Sealing material for annular barriers

Abstract

The present invention relates to an annular barrier for providing zone isolation between a first zone and a second zone in a borehole or a casing downhole, the annular barrier comprising a tubular part and an expandable element made of metal surrounding the tubular part, and the annular barrier having a circumference, a longitudinal extension and an outer face and further comprising an annular seal comprising a sealing material, the sealing material extending around the outer face of the annular barrier and having a bundle of strands wherein at least one strand comprises graphite and/or carbon.

1 - 23 . (canceled) 
     
     
         24 . An annular barrier for providing zone isolation between a first zone and a second zone in a borehole or a casing downhole, the annular barrier comprising a tubular part and an expandable element made of metal surrounding the tubular part, and the annular barrier having a circumference, a longitudinal extension and an outer face and further comprising an annular seal comprising a sealing material, the sealing material extending around the outer face of the annular barrier and having a bundle of strands wherein at least one strand comprises graphite and/or carbon. 
     
     
         25 . An annular barrier according to  claim 24 , wherein the strands comprise at least 30% graphite and/or carbon, preferably at least 50% graphite and/or carbon, more preferably at least 75% graphite and/or carbon, and even more preferably at least 90% graphite and/or carbon. 
     
     
         26 . An annular barrier according to  claim 24 , wherein each strand comprises graphite and/or carbon. 
     
     
         27 . An annular barrier according to  claim 24 , wherein the sealing material is wound around the outer face of the annular barrier with x windings, where x>1.0. 
     
     
         28 . An annular barrier according to  claim 24 , wherein the annular seal has an elongated shape and two ends. 
     
     
         29 . An annular barrier according to  claim 28 , wherein the ends overlap when seen in the longitudinal extension. 
     
     
         30 . An annular barrier according to  28 , wherein the annular seal is arranged side by side around the outer face as windings. 
     
     
         31 . An annular barrier according to  claim 30 , wherein the overlap extends over at least 10% of the circumference of the annular barrier, preferably at least 15% of the circumference, more preferably at least 30%, and even more preferably at least 40% of the circumference. 
     
     
         32 . An annular barrier according to  claim 24 , wherein the sealing material may cover less than 60% of the outer face, preferably less than 40% of the outer face, and more preferably less than 30% of the outer face. 
     
     
         33 . An annular barrier according to  claim 24 , wherein a cross-sectional shape of the annular seal may substantially be a triangle, a square, a pentagon, a hexagon or a shape having more sides. 
     
     
         34 . An annular barrier according to  claim 24 , wherein the strands abut each other. 
     
     
         35 . An annular barrier according to  24 , wherein the strands are twisted around each other, braided or forms a yarn. 
     
     
         36 . An annular barrier according to  claim 24 , wherein
 the tubular part for mounting as part of the well tubular structure has a longitudinal axis, and   the expandable sleeve surrounding the tubular part defines a space being in fluid communication with an inside of the tubular part, each end of the expandable sleeve being connected with the tubular part, wherein the annular barrier further comprises an aperture for letting fluid into the space to expand the sleeve.   
     
     
         37 . An annular barrier according to  claim 24 , wherein the aperture is arranged in the tubular part. 
     
     
         38 . An annular barrier according to  claim 24 , further comprising an adhesive between the outer face and the annular seal. 
     
     
         39 . A downhole system comprising a well tubular structure and at least one annular barrier according to  claim 24 , wherein the annular barrier comprises a tubular structure mounted as part of the well tubular structure. 
     
     
         40 . A manufacturing method for manufacturing a annular barrier according to  claim 24 , comprising the steps of:
 winding the sealing material around the outer face of the annular barrier to form the annular seal, and   fastening the sealing material by providing an adhesive between the sealing material and outer face of the annular barrier.   
     
     
         41 . An application method of providing an annular barrier according to  claim 24  in a casing or borehole, comprising the steps of:
 - inserting an annular barrier in the casing or borehole having x windings of sealing material around the outer face, where x>1.0, and - expanding the annular barrier so that the annular barrier has y windings of sealing material around the outer face, wherein y<x. 
 
     
     
         42 . An application method according to  claim 41 , wherein x>1.5 and y>1.0. 
     
     
         43 . An application method according to  claim 41 , wherein the sealing material has substantially the same length before and after expansion of the annular barrier.