분야
docxI. Introduction
II. How is CBM formed
III. Reserves
1. United States
① Powder River, Wyoming
② San Juan Basin, New Mexico
③ Black Warrior Basin, Alabama
2. Russia
3. China
4. Canada
IV. Principle and properties of production technology
V. CBM Production Technology
1. Vertical Wells
2. Gob Wells
3. Horizontal Boreholes
4. Cross-Measure Boreholes
5. Other Degasification Methods
VI. The Spotlight of CBM
VII. CBM projects status
1. United States of America
2. Canada
3. Australia
4. China
VIII. The Economic Characteristics of CBM Development Projects
IX. Concerns about CBM
1. Water Quality
2. Dried-Up Wells
3. Surface Disturbance
4. Noise
5. Coal Seam Fires
6. Regulatory Framework
X. ECBM
XI. Prospect of CBM Projects
XII. Conclusions
XIII. References
Coalbed methane (CH4) forms in one of two ways. During the earliest stage of coalification (the process that turns plant detritus into coal), biogenic methane is generated as a by-product of bacterial respiration. Aerobic bacteria (those that use oxygen in respiration) first metabolize any free oxygen left in the plant remains and the surrounding sediments. In fresh water environments, methane production begins immediately after the oxygen is depleted (Rice and Claypool, 1981). Species of anaerobic bacteria (those that don’t use oxygen) then reduce carbon dioxide and produce methane through anaerobic respiration (Rice and Claypool, 1981). When a coal’s temperature underground reaches about 122 degrees Fahrenheit, and after a sufficient amount of time, most of the biogenic methane has been generated. Also at this time nearly two thirds of the moisture has been expelled and the coal has reached a rank of subbituminous (Rightmire, 1984).
After the coal’s temperature has exceeded 122 degrees Fahrenheit due to the geothermal gradient and excessive burial, thermogenic processes begin to generate additional carbon dioxide, nitrogen, methane and water. At this point the amount of hydrocarbons or volatile matter has increased and the coal has reached a rank of bituminous (Rightmire, 1984). After the temperature exceeds 210 degrees Fahrenheit carbon dioxide production increases with little production of methane. The thermogenic production of methane does not exceed the production of carbon dioxide in high volatile high ranks of coal until the temperature is about 250 degrees Fahrenheit. The maximum generation of methane in bituminous coals occurs at around 300 degrees Fahrenheit (Rightmire, 1984).
Kuuskraa, V.A., and Brandenberg, C.F., 1989, Coalbed methane sparks a new energy industry.
Rice, D.D., 1997, Coalbed methane—An untapped energy resource and an environmental concern.
USEPA, 1999, Guidebook on Coalbed Methane Drainage for Underground Coal Mines. (http://www.epa.gov/cmop/docs/red001.pdf)
NDSL, 2008, Exploration of Coalbed Methane. (http://img.kisti.re.kr/originalView/originalView.jsp?url=/tr_img/2010202/trko201000003979.pdf)
