Annular barrier with compensation device

Abstract

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, comprising a tubular part for mounting as part of the well tubular structure, the tubular part having a longitudinal axis, an expandable sleeve surrounding the tubular part and defining 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, and an aperture for letting fluid into the space to expand the expandable sleeve, wherein the barrier further comprises a compensation device arranged in the space between the expandable sleeve and the tubular part, the compensation device having a chamber in which a piston is arranged dividing the chamber in a first and a second chamber part, the first chamber part being in fluid communication with the space and the second chamber part comprising gas.

1 . An annular barrier ( 1 ) to be expanded in an annulus ( 2 ) between a well tubular structure ( 3 ) and an inside wall ( 4 ) of a borehole ( 5 ) downhole for providing zone isolation between a first zone and a second zone of the borehole, comprising
 a tubular part ( 6 ) for mounting as part of the well tubular structure ( 3 ), the tubular part having a longitudinal axis,   an expandable sleeve ( 7 ) surrounding the tubular part and defining a space ( 13 ) being in fluid communication with an inside of the tubular part, each end ( 9 ,  10 ) of the expandable sleeve being connected with the tubular part, and   an aperture ( 11 ) for letting fluid into the space to expand the expandable sleeve,   wherein the barrier further comprises a compensation device arranged in the space between the expandable sleeve and the tubular part, the compensation device having a chamber in which a piston is arranged dividing the chamber into a first and a second chamber part, the first chamber part being in fluid communication with the space and the second chamber part comprising gas.   
     
     
         2 . An annular barrier according to  claim 1 , wherein the gas is nitrogen, neon, argon, krypton or xenon. 
     
     
         3 . An annular barrier according to  claim 1 , wherein the chamber is annular and surrounds the tubular part. 
     
     
         4 . An annular barrier according to  claim 1 , wherein the compensation device has several chambers in which pistons are arranged. 
     
     
         5 . An annular barrier according to  claim 1 , wherein one end of the sleeve is fixedly fastened to the tubular part and the other end is slidably fastened to the tubular part, and wherein the second chamber part containing the gas is arranged closest to the fixedly connected end of the sleeve. 
     
     
         6 . An annular barrier according to  claim 1 , wherein the second chamber part comprises a valve which is accessible from the inside of the tubular part, allowing refill of the second chamber part with gas. 
     
     
         7 . An annular barrier according to  claim 1 , wherein the piston comprises sealing means for sealing the second chamber part from the first chamber part. 
     
     
         8 . An annular barrier according to  claim 1 , further comprising an annulus pressure compensator ( 50 ) comprising a cylinder ( 51 ) wherein a piston ( 52 ) is arranged, a first end ( 511 ) of the cylinder being in fluid communication with the annulus and a second end ( 512 ) of the cylinder being in fluid communication with the space defined by the expandable sleeve. 
     
     
         9 . An annular barrier according to  claim 1 , further comprising a check valve ( 60 ) fluidly connecting the annulus with the space defined by the expandable sleeve. 
     
     
         10 . An annular barrier according to  claim 9 , wherein the check valve is integrated in one of the connection parts or in a wall of the expandable sleeve. 
     
     
         11 . An annular barrier according to  claim 9 , comprising a directional three-way valve ( 70 ) incorporating the check valve, the directional three-way being adapted to control the flow of fluid into the space from the annulus and from the inside of the tubular part. 
     
     
         12 . A well system comprising the well tubular structure and the annular barrier according to  claim 1 . 
     
     
         13 . A well system according  claim 12 , further having a tool ( 29 ) comprising isolation means ( 30 ) isolating an isolated part ( 28 ) of the inside ( 23 ) of the tubular part outside the aperture ( 11 ) to pressurise the isolated part ( 28 ) of the inside ( 23 ) and the space ( 13 ) to expand the expandable sleeve ( 7 ). 
     
     
         14 . A well system according  claim 13 , wherein the tool further comprises a pumping device ( 31 ) for pumping fluid from the inside of the tubular part being outside the isolated part ( 28 ) and into the isolated part ( 28 ) to expand the expandable sleeve. 
     
     
         15 . A method for maintaining a pressure within the annular barrier according to  claim 1 , comprising the steps of:
 expanding the expandable sleeve until the sleeve seals against the inside wall of the borehole, and   equalising the pressure inside the space when the temperature decreases or increases in the borehole by moving the piston and letting the gas in the second chamber part expand or diminish.