Surface Controlled Downhole Valve with Supplemental Spring Closing Force for Ultra Deep Wells

摘要

Apparatus for the activation of a deep set surface controlled subsurface valve such as a SCSSV or a gas vent valve by means of hydraulic pressure applied to an externally mounted control line includes the use of supplemental forces to assist the normal closing force to close the valve. The valve comprises a valve body with a longitudinal bore for fluid flow through, a bore closure member such as a flapper or sleeve, a hydraulic piston to provide for valve opening when pressure is applied to the control line and a plurality of spring assemblies to provide for valve closure when applied hydraulic pressure is removed. This spring closure mechanism can be configured in order to enable the valve to be set and safely operate at very deep setting depths. Another approach is the use of magnets of opposite polarity positioned in the valve, one of which is attached to an axially movable flow tube located within the valve. As the flow tube moves upwardly, the magnetic attraction force increases thereby increasing the total force available to overcome the hydraulic pressure on the piston, with a minimum magnitude of control line pressure.

主权项

1. A surface controlled, subsurface safety valve comprising:
a housing having an inlet and an outlet, a flapper valve positioned within the housing and having a flapper and a valve seat, an axially movable flow tube positioned within the housing, said flow tube adapted to open the flapper valve, a spring surrounding the flow tube and adapted to be compressed by axial movement of the flow tube, a piston adapted to move the flow tube in a downhole direction in response to fluid pressure applied from the surface to a portion of the piston, and means for supplementing the force available to move the flow tube uphole in addition to the force applied by the compressed spring to overcome the hydrostatic force acting on the piston.