Control has been restored on Mærsk Gallant after problems were encountered with a well on Statoil's Huldra field this morning, 20 October.
The rig spudded the first of six planned producers on the North Sea development in early September.
It had reached a depth of 4,860 metres and was starting work today on completing the well when gas began flowing in. That raised the downhole pressure and the blowout preventer on the drillfloor was activated.
The well has now been sealed in accordance with safety procedures. As a precaution, personnel not required for further operations are being flown off to the Veslefrikk field about 16 kilometres away.
According to Statoil emergency response leader Øivind Reinertsen, measures required to stabilise the well are now under consideration.