The Gas Ingress Isolation Valve (GiiV) was developed as a means of automatically preventing hydrocarbon returns from entering the hydraulic control system.
In the event of an Emergency Shutdown (ESD) all wellhead tree valves and downhole safety valves are automatically closed. However, the downhole safety valve control line provides a potential conduit between the well and the hydraulic control systems. Should control line integrity at the downhole safety valve fail, hydrocarbon gas can mitigate through the control line.
The GiiV is positioned close to the wellhead, typically alongside the local panel, and connects directly into the control system. The GiiV operates in complete autonomy, driven only by integral system pressure. During and ESD, the GiiV switches into a non-return valve, activated by very low system pressure. The GiiV will automatically reopen during the re-pressurisation of the control system.