This paper will discuss a variable cone expansion of casings that is realized through a two-cone expansion system with a smaller sized, fixed cone at the front and a variable cone at the back. The variable cone can be moved between an expanded position and a retracted position. During expansion, the variable cone is enlarged to its expanded position and advanced through the casing until a restriction (e.g. smaller ID wellbore outside the casing) is reached. At the restriction, the variable cone is automatically retracted to allow passage through the restriction without incurring a large force. Once passing the restriction, the variable cone will return to its expanded position. The movement of the variable cone between its two possible positions is realized through a feedback controlled mechanism.
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