A Model for ecological impact assessment from deepwater releases of Hydrocarbons (Methane)

The governments around the world and the industry are developing major programs to produce oil and gases economically for commercial use. As the production increases the risks of accidental releases also increase. Recognizing this, the development of tools for contingency and emergency planning and impact assessment have become an integral part of the exploration programs. For instance, in the United States, some of the oil and gas platforms are in the hurricane zone. Some of the rigs in Japan may be in the areas vulnerable to typhoons. Australia is known to produce gas from offshore sites which are in the cyclone zone. During Deep Water Horizon in Gulf of Mexico, model predictions have widely been used in preparation of plans for cleanup crews, in mitigation efforts and in deciding dispersant application activities. This is another example showing that a computer model that can predict the fate and transport of gasses and dissolved matters accidentally released is needed for dealing with emergencies, contingency planning, and impact assessment. Lately the contingency planning includes the design of relief wells in advance in anticipation of an unlikely event. The design of these requires information from a model that does the impact assessment.;Technology has drastically advanced to extract oil and gas deposits that exist well below 1000m deep ocean at a reasonable cost. At these depths, the high pressure and cold temperature combine to convert the gases into hydrates. Hydrates and gases dissolve in water. In contrast, some other gases which are in super saturation in ambient water may get into the existing gas bubbles (from dissolved phase to gas phase). By this way, dissolved oxygen in water may diffuse into methane bubble and transfer to a higher elevation.;This thesis discusses additions, improvements and modifications to the existing model that simulates ultra-deepwater oil/gas spills. Both dynamic behavior closer to the release point and non-dynamic behavior distant from the release point are taken into account in modeling. The model will consider both the thermodynamics and hydrodynamics of the plume. It will include all types of gas dissolutions (gas/hydrate) from the birth to the end of bubble life. Potential biochemical processes such as effects of dissolved methane on dissolved oxygen in water in the presence or respective microbes, and growth and decay of such microbes are to be included. Modeling of fate and transport of dissolved methane is a new addition to the model and resulting biochemical and physical impacts also have never been modeled.