Achieving an Industry Standard in the Assessment of Environmental Risk: Oil Spill Risk Management and the Mira Method

Abstract

ABSTRACT A quantitative approach to assess environmental risks from offshore petroleum activities is developed in this paper. Taking into account both reservoir- and project-specific data, different kinds of oil spill scenarios are analyzed. Oil characteristics and weathering properties are incorporated in a standardized geographical information system (GIS)-based oil spill modeling system, simulating oil trajectories based on wind and current data. Mapping of environmental resources is combined with a sensitivity evaluation and protection value classification. Nationally accepted criteria in Norway for identification of valued ecosystem components (VECs) are adopted to select a limited number of high priority risk indicators. Oil spill statistics are combined with occurrences of VEC resources on a seasonal basis. Oil pollution effect and damage keys have been established based on past oil spill incidents and scientific documentation. Impact assessments are based on available specific resource data and provide results related to the recovery potential of each resource component included. The recovery time is adopted as a general stand-alone parameter that allows classification of severity and ecological significance of acute oil pollution incidents. Quantitative risk results are used to describe and rank environmental risks issued from different sources and scenarios, covering different seasons and activity plans. The ranking also is used to identify high priority resources and geographic areas for contingency actions. The variability in presence and vulnerability of natural resources gives the operator the possibility of adjusting activity plans according to the time-window providing the lowest environmental risk. Contingency plans can be designed for and focused on periods or geographic areas with increased risk. The results are further used in combination with oil spill statistics to determine specific requirements for oil spill contingency systems. Requirements for key factors—such as response time, equipment, functional capability, and efficiency with respect to weather, oil type, and oil quantity—also are established. The overall efficiency of contingency systems is assessed and the risk reanalyzed to identify the potential for risk reduction. Further developments are proposed advising that risk reduction should be considered in combination with costs involved in investments, maintenance and exercises, as well as real combat action costs and compensation costs. Cost-benefit could then be assessed for different contingency arrangements, providing a basis for selection of optimal solutions for contingency systems according to the ALARP principle—“as low as reasonably practicable”—where costs of countermeasures are weighted against potential risk reduction.