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US 2011/0209874 A1Published application
Tubing Pressure Insensitive Control System
AssigneeBaker Hughes Incorporated
InventorDavid Z. Anderson
Life of this patent
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Abstract
A system isolates a control system for a downhole tool from the internal pressures in the tubing in which the tool is mounted. Opposed seals are used on a moving component in the tool so as to offset pressure induced forces regardless of the internal operating pressure of the tool. In a particular application to a subsurface safety valve the control system can be isolated from tubing pressure by offset seals between the passage and the flow tube or around exposed portions of the operating piston for the flow tube.
Claims13
A downhole tool operable with hydraulic pressure, comprising:
- a housing having a passage therethrough between connections for mounting to a tubing string and at least one control system connection for delivery of hydraulic pressure;
- a movable element in said passage exposed to pressure therein;
- an actuation system responsive to the pressure delivered to said control system connection for selectively moving said movable element;
- said movable component element comprises a flow tube mounted for reciprocal motion for rotation of a flapper mounted in said passage by selective pressure application to said control system connection;
- flow tube seals disposed between said movable element and said housing to put said flow tube in pressure balance from pressures in said passage;
- said control system further comprises an operating piston connected to said flow tube between said flow tube seals, said flow tube seals isolating said piston from pressure in said passage;
- said flow tube seals are mounted to either or both said housing and said flow tube;
- whereupon if either one of said flow tube seals contacting said flow tube fail pressure in said passage moves said piston and flow tube so that said flapper rotates closed.
5 more elements
Dependencies are inferred from the claim text.