Minimising the post expansion end drift diameter reduction of expandable tubulars by bending the end of the tubular outwards

摘要

A method of expanding a tubular downhole to eliminate or minimize the post expansion end drift diameter reduction (the amount of rebound experienced by the end of an expandable tubular after it is deformed as it relaxes) by forming a flared portion 16 at the end of the tubular or bending it outward away from its longitudinal axis. The bend outward can be by up to 15 degrees and the wall of the tubular in the region which is bent outward can be thinner 18 than the rest of the tubular 20. By providing an external recess around the tubular in the region which is bent outward a taper increasing in diameter toward the end of the tubular is formed. Openings or slots can also be provided in the end region of the tubular to further reduce the residual hoop stress at the end of the tubular.