METHOD AND APPARATUS FOR USING PRESSURE CYCLING AND COLD LIQUID CO2 FOR RELEASING NATURAL GAS FROM COAL AND SHALE FORMATIONS

摘要

A method and apparatus for sequestering carbon dioxide (CO₂) gas and releasing natural gas from underground coal and/or gas shale formations using CO₂ gas captured from the flue gas of a coal burning power plant, and processing it to produce cold liquid pressurized CO₂, and injecting the cold liquid CO₂ under pressure to create fractures within the formation and causing the CO₂ to be adsorbed into the coal or gas shale and natural gas (CH₄) to be desorbed, released and recovered. A special pressure cycling process is used to enable the pressure within the formation to be increased and decreased, including allowing the liquid CO₂ to change phase to a gaseous CO₂, and injecting the liquid CO₂ under pressure repeatedly, which causes greater expansion of the proliferation zone within the formation, and more efficiently releases CH₄.