Pilot Study of Environmental Risk Analysis Methodology Applied to Angolan Dalia FPSO

Abstract

An Environmental Risk Analysis (ERA) was conducted as a pilot study on the Dalia Total FPSO (Floating Production and Storage unit) in Angola located at about 135 km off the coast with complex subsea installations at 1400m depth. The environmental damage and its frequency resulting from the drift and fate of oil depend on many physical, chemical and environmental parameters like the location and composition of the spill, oil weathering, complex and variable surface wind and current patterns, weather conditions, sensitivity of the environmental resource etc…The detailed ERA can only be done if one can estimate the probability of a given quantity of oil to reach an environmental resource and the resulting environmental damage. The possibility to use 3D oil spill drift simulation to fulfill these technical requirements and fit with the Total HSE Reference Framework and risk Matrix is tested. The TOTAL HSE Reference Framework requires that technological risk assessments are carried out for all installations. Based on the technological risk assessment of Dalia FPSO, accidental spill scenarios were compiled and aggregated to a set of most representative scenarios including one blow out case. For each spill scenario, oil drift simulations were conducted in stochastic mode with the OSCAR model developed by Sintef i.e. repeated 246 times for a period of 5 years where met-ocean data were available. Quantities of oil and associated probabilities of presence were calculated for each cell of the model. Environmental target were identified and positioned within a Geographical Information System (GIS) also used in simulations. Environmental damages were estimated based on the MIRA method. Based on these data accidental spill scenarios could be positioned on the Total risk matrix. The pilot results as well as the acceptability of the uncertainties related to this approach are discussed.

Holistic Environmental Risk Index for Oil and Gas Industry in Colombia

“…The combination of these ranking levels determines the ranking of risks [38]. For this methodology, five papers were revised [36,[39][40][41][42]. The main findings reveal that while the risk matrix methodology is efficient and requires minimal data, the lack of consideration of statistical data in assessing the probability and consequences leads to a higher level of uncertainty in the results.…”