What is Coal Seam Gas?
Coal Seam Gas (CSG) is a natural odourless gas extracted from coal seams and is generally a cleaner fuel than natural gas, which is a petroleum based gas.
CSG produces commercial gas supplies – a relatively new and fast growing energy source. It is a natural odourless gas used just like any other form of conventional gas, either for electricity generation, or as a direct source of power for domestic, commercial and industrial use.
Currently in the United States, CSG accounts for around 15% of total natural gas consumption.
In Australia the industry is in its early stages. However in Queensland, CSG accounts for around 30% of the State’s gas and is used primarily for electricity generation and industrial use.
It has been predicted that within 5 to 8 years, 35% of eastern Australia’s energy needs will be supplied by CSG.
Coal Seam Gas is naturally produced during the creation of coal. In conventional natural gas reservoirs, gas is trapped in spaces within porous rock, whereas the methane trapped in coal is adsorbed into micropores and on the coal surface and held in place by pressure. The micropore surface area of coal is very large, and can potentially hold significantly more methane per unit volume than most conventional gas reservoirs.
Coal seams are usually saturated with water and water pressure keeps the methane adsorbed on the coal. The production of CSG involves drilling down to the coal seam and pumping water out to reduce pressure so the gas is allowed to flow out and up to the surface.
The amount of gas produced by the coal depends on geological factors and the efficiency of the well design. In a typical CSG field, several wells are drilled in close proximity, making gas production more prolific and efficient.