Patent ID: 6619388
Filing Date: 2003-09-16
Classification: E21B

Abstract:
A fail-safe, surface controlled subsurface safety valve for use in a well, comprising:a valve body having a longitudinal bore for fluid to flow through, a bore closure assembly, a pressure balanced drive assembly, and a fail safe assembly: the bore closure assembly being positioned and normally biased to close the bore to fluid flow; the pressure balanced drive assembly coupled to the bore closure assembly for driving the bore closure assembly to an open position wherein the pressure balanced drive assembly further comprises a sealed chamber filled with an incompressible fluid and the pressure of the incompressible fluid is balanced with the wellbore pressure by at least one bellows connected to the sealed chamber; and the fail safe assembly being positioned and configured to hold the bore closure assembly in the open position in response to a hold signal and to release the valve to return to the safe, closed position upon interruption of the hold signal.