Abstract: There is disclosed an expandable seal for sealing at least part of a wall of a well borehole, an expandable seal assembly comprising at least two such expandable seals, and a method of sealing at least part of a well borehole using such a seal. In one embodiment, the expandable seal (32) comprises an expandable tubular support member (34) and an inflatable seal element (36) mounted externally of the expandable tubular support member (34) for inflation radially outwardly into sealing engagement with at least part of a wall (50) of a well borehole (10). There is also disclosed a sealing apparatus for sealing at least one flow port in an expandable downhole tubular, in one embodiment, the sealing apparatus (332) comprising a sealing member (384) coupled to an expandable tubular (334), the sealing member (384) including a deformable portion (387) movable between a closed position preventing fluid flow through a flow port (356) and an open position permitting fluid flow through the flow port (356).