Curved flapper and seat for a subsurface safety valve

A curved flapper for a wellbore safety valve, the curved flapper pivoting between an open position and a closed position, and the curved flapper engaging a seat in the safety valve so as to inhibit the upward flow of fluids in the wellbore when the flapper is in its closed position, the curved flapper having a sealing surface for engaging a corresponding sealing surface on the seat when the flapper is in its closed position, the sealing surface of the flapper being configured to contact the sealing surface of the seat along a sinusoidal seating line such that the reactive force from the seat is normal to the sinusoidal seating line.

In a tubing retrievable subsurface safety valve of the type having a tubular housing adapted for connection in a production tubing string and having an actuator formed therein, a valve closure assembly is disposed within a housing chamber, the valve closure assembly comprising a curved flapper moveable between an open and a closed position in response to the actuator for opening and closing a production flow passage, and a valve seat, the valve seat being characterized by a concave conical sealing surface, and the flapper being characterized by a convex spherical sealing surface, with the sealing surface of the flapper engaging the sealing surface of the seat along a sinusoidal seam.