Annular barrier

Abstract

The present invention relates to an annular barrier for providing zonal isolation within a tubular structure or a borehole and for sealing off a first zone from a second zone, comprising a tubular metal part configured to be mounted as part of a well tubular metal structure, the tubular metal part having an outer face, an opening and an axial direction along the well tubular metal structure, a first expandable metal sleeve surrounding the tubular metal part and having a first end connected with the outer face of the tubular metal part and a second end, a second expandable metal sleeve surrounding the tubular metal part and having a first end connected with the outer face of the tubular metal part and a second end, wherein the first expandable metal sleeve and the second expandable metal sleeve each has an end section at the second end, the end section of the first expandable metal sleeve is at least partly overlapping the end section of the second expandable metal sleeve along the axial direction creating an overlapping area, the end sections are configured to slide in relation to each other, the first expandable metal sleeve and the second expandable metal sleeve define an annular space together with the tubular metal part, the first expandable metal sleeve extends from the second end of the first expandable metal sleeve away from the overlapping area in a first direction along the axial direction, and the second expandable metal sleeve extends from the second end of the second expandable metal sleeve away from the overlapping area in a second direction opposite the first direction.

1 . An annular barrier for providing zonal isolation within a tubular structure or a borehole and for sealing off a first zone from a second zone, comprising:
 tubular metal part configured to be mounted as part of a well tubular metal structure, the tubular metal part having an outer face, an opening and an axial direction along the well tubular metal structure,   a first expandable metal sleeve surrounding the tubular metal part and having a first end connected with the outer face of the tubular metal part and a second end,   a second expandable metal sleeve surrounding the tubular metal part and having a first end connected with the outer face of the tubular metal part and a second end, and   an annular space between the tubular metal part and the expandable metal sleeves,   
       wherein the first expandable metal sleeve and the second expandable metal sleeve each have an end section at the second end, the end section of the first expandable metal sleeve and the end section of the second expandable metal sleeve are at least partly overlapping along the axial direction creating an overlapping area, the end sections are configured to slide in relation to each other, the first expandable metal sleeve extends from the second end of the first expandable metal sleeve away from the overlapping area in a first direction along the axial direction, and the second expandable metal sleeve extends from the second end of the second expandable metal sleeve away from the overlapping area in a second direction opposite the first direction. 
     
     
         2 . An annular barrier according to  claim 1 , wherein the end sections of the overlapping area are unconnected to the outer face of the tubular metal part. 
     
     
         3 . An annular barrier according to  claim 1 , further comprising a third expandable metal sleeve surrounding the tubular metal part and having a first end connected with the outer face of the tubular metal part and a second end, an end section of the first end of the second expandable metal sleeve and an end section of the second end of the third expandable metal sleeve are at least partly overlapping along the axial direction creating an second overlapping area. 
     
     
         4 . An annular barrier according to  claim 1 , wherein the end sections of the overlapping area have a greater common thickness than the rest of the expandable metal sleeves. 
     
     
         5 . An annular barrier according to  claim 1 , wherein at least one sealing element is arranged between the end sections of the overlapping area(s). 
     
     
         6 . An annular barrier according to  claim 1 , wherein the end section of the first expandable metal sleeve is arranged sliding along an outer face of the second expandable metal sleeve, the end of the second sleeve provides a piston effect during expansion providing a pressure in the axial direction to the end of the second expandable metal sleeve. 
     
     
         7 . An annular barrier according to  claim 1 , wherein the end section of the second end of the second expandable metal sleeve is arranged sliding along an inner face of the first expandable metal sleeve and the end section of the first end of the second expandable metal sleeve is arranged sliding along an inner face of the third expandable metal sleeve. 
     
     
         8 . An annular barrier according to  claim 1 , wherein the overlapping area(s) remains substantially unexpanded during expansion of the rest of the expandable metal sleeve. 
     
     
         9 . An annular barrier according to  claim 1 , wherein each expandable metal sleeve is constituted by a first section and a second section, the second section is the end section. 
     
     
         10 . An annular barrier according to  claim 8 , wherein the first section has an unexpanded condition and an expanded condition, the first section is capable of expanding more than 30% than in the unexpanded condition. 
     
     
         11 . An annular barrier according to  claim 1 , wherein the end section of each sleeve has a length of at least 5% of a total length of the expandable metal sleeve in the unexpanded condition. 
     
     
         12 . An annular barrier according to  claim 1 , wherein the end section of the first expandable metal sleeve has grooves which correspond to grooves on the outer face of the end section of the second expandable metal sleeve forming a ratchet system hindering the end section of the first expandable metal sleeve from returning once moved away from the end section of the second expandable metal sleeve. 
     
     
         13 . An annular barrier according to  claim 1 , further comprising a shear pin assembly fluidly connecting the expansion opening and the annular space in order to allow expansion fluid within the well tubular structure to expand the expandable sleeve. 
     
     
         14 . An annular barrier according to  claim 1 , further comprising an anti-collapsing unit comprising an element, such as a ball, movable at least between a first position and a second position, the anti-collapsing unit having a first inlet which is in fluid communication with the first zone, and a second inlet which is in fluid communication with the second zone, and the anti-collapsing unit having an outlet which is in fluid communication with the annular space, and in the first position, the first inlet is in fluid communication with the outlet, equalising the first pressure of the first zone with the space pressure, and in the second position, the second inlet is in fluid communication with the outlet, equalising the second pressure of the second zone with the space pressure. 
     
     
         15 . An annular barrier according to  claim 1 , further comprising sealing elements arranged on an outer face of the expandable metal sleeves. 
     
     
         16 . An annular barrier according to  claim 1 , wherein the first ends of the expandable metal sleeves are welded to the outer face of the tubular metal part.