Wells – Automatic
Reexamination Certificate
1999-04-29
2001-08-07
Neuder, William (Department: 3672)
Wells
Automatic
C166S066400, C166S066600, C166S332600
Reexamination Certificate
active
06269874
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates to surface controlled subsurface safety valves. More particularly, the invention relates to electro-hydraulic actuation systems for such valves.
2. Prior Art
Surface controlled subsurface safety valves have been used for many years to prevent such occurrences as “blowouts” and other dangerous well conditions. Safety valves are designed so that if they fail, they fail in a safe position so that upon a break in the hydraulic fluid system, conventionally supplied at the surface and extended in a small diameter high pressure tubing line downhole, the power spring in the safety valve closes the flapper of the safety valve. The power spring must be able to lift the hydraulic column to the surface. This requires very strong springs and consequently, high opening pressures for valves set very deeply within the earth
s crust.
More recently, electromechanical actuators have been conceived employing electrically actuated mechanical means to open the flapper. The electromechanical systems are extremely effective for installations in which they are specified but different wells have different requirements and the art is still in need of other types of actuating systems.
SUMMARY OF THE INVENTION
The prior art need as noted above is alleviated by the electro-hydraulic surface controlled subsurface safety valve operating system of the invention.
The electro-hydraulic system employs in its broadest concept, a pump having a fluid supply attached thereto, the pump being connected directly to the safety valve. The pump is operated by a downhole electronics package and/or surface electronics package which controls the pump and additionally powers an electrically controlled dump valve connected to the hydraulic discharge fluid line connected between the pump and the conventional subsurface safety valve. When the solenoid of the dump valve is powered, the dump valve is closed and pressure generated by the pump is transmitted to the safety valve to operate the same. Upon interruption of power whether by design or by happenstance, the solenoid on the dump valve opens and the safety valve shuts, the power spring thereof being powerful enough to move the small amount of hydraulic fluid necessary back into the fluid supply chamber or reservoir through the dump valve. Thus the valve is quickly (about 5 seconds) and easily closed by interrupting power at the surface and additionally closes in the event power is lost for any other reason.
An advantage of the system is that it preferentially maintains the hydraulic fluid reservoir downhole and in proximity to the other components of the system. This avoids the long fluid column to the surface that is part of most systems in the prior art. This also eliminates the necessity of a strong power spring when the valve is set deep as the hydraulic column does not extend to the surface. The safety valve power spring needs to lift the weight of moving parts and overcome friction, both known from prior art.
Two pump arrangements are contemplated for the system, although other pumping arrangements could be substituted. The system preferably employs a pressure compensated annular reservoir within which the pump, a manifold and dump valve are disposed. Advantages are gained by placing these components in the hydraulic fluid of the reservoir. More specifically, the components are protected from wellbore fluids by the enclosed hydraulic fluid and may thus be constructed from less expensive materials. The pump remains well lubricated and cooled.
The above-discussed and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings.
REFERENCES:
patent: 4215746 (1980-08-01), Hallden et al.
patent: 5226348 (1993-07-01), Dezelan et al.
patent: 5358035 (1994-10-01), Grudzinski
patent: 5832996 (1998-11-01), Carmody et al.
patent: 2 267 922 (1993-12-01), None
patent: 2 310 228 (1997-08-01), None
Rawson Michael S.
Tompkins Charles M.
Trott Doug
Baker Hughes Incorporated
Cantor & Colburn LLP
Neuder William
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