FREQUENCY ANALYSIS OF ACCIDENTAL OIL RELEASES FROM FPSO OPERATIONS IN THE GULF OF MEXICO

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The MMS is investigating the potential impact of the operation of Floating Production, Storage and Offloading installations (FPSOs) in the Gulf of Mexico. One of the concerns of the MMS is the potential negative effect on the environment from accidental oil releases, and in connection with this they have contracted Ecology and Environment to conduct an environmental impact study. Ecology and Environment will calculate the consequences of oil releases on the marine and coastal resources and combine these findings with estimated frequencies of accidental releases. The work to estimating the frequency of accidental oil releases from FPSO operations has been sub-contracted to DNV. This report presents DNV’s findings.
Scope of Work
DNV’s scope of work includes predicting the frequency of unique accidental releases from operation of a generic FPSO in the GoM. The specification for the FPSO is taken from the “Scenario Report, Environmental Impact Statement on Floating, Production, Storage, and Offloading Systems on the Gulf of Mexico Outer Continental Shelf” which provides an outline description of the FPSO and its operation. Where insufficient details are provided in the Scenario Report DNV has used judgement and experience of earlier FPSO risk analyses to supplement the information given. Good practice has been generally assumed.

The scope of the study includes:

• All aspects of operation of the FPSO from the wellheads, through oil and gas production to export of the oil by shuttle tanker, and the gas by pipeline to shore.
• Shuttle tanker transit risks to a shore terminal.
• The various utilities provided by the FPSO required for operation and support of the people manning the installation.
• External and environmental risk factors are also assessed.

The study does not include construction, installation commissioning and decommissioning of the FPSO, nor does it include drilling or work over of the wells. These were specifically excluded from the scope of work by MMS.
In addition to the basecase, the Scenario Report identifies options for the FPSO and its operation that may affect the environmental risk presented. These options have been qualitatively assessed to consider what impact, if any, they have on the overall risk. Also, DNV has identified a number of mitigation measures to reduce the risk due to accidental oil releases.