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Coal seam methane

The Liverpool Plains and Ranges are also being explored by Santos Ltd for coal seam gas (CSG, or CBM, coal bed methane gas – see below). Often referred to (by gas companies) as a more environmentally-friendly fuel extraction than coal mining, CSG extraction nevertheless is not without considerable risks to water supplies and the environment.

A Santos Project in East Java, Indonesia has been declared a disaster zone after an exploration well could not be contained in 2006. The well spews out 40 Olympic-sized swimming pools worth of hot, volcanic mud every day and has already displaced 50,000 people, submerged homes, factories and schools. The question has to be asked: what guarantees of environmental safety were these poor people given during exploration and what are these guarantees worth now?

Santos were made aware of the potentially unstable Hunter Mooki Fault System here at the recent community meeting at Blackville. We don’t want an unnatural disaster here in the Liverpool Plains!

CSG extraction also requires the dewatering of the aquifers contained with the gas which means these deep bores (>800m) will be puncturing through our good water supplies and the prospect of contamination between supplies is real. Just like for coal.

Water found with CSG is always highly saline and has the potential to contain heavy metals, sorbed on the surface or compounded within the fine suspended particulate matter, yet another environmental hazard. CSG water has to be ponded, trucked out, or forced back into the ground under pressure. The sheer volume of this ‘waste water’ is a huge concern as is the potential for ‘good water’ to migrate towards the coal seam voids and depletion of quality water aquifer pressures due to unloading changes caused by water and gas extraction. Heavy machine-based fracturing of the coal seam to get the gas to flow can also lead to unpredictable venting of CSG which readily poisons the soil and water supplies above, yet another potential hazard with this ‘cleaner’ fuel.

As the General Manager of Sydney Gas (drilling in picturesque Wollombi) said “I’m not going to say there’s a zero chance of water contamination”. Same old mining story. A fuller description of CSG hazards by independent consultants is available here.

Be sure to check out the Caroona Coal Action Group by following this link here:



by C. M. ATKINSON, January 2005.

or click here for the latest report from Caroona Coal Action Group on CSG

Coal bed methane gas (CBM, or coal seam methane)

“Coal seam gas refers to methane sorbed into the solid matrix of the coal. The presence of this gas is well known from its occurrence in underground coal mining, where it presents a serious safety risk. Coal bed methane is distinct from a typical sandstone or other conventional gas reservoir, as the methane is stored within the coal by a process called adsorption. The methane is in a near-liquid state, lining the inside of pores within the coal (called the matrix). The open fractures in the coal (called the cleats) can also contain free gas or can be saturated with water.” [1]

This coal gas can be extracted by various drilling techniques and used as the natural petroleum gas.

For more information and a comprehensive description, click here to go to Hunter Gas Action group.

[1] Adsorption is a process that occurs when a gas or liquid solute accumulates on the surface of a solid or a liquid (adsorbent), forming a film of molecules or atoms (‘the adsorbate’). It is different from absorbtion, in which a substance diffuses into a liquid or solid to form a solution. The term sorption encompasses both processes.


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