Method and system for surplus expansion of a bell section at a lower end of an expanded tubular

Abstract

A method for expanding a lower bell section of an expandable tubular to a larger diameter than upper parts thereof utilizes an expandable bell cone ( 1 ) with circumferentially spaced segments ( 2 ) that expand in response to axial force and automatically retract in response to removal of the axial force, wherein gaps (A) are present between the expanded segments ( 2 ) and the tailends ( 2 A) at the gauge of the segments are slightly skewed to mitigate the effect of the gaps (A) on the flattening of the expanded bell sections between the segments ( 2 ).

1 . A method for expanding a bell section at a lower end of an expandable tubular to a larger diameter than upper parts of the expandable tubular, the method comprising:
 expanding the tubular with a primary expansion cone to a predetermined expanded width; and   expanding the bell section of the tubular to a larger width than the predetermined expanded width using a bell cone with segments circumferentially spaced around on a conical surface such that the segments expand in response to axial force and automatically retract in response to removal of the axial force,   
       wherein:
 gaps are present between the expanded segments and the tail-ends at the gauge of the segments are slightly skewed to mitigate the effect of the gaps on the flattening of the expanded bell sections between the segments; and 
 the segments are circumferentially spaced in a V-shaped groove between a pair of adjacent conical surfaces having top angles and friction coefficients to allow the segments to retract in the absence of axial pressure directed towards the gauge of the segments. 
 
     
     
         2 . A system for expanding a bell section at a lower end of an expandable tubular to a larger diameter than upper parts of the expandable tubular comprises:
 a primary expansion cone for expanding the tubular to a predetermined expanded width; and   a segmented bell cone for expanding the bell section of the tubular to a larger width than the predetermined expanded width using a bell cone with segments circumferentially spaced around on a conical surface such that the segments expand in response to axial pressure and automatically retract in response to removal of the axial pressure,   
       wherein:
 gaps are present between the expanded segments and the tail-ends at the gauge of the segments are slightly skewed to mitigate the effect of the gaps on the flattening of the expanded bell sections between the segments; and 
 the segments of the bell cone are circumferentially spaced in a V-shaped groove between a pair of adjacent conical surfaces having top angles and friction coefficients to allow the segments to retract in the absence of axial pressure directed towards the gauge of the segments.