US Patent 10954749 Bidirectional downhole isolation valve

A method of drilling a wellbore includes deploying a drill string into the wellbore through a casing string disposed in the wellbore casing string having an isolation valve. The method also includes drilling the wellbore into a formation by injecting drilling fluid through the drill string and rotating a drill bit of the drill sting and retrieving the drill string from the wellbore until the drill bit is above one or more valve members of the isolation valve. The method further includes closing the valve members, thereby bidirectionally isolating the formation from an upper portion of the wellbore.