Abstract: A well control valve assembly prevents flow from or to completion segments further downhole from the well control valve assembly once the stimulation stimulation/shifter string has been removed from the production tubing string. The well control valve assembly features a shaped flapper plate which, when opened, conforms closely to the shape and size of the production tubing string's interior diameter. The flapper plate is biased toward a closed position by a compression spring arrangement that includes an arm which levers the plate upward toward a seating surface. The valve assembly's closure is mechanically induced and is not responsive to a sensed well condition.

Abstract: A flapper valve assembly when closed permits flow through in one direction and prevents flow in the opposite direction. When open, two way flow may occur and the flapper valve member is biased toward closed position, to sealingly engage an annular seat, by one or more springs in the wall of the flapper valve housing. This structure provides a greater closing force applied to the flapper valve through a tension member connected to the flapper valve hinge. Three forms of tension members are disclosed.

Abstract: An improved subsurface safety valve has a flapper plate which is held open by an operator tube, and which can be closed rapidly during high flow operating conditions without damage to the flapper plate or to the operator tube. The operator tube is telescopically coupled within a tubular piston. Retraction of the operator tube relative to the piston is yieldably opposed by a compression wave spring which is interposed between the operator tube and the piston. Telescoping retraction of the operator tube within the piston is limited by engagement of the operator tube against an internal shoulder of the piston. Damage to the flapper closure plate, pivot pin and operator tube is avoided by effectively decoupling the operator tube from the inertia load presented by the hydraulic piston and column of hydraulic control fluid.