US Patent 9518445 Bidirectional downhole isolation valve

An isolation valve for use in a wellbore includes: a housing; a piston longitudinally movable relative to the housing; a flapper carried by the piston for operation between an open position and a closed position, the flapper operable to isolate an upper portion of a bore of the valve from a lower portion of the bore in the closed position; an opener connected to the housing for opening the flapper; and an abutment configured to receive the flapper in the closed position, thereby retaining the flapper in the closed position.