Rock anchor

Abstract

The present invention relates to a formation fixation device for securing a tubular in an open-hole wellbore, the formation fixation device comprising a tubular part, a fixation unit and a fluid passage. Furthermore, the invention relates to a downhole fixation system for securing a casing comprising a first end and a second end in an open-hole wellbore and to a method of permanently fixating a tubular part in an open-hole wellbore as well as to use of a formation fixation device according to the invention for fixating a tubular part in an open-hole wellbore.

1 . A formation fixation device ( 1 ) for securing a tubular in an open-hole wellbore, the formation fixation device ( 1 ) comprising:
 a tubular part ( 10 ) extending in an axial direction, the tubular part ( 10 ) having an exterior surface ( 11 ) and a hollow interior ( 29 ),   a fixation unit ( 20 ) arranged at the exterior surface ( 11 ) of the tubular part ( 10 ), the fixation unit having a first end ( 21 ) and a second end ( 22 ) movable in relation to one another in the axial direction, and   a fluid passage ( 28 ) extending from the hollow interior to one of the ends ( 21 ,  22 ) of the fixation unit;   wherein at least one of the ends ( 21 ,  22 ) of the fixation unit is moved when the tubular part is pressurised from within, forcing the fixation unit to project in a radial direction in relation to the tubular part, whereby the fixation unit enters into a projected position.   
     
     
         2 . A formation fixation device according to  claim 1 , wherein the fixation unit comprises a locking mechanism ( 50 ) for permanently locking the fixation unit in the projected position. 
     
     
         3 . A formation fixation device according to  claim 1 , wherein the fixation unit comprises a slotted liner ( 26 ) having a plurality of members ( 23 ) connecting the first end and the second end, the members being projected in a radial direction in relation to the tubular part when the ends of the fixation unit are moved towards each other. 
     
     
         4 . A formation fixation device according to  claim 3 , wherein the slotted liner surrounds the tubular part. 
     
     
         5 . A formation fixation device according to  claim 3 , wherein each of the members has a bend initiator ( 24 ), such as a transverse slot or fold, arranged substantially in a middle part of each member in the axial direction. 
     
     
         6 . A formation fixation device according to  claim 2 , wherein the fixation unit comprises two pivotally connected members ( 31 ). 
     
     
         7 . A formation fixation device according to  claim 1 , wherein the fixation unit is arranged in a recess in the tubular part. 
     
     
         8 . A formation fixation device according to  claim 1 , wherein one of the ends of the fixation unit constitutes a piston part ( 30 ) comprising a surface ( 40 ) adapted for receiving a force induced by a pressurised medium contained in the hollow interior of the tubular part. 
     
     
         9 . A formation fixation device according to  claim 1 , wherein both ends of the fixation unit constitute a piston part comprising a surface adapted for receiving a force induced by a pressurised medium contained in the hollow interior of the tubular. 
     
     
         10 . A formation fixation device according to  claim 1 , wherein both ends of the fixation unit are movable in relation to the tubular part. 
     
     
         11 . A formation fixation device according to  claim 1 , wherein the fixation device comprises a plurality of fixation units. 
     
     
         12 . A downhole fixation system for securing a casing comprising a first end and a second end in an open-hole wellbore, the fixation system comprising:
 the formation fixation device according to  claim 1 ,   a casing connected with the tubular of the formation fixation device,   one or more annular barriers comprising a tubular part and a surrounding expandable sleeve, and   a pressure creating device fluidly connected to the hollow interior of the tubular part of the formation fixation device.   
     
     
         13 . A downhole fixation system according to  claim 12 , wherein the pressure creating device is a downhole tool adapted to be arranged in fluid connection with the fluid passage. 
     
     
         14 . A downhole fixation system according to  claim 12 , wherein the pressure creating device is a pump positioned outside the wellbore. 
     
     
         15 . A method of permanently fixating a tubular part in an open-hole wellbore, the method comprising the steps of:
 connecting the permanent formation fixation device according to  claim 1  with one or more casing elements,   positioning the formation fixation device at a predetermined location in an open-hole wellbore, and   activating the fixation unit by applying a hydraulic pressure to one of the ends of the fixation unit, whereby the fixation unit engages with the sides of the wellbore.   
     
     
         16 . Use of a formation fixation device according to  claim 1  for fixating a tubular part in an open-hole wellbore.