The present invention is directed to a reinflatable external casing packer which is operable in three modes, including a filling mode of operation, a locking mode of operation, and a reinflation mode of operation. A valve system is provided which allows for selective filling and reinflation of the external casing packer in response to suspected or detected loss of pressure within the inflation chamber. The present invention may also be characterized as a method of placing a wellbore.
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