Investigation of the Fate and Transport Behaviours of Spilled Oil and Development of a State-of-the-Art Canadian Oil Spill Emergency Response Model

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Oil and gas resources are of significant economic importance to Canada’s economy. The oil and gas industry in Canada is continuously growing and several major oil exploration and transportation projects from coast to coast have been announced recently. Increased oil and gas activity raises the risk of marine oil spills, which is of significant concern because of the potentially devastating environmental effects. The recent Deepwater Horizon disaster has shown that spills in the deep water environment present extremely difficult response logistics; hence, it is vital that a reliable oil spill model be available to predict the trajectory of oil and help allocate the limited response resources. Unfortunately, our knowledge on the fate and transport behaviour of spilled oil in the marine environment is still very poor, and there is an urgent need to improve existing oil spill models. This research program is aimed at advancing our understanding of the fate and transport behaviour of spilled oil in the marine environment, and continuously improving our ability to predict the movement of oil and its ultimate fate. Currently, a major barrier in the modeling of subsurface oil spills is the lack of experimental data on oil droplet size distribution, which plays a critical role in determining the ultimate fate of the oil. Therefore, this research will address this lack by conducting meso-scale experiments in a 30 m tank, and releasing oil underwater in a combination of different release rates, dispersant dosage, and oil types. Droplet size will be measured by a combination of three different instruments to capture the whole range of droplets from a few microns to several millimeters. A mathematical model of the distribution will be developed and then integrated with an existing oil spill model to study the effects of the distributions on oil mass balance and trajectory. Previous studies have shown that high concentrations of suspended sediments in coastal waters can change the behavior of spilled oil significantly, and may lead to potential settling of oil at the seabed. This results from the formation of oil-mineral aggregates whose densities are often higher than that of the ambient water. To accurately predict the fate and trajectory of oil, it is very important to include this process in an oil spill model, but none of the existing models consider this process. Therefore, another objective of this research is to develop a mathematical model to simulate oil-mineral aggregate formation. This will be achieved by extending a single particle type aggregation kinetic model to particles of different densities (oil and sediments) and determining the collision coefficients based on existing experimental data. The new aggregation model will then be incorporated into a general oil spill model to extend its applicability, and to improve the accuracy of its prediction. The recent Gulf of Mexico oil spill disaster demonstrated the importance of using an integrated operational ocean circulation/oil spill model to provide real time prediction and help to allocate limited response resources. Because Canada currently lacks such a system, it is the objective of this study to develop it by integration of the new advanced oil spill model (using new knowledge on both droplet size distribution and OMA formation) with a well validated, operational, ocean circulation model for the east coast of Canada. In summary, this proposed research aims to not only advance our knowledge in two key areas of oil spill behavior, but also provide an important operational tool that will help regulatory agencies and spill responders track the oil in real-time and make more effective decisions concerning the adoption of proper oil spill countermeasures.