re: Ann: Gas flows to surface in CSG Project ... What is Coal...

re: Ann: Gas flows to surface in CSG Project ... What is Coal Seam Gas?

Coal seam gas (CSG) is a natural gas which is mainly composed of methane. It is a by-product of ancient plant matter that has formed over millions of years by the same natural processes which produce coal.

As an end-use product, CSG is the same as natural gas. In Australia it is used in natural gas appliances, for example, heaters and stoves. It is also used by various industries for the generation of electricity.

CSG 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 (the technical term for this is adsorption.)

A combination of water and ground pressure traps the gas in the fractures, or cleats, of underground coal seams.

These fractures may be interconnected and permeable, allowing the gas and water to flow freely through them.

The level of gas that can be produced from a coal bed depends on the thickness of the coal, gas content, permeability and the depth of the coal seam.

In Australia, coal seams that can produce CSG economically are usually 200 to 1,000 metres below the surface.