Author(s): Malinda R. Wimalaratne; Poojitha D. Yapa
Linked Author(s):
Keywords: Deepwater gas plumes; Gas dissolution; Dissolved methane biodegradation; Dissolved oxygen decay
Abstract: Underwater oil, gas, and hydrate exploration and production activities have increased significantly in the recent past, as global industry have been looking for offshore energy sources. With the increase of these activities the potential threat of accidents have increased. Recognizing this, the development of modeling tools for emergency response, contingency planning, and impact assessment have become an integral part of the mitigation programs. For releases at depths below ~500m, the high pressure and cold temperature combine to convert the gases into hydrates. Hydrates and gases dissolve in water. These dissolved hydrocarbons feed bacterial masses in ambient water while affecting aqueous oxygen in water column. In contrast, some other gases dissolved in ambient water may get into the existing gas bubbles (from aqueous phase to gas phase). By this way, dissolved oxygen in water may diffuse into hydrocarbon bubble and transfer to a higher elevation. Recognizing all these needs we developed a comprehensive model (MEGADEEP-Eco) to simulate many of the processes observed due to a deepwater oil/gas release. This paper presents the model development, validation with limited experimental data, and a scenario simulation. Ecological aspects due to subsea spill such as biodegradation of dissolved methane decay in dissolved oxygen and changes in respective biological species have been modeled in MEGADEEP-Eco and studied with a hypothetical methane release simulation in GoM.
Year: 2016