Back to results
US 9,145,757 B2Granted
Failsafe hydrostatic vent
AssigneeWeatherford Technology Holdings, LLC
InventorRonald Williams
Life of this patent
Estimating the term…
Abstract
An automatic vent valve and method for use is provided equalizing the pressure in at least two lines. A housing has a first piston that compresses a bias device when the second pressure source supplies sufficient pressure. Upon a sufficient reduction in pressure the first piston releases a second internally held coaxial piston to allow fluid to flow from a first pressure source towards a second pressure source, thereby equalizing the pressure between the two pressure sources.
Claims13
The method of equalizing pressure between a control line and a balance line of a hydraulically controlled downhole safety valve, the method comprising:
- supplying pressure from a first pressure source to a face of a first piston thereby causing a force opposing shifting of the first piston from a first piston first position to a first piston second position, said shifting being caused by a biasing device acting on the first piston;
- and
- supplying pressure from a second pressure source to a face of a second piston thereby causing a force urging the second piston from a second piston first position to a second piston second position, the second piston being retained in place by a lug supported by an interior surface of the first piston;
- wherein:
- a reduction in said pressure from the first pressure source allows the biasing device to overcome the force opposing shifting of the first piston from the first piston first position to the first piston second position, thereby shifting the first piston from the first piston first position to the first piston second position, withdrawing support for the lug, and unlocking the second piston, thereby allowing the force urging the second piston from the second piston first position to the second piston second position to shift the second piston from the second piston first position to the second piston second position;
- unlocking the second piston includes removing support for the lug disposed within a port of the second piston as a result of the shifting of the first piston;
- and
- said shifting of the first and second pistons establishes a fluid flow path between the control line and the balance line.
5 more elements
A downhole assembly comprising:
- a wellbore safety valve having a flapper to isolate fluids below the safety valve, the flapper being biased toward a closed position by a spring and held in an open position by a hydraulic control line;
- a balance line configured to oppose pressure exerted by the control line in the event that the control line is damaged;
- and
- an automatic pressure vent valve coupled to the hydraulic control line and the balance line and configured to allow excess pressure in the control line to bleed down to match the pressure in the balance line, the automatic pressure vent valve comprising:
- a first piston disposed within a bore of an outer housing, the first piston having a face in fluid communication with the balance line and a recess formed in a portion of a longitudinal partial bore of the first piston;
- a biasing device imposing a force on the first piston opposing a force resulting from pressure in the balance line acting on the first piston face;
- a sleeve affixed to the outer housing, inserted into the longitudinal partial bore of the first piston, and having a port formed through a wall thereof;
- at least one lug disposed within the port and supported by an interior of the longitudinal partial bore of the first piston;
- and
- a second piston disposed at least partially within the sleeve and having a face in fluid communication with the control line;
- wherein balance line pressure being reduced below control line pressure allows the biasing device to shift the first piston such that the at least one lug moves radially outwardly into the recess, thereby allowing a force resulting from pressure in the control line to move the second piston so as to establish fluid communication between the control line and the balance line through the sleeve.
8 more elements
Dependencies are inferred from the claim text.