Abstract B135

The objective of this research was to conduct a Comparative Risk Analysis for a Spar-based Floating Production Storage and Offloading (FPSO) facility in the Gulf of Mexico. This work represents an extension of a previously completed project where the oil spill and fatality risks were analyzed for a tanker-based FPSO in the Gulf of Mexico (Gilbert et al. 2001). In the earlier work, the risks for the tanker-based FPSO were compared with three types of deepwater production systems that have already been operated successfully in the Gulf of Mexico: a Spar and a Tension Leg Platform (TLP) with oil pipelines; and a shallow-water jacket serving as a hub and host to deepwater production. The results from the original project guided the current research in the following ways:

• Oil spills due to transportation from the facility to the shore terminal was the main discriminator between the various systems. Therefore, this risk was the focus of the current project and a comparison was developed for the spar-based FPSO (oil transport through storage on the facility and offloading to shuttle tankers) with a conventional spar (oil transport through a pipeline).
• An important factor in the oil-spill risk was how the distributions of the largest spill sizes were modeled. Developing a practical method to accommodate different assumptions for these distributions and to incorporate the uncertainty in these distributions was addressed in the current project.
• The measure of risk for oil spills in the original work was the average volume spilled in the operational lifetime of a facility, where the average represents the average for a large fleet of similar facilities operating in the Gulf of Mexico. In order to gain additional insight into the risk, the variability in performance between individual facilities was also addressed in the current project.
• There was significant uncertainty in the estimated value for the average volume spilled for each facility type, such that it was very difficult to distinguish the estimated performance of one type of facility from another. In the current project, an approach was developed to use operational data from these facilities to update the estimated performance so that the risk could be periodically re-assessed in the future as more data become available.

This report provides a brief description of the methodology and a summary of the major results and conclusions. A more detailed description of this work is provided in Chemadurov (2002).