A method of isolating a section of a drilled bore (10) containing a problem zone (12) comprises: providing a section of tubing (16); locating the tubing in the section of the bore; and expanding the tubing and forming at least an outer portion (20) of the tubing to conform to irregularities in the bore wall, to isolate the problem zone. The tubing may feature a formable outer section (20), and the expansion of the tubing may be achieved using a compliant rotary expander.
