The L5A platform was out of production and depressurised at the time of the incident.
The accident occurred during tests on a heat exchanger that was pressurized with water, a GDF Suez spokeswoman told Reuters. Furthermore, there was a breach in the exchanger for an as yet unknown reason that hit three people, she added.
The platform had 16 people on it at the time, including the casualties, and it has not been evacuated.
“We received a call at 9:50 a.m. that two people were dead and one seriously injured after an accident during testing of rig equipment,” coastguard spokesman Peter Verburg told AFP.
The injured person was flown to a hospital in northern Dutch city Leeuwarden where he is reported to be in stable condition.
The field has been under development and the L5A platform was scheduled for completion this month.
Partners in the L5a production license are GDF SUEZ E&P Nederland BV (60% and operator) and the Dutch state represented by Energie Beheer Nederland BV (40%).