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Abstract

The presence of natural gas hydrates at all active and passive continental margins has been proven. Their global occurrence as well as the fact that huge amounts of methane and other lighter hydrocarbons are stored as natural gas hydrates has led to the idea of using hydrate bearing sediments as an energy resource. However, natural gas hydrates remain stable as long as they are in mechanical, thermal and chemical equilibrium with their environment. Thus, for the production of gas from hydrate bearing sediments, at least one of these equilibrium states must be disturbed e.g. by depressurization, heating or addition of chemicals such as CO2. Depressurization, thermal or chemical stimulation may be used alone and also in combination. Producing hydrocarbons from hydrate bearing sediments by CO2 injection, in particular, suggests the potential of an almost greenhouse gas neutral use of this unconventional natural gas resource. In any case, the exploitation of natural gas hydrates is a technical challenge. The GFZ was already involved in the first real production test at the Mallik testsite in Canada in 2001/2002 using thermal stimulation. Within the framework of the German joint research project SUGAR scientists from GFZ German Research Centre for Geosciences developed and tested an innovative method using in situ combustion for thermal stimulation on a pilot plant scale. Preliminary results are quite promising: this kind of thermal stimulation, combined with depressurization may be an efficient method to produce gas form natural gas hydrate deposits.