Dual path subsea control system
AssigneeSchlumberger Technology Corporation
InventorTerrell Eugene Dailey, Jr.
Life of this patent
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Abstract
A technique enables protection of subsea wells. The technique employs a subsea test tree and associated control system to ensure control over the well in a variety of situations. The subsea test tree may be formed with an upper portion releasably coupled to a lower portion. The upper portion employs at least one upper shut-off valve, and the lower portion employs at least one lower shut-off valve to protect against unwanted release of fluids from either above or below the subsea test tree. The subsea test tree also is coupled with the control system in a manner which allows control to be exercised over the at least one upper shut-often valve and the at least one lower shut-off valve.
Claims20
A subsea wellhead control system, comprising:
- a subsea test tree having an upper part and a lower part connecting at a disconnect point;
- the upper part comprising a retainer valve;
- the lower part comprising a ball valve and a flapper valve;
- a control system for controlling actuation of the subsea test tree including the retainer valve, the ball valve and the flapper valve;
- and
- the control system comprising a primary valve coil that is connected to and actuated by a primary control path and a secondary valve coil that is connected to and actuated by a secondary control path, the primary and secondary control path both extending through a first umbilical;
- the primary control path connecting with a master programmable logic controller and the secondary control path connecting with a slave programmable logic controller.
A subsea control system, comprising:
- a subsea test tree;
- a control system for actuating at least one part of the subsea test tree, comprising a primary valve coil that is connected to and actuated by a primary control path and a secondary valve coil that is connected to and actuated by a secondary control path, the primary and secondary control paths both extending through a first umbilical that extends from surface to the control system;
- the primary control path connects with a master programmable logic controller and the secondary control path connects with a slave programmable logic controller.
A method for controlling a subsea wellhead, comprising:
- forming a subsea test tree;
- positioning the subsea test tree in a subsea installation;
- coupling the subsea test tree with a control system to control and actuate at least one portion of the subsea test tree;
- an umbilical connecting to the control system;
- and
- actuating the at least one portion of the subsea test tree by sending a signal from a master programmable logic controller on a primary control path, interpreting the signal from the master programmable logic controller with a slave programmable logic controller, and sending a duplicate command with the slave programmable logic controller on a secondary control path to a secondary valve coil, wherein the primary and secondary control paths both extend through the umbilical.
Dependencies are inferred from the claim text.