FAQ’s about Coal Bed Methane

Coal bed methane is also known as coal seam gas and coal seam methane as well. Methane is one of the main components of natural gas which is required to day as a major energy source. Extraction and development of GBM plants have increased since the 1900s as opposed to much earlier exploitation happening on the American grounds.

To get some more information about Coal Bed Methane let's take a look at some frequently asked questions about it:

Qs1. What is Coal Bed Methane?

Ans: Coal Bed Methane is methane found in the coal seams underground. One of the main sources of natural gas is the substance called methane, CH4. This gas is produced by the non traditional means and thus even though it is sold as traditional natural gas it is produced in a very different manner. CBM is either made from biological processes which are a result of microbial action or from thermal processes which occurs due to the increasing depth at which the coal is situated. Many times the coal seam is saturated with water and the methane is held within the coal by the water pressure.

Qs.2 Where does the CBM exist?

Ans: As per the findings the currently the coal bed methane is found at the following places. (Note the areas keep increasing due to the constant research and developments)

Australia:

Bowen Basin, (Fairview, Spring Gully, Scotia,) in Queensland, Australia
Surat Basin, Kogan, Windibri, Daandine, Berwyndale, Tipton West in Queensland, Australia
You could check out the website for Metgasco for some more info at www.metgasco.com.au

Canada:

Telkwa coalfield in British Columbia
Western Canadian Sedimentary Basin in Alberta

United States:

Cahaba Basin in Alabama
Black Warrior Basin in Alabama
Cherokee Basin in Kansas
Powder River Basin in Wyoming and Montana
Slater Dome Basin in Wyoming and Colorado
San Juan Basin in Colorado and New Mexico
Raton Basin in Colorado and New Mexico

Qs.3 How do they estimate the amount of methane gas that can be extracted from a region?

Ans: Today there are two methods of estimating the amount of methane gas that can be found from a coal seam. One method involves estimating the reserve of methane by boring to the top of the coal seam and then extracting a core from the coal. The amount of methane that is extracted from this core is used to estimate the amount of methane that is available per unit volume of coal.
Another method is if cores are drilled and the released methane gas is observed then the estimated amount of gas can be determined. The limitations to this method though is there is too much disturbance caused to the coal seam core before the gas released can be measured and secondly it is too expensive and thirdly not every region that potentially has CBM has been drilled and explored.

Qs.4 How do gas companies extract methane from the coal seams?

Ans: Coalbed 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 coalbed 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.