Production from the Tordis subsea installation was being started up after a four-day planned shutdown when the spill occurred. Equinor estimated that 17.5 m3 of oil escaped, and a slick measuring 3 500 by 500 metres formed on the north side of the platform.
An investigation of the incident was initiated by the PSA on 29 April.
The direct cause of the spill was that the water outlet from the Tordis inlet separator was opened too early. Combined with emulsion problems, this allowed oil to flow out with the water, through the water treatment plant and from there to the sea.
Underlying causes identified by the PSA include:
- impairments to level and oil-in-water meters
- lack of risk assessment of equipment impairments and the impact of corrosion inhibitors on produced-water quality during a start-up
- deficiencies in the system and operating documentation
- a lot for control room operators to deal with overall during a start-up.
Conditions identified by the investigations which could be important for safe operation but which were not directly significant for the incident include impairments and inappropriate design resulting from many overrides of process safety functions.
Nonconformities and improvement points
The PSA has identified three nonconformities related to:
- overriding the process safety system
- deficiencies in system and operating documentation
- lack of risk assessment when starting up Tordis production.
Furthermore, two improvement points have been identified in relation to:
- control of the process plant
- use of information envelopes on displays in the control room.
The PSA’s investigation has identified serious breaches of the regulations, and Equinor has therefore been given the following order.
Pursuant to section 69 of the framework regulations on administrative decisions, see section 26 of the activities regulations on safety systems, Equinor is ordered to review internal requirements in Equinor and established routines on Gullfaks C in order to ensure that overriding of safety systems is conducted in accordance with the regulatory requirements. See chapter 9.1.1 of the report.
The deadline for compliance with the order is 30 September 2021. We must be notified when the order has been complied with.