Coal Bed Methane

  • Coalbed methane (CBM or coal-bed methane), coalbed gas, coal seam gas (CSG), or coal-mine methane (CMM) is a form of natural gas extracted from coal beds.
  • In recent decades it has become an important source of energy in United States, Canada, Australia, and other countries.
  • The term refers to methane adsorbed into the solid matrix of the coal.
  • It is called ‘sweet gas’ because of its lack of hydrogen sulfide.
  • The presence of this gas is well known from its occurrence in underground coal mining, where it presents a serious safety risk.
  • Coalbed methane is distinct from a typical sandstone or other conventional gas reservoir, as the methane is stored within the coal by a process called adsorption.
  • The methane is in a near-liquid state, lining the inside of pores within the coal (called the matrix).
  • The open fractures in the coal (called the cleats) can also contain free gas or can be saturated with water.[citation needed]
  • Unlike much natural gas from conventional reservoirs, coalbed methane contains very little heavier hydrocarbons such as propane or butane, and no natural-gas condensate.
  • It often contains up to a few percent carbon dioxide.

Source: Wiki

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