System for expanding a tubular element in a borehole

摘要

A system is disclosed for lining a borehole. The system comprises a radially expandable tubular element extending into the borehole. The wall of the tubular element at a downhole end thereof is bent radially outward and in axially reverse direction so as to define an expanded tubular section extending around an unexpanded tubular section. The unexpanded tubular section includes a weld interconnecting first and second wall portions of the wall. An actuator is arranged to move the unexpanded tubular section downward relative to the expanded tubular section so as to further expand the tubular element by bending the wall of the tubular element at the lower end thereof radially outward and in axially reverse direction. At least one strengthening member is arranged at the outer surface of the unexpanded tubular section, extending in a direction across the weld. Each strengthening member has a resistance to stretching in said direction across the weld.