The present invention relates to an annular barrier for mounting as part of a well tubular structure, the annular barrier being adapted to be expanded in an annulus between the well tubular structure and an inside wall of a borehole. Furthermore, the invention relates to a method of expanding an annular barrier in an annulus and to a downhole system.
In hydro-carbon producing wells, annular barriers or packers are often used to seal off a section of the borehole, such as an oil producing zone in the formation. The section may be sealed off to avoid excessive amounts of water flowing into the production casing from other parts of the borehole.
Known annular barriers often comprise a tubular part extending in a longitudinal direction, such as a casing surrounded by an expandable sleeve. The expandable sleeve is expanded in an annulus between the casing and an inside wall of a borehole. In such a construction, the expandable sleeve is often arranged substantially concentrically in relation to the tubular part, and a centre axis of the expandable sleeve coincides with a centre axis of the tubular part. The centre axis of the expandable sleeve thus extends inside the tubular part.
When designing a well, it is difficult to establish the exact diameter of the borehole. Further, the diameter may vary substantially along the extension of the borehole due to changes in the composition of the formation. The walls of the borehole may for example partly collapse during or after drilling, or fluid flowing in the well may erode the walls, thereby affecting the diameter of the borehole.
Several drawbacks exist in relation to annular barriers of the prior art. Known annular barriers may be expanded to have an outer diameter of maximum 20-30% beyond the outer diameter of the casing. This may be adequate in some parts of the well, however, in sections of the well having an increased diameter, it may not to sufficient to provide a proper seal between the casing and the wall of the borehole.
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 annular barrier being able to seal a larger annulus surrounding a well tubular 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 mounting as part of a well tubular structure, the annular barrier being adapted to be expanded in an annulus between the well tubular structure and an inside wall of a borehole, and the annular barrier comprising:
Hereby, the annular barrier may be sufficiently expanded for sealing a larger annulus than annular barriers of the prior art.
In an embodiment of the invention, a centre axis of the expandable tube may be arranged outside the tubular part.
Furthermore, the centre axis of the expandable tube may coil around the tubular part in the longitudinal direction.
Moreover, the expandable tube may coil around the tubular part in the longitudinal direction.
In an embodiment, an inner space of the expandable tube may be in fluid communication with an inner passage of the tubular part.
Additionally, a cross-section of the expandable tube in a relaxed position may be substantially oval-shaped.
Further, a shape of a cross-section of the expandable tube in a relaxed position may comprise multiple creases.
In addition, a cross-section of the expandable tube in an expanded position may be substantially circular.
In one embodiment, the annular barrier may comprise a plurality of expandable tubes extending on the outside of the tubular part in the longitudinal direction.
The annular barrier according to the invention may further comprise a sealing element provided on an outer surface of the one or more expandable tube(s) for providing sealing against the inside wall of the borehole.
Moreover, the sealing element may be an expandable sleeve extending on the outside of the one or more expandable tube(s).
In addition, the sealing element may be made of metal, polymer, elastomer, rubber or a swellable material.
Furthermore, the one or more expandable tube(s) may at least partly be embedded in a sealing material.
The annular barrier may further comprise one or more sealing bands encircling the sealing element or the expandable sleeve to provide additional sealing.
Moreover, the annular barrier may comprise a connecting part arranged on the outside of the tubular part for attaching the one or more expandable tube(s) to the tubular part.
In an embodiment, the connection part may attach one end of each of the one or more expandable tube(s) to the tubular part.
Additionally, the annular barrier may comprise a second connection part for attaching the opposite end of each of the one or more expandable tube(s) to the tubular part.
Furthermore, the annular barrier may comprise a fixed connection part and a sliding connection part for attaching opposite ends of the one or more expandable tube(s).
In an embodiment of the annular barrier, the connection part may comprise one or more fluid channel(s) for providing fluid communication between the inner space of the one or more expandable tube(s) and the inner passage of the tubular part.
Moreover, an outer diameter of the annular barrier in an expanded position may be up to 150% of an outer diameter of the tubular part.
In addition, an outer diameter of the annular barrier in an expanded position may be 140% to 150% of an outer diameter of the tubular part.
Hereby, the annular barrier may be able to provide sufficient sealing in wellbores having a greatly varying inner diameter.
The present invention furthermore relates to a method of expanding an annular barrier as described above in an annulus between a well tubular structure and an inside wall of a borehole, the method comprising the step of:
In an embodiment, the fluid may be injected into the inner space by pressurising an inner passage of the tubular part, and a fluid is thereby injected into the well tubular structure, providing fluid communication between the inner passage of the tubular structure and the inner space of the expandable tube(s).
Finally, the invention relates to a downhole system comprising:
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
a and 1b show longitudinal cross-sectional views of an annular barrier in a relaxed position and an expanded position, respectively,
a shows a cross-sectional view of the annular barrier of
b shows a cross-sectional view of the annular barrier of
c shows a transverse cross-sectional view of another annular barrier comprising expandable tubes partially embedded in a sealing element,
a shows an annular barrier in a relaxed position, comprising a coiled tube,
b shows a longitudinal cross-sectional view of the annular barrier of
c shows a cross-sectional view of the annular barrier of
a shows the annular barrier of
b shows a longitudinal cross-sectional view of the annular barrier of
a and 5b show longitudinal cross-sectional views of another annular barrier in a relaxed position and an expanded position, respectively, comprising a sealing element provided on an outer surface of the expandable tube,
a and 6b show longitudinal cross-sectional views of another annular barrier in a relaxed position and an expanded position, respectively, comprising a sealing element in the form of an expandable sleeve,
a and 7b show longitudinal cross-sectional views of another annular barrier in a relaxed position and an expanded position, respectively, comprising yet another configuration of a sealing element, and
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.
a and 1b show an annular barrier 1 for being mounted as part of a well tubular structure 3 in a downhole system 100 as shown in
As shown in
In
a and 2b are cross-sectional views of the annular barrier shown in
In
Another configuration of an annular barrier according to an embodiment of the invention is shown in
In
In another configuration, the annular barrier 1 of
a and 7b show yet another configuration of the annular barrier 1 where the expandable tube 7 is at least partially embedded in the sealing element 8. Thus, the sealing element 8 expands as the expandable tubes are expanded, thereby increasing the outer diameter of the sealing element, and the sealing element is moved outwards away from the tubular part during expansion.
When the annular barriers 1 described above are expanded, the outer diameter D1e of the annular barrier in an expanded position, as shown in
The downhole system 100 further comprises a plurality of valve sections 105 for letting hydrocarbon-containing fluid into an inner space 31 of the well tubular structure 3. The valve section 105 may contains inflow control valves 106 and/or a fracturing valve 107. Further, a screen 108 may be arranged opposite the valves. The well tubular structure 3 may be a production casing or injection casing and/or comprise a multitude of other functional elements, such as sliding sleeves, screens, gravel packs, etc.
In use, one or more annular barriers 1 are mounted as part of a well tubular structure 3, such as a casing, and lowered into a borehole 4. When the annular barriers 1 are to be expanded, e.g. when a hydro carbon producing zone of the formation is to be sealed off, the well tubular structure 3 is pressurised from within by injecting a fluid. As the inner space 73 of the one or more expandable tube(s) 7 of the annular barrier(s) 1 is in fluid communication with the pressurised inner space 31 of the tubular part 6, the one or more expandable tube(s) are expanded.
Furthermore, the expandable tubes 7 may be made of any kind of suitable metal.
The expandable sleeve 81 of the annular barrier 1 may be made of metal, polymers, an elastomeric material, silicone or natural or synthetic rubber.
The fluid used for expanding the expandable tubes 7 may be any kind of well fluid present in the borehole surrounding the tool and/or the well tubular structure 3. Also, the fluid may be cement, gas, water, polymers or a two-component compound, such as powder or particles mixing or reacting with a binding or hardening agent. Part of the fluid, such as the hardening agent, may be present in the cavity between the tubular part 6 and the expandable tube 7 before injecting a subsequent fluid into the cavity.
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.
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.
Number | Date | Country | Kind |
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12162460.5 | Mar 2012 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2013/056469 | 3/27/2013 | WO | 00 |