Abstract: Method and systems for opening and closing a subsurface valve are disclosed. A rod piston forms a first piston chamber, a second piston chamber and a third piston chamber within a housing. The first piston chamber is fluidically coupled to a high tubing pressure and the second piston chamber is fluidically coupled to a surface control line and a first compartment of a storage chamber. The third piston chamber is coupled to a second compartment of the storage chamber. A flow tube couples the rod piston to a flapper. The rod piston is moved between a first position and a second position in response to a change in a pressure in at least one of the first piston chamber, the second piston chamber and the third piston chamber. The movement of the rod piston between the first position and the second position at least one of opens and closes the flapper.

Abstract: A safety valve can be disposed in a wellbore that is through a fluid-producing formation. The safety valve can include a flow tube that is allowed to move at least partially independent, or free, from a piston assembly to avoid negative effects from forces on the flow tube from a closing assembly, such as one including a flapper. For example, the flow tube may not be required to be rigidly connected to a piston assembly such that the flow tube can move more than the piston assembly moves.

Abstract: Method and systems for opening and closing a subsurface valve are disclosed. A rod piston forms a first piston chamber, a second piston chamber and a third piston chamber within a housing. The first piston chamber is fluidically coupled to a high tubing pressure and the second piston chamber is fluidically coupled to a surface control line and a first compartment of a storage chamber. The third piston chamber is coupled to a second compartment of the storage chamber. A flow tube couples the rod piston to a flapper. The rod piston is moved between a first position and a second position in response to a change in a pressure in at least one of the first piston chamber, the second piston chamber and the third piston chamber. The movement of the rod piston between the first position and the second position at least one of opens and closes the flapper.

Abstract: A safety valve can be disposed in a wellbore that is through a fluid-producing formation. The safety valve can include a flow tube that is allowed to move at least partially independent, or free, from a piston assembly to avoid negative effects from forces on the flow tube from a closing assembly, such as one including a flapper. For example, the flow tube may not be required to be rigidly connected to a piston assembly such that the flow tube can move more than the piston assembly moves.