Annular barrier having expansion tubes

Abstract

The present invention relates to an annular barrier ( 1 ) for mounting as part of a well tubular structure ( 3 ), the annular barrier being adapted to be expanded in an annulus ( 2 ) between the well tubular structure and an inside wall ( 41 ) of a borehole ( 4 ). The annular barrier comprises a tubular part ( 6 ) extending in a longitudinal direction, one or more an expandable tube(s) ( 7 ) each having a centre axis ( 72 ) extending outside the tubular part in the longitudinal direction, and a sealing element ( 8 ) in the form of an expandable sleeve provided on an outer surface of the one or more expandable tube(s) for providing sealing against the inside wall of the borehole, the expandable sleeve extending on the outside of the one or more expandable tube (s). Furthermore, the invention relates to a method of expanding an annular barrier in an annulus and to a downhole system.

1 . 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 for sealing off a hydro carbon-producing zone of a formation, and the annular barrier comprising:
 a tubular part extending in a longitudinal direction,   one or more expandable tubes each having a centre axis extending outside the tubular part in the longitudinal direction, and   a sealing element in the form of an expandable sleeve provided on an outer surface of all of the expandable tube(s) for providing sealing against the inside wall of the borehole,   the expandable sleeve extending on the outside of all of the expandable tube(s) in relation to the tubular part and being attached to a connection art or being attached to the tubular art.   
     
     
         2 . An annular barrier according to  claim 1 , wherein the centre axis of the expandable tube coils around the tubular part in the longitudinal direction. 
     
     
         3 . An annular barrier according to  claim 1 , wherein an inner space of the expandable tube is in fluid communication with an inner passage of the tubular part. 
     
     
         4 . An annular barrier according to  claim 1 , wherein a cross-section of the expandable tube in a relaxed position is substantially oval-shaped. 
     
     
         5 . An annular barrier according to  claim 1 , wherein a cross-section of the expandable tube in an expanded position is substantially circular. 
     
     
         6 . An annular barrier according to  claim 1 , wherein the annular barrier comprises a plurality of expandable tubes extending on the outside of the tubular part in the longitudinal direction. 
     
     
         7 . An annular barrier according to  claim 1 , further comprising a connecting part arranged on the outside of the tubular part for attaching the one or more expandable tube(s) to the tubular part. 
     
     
         8 . An annular barrier according to  claim 1 , wherein the connection part comprises 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 passaged of the tubular part. 
     
     
         9 . An annular barrier according to  claim 1 , wherein an outer diameter (D 1   e ) of the annular barrier in an expanded position is up to 150% of an outer diameter (D 2 ) of the tubular part. 
     
     
         10 . An annular barrier according to  claim 1 , wherein an outer diameter (D 1   e ) of the annular barrier in an expanded position is 140% to 150% of an outer diameter (D 2 ) of the tubular part. 
     
     
         11 . A method of expanding an annular barrier according to  claim 1  in an annulus between a well tubular structure and an inside wall of a borehole, the method comprising the step of:
 expanding the one or more expandable tube(s) by injecting a fluid into an inner space of the expandable tube(s), whereby a cross-section of the expandable tube(s) is transformed from a substantially oval shape to a substantially circular shape. 
 
     
     
         12 . A downhole system comprising:
 a well tubular structure, and   one or more annular barrier(s) according to  claim 1 , mounted as part of the well tubular structure.