Downhole check valve comprising a burst disk

摘要

A valve system is provided for use in a tubing string. The valve system comprises a valve device arranged to open a passage to fluid flow upon application of a fluid pressure to the valve device, wherein the valve device is provided with an interior space for passage of a tool string therethrough, and a seal member arranged to seal the interior space. The seal member is configured to rupture upon contact with the tool string moved through said interior space.