Abstract: A tubing retrievable safety valve assembly and related methods are disclosed herein. The assembly includes a primary flapper, a secondary flapper, a flow tube, and a protective sleeve. The flow tube is shiftable between a downhole position that holds the primary flapper in an open position and an uphole position that allows the primary flapper to move to a closed position. The protective sleeve, when positioned in an uphole position, holds the secondary flapper valve in an open position. The protective sleeve is shiftable to a downhole position to allow the secondary flapper to move to a closed position, for example, upon failure of the primary flapper.

Abstract: A flow control system for a well includes a primary safety valve and a secondary safety valve disposable within a valve body of the primary safety valve. The secondary safety valve may include a control line port for receiving control fluid pressure from the same control line as the primary safety valve. A choke in fluid communication with the control line port delays a closing of the secondary safety valve relative to a closing of the primary safety valve in response to a decrease in the control fluid pressure.

Abstract: A subsurface safety valve assembly that includes a valve housing comprising a valve seat with a circumference and a seat seal surface. The valve assembly also includes a flapper rotatably connected to the valve housing and comprising a flapper seal surface. The flapper is rotatable into sealing engagement with the seat seal surface in a closed position to form a circumferential surface-to-surface seal. The valve assembly also includes a dovetail groove cut into the seat seal surface or the flapper seal surface and a seal ring held within the dovetail groove and positioned to form a seal against the seal ring when the flapper is in the closed position. The seat seal surface, the flapper seal surface, the dovetail groove, and the seal ring are shaped such that the load on the seal ring is uniform around the seal ring when the flapper is in the closed position.

Abstract: A flow control system for a well includes a primary safety valve and a secondary safety valve for controlling flow from production tubing in the well. The primary safety valve includes a first valve body, a first flapper, a first control line port for receiving control fluid pressure from a control line, and a first actuator operable to open the first flapper in response to the control fluid pressure. The secondary safety valve is disposable within the valve body of the primary safety valve. The secondary safety valve also includes a second valve body, a second flapper, a second control line port for receiving control fluid pressure from the same control line as the primary safety valve when the secondary safety valve is disposed in the first valve body of the primary safety valve, and an actuator operable to open the second flapper in response to the control fluid pressure.

Abstract: A subsurface safety valve assembly that includes a valve housing comprising a valve seat with a circumference and a seat seal surface. The valve assembly also includes a flapper rotatably connected to the valve housing and comprising a flapper seal surface. The flapper is rotatable into sealing engagement with the seat seal surface in a closed position to form a circumferential surface-to-surface seal. The valve assembly also includes a dovetail groove cut into the seat seal surface or the flapper seal surface and a seal ring held within the dovetail groove and positioned to form a seal against the seal ring when the flapper is in the closed position. The seat seal surface, the flapper seal surface, the dovetail groove, and the seal ring are shaped such that the load on the seal ring is uniform around the seal ring when the flapper is in the closed position.