Patent ID: 7926575

Claim:
An apparatus for selectively preventing and allowing operation of a pressure controlled well tool, the apparatus comprising: a housing assembly; a mandrel assembly disposed within the housing assembly that together at least partially define a first chamber operable to contain a compressible fluid, a second chamber operable to contain a substantially incompressible fluid and a third chamber operable to contain a power fluid; a power piston movably disposed between the second and third chambers and operable to communicate pressure between the second and third chambers; a fluid spring piston movably disposed between the first and second chambers and operable to communicate pressure between the first and second chambers; a fluid metering device disposed within a passageway of the second chamber and operable to communicate a predetermined flow rate of the substantially incompressible fluid between a first portion of the second chamber and a second portion of the second chamber in response to differential pressure between the first and second chambers; and a pressure-releasable valve disposed in a bypass passageway that selectively provides a fluid path for the substantially incompressible fluid around the fluid metering device, the pressure-releasable valve responsive to a predetermined pressure differential between the first and second chambers to selectively allow fluid communication through the bypass passageway.