substantially cheaper to use for mounting of the expandable metal sleeve to the tubular metal part as this solution is less time-consuming than welding. The bite connection fastens the expandable metal sleeve to the tubular metal part using the threaded connection to the expandable metal sleeve and rotating the connection ring so that the bite, i.e. the cutting ring <NUM>, is forced to press and/or cut into the outer part face of the tubular metal part. The bite connection provides a very simple way of mounting the expandable metal sleeve to the tubular metal part, and the connection may be performed on site, i.e. on the rig or platform.

The invention further relates to a downhole system <NUM> as shown in <FIG> which comprises the annular barrier <NUM> and the well tubular metal structure <NUM>, where the tubular metal part of the annular barrier is mounted as part of the well tubular metal structure.

When mounting the expandable metal sleeve <NUM> of the annular barrier <NUM> to the tubular metal part <NUM>, the expandable metal sleeve is first positioned around the tubular metal part in the predetermined position of the annular barrier <NUM> when positioned in the well. Next, the expander tool <NUM> is positioned inside the tubular metal part opposite the groove <NUM> of the expandable metal sleeve, as shown in <FIG>. In <FIG>, the tubular metal part and the surrounding expandable metal sleeve are arranged in a fixture <NUM> of a tool part <NUM>, and the expander tool is expanded by projecting the parts <NUM> radially outwards until the tubular metal part bulges into the groove, forming a projection engaging the groove and fastening the expandable metal sleeve to the tubular metal part. The expander tool may comprise a plurality of radially moving parts <NUM> having spikes <NUM> which are moved radially outwards to expand the outer diameter of the tool, thus pressing the spikes into the tubular metal part, deforming that part of the tubular metal part and forming the projections <NUM> and indentations <NUM> so that the tubular metal part is formed with a bulging cross-sectional shape. When the expander tool expands radially outwards, the sealing element in the groove is compressed, resulting in a slightly inherent spring force in the sealing element <NUM> so that when the pressure is released again, the sealing element decompresses, filling out the small gap between the groove and the projections.

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, a completion or an 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 "casing" or "well tubular metal structure" 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 downhole tractor can be used to push the tool all the way into position in the well. The downhole tractor may have projectable arms with wheels that 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®.

Claim 1:
An annular barrier (<NUM>) for providing zonal isolation in an annulus (<NUM>) downhole between a well tubular metal structure (<NUM>) and another well tubular metal structure (3b) or a wall (<NUM>) of a borehole (<NUM>), the annular barrier having an axial extension (L) and comprising:
- a tubular metal part (<NUM>) with an inner part face (<NUM>) and an outer part face (<NUM>) and configured to be mounted as part of the well tubular metal structure, and
- an expandable metal sleeve (<NUM>) surrounding the tubular metal part, forming an expandable space (<NUM>) therebetween; the expandable metal sleeve being configured to be expanded in a well downhole from a first outer diameter (D1) to a second outer diameter (D2) in order to abut against the well tubular metal structure or the wall of the borehole, the expandable metal sleeve (<NUM>) having a first end part (<NUM>), a second end part (<NUM>) and an outer face (<NUM>), and at least one of the end parts comprising at least one circumferential groove (<NUM>) facing the outer part face, characterized in that the tubular metal part bulges radially outwards in relation to the axial extension, forming at least one circumferential projection (<NUM>) engaging the groove, providing a connection of the expandable metal sleeve to the tubular metal part.