What is coal bed methane? It is another name for natural gas that is being recovered from seams of coal that are too deep to mine. As coal breaks down into other hydrocarbons, through heat, pressure and organic means, it gives off natural gas composed of mostly methane. Natural gas recovered from coal seams is often considered "sweet" since it is free of hydrogen sulfide. Coal bed methane is often found in a near liquid state, locked in the pores of the coal with free gas trapped in the fissures that run through the coal seam. Coal bed methane does not contain many of the heavier elements of natural gas such as propane or isobutane. It may be mixed with water, which must be extracted from the gas and pumped back in the ground. This poses some environmental challenges.
There are many of these layers of gas producing coal scattered across the United States.
Coal bed methane now accounts for an estimated nine percent of domestic natural gas production. It is now possible to recover even more gas from coal seams with the technology of horizontal drilling. A well that breaches the coal seam at an angle is able to extract much more natural gas or coal bed methane than a vertical well.
Using sophisticated directional sensors known as MWD or measure while drilling, as well as information from mudlogging which analyzes drill bit cuttings at the surface, an oil company can keep the drill bit in a thin zone of just a few feet thick and drill up to several thousand feet of lateral wellbore through the gas rich coal seam.
It is estimated by the U.S. Geological Survey that there are over 700 trillion cubic feet of natural gas in the form of coal bed methane in reserves throughout the U.S. Along with recently discovered shale gas reserves such as the Marcellus shale and Barnett shale, natural gas represents an extremely valuable part of America's energy future. For more about how coal bed methane is recovered see this article about horizontal drilling techniques. http://energyindustryphotos.com/horizontal_drilling_methods.htm