Consequence Analysis of a Liquefied Natural Gas Floating Production Storage Offloading (LNG FPSO) Leakage

Abstract

A quantitative risk assessment comprises some basic activities that have to be developed to allow the quantification of the risks involved in the operation of a system or process under analysis. Basically, the likelihood of the undesired events has to be identified as well as their consequences must be calculated. When the risks in the operation of a marine vessel are analyzed, the same process has to be followed. For each specific phase of the marine vessel mission, all of the undesired events must be accurately determined and evaluated. Many different types of undesired events must be investigated, such as: fire, explosion, collision, falling objects and marine hazards. There are many techniques involved in the estimation of the likelihood of the events and the same occurs for the evaluation of their consequences. The purpose of this paper is to study a leakage during a cargo offloading considering a LNG shuttle tanker and a Liquefied Natural Gas Floating Production Storage Offloading (LNG-FPSO) in the Pre Salt Brazilian coast. Once defined the feasible scenarios and the total quantity discharged, the consequences will be evaluated using physical models described in the literature and implemented in commercial softwares. The main idea is to identify all possible consequences and verify their magnitudes. As this is an isolated study, where the likelihood of the event will not be estimated, the final objective is to use the results obtained to predict mitigating measures to the system. This is not a simple task due to the complexity of the phenomena developed after the leakage. In order to verify the extension of possible spread events it is also necessary the identification of many variables, including the atmospheric conditions, the sea condition, the ignition sources, the vessels nearby, the shuttle tanker(s), and the positioning of the vessels involved in the offloading operation.