About coal seam gas
- How is coal seam gas (CSG) different from conventional gas?
- How is coal seam gas different from underground coal gasification (UCG)?
- What is liquefied natural gas (LNG)?
Coal seam gas (CSG) is a natural gas, consisting primarily of methane, which collects in underground coal seams by bonding to the surface of coal particles.
The coal seams are generally filled with water, and it is the pressure of the water that keeps the gas as a thin film on the surface of the coal.
Coal seam gas is extracted through wells drilled into coal seams. The initial phase of CSG production usually involves the extraction of water from the coal seams in order to reduce the water pressure and release gas from the coal.
If the pressure within the seam is high, the gas may flow to the surface unaided. Conversely, the gas may have to be pumped to the surface if the pressure is lower. When coal seam gas comes to the surface, water in the gas is separated.
Coal seam gas is used in the same ways as natural gas, including fuelling natural gas appliances, such as heaters and stoves, and the generation of electricity.
How is coal seam gas (CSG) different from conventional gas?
CSG is a natural energy resource that is often referred to as 'unconventional'. Conventional oil and gas refers to resources that once drilled into automatically produces a flow up the well.
All unconventional gas resources are 'locked' and require a stimulation process (which can include hydraulic fracturing or fraccing) to 'unlock' the gas and allow it to flow to the surface.
How is coal seam gas different from underground coal gasification (UCG)?
UCG is the process by which coal is converted to gas underground via enforced combustion. UCG is used to access coal resources that are either uneconomic to work by conventional open cut or underground coal mining methods, or are inaccessible due to depth, geology or other mining and safety considerations.
Read more about UCG in Queensland.
What is liquefied natural gas (LNG)?
LNG facilities cool coal seam gas to minus 161°C. At this point the gas becomes liquid, reducing it to 1/600 of its original size. This liquid is then known as LNG and becomes a product that can be shipped safely and economically to Queensland’s export markets.
LNG is used in the same way as coal seam gas, including fuelling natural gas appliances, such as heaters and stoves, and generating electricity.
Last updated 7 December 2011