Abstract: A flow tube is axially moveable within an actuator body between a first axial position and a second axial position for actuating a downhole tool, such as for closing a subsurface safety valve. The flow tube includes an interior flow bore for conveying fluids from the tubing string through the actuator body. An external flow tube profile defined on the flow tube includes an upper shoulder for engagement with a wiper in the first axial position, a lower shoulder for engagement with the wiper in the second axial position, and a clearance path between the upper and lower shoulders for allowing viscous flow past the wiper when the flow tube is moved between the first and second axial positions.

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 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 flow tube is axially moveable within an actuator body between a first axial position and a second axial position for actuating a downhole tool, such as for closing a subsurface safety valve. The flow tube includes an interior flow bore for conveying fluids from the tubing string through the actuator body. An external flow tube profile defined on the flow tube includes an upper shoulder for engagement with a wiper in the first axial position, a lower shoulder for engagement with the wiper in the second axial position, and a clearance path between the upper and lower shoulders for allowing viscous flow past the wiper when the flow tube is moved between the first and second axial positions.