Wells – Valves – closures or changeable restrictors – Longitudinally movable operator
Reexamination Certificate
1999-07-29
2001-09-04
Neuder, William (Department: 3672)
Wells
Valves, closures or changeable restrictors
Longitudinally movable operator
C166S324000, C166S325000, C166S374000
Reexamination Certificate
active
06283217
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a subsurface safety valve used for controlling fluid flow in a well conduit and, more particularly, to an equalizing subsurface safety valve.
2. Description of the Related Art
Subsurface safety valves are commonly used in wells to prevent uncontrolled fluid flow through the well in the event of an emergency, such as to prevent a well blowout. Conventional safety valves use a flapper which is biased by a spring to a normally closed position, but is retained in an open position by the application of hydraulic fluid from the earth's surface. A typical subsurface safety valve is shown and described in U.S. Pat. No. 4,161,219, which is commonly assigned hereto.
When the flapper is in the closed position, well fluid pressure below the flapper acting upon a relatively large surface area of the flapper makes opening of the flapper difficult. This difficulty in opening cannot be easily overcome simply by increasing the force exerted against the flapper by an opening piston and cylinder assembly because the relatively small cross-sectional area of the opening piston and cylinder assembly would require a fluid pressure that may burst the control line carrying hydraulic fluid from the earth's surface to the piston and cylinder assembly. Additionally, when the flapper is opened the initial flow of well fluid is relatively rapid which tends to etch, or erode, the primary sealing surface of the flapper. Any damage to this primary sealing surface is extremely critical because it is this sealing surface which must be intact to prevent uncontrolled flow of well fluids and to prevent a possible well blow out. The present invention solves these difficulties by providing a subsurface safety valve with an equalizing mechanism to allow the pressure above and below the flapper to equalize prior to the complete opening of the flapper.
SUMMARY OF THE INVENTION
The present invention is directed generally to a subsurface safety valve with a pressure equalizing mechanism. In a broad aspect, the equalizing subsurface valve of the present invention may include a body member having a longitudinal bore extending therethrough; a valve closure member mounted within the body member to control fluid flow through the longitudinal bore; a valve actuator disposed within the body member and remotely shiftable to move the valve closure member between open and closed positions; an actuating key releasably engageable with the valve actuator and moveable in response to movement of the valve actuator when engaged therewith; and an equalizing plug disposed for reciprocal movement within a plug bore in the body member and along an axis generally parallel to the longitudinal bore in response to movement of the actuating key, the equalizing plug alternately permitting and preventing fluid communication between the longitudinal bore adjacent a first surface of the valve closure member and the longitudinal bore adjacent a second surface of the valve closure member. Another feature of this aspect of the invention is that the valve actuator includes a sleeve member disposed for movement within the longitudinal bore and a piston disposed within the body member and remotely shiftable to move the sleeve member within the longitudinal bore.
Another feature of this aspect of the invention is that the piston is a rod piston movably disposed within a cylinder in a side wall of the body member with one side of the piston adapted to be in communication with a source of hydraulic fluid for moving the sleeve member within the longitudinal bore. Another feature of this aspect of the invention is that the piston is an annular piston disposed about the sleeve member and is moveable in response to application of hydraulic fluid. Another feature of this aspect of the invention is that the actuating key includes a latching finger that is releasably engageable with a recess in the sleeve member. Another feature of this aspect of the invention is that the actuating key further includes an actuating surface, and an inclined surface disposed between the latching finger and the actuating surface, and the body includes an inclined diverting surface that cooperates with the inclined surface on the actuating key to disengage the latching finger from the recess in the valve actuator. Another feature of this aspect of the invention is that the actuating surface on the actuating key is disposed to contact the contact surface on the equalizing plug and shift the equalizing plug to an open position when the actuating key is engaged with and moved in response to movement of the valve actuator. Another feature of this aspect of the invention is that the recess includes a first latching surface inclined toward the first end of the body member, and the latching finger includes a second latching surface inclined toward the first end of the body to mate with the first latching surface when the latching finger is engaged with the recess. Another feature of this aspect of the invention is that the recess includes a first latching surface inclined toward a second end of the body member, and the latching finger includes a second latching surface inclined toward the second end of the body to mate with the first latching surface when the latching finger is engaged with the recess. Another feature of this aspect of the invention is that the recess includes a first latching surface substantially perpendicular to an outer surface of the valve actuator, and the latching finger includes a second latching surface substantially perpendicular to an inner surface of the actuating key to mate with the first latching surface when the latching finger is engaged with the recess. Another feature of this aspect of the invention is that the actuating key is biased against the valve actuator by a coil spring. Another feature of this aspect of the invention is that the actuating key is biased against the valve actuator by a leaf spring. Another feature of this aspect of the invention is that the actuating key is biased against the valve actuator by a Belleville washer. Another feature of this aspect of the invention is that the actuating key is biased against the valve actuator by a garter spring. Another feature of this aspect of the invention is that the actuating key is biased against the valve actuator by a C-spring. Another feature of this aspect of the invention is that the actuating key is biased against the valve actuator by an inclined contact surface of the equalizing plug. Another feature of this aspect of the invention is that the equalizing plug is a generally cylindrical plug having an internal fluid flow passageway therethrough and an annular sealing surface adjacent a first end thereof for cooperable sealing engagement with an annular sealing surface formed within the plug bore. Another feature of this aspect of the invention is that the annular sealing surface on the plug further includes a pliable annular sealing surface. Another feature of this aspect of the invention is that the annular sealing surface formed within the plug bore further includes a pliable annular sealing surface. Another feature of this aspect of the invention is that the internal fluid flow passageway includes a generally longitudinal passageway extending from a contact surface adjacent a second end of the plug and disposed in fluid communication with at least one radially-disposed opening, the at least one radially-disposed opening exiting the plug at a location between the contact surface and the annular sealing surface of the plug. Another feature of this aspect of the invention is that the valve may further include an annular housing having a series of baffles to induce a pressure drop as well fluids flow therepast so as to reduce erosion as the well fluids flow through the equalizing plug and reduce the amount of debris entrained in well bore fluids from flowing through the equalizing plug. Another feature of this aspect of the invention is that the equalizing plug is biased within the plug bore in
Goldstein & Healey L.L.P.
Neuder William
Schlumberger Technology Corp.
Walker Zakiya
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