EXPANDABLE SEAL

A high-pressure capable sealing apparatus and method for sealing against an interior surface of a cylindrical tubular member provides the ability to expand to a larger diameter from a given running diameter and to transition back to the original diameter. The sealing apparatus may include a ring assembly with a metallic ring characterized by a uniform axial cross-sectional profile having an outward-facing convexity and an inward-facing concavity. A plurality of slits may be radially formed through the ring about the outer surface to relieve stress within the ring during radial expansion. A circular resilient gasket may be at least partially coaxially disposed within the ring concavity. The ring assembly may be located between uphole and downhole shoulders, which may be selectively axially movable with respect to one another so as to selectively axially compress and radially expand the ring into sealing engagement with a tubular member.