It was a shell related incident, more details from their internal website:
On Tuesday evening (21 November) a power breakdown occurred on the K15 Bravo, a NAM installation in the North sea, located 50 kilometres from the Dutch coast off Den Helder. As a precautionary measure 13 employees were evacuated from the platform by a Bristow operated helicopter. During the flight to Den Helder the helicopter had to make an emergency landing 12 kilometres offshore. The reasons for this are still unknown. The coastguard has confirmed that all passengers - 13 employees and 4 crew members - are safe and sound. NAM mobilised its emergency procedures together with the municipality services. Family members have been informed. One employee was in hospital for a short period of time concerning signs of hypothermia. All employees are now home again. Further information will be provided once further details of the incident become known.
Figas