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Oil Platform Leaks
The aim of this challenge is to determine the likely trajectory of the slick resulting from a (simulated) leak at an oil platform and the likelihood that sensitive coastal habitats, species or tourist beaches are affected. Specifically it provides a preliminary assessment of the likely impact of the oil within 24 and 72 hours of the start of the challenge.
The challenge serves as a case study for the availability of data, the required response time for a preliminary (within 24 hrs) and a refined impact assessment (within 72 hours) and to aid in identifying possible data gaps. The European Commission ensures the participation of the European Maritime Safety Agency for this simulation.
On Tuesday, May 10, 2016 at 11:24 AM, an email was received from DG MARE: “At 8:15 CET this morning (10/05/2016), an accident took place during an inspection of the re-activated Brent Delta Platform in preparation of final decommissioning and dismantling. About 5000m3 of crude oil per day leaks from the platform at a depth of 70m in the water column. It is anticipated that the leak will be sealed after 48 hours with the notification that about 5000m3 of oil per day leaked from the Brent Delta Platform with an expected duration of 48 hours.”
Method and assumptions
The GNOME (General NOAA Operational Modelling Environment) model, developed by the Emergency Response Division of NOAA's Office of Response and Restoration, was used to predict the possible route, or trajectory, a pollutant might follow in or on a body of water, such as in an oil spill.
The following assumptions were required:
- The GNOME model can only model spills at the sea surface. The oil spilled is relatively light and will reach the surface rapidly.
- Brent Crude is a major trading classification of sweet light crude oil that serves as a major benchmark price for purchases of oil worldwide. This grade is described as light because of its relatively low density, and sweet because of its low sulphur content (circa 0.37%). GNOME can only simulate a few oil types. The “medium crude” oil as specified in the GNOME model was used in the challenge as this is the closest match to Brent Crude.
- In the model scenario it was assumed that the oil was released:
- at the sea surface instantaneously;
- at the start of the spill and;
- at the location of the platform.
Results on 11/05/2016 (after 24 hours)
The 24h report showed that at the end of the simulation (90 hours after the spill) 36% had evaporated and dispersed, and 64% was floating.
Based on this first preliminary assessment it is likely that:
- There was a threat to coastal habitat/species, according to the worst case scenario;
- There was no information available on tourist beaches, therefore it was unknown if there was a threat to tourist beaches;
- The following locations were threatened (indicated by the black crosses in the figure below):
- Platforms surrounding the spill site
- The Shetland Islands
- Norway, south of Bergen
- The Natura 2000 areas: Pobie Bank Reef; Hermanesss, Saxa vord and Valla Field; Keen of Hamar; Fetlar, North Fetlar; Yell Sound Coast; Noss; Mousa; Sumburgh Head.
- Potentially the nationally designated area Jærstrendene
Figure 1 Overview of the impacted location after the Brent Delta spill according to the best guess, no regret simulation.
The following has been identified as a first/ indication of data gaps limiting the preliminary assessment:
- Tourist beaches
- Shipping lanes
These issues were addressed within the complete impact assessment and/or the main report.
Results on 13/05/2016 (after 72 hours)
Based on oil spill simulation modelling it is predicted that, 132 hours after the spill, 42% had evaporated and dispersed, and 58% remained floating on the sea. As a worst case, 4% (400 m3) of the total amount of spilled oil could beach, posing a threat to coastal habitat/species in the UK and Norway, as indicated by the black crosses on the coast lines (beached oil) in the figure below.
The main identified gaps, in the available data, limiting this refined assessment were:
- Tourist beaches (especially the locations of tourist beaches at the Shetlands);
- Shipping lanes;
- Fisheries activity on a time scale shorter than a whole year;
- Distribution data of birds and sea mammals, and possibly other biological distribution data.
These issues are addressed within the main data adequacy report.
Figure 2 Overview of the impacted location after the Brent Delta spill according to the best guess, no regret simulation.
The challenge rehearsal was performed in the Summer of 2014, and after incorporating feedback from project partners and DG-MARE, IMARES were ready and prepared for the real challenge. You can view the results of the challenge rehearsal, based on webpages originally prepared by DG-Mare.