Environmental Engineering Reference
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reserves in the Cooper Basin in eastern Australia. Western Australia has very
large conventional gas reserves offshore, supplying local demand and pro-
viding LNG exports. Shale gas exploration in Australia is still in its infancy
but recent reports suggest enormous reserves and a potential for shale gas
extraction eventually to dwarf CSG. 26
3.1 CSG Extraction Technology
Coal seam gas is found in cracks, pores and micropores in coal seams, where
it is held in place either as free gas or adsorbed onto coal surfaces. It is
important to point out that the extraction technologies for CSG and shale gas
are commonly quite different. Fracking - hydraulic fracturing, in which
water mixed with sand and various chemicals is forced at very high pressure
into shale beds or coal seams to release trapped gas - is fundamental to
shale gas extraction, whereas the fundamental process for CSG extraction is
dewatering, i.e. pumping water out of the coal seam to release trapped gas.
The 'produced' water and the gas are separated at the surface and each is
removed in its own network of pipes (see Figure 2), the gas to processing
facilities and eventually to market, and the water to holding ponds and
eventually (it is hoped) to treatment and recycling. In most cases the CSG is
naturally of 'pipeline quality' and, apart from drying, requires minimal
treatment. 27
As stated above, fracking is not universal in CSG extraction, but neither is
it entirely absent. A rule of thumb used in Queensland is that fracking occurs
Figure 2 The CSG extraction process.
(Source: Natural CSG, http://www.naturalcsg.com.au/ last accessed 28/01/2014).
 
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