Consequence analysis for the risk-based design of offshore safety system

Dadashzadeh, Mohammad (2013) Consequence analysis for the risk-based design of offshore safety system. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

Safety measure design and accident predictive and prevention strategies are critical in the offshore process. The key area of concern in an offshore facility is a major event such as a fire, an explosion and the release of hazardous materials. The recent BP Transocean Deepwater Horizon accident is an example of safety protocols either being inadequate or response being inefficient and ineffective. Understanding the consequences of major release events is a key step in safety measure design and consequence assessment of major events. The assessment includes the definition of different release scenarios, release modeling, event modeling, and damage/loss quantification. The consequence assessment is an important step of risk estimation and is subsequently used to design safety measures. -- To address release scenario modeling, a new methodology is developed in the current study to revise the emission factor estimation methods earlier developed by USEPA. Applying a non-linear regression approach, a new set of equations is introduced to estimate emission rates. Having ΔAIC values of more than 10, in the categories of pump seals, connectors, flanges and others, the equations replace USEPA's proposed correlation equations for oil and gas facilities. -- Computational Fluid Dynamics (CFD) is used to simulate different release scenarios, particularly to study fire, explosion and toxic dispersion. The Flame Acceleration Simulator (FLACS), a CFD tool, is used to model explosion and toxic dispersion of combustion products. To improve the consequence modeling work, a systematic approach for CFD modeling of Vapour Cloud explosion (VCE) is also introduced. Fire Dynamic Simulator (FDS) is used to model pool and jet fires. -- A novel integrated approach in modeling the evolving accident scenarios is also developed in the current study. To develop the toxic risk profile of combustion products of an installation, a risk-based approach is proposed, overcoming the shortcomings of a concentration-based approach. -- The newly developed approaches and models are tested on real-life case studies.

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