Coal seam gas - what is it and what happens to the water ...

Excerpt from Sunshine Gas Bidder's Statement:

Set out below are answers to some key questions that you may have about CSG and QGC.

What is coal seam gas (CSG)?

CSG is composed mostly of methane gas and typically forms during the coalification process within coal seams (QGC’s CSG generally consists of 96-98 per cent methane). The coal seams are usually saturated with water, and the methane is held within the coal by water pressure.

How is CSG extracted?

The CSG is extracted via wells which are drilled through the coal seams. The water is pumped out, and the CSG is desorbed or released from the coal. If the pressure within the seam is high the gas may flow to the surface unaided.

What happens to the CSG and surplus water once it has reached the wellhead?

The CSG and water are separated at the wellhead and the gas is piped to a compression plant where it is dried and compressed before it is transported via a pipeline to customers. The water is conveyed to an evaporation pond. QGC has recently entered into an agreement to supply half a billion litres of drinking water annually to the town of Miles and has offered its water for sale for both coal mining and town water purposes.
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See - QGC - Sunshine Gas Bidder's Statement.