Studies Towards the Development of a CH4 Production Technology By CO2 Sequestration into Submarine Hydrate Reservoirs

In the recent past, international research efforts towards exploitation of submarine and permafrost hydrate reservoirs have increased substantially. Emission neutral exploitation of CH4-hydrates could potentially be achieved in a combined process with CO2 injection and storage as CO2-hydrate. In the German gas hydrate initiative SUGAR, a combination of experimental and numerical studies is used to elucidate the process mechanisms and technical parameters on different scales. Among the parameters tested so far are the CO2 injection regime, the injection temperature and the reservoir pressure / temperature conditions. It was shown that CH4 production is optimal at intermediate reservoir temperatures (8 °C) compared to lower (2 °C) and higher temperatures (10 °C). The reservoir pressure, however, was of minor importance for the production efficiency. The injection of heated CO2 into the hydrate reservoir induces a variety of spatial and temporal processes which result in substantial bulk heterogeneity. Current numerical simulators are not able to predict these process dynamics and it is important to improve available transport-reaction models. Our results confirm that experimental studies are important to better understand the mechanisms of hydrate dissociation and conversion at CO2-injection conditions as a basis towards the development of a suitable hydrate conversion technology.