Phase Field Theory Modeling of CH4 and CO2 Fluxes from Exposed Natural Gas Hydrate Reserviors

• Main Author: Baig, Khuram
• Format: Master Thesis
• Language: English
• Published: The University of Bergen 2009
• Subjects: 752199; Arctic; Barents Sea; Bear Island; Ice; permafrost
• Online Access: https://hdl.handle.net/1956/3625

Natural gas hydrates are widely distributed in sediments along continental margins, and harbor enormous amounts of energy. Gas hydrates are crystalline solids which occur when water molecules form a cage like structure around a non-polar or slightly polar (eg. CO2, H2S) molecule. These enclathrated molecules are called guest molecules and obviously have to fit into the cavities in terms of volume. Massive hydrates that outcrop the sea floor have been reported in the Gulf of Mexico (MacDonald, et al., 1994). Hydrate accumulations have also been found in the upper sediment layers of Hydrate ridge, off the coast of Oregon and a fishing trawler off Vancouver Island recently recovered a bulk of hydrate of approximately 1000kg (Rehder, et al., 2004). Håkon Mosby Mud Volcano of Bear Island in the Barents Sea with hydrates openly exposed at the sea bottom (Egorov, Crane, Vogt, Rozhkov, & Shirshov, 1999). In oil and gas industry the most common guest molecules are methane, ethane, propane, butane, carbon dioxide and hydrogen sulfide. But hydrocarbons with up to seven carbons can create hydrate. The worldwide energy contained in hydrates is huge. But at the same time many of the natural hydrate resources are not well trapped below clay and shale layers and dissociate through contact with under saturated water. Arctic hydrates may be covered by ordinary geological trapping mechanisms and ice layers of varying thickness. The integrity of the geological trappings in these areas are, to a large extent unknown and many potential scenarios can occur when the ice is shrinking in these areas. One of the largest environmental problems facing mankind in the 21st century is the impacts on global weather patterns due to greenhouse gases like methane, carbon dioxide and chlorofluorocarbons. It also effects the distribution of ecosystems and sea level change due to the impact of increased temperature on the melting of arctic ice and the shrinking of other permafrost ice like for instance glaciers. As a greenhouse gas CH4 is in the ...