SUBSURFACE CARBON DIOXIDE STORAGE THROUGH CLATHRATE HYDRATE FORMATION

Abstract

Rising atmospheric emissions as a result of fossil fuel consumption is a major concern for the developed and developing countries, considering the role it plays in the greenhouse effect and hence global climate change. Various schemes for underground CO₂ storage (viz. geologic disposal into coal seams, depleted oil/gas reservoirs, salt caverns, and deep oceans) have already been reported in the literature. Subsurface CO₂ storage through clathrate hydrate formation is a novel option for the reduction of atmospheric carbon content and permanent underground CO₂ disposal over geological periods. Depths of CO2 injection, respective pressure-temperature conditions, water salinity etc. are all important factors for successful CO₂ sequestration. Furthermore if CO2 is injected/stored in methane hydrate reservoirs it could be possible to produce low-carbon methane energy, thereby offsetting the cost of CO₂ transportation and disposal. In this communication, we present the results of experiments carried out to understand the mechanisms of CH₄ displacement in hydrate structure by injected CO₂ and the formation of simple CO₂ or mixed CH₄-CO₂ hydrates, thereby simulating the conditions of CO₂ injection into CH₄ hydrate reservoirs. We used two sets of experimental rigs specifically designed for studying gas hydrates in porous media. They are the Medium Pressure Glass Micromodel (80 bar) for visual observation of gas hydrate formation / dissociation and distribution in porous media, and the Ultrasonic Rig (400 bar) for studying CO₂ sequestration in CH₄ hydrates in synthetic porous media.