Performance Standards for Oil Spill Risk

Abstract

Abstract Oil spill risk assessments are carried out in different ways, depending on the background for and the purpose of the analysis. One reason for these differences is the fact that oil spill risk assessment is a discipline at the interface between the technical/statistical analysis in Quantitative Risk Assessments (QRAs) and the biological/socio-economic analysis in Environmental Impact Assessments (EIAs). As a consequence of the EU Offshore Safety Directive (2013/30/EU), the risk of major environmental accidents shall now be included in QRAs for offshore oil & gas installations. Environmental Critical Elements (ECEs) shall be defined, in parallel to the Safety Critical Elements (SCE), which are analysed in QRAs. Moreover, limit values need to be defined for oil spill risk. Whereas including oil spill risk in QRAs has only been carried out systematically the latest few years, it has for many years been included in EIAs. But the extend of such analysis has varied significantly, also for the same type of projects in the same environmental settings. This paper reviews the background for the oil spill risk analysis in QRAs and EIAs, and outlines how the approaches used differs, where the QRAs analyse the likelihood component most detailed, and the EIAs analyse 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 likelihood of accidental scenarios and the consequences in terms of number of fatalities. Also, QRAs have been carried out with the aim of identifying which elements of the system should be improved in order to reduce the likelihood of accidental events, and to identify mitigation measures that can be applied when the likelihood has been reduced as much as reasonably practicable. In contrast, EIAs has mainly focused on the consequences of oil spills which are taking place; oil dispersion is modelled, and the biota, fishery and beaches possibly being impacted are being identified and assessed. The analysis has to a large degree been qualitative in contrast to the quantitative analysis in the QRAs; partly because the consequences of oil spills are so diverse, but probably also because EIAs typically are authored by biologist mainly focusing on qualitative analysis of the impacts on the marine life, whereas QRAs are mainly authored by engineers focused on the quantitative aspects. By highlighting the background for and the difference between oil spill risk analysis carried out in QRAs and 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 connection between oil spill risk analysis carried out for QRAs and oil spill risk analysis carried out for EIAs.