About Coal Seam Gas in Queensland
Coal seam gas (CSG) is an important energy resource in Queensland and production of this gas now makes up an increasing proportion of Queensland gas demand.
Queensland is highly prospective for CSG due to a combination of favourable geology and extensive coal resources. Coal seams are thick and multiple seams are present in many basins, with vast resources shallower than 1000m.
Interest in CSG as an energy source has increased significantly in recent years and exploration has steadily grown.
As at 30 June 2009, proved and probable CSG reserves (2P) reached 18,289 petajoules (Pj). Actual CSG production increased from 4 Pj in 1998-99 to 151 Pj in 2008-09 The Queensland Government is encouraging a transition from coal to gas as an effective mechanism to reduce greenhouse gas emissions. Under its Smart Energy Policy, by 2010 15% of all electricity sold in Queensland is to be sourced from gas-fired generation. This requirement may be increased to 18% in the future.
For further information www.deedi.qld.gov.au
What is Coal Seam Gas?
CSG occurs naturally within coal deposits. Consisting primarily of Methane gas (CH4) it is formed when the coal itself is formed. The gas remains attached (adsorbed) to the coal by formation pressure and water. Because of natural fractures called cleats, coal has a large internal surface area and is capable of holding larger volumes of gas than conventional sandstone reservoirs. The amount of gas present in a coal seam depends on the depth of the seam, the thickness and the extent to which the fracture system is interconnected.
When water is pumped from holes drilled into the coal seam the pressure is reduced and gas is released from the coal. As pumping progresses water production declines and gas production increases.
At the surface, the methane, other gases and water are separated.
Expert advice suggests that the Galilee area is also prospective for conventional hydrocarbons. Further studies to this effect will be undertaken once the current CSG exploration programmes have been completed.
A total of six petroleum exploration and two deep stratigraphic wells have previously been drilled within the permit areas. Most encountered significant hydrocarbon shows and minor oil and gas recoveries have been made from subsequent testing. Other petroleum wells to the south, east and west of these permits have also encountered significant hydrocarbon shows.