Sub sea control and monitoring system

1. A system for monitoring or controlling at least one device mounted on a tubing string of a subsea well, the system comprising:

a down-well cable for conveying a signal to or from at least one device mounted on the tubing string of the subsea well;

a temporary surface cable for conveying a signal between the at least one device and a first monitor or control station prior to or during installation of the tubing string in the subsea well;

a permanent surface cable for conveying a signal between the at least one device and a second monitor/control station after installation of the tubing string in the subdata well; and

switch means configurable between a first configuration, in which the down-well cable and the temporary cable are connected, and a second configuration, in which the down-well cable and the permanent cable are connectable.

2. A system according to claim 1 wherein, in the first configuration of the switch means the down-well cable and the permanent cable are not connected, and in the second configuration of the switch means the down-well cable and the temporary cable are not connected.

3. A system according to claim 2 wherein, prior to or during installation, the switch means is configurable in the second configuration such that the down-well cable and the temporary cable are not connected, so as to allow testing of the temporary cable to be performed.

4. A system according to claim 1 wherein in the second configuration, the permanent cable is connected to the down-well cable by a wet-mate-type connector.

5. A system according to claim 1 wherein the switch means is made to adopt the first configuration by engagement of an installation tool with tubing during installation of the tubing in the well.

6. A system according to claim 1 wherein the switch means is made to adopt the second configuration by disengagement of an installation tool from tubing immediately after installation of the tubing in the well.

7. A system according to claim 5 wherein the switch means is located in a tubing hanger, from which a tubing string is arranged to hang, and the installation tool is a tubing hanger running tool which is arranged to engage the tubing hanger during installation of the tubing hanger, at which time the switch means is made to adopt the first configuration, and which tubing hanger running tool is arranged to be disengaged from the tubing hanger immediately after installation of the tubing hanger, at which time the switch means is made to adopt the second configuration.

8. A system according to claim 1 wherein the switch means is made to adopt the second configuration by retraction of a switch member from the switch means into an installation tool used to install a tubing string in the well.

9. A system according to claim 8 , wherein the switch means is located in a tubing hanger, from which the tubing string is arranged to hang, and the installation tool is a tubing hanger running tool which is arranged to engage the tubing hanger during installation of the tubing hanger, at which time the switch means is made to adopt the first configuration, wherein the switch means can be made to adopt the second configuration by retraction of the switch member from the switch means into the tubing hanger running tool.

10. A system according to claim 1 wherein the switch means comprises a mechanically operable switch.

11. A system according to claim 1 wherein the switch means comprises an electrically or electronically or optically operable switch.

12. A system according to claim 1 wherein the first and second monitor/control stations comprise the same monitor/control station.

13. Switch means for use in switching a signal from at least one device mounted on a tubing string of a subsea well, the switch means being configurable between a first configuration, in which a down-well cable, for conveying a signal from or to at least one device mounted on the tubing string of a well, and a temporary surface cable for conveying a signal between the at least one device and a first monitor/control station prior to or during installation of the tubing string in the subsea well are connected,

and a second configuration, in which the down-well cable and a permanent surface cable for conveying a signal between the at least one device and a second monitor/control station after installation of the tubing string in the subsea well are connectable.

14. Switch means according to claim 13 wherein the switch means comprises a mechanically operable switch.

15. Switch means according to claim 13 wherein the switch means comprises an electrically or electronically or optically operable switch.

16. A method of monitoring or controlling at least one device mounted on a tubing string of a subsea well, the method comprising:

monitoring or controlling said device via a temporary surface cable connected to a down-well cable and arranged to convey a signal between the at least one device and a first monitor or control station prior to or during installation of the tubing string in the subsea well, in a first configuration;

monitoring or controlling said device via a permanent surface cable connected to the down-well cable and arranged to convey a signal between the at least one device and a second monitor/control station after installation of the tubing string in the subsea well, in a second configuration;

and switching between the first and second configurations.