Coalbed gas, or coalbed methane (CBM), is a new natural gas resource that has come to the industry's attention just recently. Unlike trap-dependent conventional natural gas, CBM is preserved by adsorption to the internal surfaces of micro-pores and fractures in coalseams, which serve as both gas source rocks and container rocks. To produce CBM, the coalseam has to be depressurised through dewatering to allow the CBM "desorption-diffusion-percolation" process to occur. Therefore, CBM is an unconventional natural gas.
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