The study looked at why coalbed methane production decreases quickly in high-rank coal reservoirs. By examining fractures and pores in the coal, as well as how stress affects permeability, researchers found that the productivity of coalbed methane drops rapidly after a few months of development. This decrease is due to a combination of stress and coal shrinkage. The study suggests new techniques for extracting methane from high-rank coal reservoirs based on their unique physical properties.