CBM (Coal Bed Methane) is the product of a maturation of essentially vegetable organics, buried for years with high pressure and temperature, that solidify and get enriched with carbon.
The Lorraine Coal is known for its high gas content (more than 96% CH4). The coal seams, dated from Carboniferous period, are very thick (up to 15 m) and were extracted by an important mining activity up to 2004.
The pumping of the water, naturaly present in the coal, will decrease the pressure in the coal seam. The gas molecules detach from the coal matrix and migrate up to well using its natural fractures network (cleats). No stimulation nor hydrolic fracturing is requested to produce the gas.