| 摘要 |
The invention concerns a fluid energized control system for controlling the valves of subsea wellheads and for controlling other like mechanical devices designed for fluid actuation. A single protective conduit is connected at one extremity thereof to a control facility while its other extremity terminates in connection structure located adjacent or attached to a remotely located wellhead or other mechanical device. Suitable actuator control conduits extend from a plurality of fluid-controlled wellhead valve actuators and are connected in fluid communication to the connection structure. The terminal connection structure is provided with internal fluid passages communicating with respective ones of the actuator conduits and defines a pig-receiving recess. A locomotive pig is inserted into the protective conduit at the control facility and is moved within the protective conduit by fluid pressure applied from a suitable source of pressurized fluid or by a combination of fluid pressure applied at one side of the pig and a suction applied to the other side of the pig. A plurality of valve control conduits are connected to the pig in fluid communication with corresponding fluid passages formed in pig structure. The control conduits are pulled through the protective conduits by the pig as fluid pressure is applied. As the pig enters the pig-receiving recess, it is oriented, if necessary, by appropriate orienting structure and is locked into assembly within the recess with appropriate fluid passage structure of the pig disposed in fluid communication with corresponding fluid passages in the terminal connection structure. A plurality of pilot valves, provided within or adjacent the pig or terminal connection structure, are controlled by application of fluid pressure through the control conduits and serve to control communication of pressurized actuating fluid, carried in the protective conduit externally of the control conduits, to the actuating conduits of the subsea wellhead. The valve actuators are energized by the actuating fluid responsive to actuation of the pilot valves. An accumulator and pressure-balancing circuit are communicated to the fluid circuitry of each of the valve actuators in order to allow quick energized and deenergized actuation of the valve actuators. Fluid pressure is transferred from the accumulator and pressure-balancing circuitry to the actuator fluid supply of the fluid system upon reduction of pressure in the actuator fluid supply and such transfer may be aided by the hydrostatic head of the sea water in which the system is submerged.
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