A method of producing methane by injecting inert gas, such as nitrogen, through an injection well into a solid carbonaceous subterranean formation (e.g., coal) and recovering methane from a production well(s). Methane desorption is achieved by reduction in methane partial pressure rather than by reduction...http://www.google.com/patents/US5014785?utm_source=gb-gplus-sharePatent US5014785 - Methane production from carbonaceous subterranean formations
