Coalbed methane (CBM), also known as coal-bed gas, is a form of natural gas that is extracted from coal beds located below the Earths surface. In recent years, CBM has gained acceptance and become a major source of natural gas production and has become an important source of energy in many countries.
The presence of CBM in coal is known to have originated from the expulsion of methane by bacteria during coalification. The formation of CBM is generally accepted to have occurred prior to the burial of the coalbed. The gas is held in place by the matrix of the coal and adsorbed onto the interior surfaces of the coal particles. The amount of methane contained in a coal seam is proportional to the methane content of the original organic matter.
The production of CBM involves the drilling and completion of a gas well (or cbm extraction well) that penetrates the coalbed. The well is then completed to allow the flow of underground gas, usually at a temperature of between 25-100°C. After production has been established, the pressure in the well is reduced to bring the gas to the surface. In tight coals, hydraulic fracturing may be required to increase permeability and production.
The main benefits of CBM production are the abundant reserves, low cost of development, environmentally friendly qualities and low emissions. The production of CBM is generally much more cost-effective than other forms of energy production, such as oil and gas. As a result, CBM has become increasingly attractive for energy production in many countries.
CBM is generally considered to be less harmful to the environment than other fossil fuels such as oil and gas. This is due to its low emission rate, as methane is the cleanest burning fossil fuel. In addition, CBM is often found in areas that lack any other fuel resources, making it ideal for local power generation.
The main challenges faced in CBM extraction are the potential of adverse geological and environmental effects, the requirement for significant capital investment, and increased water contamination caused by the extraction process. In addition, the high cost of hauling the gas to the surface can often be prohibitive.
Nevertheless, CBM can provide a renewable source of energy and can be a valuable addition to the energy mix of many countries. With the increasing demand for energy and the availability of CBM in many countries, it is likely that its production will continue to increase in the future.
