Editing Coalbed methane extraction (section)

==Basic principles==
Methane [[Adsorption|adsorbed]] into a solid coal matrix (coal macerals) will be released if the coal seam is depressurized.  Methane may be extracted by [[well drilling|drilling wells]] into the coal seam. The goal is to decrease the water pressure by pumping water from the well.  The decrease in pressure allows methane to desorb from the coal and flow as a gas up the well to the surface. Methane is then compressed and piped to market.

The objective is to avoid putting methane into the water line but allow it to flow up the backside of the well (casing) to the compressor station. If the water level is pumped too low during dewatering, methane may travel up the tubing into the water line causing the well to become "gassy". Although methane may be recovered in a water-gas separator at the surface, pumping water and gas is inefficient and can cause pump wear and breakdown.