Abstract: An integral multistage safety valve is designed to provide a second level of protection should a first stage fail. The valve may be used in oil and/or gas wells. The interior portion of the multiphase safety valve is designed so as to reduce turbulence and pressure loss through the valve when the valve is in an open position. The valves may be independently operable, or operable with a single control line. The multi-stage valve reduces the number of body joints required to construct two identical valves thereby reducing cost and potential leak paths and increasing reliability of the system.

Abstract: A wireline retrievable injection valve for an oil or gas well has an internal valve that is initially moved to open a flapper safety valve and also opens to allow fluid flow through the valve. The internal valve includes a sleeve that opens the flapper safety valve and shields the flapper safety valve from fluid. In this manner the flapper valve is protected from being caused to “flutter” or “chatter” due to pressure variations in the fluid flow, thereby damaging the seat.

Abstract: A subsurface safety valve is operable to close a fluid flow path by virtue of an axially movable flow sleeve. The valve includes a recockable linear actuator and a latch mechanism so that the valve can be moved from an open to a closed position as a result of axial movement of the flow sleeve without overcoming the pressure head and frictional forces currently encountered in conventional safety valves.

Abstract: Apparatus and method are provided for placing a dual pressure barrier in a vertical or horizontal well and verifying by pressure sensors in the well that the pressure barriers are operable. Communication of data from the well may be by electromagnetic or acoustic signals, and the data may be acquired on a ship near the well.

Abstract: A method and apparatus for controlling the flow of fluid in an injection well includes a main valve assembly having a valve and a retrievable nozzle selective lock assembly (RNSLA). The RNSLA is operable when positioned within the valve body to open the valve when fluid is pumped into the well and closes the valve when fluid flow is terminated. The RNSLA includes a replaceable orifice nozzle so that orifices of different dimensions may be used in conjunction with the valve assembly. In an alternate embodiment, the RNSLA includes a variable output nozzle assembly to maintain the valve in a protected open position without chattering over a wide range of flow rates.