Coal bed methane

Coal bed methane (CBM) is an odorless, colorless,
flammable gas that occurs naturally in coal seams.
It is the same gas that poses a safety risk to underground coal miners. Historically, when natural gas was cheap or had no commercial value, CBM was treated as a nuisance by miners and vented from mines. However, as demands for natural gas developed, especially in recent years, drilling companies began to sink wells into coal seams to recover CBM for commercial uses.

Pennsylvania is estimated to have at least 2.5 trillion cubic feet of CBM reserves. Hundreds of CBM wells already operate within the state, principally in Greene, Washington, Fayette, Indiana and Cambria Counties.

CBM drilling operations raise some different
environmental issues than do deep-shale drilling operations.

  1. Although horizontal drilling and hydraulic fracturing are used in both types of wells, much less water is needed to frac a CBM deposit; coal is much more porous than shale so it more freely releases the gas it holds.
  2. The water produced by CBM wells tends to have much lower levels of dissolved solids, minerals and naturally occurring radioactive materials than does the water produced by deep shale wells. This reduces — but doesn't eliminate — water treatment demands.
  3. Coal seams containing CBM lie hundreds — rather than thousands — of feet beneath the surface so they are often close to underground sources of drinking water (USDWs). Accordingly, any toxic chemicals used to frac coal seams to produce CBM may pose a greater risk to USDWs and human health than they would if pumped thousands of feet below the surface to produce gas from deep shale deposits.

CBM drilling in Pennsylvania raises property rights issues.
Under the Pennsylvania Supreme Court's 1983 decision in U.S. Steel Co. v. Hoge, CBM belongs to the owner of the coal in which it occurs rather than the owner of the surface estate. Because the ownership of the coal and surface estates are often (and perhaps usually) separate in Pennsylvania, CBM drillers may be able to lawfully conduct drilling operations on surface owners' land without having to pay a lease fee for drilling rights, pay royalties on gas produced, or, in some instances, obtain the surface owner's approval before siting their operations.