Extraction of Coal Bed Methane
Extraction of any natural reserve requires masterful engineering and scientific applications so that you get the most work done at the lowest cost and without impacting the environment too much. This is the gas company's responsibility that they do so in the best manner possible.
Extraction Tube:
Coal bed methane travels with the ground water that is present in the coal seam and so the extraction of the CBM requires the pumping of the available water from the seam so that the water pressure that holds the gas in the seam is reduced. As the coal bed methane has very low solubility in the water it readily separates from the water as the pressure keeps decreasing. This allows it to be piped out of the well separately from the water. The water moving from the coal seams to the well bore quickens the gas migrations towards the well.
To extract the methane gas a steel encased hole is drilled all the way to the coal seam which is generally 100-1500 meters below ground. Then as the pressure within the coal seam decreases, because of the hole to the surface which is pumping small amounts of water from the coal bed, both the "produced water" and the gas escape to the surface through these steel tubes.
This extracted gas is then sent to the compressor station from whereon it is sent into the natural gas pipelines. This produced water needs to be disposed of correctly so that the highly saline water and high sodium content water does not affect the soil and plant growth. This can be done either by sending the water to holding ponds, evaporation/precipitation tanks, released into streams or can be used for irrigation of salt tolerant plants.
Quantity of Methane:
Coalbed methane wells many times produce at lower gas rates as compared to conventional reservoirs; typically peaking at a close 300,000 cubic feet that is 8,500 cubic meters a day. This extraction can also have large initial costs as well. The production well of Coal Bed Methane are usually marked by a "negative decline" in which the gas production rate in the beginning increases as the water is pumped off and the gas begins to desorb and flow. There are very few differences from a dry CBM well and a standard gas well.
Extraction of any natural reserve requires masterful engineering and scientific applications so that you get the most work done at the lowest cost and without impacting the environment too much. This is the gas company's responsibility that they do so in the best manner possible.
Extraction Tube:
Coal bed methane travels with the ground water that is present in the coal seam and so the extraction of the CBM requires the pumping of the available water from the seam so that the water pressure that holds the gas in the seam is reduced. As the coal bed methane has very low solubility in the water it readily separates from the water as the pressure keeps decreasing. This allows it to be piped out of the well separately from the water. The water moving from the coal seams to the well bore quickens the gas migrations towards the well.
To extract the methane gas a steel encased hole is drilled all the way to the coal seam which is generally 100-1500 meters below ground. Then as the pressure within the coal seam decreases, because of the hole to the surface which is pumping small amounts of water from the coal bed, both the "produced water" and the gas escape to the surface through these steel tubes.
This extracted gas is then sent to the compressor station from whereon it is sent into the natural gas pipelines. This produced water needs to be disposed of correctly so that the highly saline water and high sodium content water does not affect the soil and plant growth. This can be done either by sending the water to holding ponds, evaporation/precipitation tanks, released into streams or can be used for irrigation of salt tolerant plants.
Quantity of Methane:
Coalbed methane wells many times produce at lower gas rates as compared to conventional reservoirs; typically peaking at a close 300,000 cubic feet that is 8,500 cubic meters a day. This extraction can also have large initial costs as well. The production well of Coal Bed Methane are usually marked by a "negative decline" in which the gas production rate in the beginning increases as the water is pumped off and the gas begins to desorb and flow. There are very few differences from a dry CBM well and a standard gas well.