Editing Coalbed methane extraction (section)

==Areas with CBM extraction==
Tens of thousands of methane wells have been drilled, and extensive support facilities such as roads, pipelines, and compressors have been installed for CBM extraction in the [[Powder River Basin]] of northeast [[Wyoming]] and southeast [[Montana]] and now in India at West Bengal- Ranigunj, Panagarh, etc. Seven percent of the [[natural gas]] (methane) currently produced in the [[United States]] comes from CBM extraction. Methane from coalbed reservoirs can be recovered economically, but disposal of water is an environmental concern.

There are also sites in Central Scotland at Letham Moss.<ref>{{Cite web |last=NatureScot |date=2020-08-25 |title=Career through a lens: my favourite photographic memories |url=https://scotlandsnature.blog/2020/08/25/career-through-a-lens-my-favourite-photographic-memories/ |access-date=2023-11-04 |website=Scotland's Nature |language=en}}</ref>
 
Most gas in coal is stored on the internal surfaces of organic matter. Because of its large internal surface area, coal stores 6 to 7 times more gas than the equivalent rock volume of a conventional gas reservoir. Gas content generally increases with coal rank, with depth of burial of the coal bed, and with reservoir pressure. Fractures, or cleats, within coal beds, are usually filled with water. Deeper coal beds contain less water, but that water is more saline. Removing water from the coal bed reduces pressure and releases methane. Large amounts of water, sometimes saline [[brine]], are produced from [[coalbed methane]] wells. The greatest water volumes are produced during the early stages of production. Environmentally acceptable disposal of brine is a major cost factor for economic methane production. Fresh water may be discharged on the surface, but the brine is usually injected into the rock at a depth where the salinity of the injected brine is less than the [[connate fluids]] of the host rock. Evaporation of water for recovery of potentially salable solid residues might be feasible in regions having high evaporation rates.<ref>[http://energy.usgs.gov/factsheets/Coalbed/coalmeth.html Coalbed methane] {{webarchive|url=https://web.archive.org/web/20060918195447/http://energy.usgs.gov/factsheets/Coalbed/coalmeth.html |date=2006-09-18 }}</ref>