Performance Standards for Oil Spill Risk

摘要

Oil spill risk assessments are carried out in different ways,depending on the background for and the purposeof the analysis.One reason for these differences is the fact that oil spill risk assessment is a discipline atthe interface between the technical/statistical analysis in Quantitative Risk Assessments(QRAs)and thebiological/socio-economic analysis in Environmental Impact Assessments(EIAs).As a consequence of the EU Offshore Safety Directive(2013/30/EU),the risk of major environmentalaccidents shall now be included in QRAs for offshore oil & gas installations.Environmental CriticalElements(ECEs)shall be defined,in parallel to the Safety Critical Elements(SCE),which are analysedin QRAs.Moreover,limit values need to be defined for oil spill risk.Whereas including oil spill risk inQRAs has only been carried out systematically the latest few years,it has for many years been includedin EIAs.But the extend of such analysis has varied significantly,also for the same type of projects in thesame environmental settings.This paper reviews the background for the oil spill risk analysis in QRAs and EIAs,and outlines howthe approaches used differs,where the QRAs analyse the likelihood component most detailed,and the EIAsanalyse the consequence component most detailed.The reason for these differences is mainly historical.QRAs have traditionally been carried out focused on safety risk for people,calculating the likelihoodof accidental scenarios and the consequences in terms of number of fatalities.Also,QRAs have beencarried out with the aim of identifying which elements of the system should be improved in order toreduce the likelihood of accidental events,and to identify mitigation measures that can be applied whenthe likelihood has been reduced as much as reasonably practicable.In contrast,EIAs has mainly focusedon the consequences of oil spills which are taking place; oil dispersion is modelled,and the biota,fisheryand beaches possibly being impacted are being identified and assessed.The analysis has to a large degreebeen qualitative in contrast to the quantitative analysis in the QRAs; partly because the consequences of oilspills are so diverse,but probably also because EIAs typically are authored by biologist mainly focusingon qualitative analysis of the impacts on the marine life,whereas QRAs are mainly authored by engineersfocused on the quantitative aspects.By highlighting the background for and the difference between oil spill risk analysis carried out in QRAsand EIAs,respectively,it is the ambition to provide a more enlightened basis for selecting methods and level of detail in oil spill risk analysis for various types of projects,and to establish a closer connectionbetween oil spill risk analysis carried out for QRAs and oil spill risk analysis carried out for EIAs.