News Release, Kansas Geological Survey, Dec. 6, 2001
Geologists say that the coal that underlies much of the eastern fourth of the state could be a potential source of methane, or natural gas. In places, companies have begun aggressive drilling programs to produce the gas, called coalbed methane.
Survey geologist Larry Brady has studied the state's coal resources for more than 30 years. Brady said that coalbed methane is naturally present in many of the coal layers in eastern Kansas. By drilling wells into the coal, that gas can be removed from the coal beds and pumped to the surface.
Kansas already produces large amounts of natural gas (550 billion cubic feet in the year 2000), but nearly all of it comes from conventional sources, such as underground limestone and sandstone layers, many of which are several thousand feet deep. The Hugoton natural gas field in southwestern Kansas, for example, is one of the largest natural gas fields in North America.
Small amounts of coalbed methane have been produced in Kansas for the past decade. Much larger amounts are produced in other parts of the country, particularly in the San Juan basin of southwestern Colorado and New Mexico, in Wyoming, Montana, and Utah, and in Alabama.
In Kansas, production is limited, in part because many coal beds are thin, and a well must encounter several layers in order to be profitable. Wells also need to be fairly close to a pipeline to transport the gas. And wells produce large amounts of water, in addition to coalbed methane, that must then be disposed of by injecting it into deep geologic formations.
"Still, Kansas coal beds have a great deal of potential for producing methane," said Brady.
As a result, private companies have drilled more than 100 wells for coalbed methane in the past year. Most of the interest has focused on Montgomery, Wilson, Labette, and Chautauqua counties in southern Kansas. Other parts of eastern Kansas have been leased by companies for possible exploration for the gas.
While coalbed methane wells don't always produce huge amounts of gas, they do produce for long periods. Wells in northeastern Oklahoma have produced methane for as long as 40 years.
"An average coalbed methane well in Kansas can produce 60 million cubic feet of natural gas over a two-year period," said Brady. "That gas has a value of more than a hundred thousand dollars. Some Kansas wells have produced now for more than 10 years. If enough of these wells are drilled and produced, the potential is great."
In 1993, the Kansas Geological Survey drilled in Leavenworth County to help geologists understand the potential for coalbed methane in northeastern Kansas.
"That well encountered 13 different coal beds, including one that was more than two feet thick," said Brady. "Few of these layers are thick enough to support coalbed methane production by themselves. But a number of areas in eastern Kansas are underlain by several coal layers that, together, may support production."
Most of the coal in Kansas was deposited during the Pennsylvanian Period of geologic history, also known as the Coal Age, about 305 million years ago. Those deposits were formed from vegetation that grew along the edge of a brackish sea. It took about 10 feet of vegetation to eventually form about one foot of coal. All of the coal found in eastern Kansas is bituminous--that is, slightly softer and capable of producing less energy than anthracite coal.
"But some types of bituminous coal, including those in Kansas, are ideal for methane to be present in large quantities," said Brady.
The coal itself has been mined in the state since territorial times, either through underground mines or, more recently, through strip mines. However, because Kansas coals are relatively thin, contain somewhat high amounts of sulfur, and are, in many places, covered by a thick layer of overburden, coal mining in the state has decreased over the years. Today, only one or two mines generally operate in eastern Kansas at any given time, and most of the coal burned in Kansas is shipped in from western states, especially Wyoming.
However, coalbed methane is reviving interest in the state's coal resources.
"This is an unconventional source of gas that has the potential to make a big economic impact," said Brady.