Radially expanding a tubular element

Abstract

The invention relates to a method of radially expanding a tubular element. The method comprises inducing the wall of the tubular element to bend radially outward and in axially reverse direction so as to form an expanded tubular section extending around an unexpanded section of the tubular element, said wall having a resistance to radially outward bending and a resistance to stretching in circumferential direction. Said wall is provided with at least one of primary means for increasing the resistance to radially outward bending of the wall, and secondary means for reducing the resistance to stretching in circumferential direction of the wall.

1 . A method of radially expanding a tubular element, the method comprising inducing the wall of the tubular element to bend radially outward and in axially reverse direction so as to form an expanded tubular section extending around an unexpanded section of the tubular element, said wall having a bending stiffness and a resistance to stretching in circumferential direction, wherein said wall is provided with at least one of primary means for increasing the bending stiffness of the wall, and secondary means for reducing the resistance to stretching in circumferential direction of the wall. 
   
   
       2 . The method of  claim 1 , wherein said primary means comprises at least one stiffening member extending in longitudinal direction along said wall. 
   
   
       3 . The method of  claim 2 , wherein the stiffening member is connected to at least one of the outer surface and the inner surface of said wall. 
   
   
       4 . The method of  claim 2 , wherein the stiffening member and the wall are integrally formed. 
   
   
       5 . The method of any  claim 2 , wherein said primary means comprises a plurality of said stiffening members regularly spaced along the circumference of the tubular element. 
   
   
       6 . The method of  claim 1 , wherein said secondary means comprises at least one groove formed in said wall, each groove extending in longitudinal direction of the tubular element. 
   
   
       7 . The method of  claim 6 , wherein the groove is formed in at least one of the outer surface and the inner surface of said wall. 
   
   
       8 . The method of  claim 6 , wherein said secondary means comprises a plurality of said grooves regularly spaced along the circumference of the tubular element. 
   
   
       9 . The method of  claim 1 , wherein said bending of the wall occurs in a bending zone of the tubular element, and wherein the method further comprises progressively increasing the length of said expanded tubular section by inducing the bending zone to move in axial direction along the tubular element. 
   
   
       10 . The method of  claim 1 , wherein the wall is induced to bend by moving the unexpanded tubular section in axial direction relative to the expanded tubular section. 
   
   
       11 . The method of  claim 1 , wherein the tubular element extends into a wellbore formed in an earth formation. 
   
   
       12 . The method of  claim 11 , wherein the expanded tubular section extends between the wellbore wall and the unexpanded section of the tubular element. 
   
   
       13 . The method of  claim 11 , wherein said bending of the wall is started at a lower end portion of the tubular element. 
   
   
       14 . The method of  claim 1 , wherein the expanded tubular section is kept substantially stationary in the wellbore and the unexpanded tubular section is moved in downward direction of the wellbore to induce said bending of the wall. 
   
   
       15 . The method of  claim 14 , wherein a downward force is exerted to the unexpanded tubular section to move the unexpanded tubular section in downward direction of the wellbore. 
   
   
       16 . The method of  claim 1 , wherein the wellbore is being drilled with a drill string extending through the unexpanded tubular section. 
   
   
       17 . The method of  claim 16 , wherein the unexpanded tubular section and the drill string are simultaneously lowered through the wellbore during drilling with the drill string. 
   
   
       18 . The method of  claim 1 , wherein the expanded tubular section is compressed against the wellbore wall or against another tubular element arranged in the wellbore as a result of the expansion process. 
   
   
       19 . A radially expanded tubular element obtained with the method of  claim 1 . 
   
   
       20 . (canceled) 
   
   
       21 . (canceled)