Coal-bed Methane (CBM) has been traditionally extracted from coal seams through coal pit borehole mining. Coal miners have employed various methods to extract coal-bed methane (CBM) from coal seams. The most common means is the borehole mining method, which involves drilling a series of boreholes in an underground coal mining operation to extract methane from the coal seams.
In the borehole mining process, a digging device, such as a drill bit, is used to bore into the coal seam and extract the methane gas. CBM that is extracted from coal seams is cleared out of the borehole, powder, and immediately released into the atmosphere. The amount of CBM that can be extracted from a single borehole can range from several hundred to several thousand cubic meters of methane depending on the seam depth and thickness.
Borehole mining operations may be hazardous to miners and the environment, particularly when large amounts of CBM is present in a coal seam. CBM extraction can increase risk of potential explosion by creating an increased concentration of methane gas in the coal seam and around surrounding coal mines. In addition to explosion risk, borehole mining poses the risk of diversion of excessive amounts of water into the coal seam, potentially resulting in flooding. The use of sealed boreholes can reduce this risk.
The extracted methane is usually utilized through flaring or re-injection into the coal seam for later extraction. Flaring is increased danger on underground mine works, and also releases CO2 into the atmosphere. It is far preferable to re-inject the methane for extraction at a later date.
In terms of the economic feasibility of borehole mining, the British Geological Survey estimates that one cubic meter of methane extracted from a given seam will produce between £0.010 to £0.025 of revenue. While this may appear to be low, the rapid extraction of large volumes of CBM can potentially create significant revenue.
In conclusion, CBM extraction through borehole mining poses potential risks to miners and the environment. It is necessary to implement safety protocols in order to mitigate the potential harms posed by CBM extraction. The costs associated with borehole mining may be relatively low, but the potential for revenue generated by the extraction of large volumes of CBM can potentially make it a viable option.
