Extraction of natural gas from subsea gas hydrate deposits coupled with CO2 storage - Modeling and simulation

Natural gas hydrates found worldwide in subsea sediments are of rising economical and ecological interest. The vast amount of carbon assumed in gas hydrate deposits can help to overcome a shortage of fossil energy resources in the future. To increase their potential for energy applications today new technological approaches for the extraction of natural gas from gas hydrate deposits are being discussed and developed. The incineration of hydrate based natural gas can contribute to the energy supply but the coupled CO2 emission causes climate change effects. To develop a sustainable hydrate based energy supply system the sequestration of CO2 has to be coupled with the CH4 production from the hydrate deposit. Due to this demand the simultaneous storage of CO2 in hydrate deposits has to be de veloped. From the thermodynamic point of view this process seems to be applicable because CO2 hydrate is more stable than CH4 hydrate. Regarding technological implementation many problems have to be overcome. Especially mixing, heat and mass transfer in the reservoir are limiting factors causing very long process times. Within the scope of the German research project »SUGAR« different technological approaches are evaluated and compared using numerical models for dynamic system simulations and analysis. Therefore, detailed mathematical models for most relevant chemical and physical effects are developed. Basic aspects of gas hydrate formation/destabilisation and mass and heat transport mechanisms are considered and implemented into simulation programs like CMG STARS and UMSICHT-HyReS.