This application is the U.S. national phase of International Application No. PCT/EP2012/067819, filed 12 Sep. 2012, which designated the U.S. and claims priority to EP Application No. 11181068.5, filed 13 Sep. 2011, the entire contents of each of which are hereby incorporated by reference.
The present invention relates to an annular barrier to be expanded in an annulus between a well tubular structure and an inside wall of a borehole downhole for providing zone isolation between a first zone and a second zone of the borehole.
In wellbores, annular barriers are used for different purposes, such as for providing an isolation barrier. An annular barrier has a tubular part mounted as part of the well tubular structure, such as the production casing, which is surrounded by an annular expandable sleeve. The expandable sleeve is typically made of an elastomeric material or metal. The sleeve is fastened at its ends to the tubular part of the annular barrier.
In order to seal off a zone between a well tubular structure and the borehole or an inner and an outer tubular structure, a second annular barrier is used. The first annular barrier is expanded on one side of the zone to be sealed off, and the second annular barrier is expanded on the other side of that zone, and in this way, the zone is sealed off.
The pressure envelope of a well is governed by the burst rating of the tubular and the well hardware etc. used within the well construction. In some circumstances, the expandable sleeve of an annular barrier may be expanded by increasing the pressure within the well, which is the most cost-efficient way of expanding the sleeve.
Expanding the expandable sleeve by increasing the pressure within the well requires a high expansion pressure. Using such a high expansion pressure applies great stressing forces to the expandable sleeve, and the expandable sleeve may rupture during expansion. The rupture of an expandable sleeve is very undesirable since the outside of the well casing, i.e. the borehole environment, becomes fluidly connected with the inside of the well casing, thereby polluting the production fluid, e.g. crude oil, with fluids containing less oil, e.g. drilling mud.
Expanded annular barriers may be subjected to a continuous pressure or a periodic high pressure from the outside, either in the form of hydraulic pressure within the well environment or in the form of formation pressure. In some circumstances, such pressure may cause the annular barrier to collapse, which may have consequences for the area which is to be sealed off by the barrier as the sealing properties are lost due to the collapse. Therefore, annular barriers are designed to withstand large pressure to avoid collapse. The ability of the expanded sleeve of an annular barrier to withstand the collapse pressure is referred to as the collapse rating.
The ability of the expanded sleeve of an annular barrier to withstand both the expansion pressure during expansion of the annular barrier and withstand the collapse pressure during the lifetime of the annular barrier, which may easily exceed 20 years, is thus affected by many variables, such as strength of material, wall thickness, surface area exposed to the collapse pressure, temperature, well fluids, etc. To increase resistance against rupture and collapse of the annular barrier, expandable sleeves are therefore conventionally made thicker and even braced with bracing elements to avoid collapse. However, rupture of the expandable sleeve typically arises due to irregularities in the material leading to a “weak area” on the expandable sleeve, and therefore even the strongest expandable sleeves being expandable by an available expansion pressure in the well may rupture due to these “weak areas”. Producing a “perfect” expandable sleeve without any “weak areas” is practically impossible even with modern high standard material synthesis techniques, at least in a scaled production facility producing bulk annular barriers for the oil producing industry.
It is thus desirable to provide a solution wherein the annular barrier is improved so that it does not rupture during expansion or collapse when expanded, without having to increase the thickness of the expandable sleeve to levels where the expandable sleeve cannot be inflated by the available expansion pressure in the well.
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 solution which does not rupture during expansion while still maintaining a required collapse rating.
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 to be expanded in an annulus between a well tubular structure and an inside wall of a borehole downhole for providing zone isolation between a first zone and a second zone of the borehole, comprising
In one embodiment, the sleeves may have a length, and the first face of the first safety metal sleeve may abut the face of the expandable metal sleeve along the whole length of the expandable metal sleeve.
Moreover, the first safety metal sleeve may have a first inner face abutting the outer face of the expandable metal sleeve.
The annular barrier as described above may further comprise a second safety metal sleeve surrounding the tubular part, the expandable metal sleeve and said second safety metal sleeve having a second inner face facing the safety metal sleeve, each end of the second safety metal sleeve being connected with the connection part which is connected with the tubular part.
Also, the annular barrier as described above may comprise a third safety metal sleeve, said third safety metal sleeve having a third inner face facing the second outer face of the second safety metal sleeve, each end of the third safety metal sleeve being connected with the connection part which is connected with the tubular part.
Further, the annular barrier as described above may comprise a plurality of additional safety metal sleeves surrounding the tubular part and the safety metal sleeves being the first and second safety metal sleeves and being connected with the connection part which is connected with the tubular part.
In addition, the expandable metal sleeve and safety metal sleeve may have different required expansion pressures, i.e. the pressure required to expand one sleeve may be different from sleeve to sleeve.
Moreover, the expandable metal sleeve and safety metal sleeve may be made from different materials.
Said sleeves may have a thickness and the thickness of the expandable metal sleeve may be greater than the thickness of the safety metal sleeve.
Also, the sleeves may have a thickness, the thickness of the first safety metal sleeve being smaller than the thickness of the expandable metal sleeve and greater than the thickness of the second safety sleeve.
Additionally, the sleeves may have a thickness, the thickness of the first safety metal sleeve being smaller than the thickness of the expandable metal sleeve and smaller than the thickness of the second safety sleeve.
Furthermore, the safety metal sleeve may have a higher ductility than the expandable metal sleeve.
The expandable metal sleeve may have a higher yield strength than the safety metal sleeve.
More specifically, the thickness of the expandable metal sleeve may be at least 10% greater than the thickness of the safety metal sleeve(s), preferably at least 15% greater than the thickness of the safety metal sleeve(s), and more preferably at least 20% greater than the thickness of the safety metal sleeve(s).
In an embodiment, the first safety metal sleeve may be made of a material having an elongation of more than 10% of an elongation of the material of the expandable metal sleeve.
Also, one of the safety metal sleeves may be made of a material more ductile than a material of the expandable metal sleeve.
Said expandable metal sleeve may have a length being substantially equal to a length of the first and second sleeves in an unexpanded condition of the annular barrier.
Further, the expandable metal sleeve may be made of a material having a yield strength which is higher than a yield strength of a material of the first and/or second safety metal sleeve.
In addition, the expandable metal sleeve may be made of a material having a yield strength which is at least 10% higher than a yield strength of a material of the first and/or second sleeve, preferably at least 15% higher and more preferably at least 20% higher than a yield strength of the material of the first and/or second sleeve.
Moreover, the expandable metal sleeve may have an unexpanded outside diameter and an expanded outside diameter, the expanded diameter of the expandable metal sleeve being at least 10% larger than the unexpanded diameter, preferably at least 15% larger than the unexpanded diameter, more preferably at least 30% larger than the unexpanded diameter.
The second sleeve may have circumferential elements restricting a free expansion of at least the second safety sleeve.
In an embodiment, the additional sealing element surrounding an outermost safety sleeve may comprise an intermediate layer of elastomer, rubber or polymer arranged between the outermost safety metal sleeve and a sealing element sleeve.
Furthermore, the safety metal sleeve closest to the inside wall of the borehole may be made from a sealing metal material.
Also, the safety metal sleeve closest to the inside wall of the borehole may comprise at least one sealing element.
Finally, the annular barrier according to the present invention may further comprise a protective layer of lames on the outer face of the safety metal sleeve closest to the inside wall of the borehole.
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
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.
When using several additional safety metal sleeves such as shown in
The thickness of the expandable metal sleeve shown in
An annular barrier may comprise several additional safety metal sleeves 10, such as three additional safety metal sleeves 10, such as four additional safety metal sleeves 10, such as five additional safety metal sleeves 10, or even more additional safety metal sleeves.
The safety metal sleeve of
The annular barrier of the present invention may be improved with respect to sealing properties towards the inside wall 4 of the borehole by adding an additional sealing element surrounding an outermost safety sleeve, which comprises an intermediate layer of elastomer, rubber or polymer arranged between the outermost safety metal sleeve and a sealing element sleeve. Also, other known sealing elements may be added to the annular barrier surrounding the outermost safety sleeve to improve sealing properties of the annular barrier.
Also, the outermost safety metal sleeve may be made from or comprise a sealing metal material. If additional sealing elements surrounding the outermost safety metal sleeve are inappropriate for other reasons such as limited space in the annulus, the outermost safety metal sleeve may be made from a material having good sealing properties such as high ductility.
Also, the annular barrier may comprise restricting a free expansion of the sleeves.
The expandable metal sleeve 7 and the additional safety metal sleeves 8, 9, 10 may be made from different materials, one having a higher strength and thereby lower ductility than the other material having a lower strength but higher ductility. Hereby, the annular barrier may comprise the materials adapted to provide high strength or high ductility in a preferred combination. Once expanded, the overall effect is an annular barrier with a higher collapse resistance and higher resistance towards rupture during expansion.
Also, the metal used for the sleeves may have an elongation of 10-35%, preferably 25-35%. The metal may have a yield strength (cold worked) of 500-1000 MPa, preferably 500-700 MPa. The sleeves may be a cold-drawn or hot-drawn tubular structure.
The thickness of the expandable metal sleeve may preferably be at least 10% greater than the thickness of the safety metal sleeves, and more preferably at least 15% greater than the thickness of the safety metal sleeves, and even more preferably at least 20% greater than the thickness of the safety metal sleeves.
The thickness of the safety metal sleeve may be 0.5 mm to 5 mm, and the thickness of the expandable metal sleeve may be 5 mm to 20 mm.
Furthermore, the safety metal sleeves may preferably be made from a material having an elongation of more than 10% of an elongation of the material of the expandable metal sleeve.
The annular barrier may preferably comprise an expandable metal sleeve made from a material having a yield strength which is at least 10% higher than a yield strength of a material of the first and/or second safety metal sleeve, or more preferably at least 15% higher and even more preferably at least 20% higher than a yield strength of the material of the first and/or second safety metal sleeve.
Also, the expandable metal sleeve may have an unexpanded outside diameter and an expanded outside diameter, the expanded diameter of the expandable metal sleeve being at least 10% larger than the unexpanded diameter, preferably at least 15% larger than the unexpanded diameter, and more preferably at least 30% larger than the unexpanded diameter.
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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11181068 | Sep 2011 | EP | regional |
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PCT/EP2012/067819 | 9/12/2012 | WO | 00 | 5/14/2013 |
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WO2013/037816 | 3/21/2013 | WO | A |
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International Preliminary Report on Patentability issued in International Application No. PCT/EP2012/067819 dated Mar. 18, 2014. |
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Number | Date | Country | |
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20140196887 A1 | Jul 2014 | US |