CO2 storage in deep unminable coal seams

The gas storage mechanism in coal seams, adsorption, is distinctively different from that in oil and gas reservoirs and aquifers, where injected CO2 occupies the pore space as a separate phase or is dissolved in water or oil. Over the last two decades coalbed methane (CBM) has become an important source of (unconventional) natural gas supply in the United States. Carbon dioxide enhanced coalbed methane recovery (CO2-ECBM) is an emerging technology, which has the potential to store large volumes of anthropogenic CO2 in deep unminable coal formations (coalbeds), while improving the efficiency and potential profitability of coalbed methane recovery.