Abstract: Methods and apparatus for isolating the producing zone of a well during workover operations, particularly where the well is equipped with a production string and a submersible electric pump suspended thereon. A packer and isolation valve are set in the well above the producing zone, and a hydraulically operable control suspended on the pipe string below the pump is releasably coupled to the valve and arranged to enable remote control of the valve from the surface by adjusting the pressure of fluids in the production string or in the well annulus.

Abstract: In accordance with an illustrative embodiment of the present invention, a valve placed in a subsea blowout preventer stack during a production test of a well producing gas comprises a valve body containing two valve elements in series and a releasable control unit. A fluid to inhibit the formation of natural-gas hydrates can be injected into the valve body by means of a pump on the surface and through a high-pressure hose. A lateral connector fixed to the control unit is fitted in a sealed manner into a receptacle on the valve body to allow reconnection of the inhibiting fluid injection system.