Results of Environmental Risk Analysis Carried out on Offshore Dunbar Installation

Environmental Risk Analysis (ERA) is a powerful means to ensure that all prevention and protection measures required to lower the environmental risk of oil and gas installations to an acceptable level have been identified. The Company is so convinced of its usefulness that conducting ERAs is now mandatory for all its installations. An Environmental Risk Analysis was recently conducted by the Company UK affiliate on Dunbar offshore installation located in the northern North Sea at about 140 km of Shetland Islands (West) and 150 km to Norway (East) and at about 140 m water depth. The applied methodology takes into account the hydrocarbon spill trajectory and the probabilities that hydrocarbon reaches any environmental resources. The damage is estimated on the basis of fraction of habitat or species degraded and recovery time of the ecosystem, based on simple exposure-effect relationship constructed from observed effects of historical spills. The accidental scenarios are displayed on a risk matrix and environmental risk is assessed. 4 oil spill scenarios have been selected as representing most of oil spill cases on the basis of the technological risk assessment. Oil drift simulations were conducted in stochastic mode with OSCAR tool, on the basis of 7 years of historical wind and current data covering the studied area. Quantities of oil and associated probabilities of presence were calculated for each grid cell of the model. Shoreline habitats, seabirds and marine mammals have been identified as Valued Ecosystem Component for the study and geographically positioned. On the basis of severity assessment and frequency of damage calculations, scenarios could be plotted on the Company risk matrix. It is found out that the remote location of Dunbar platform together with oil characteristics and current flow pattern in the area of the study tend to limit the environmental risk.