Control of sub surface safety valves

摘要

A well installation includes a metallic structure having downhole metallic tubing for conveying product towards the surface, a sub surface safety valve disposed in the downhole metallic tubing for interrupting flow of product towards the surface when closed and allowing flow of product towards the surface when open. Also, valve control means are disposed downhole and arranged for detecting electrical signals in the downhole metallic tubing and for holding the valve open while receiving an electrical signal, and surface signaling means for applying an electrical signal to metallic structure of the well for transmission via the downhole metallic tubing towards the valve control means so as to hold the valve open. The system can be made more robust by ensuring that the control means will only hold the valve open while receiving a signal of given characteristics to help prevent stray currents erroneously holding the valve open.

主权项

1. A well installation comprising, metallic structure including downhole metallic tubing which includes production tubing for conveying product towards the surface, a sub surface safety valve disposed in the production tubing for interrupting flow of product towards the surface when closed and allowing flow of product towards the surface when open, a valve control module disposed downhole and arranged for detecting electrical signals in the production tubing and for holding the valve open while receiving an electrical signal, and surface signaling apparatus for applying an electrical signal to the metallic structure of the well for transmission via the downhole metallic tubing towards the valve control module so as to hold the valve open, wherein the installation comprises a retro-fittable tool which is housed within the production tubing and comprises the valve control module, the valve control module having a spaced pair of contacts for contacting with the production tubing at a respective pair of locations spaced from one another along the length of the production tubing so that a first contact in the pair is located at a different longitudinal position on the production tubing than a second contact in the pair, and in use, a proportion of an electric current flowing in the production tubing is picked up by the first contact, flows through the valve control module, and returns to the production tubing via the second contact to facilitate detection of signals at the valve control module.