According to Geosciences Australia, as at December 2008 the proven and probable (2P) reserves of coal seam gas (CSG, or coal bed methane as it is known elsewhere in the world) in Australia were 16,179 Petajoules, an 116% increase over the 2007 reserves.
This expansion shows clearly the rapidly growing interest by the energy sector in non-traditional gas sources in Australia (and around the world, in the USA especially). In 2007-08, CSG accounted for around 10 per cent of total gas consumption in Australia and about 80 per cent in Queensland. The strong growth in CSG production reflects the Queensland Government’s energy and greenhouse gas reduction policies, in particular the requirement that 13 per cent of grid connected power generation in the State be gas-fired
Major Coal and CSG basins in Australia are in Queensland (Bowen and Surat), and in NSW (Clarence Moreton, Gloucester, Sydney and Gunnedah). Tight gas (a different type of ‘non-traditional’ gas source) accumulations are located in on-shore Western Australia and South Australia, while potential shale gas resources (ditto) are located in the Northern Territory.
Companies drilling boreholes or wells for coal seam gas extraction are entering and drilling on properties in both good and marginal agricultural land, in the Surat Basin around Chinchilla and Dalby. They were the subject of an ABC TV feature on our national flag-ship current affairs program ‘Four Corners’ a few weeks ago. The Surat coal basin overlies the iconic Great Artesian groundwater basin. The Lake Eyre (surface water) Basin is also being explored by the mining companies, potentially threatening its natural values even though coal seam gas production takes place hundreds of metres underground.
Land ‘owners’ in Australia own only the top soil and ground surface, not the subsoil and mineral reserves below, so mining companies cannot be prevented from entering a property and drilling once they have planning approval.
An ABC Environment feature reported that about 3000 wells have been drilled in Queensland. An industry spokesman said that around 1600 gas wells in Queensland are actively producing gas. Activists in NSW report that 15 coal seam gas wells have been approved for drilling in the Illawarra region that supplies Sydney’s drinking water. And recently, exploratory drilling in Sydney has caused alarm in many quarters.
I am not a mining engineer, but I am interested in how the mining and energy sector uses and impacts on water resources in Australia. And water is an essential resource in CSG production. How so?
Firstly, water is used in many (not all) CSG drilling to enable ‘fraccing’ (or ‘fracking’). This is the process by which water, sand (or similar) and various chemicals are pumped (via a well) into a coal seam, causing it to fracture. The fissures and cracks thus created allow space for the ‘adsorbed’ coal gas (mostly methane) to diffuse into. Secondly, groundwater that naturally overlays a coal seam may need to be pumped out to ‘depressurise’ the coal formation so the gas will flow back to the surface..
While lagging behind the USA, CSG production is becoming a hot issue in Australia, with concerns about water being often at the core. Not unlike the USA, a number of water use, environmental and public health concerns have been raised. They include:
- Potential cross contamination between aquifers of differing water qualities, brought about by unsuitably controlled and monitored fraccing
- Contamination of surface water with the toxic chemicals used in the fraccing process, including the so-called BTEX group (benzene, toluene, ethylbenzene and xylene). Note, BTEX usage has now been banned in Queensland
- Leakage of methane gas from poorly sealed wells or fractures into aquifers or into atmosphere. (This is (presumably) what has led to the ignitable drinking water in the USA, highlighted in the documentary ‘Gasland’)
- The volume of groundwater that is brought to the surface which needs to flow somewhere (potential stream impacts). The pumped groundwater may be re-injected in some cases to re-pressurise exhausted seams.
- Potential subsidence of the surface, which would change drainage and erosion patterns in surface water flows. A potential cumulative regional-scale impacts of multiple developments have been highlighted in a recent report by Geoscience Australia (more on that next time)
- Salinity – Pumped groundwater typically contains significant concentrations of salts. The salinity of CSG water is variable but total dissolved solids values may vary from 200 to more than 10,000 milligrams per litre (cf. good quality drinking water which has total dissolved solids values of up to 500 milligrams per litre).
In media reports last month, the NSW Opposition promised to apply a tougher assessment process to mining and coal seam gas extraction if elected in this month’s State election, including a moratorium for all new mine and gas licenses for up to a year. Then opposition spokesman on primary industries and energy Duncan Gay told the Weekend Australian Financial Review that there were “some agricultural lands in NSW where mining should not occur”. Instead, there should be a “strategic approach to the whole interface of mining and agriculture”.
His party won a landslide election victory last Saturday, so it will be interesting see if they follow through with their promise. Clearly, in a party coalition that traditionally represents both agricultural and big end of town interests, getting the balance between competing sectors right here is going to be challenging. Gay also said. “We’re not anti-mining; we believe there should be balanced development”. Therein lies the political challenge!
Since October 2008, the Queensland government has had a published CSG water management policy, aiming to ensure that salt produced through CSG activities does not contaminate the environment, and to encourage the beneficial use of treated CSG water. The following matters are covered:
- Discontinue the use of evaporation dams as a primary means to dispose of CSG water; remediation of existing evaporation dams is to occur within three years with transitional arrangements to be developed in consultation with industry.
- Dams necessary for water aggregation and the storage of brine from treatment facilities are to be fully lined to a standard determined by DERM (sate water and environment agency).
- CSG producers are responsible for treating and disposing of CSG water.
- CSG water must be treated to a standard defined by DERM before disposal or supply to other water users.
- A CSG water management plan (CWMP) is to be incorporated into the environmental management plan (EMP) required for a large scale coal seam gas environmental authority application.
- CSG water in excess to that which can be directly injected or beneficially used, is to be aggregated for disposal.
Exactly how this policy is being enforced I will seek to find out. I plan to follow and report more on the issue of coal seam gas production and water resource impacts in Australia over the coming year.