Coalbed Methane Earthcache EarthCache
Coalbed Methane Earthcache
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Located along the Highway 31, west of Huntington, Utah, the posted coordinates take you to a highway turnout with information panels, where you will find the answers for this earthcache.
Coalbed methane is natural gas that is locked in subsurface coal seams and has been generated during the conversion of plant material to coal (the process known as coalification). It is nearly identical with natural gas, and is transported and used as an energy source in natural gas applications. During the Late Cretaceous age, some 70 million years ago, this area located on the southwest edge of the Uinta Basin, was a series of deltas that flowed eastward into the great inland seaway.
During coalification, plant material that accumulated and was preserved in ancient swamps and bogs at rates fast enough to prevent decay (oxidation) begins to compact upon burial. The material is first converted to peat as much of the water in the original material is expelled. As the temperature increases with further burial, ever-increasing ranks of coal form, starting with lignite, followed by subbituminous coal and bituminous coal. If the heat (and pressure) is great enough, anthracite (the highest rank of coal) forms. Biogenic methane (that attributed to bacterial activity) is first to form. When the temperature exceeds that in which bacteria can live, thermogenic methane (that attributed to heating) forms.
At these different stages of coalification, various hydrocarbons (called volatile matter, including methane), along with carbon dioxide, nitrogen, and water, are released. Increased temperatures throughout burial drive off volatile matter. The coalification process can stop at any time, depending on geologic conditions, leaving what we see today as varying ranks of coal. Much of the methane generated by the coalification process escapes to the surface or migrates into adjacent reservoir or other rocks, but a portion is trapped within the coal itself, primarily adsorbed on or absorbed within micropores of the coal.
Through this process, coal contracts and fractures in a distinctive manner. The fractures align themselves according to the existing stress fields in the earth. These fractures are called cleat and they provide permeability pathways through which the fluids may pass. Some gas may escape the coal. However, if formation pressure is sufficient, quantities of methane are retained in the pressurized coal matrix in an adsorbed state.
Following this transformation, the Sevier uplift brought the coals closer to the surface. Erosional forces cut valleys into the uplifted sections, exposing the shallow coals. Today, these shallow coal outcrops are the focus of the mining operations in the immediate area, while deeper unmineable coals are now being developed for their natural gas potential.
Underground coal mines have long been recognized as hazardous environments for miners and their equipment. Methane displaces oxygen within the tunnels and can lead to suffocation or explosions. Many miners and mining tunnels/equipment have been lost due to inadequate venting of the methane gas. Venting of coal mines releases the methane safely to the atmosphere, but does not allow the methane to be collected or used.
Mining engineers and scientists considered the presence and possible productive use of the methane from coal beds in the mid 1900s, but early attempts at recovery met with only marginal and costly success. Not until the open hole well method of extraction was discovered and perfected was Coalbed Methane seen as a real and recoverable energy source. By the early 1980’s, commercial production of Coalbed Methane quickly followed.
Coalbed Methane is produced by non-traditional means, and therefore, while it is sold and used the same as traditional natural gas, its production is very different. A portable drilling rig is used to drill a hole approximately 8 inches in diameter to access the coal seam. Formation evaluation surveys are obtained to evaluate the coal’s potential. Finally, steel casing is placed in the hole and cemented. The drill rig is then removed and holes shot through the casing provide direct access to the coal seam. Natural gas is then produced with the aid of a pumping unit. Produced fluids are piped to a central producing facility where the gas is processed and sent to gas powered power plants, homes and businesses. Currently, natural gas from coal beds accounts for approximately 7% of total natural gas production in the United States. New and emerging uses include natural gas powered vehicles and a key fuel component for fuel cells.
According to the Coalbed Methane Association of Alabama, 13% of the land in the lower 48 United States has some coal under it, and some of this coal contains methane - either in the form we know as traditional natural gas or as Coalbed Methane. The largest known concentration (56%) of Coalbed Methane in the United States is in the Rocky Mountains of Wyoming, Utah, New Mexico, Colorado, and Montana. According to the United States Geological Survey, the Rocky Mountain Region has extensive coal deposits bearing an estimated 30-58 trillion cubic feet of Coalbed Methane, extractable in these basins using current technology. While impressive, this represents only one third of the total 184 trillion cubic feet of natural gas in the Rocky Mountain region.
Within the Rocky Mountain Region, untapped sources of Coalbed Methane exist in the Powder River Basin of Wyoming and Montana, the Greater Green River Basin of Wyoming, Colorado, and Utah, the Uinta-Piceance Basin of Colorado and Utah, and the Raton and San Juan Basins of Colorado and New Mexico.
The above information was taken from the Information Panels at the Earthcache Site and a Kentucky Geological Survey Fact Sheet on Coalbed Methane.
To log this cache:
Send me an email with the first line reading Coalbed Methane Earthcache. In the email answer the following questions:
1. How far below the surface is the Coalbed Methane found in this area?
2. In what geologic formation can Coalbed Methane be found?
3. What two additives are initially pumped into the coals to increase the natural productivity?
4. Name the titles of the five topics on the Coalbed Methane information?
BONUS: Post a picture of anything you found interesting at this location – except the information on the displays.
After e-mailing the answers, go ahead and log your cache. I may or may not be able to respond in a timely manner, and may only do so if necessary.
ANY LOGS POSTED WITH THE ANSWERS ON THIS PAGE WILL BE DELETED!
* * FTF Congrats to VR 34 * *
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