Coal seam gas (CSG)

is methane gas stored within coal seams.

As an end-use product, CSG is the same as natural gas, and can be utilised in all natural gas appliances and commercial applications. The difference between CSG and other natural gas is mostly how it occurs in nature. CSG collects in the coal seam by bonding to the surface of coal particles, whereas other natural gas is stored in the pore spaces between grains of sandstone or similar rock.

Coal seams in the ground are generally filled with water, and it is the pressure of the water that keeps the gas adsorbed as a thin film on the surface of the coal. The cleats, the fracture system of coal, may be interconnected and permeable. In a high quality CSG deposit the cleats are permeable enough to allow gas and water to flow freely through them.

The level of gas produced from a coal bed is dependent on the thickness of the coal, gas content, permeability and the depth of the coal seam.

The coal seams that can produce CSG economically are usually between 200m to 1,000m below the surface.

Origin is Australia’s largest producer of coal seam gas.

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