StatoilHydro publishes report into Norwegian rig's oil spill

Paul Boughton

Norwegian company StatoilHydro has published a report which investigates the environmental impact of a crude oil spill at its Statfjord A North Sea platform in December 2007.

On the morning of 12th December 2007, during oil offloading from the Statfjord A platform in the North Sea (Fig. 1), about 4000m3 standard cubic metres of crude oil was spilled into the sea. The accident occurred when the tanker Navion Britannia was loading oil from a loading buoy.

The Statfjord field is located around 200 km west of Bergen, close to the border of the UK continental shelf, and operator StatoilHydro quickly instigated a number of environmental investigations to identify and, if required, reduce the environmental impacts.

Sintef, the Institute of Marine Research (IMR) and the Norwegian Institute for Nature Research (NINA) were also involved in these investigations. These specialists have just concluded that the oil spill, now thought to be around 4400 m3 and the second largest on the Norwegian continental shelf, did not cause any demonstrable environmental harm.

Three days after the incident there were no longer any visible traces of the oil on the sea surface. Analyses from Sintef show that after a couple of days 25 per cent of the oil had evaporated and 15 per cent had dissolved. The rest of the oil had been mixed into the churning water as droplets, gradually dissolving and eaten by the ocean's own bacteria.

"Because of heavy waves and wind, the oil was quickly mixed into the sea," says Hanne Jorun Storhaug Ervik, StatoilHydro's project manager for the investigation. "The weather conditions were on our side and nature took care of itself."

Measurement of oil components in fillet of fish from the North Sea caught in December 2007 and January 2008 indicate that all components were below the detection limit.

"More than 170 fish samples have been analysed without any traces of oil being found in the fish fillets," said Bjorn Einar Grosvik of the IMR. "Consequently, there is no reason for saying that the spill has reduced the quality of North Sea fish fillets."

Other analyses of oil components in liver show slightly higher oil values in haddock during the first days after the spill than what has been reported earlier in haddock caught in the North Sea. This was, however, not the case for cod and pollack. Furthermore, no dead birds were found after the oil spill.

The purpose of the investigation was to identify and reduce the environmental impacts of the Statfjord oil spill.

"Our goal is zero harm to the environment in which we operate, and we immediately started extensive investigations and analyses," added Eva Oglaend Bjornestad, environmental coordinator for Statfjord.

"We have gained further knowledge about environmental affects of oil spills and experience that will be useful both to StatoilHydro personnel and external professional communities," she added.

Since the accident, the company has opened a new oil spill accident in conjunction with the Murmansk regional government. According to StatoilHydro this marks a new milestone in the environmental cooperation between the two organisations. Murmansk itself is used as a transhipment port for loading crude oil into large tankers sailing to Europe and the US.

The laboratory's task is to analyse the oil samples taken from all the crudes loaded for export in Murmansk.

"International experience from major oil spills shows that the spilt oil can be collected much more efficiently if its characteristic properties are known," said president of StatoilHydro in Russia, Bengt Lie Hansen. "This is an important cross-boarder project, as the results of the analysis will be available to both Russian and Norwegian authorities," he added.

Premises for the laboratory were provided by the Murmansk regional authorities at their Federal State Enterprise Murmansk Centre for Standardisation, Metrology and Certification.

Regional authorities will also ensure that the laboratory gets the required oil samples. StatoilHydro has supplied the necessary equipment and organised personnel training in co-operation with Norway's Sintef research foundation in Trondheim.

Opening of the oil spill laboratory is a part of a broad environmental programme aimed at strengthening emergency response to oil spills off north-western Russia, implemented jointly by StatoilHydro and Murmansk regional government within the framework of a memorandum of understanding about technical and economic co-operation.

"The Barents Sea is a unique ecosystem, and in addition to that it is our joint fishing ground with Norway. This is why we claim that the upcoming oil and gas projects must be carried out in strict compliance with the European environmental standards and in close cooperation between all the participants," says Yuri Evdokimov, governor of the Murmansk region. "We need to create a front-edge emergency preparedness system that could be further upgraded and developed," he added.

Meanwhile, an incident at the Mongstad refinery in August 2008 had a considerably higher accident potential than originally expected. The incident is under investigation by StatoilHydro.

On Saturday 23rd August there was a failure in the power supply to important control units for the sliding valves in the cracker plant at Mongstad. This led to extensive smoke development from the emergency stack in the cracker plant and somewhat later a fire in the top of the stack.

The findings of the ongoing investigation show that the incident quickly could have escalated further as air could have forced its way into the reactor and led to what the company describes as an 'explosive development'.

This was prevented by an emergency stop. An explosion in the cracker reactor could have had major and highly serious impacts on people, the environment and the plant.

During the incident 17 people were present in the cracker complex to prepare a scheduled shutdown of the plant.

"This is a serious incident which both the unit at Mongstad and StatoilHydro must learn from," says Einar Stromsvåg, senior vice president for the manufacturing cluster.

Mr Stromsvåg continued: "In the ongoing investigation effort we must turn all stones to ensure that we understand what happened and why. This applies not only to the technical, but also to the organisational and human aspects. It is important that we have an overall understanding of the incident and develop concrete measures to avoid this type of incident in the future."

Astudy has also been initiated to determine the scope of the emission that occurred during the incident and any health and environmental impacts.

The cracker has been shut down for extensive maintenance and modification work during an ongoing scheduled shutdown. Further improvement measures have also been implemented as a result of the incident.

"Much higher robustness and independence have been built into the important control systems that failed during the incident. The technical integrity of the plant has thus been strengthened," added Stromsvåg.

Based on experience from the incident organisational and skills upgrading measures have also been introduced to strengthen the human barriers.

The incident is currently being investigated and the resulting overview of long-term actions will be finalised on the basis of the investigation report. The final conclusions of the investigation effort are expected to be ready in early 2009 and will then be submitted to the Petroleum Safety Authority Norway.