Water is the lifeblood of communities across Australia, and responsible developers of natural gas resources recognise the importance of safe, secure and sustainable water sources and supplies.
There’s many stories told about the impact of natural gas development on water supplies, but what is fact, and what is fiction?
The risk of gas exploration and extraction activities contaminating groundwater is considered to be relatively low – due mainly to the techniques used to drill gas wells, and the levels of protection built into the design and operation of the gas wells.
According to the CSIRO, groundwater contamination from coal seam gas operations is considered a low risk for the following reasons:
- Hydraulic fracturing, when conducted correctly, is unlikely to introduce hazardous concentrations of chemicals into groundwater or to create connections between fresh and coal-containing aquifers
- Most of the chemicals are of low inherent toxicity, undergo considerable dilution, and the majority (60-80 per cent) are understood to be removed during flow back of the hydraulic fracturing fluid to the well from the coal seam.
- Water extraction from coal seams makes cross‑contamination of aquifers unlikely; most of the inter-aquifer transfer will be of higher quality water into neighbouring coal measures as water flows from high to low pressure.
According to West Australian experts, hydraulic fracturing has been used on 2.5 million wells worldwide without a single confirmed case of groundwater contamination.
In the United States, the Department of Energy and the Groundwater Protection Council concluded that:
“In fact, based on over sixty years of practical application and a lack of evidence to the contrary, there is nothing to indicate that when coupled with appropriate well construction; the practice of hydraulic fracturing in deep formations endangers ground water. There is also a lack of demonstrated evidence that hydraulic fracturing conducted in many shallower formations presents a substantial risk of endangerment to ground water”
In Australia, responsible developers of natural gas resources conduct extensive groundwater monitoring to ensure that any potential impacts on local water sources are identified quickly.
It’s a stance backed by the Commonwealth Standing Committee on Energy and Resources, who say:
“Initial and ongoing monitoring can inform the development of impact management strategies to ensure the effect on the level and quality of water resources is kept within acceptable limits as determined by the regulator. A comprehensive monitoring program will also assist in the detection and remediation of legacy wells from previous water uses located on tenements held by companies.”
There’s a common misconception that natural gas development will lead to water supplies becoming contaminated with methane gas.
The Queensland Gasfields Commission investigated soil gas surveys undertaken during the 1980s and 1990s in the Surat, Eromanga, Cooper, Georgina, Bowen and Galilee Basins and found methane levels ranging from less than 10ppm to 240ppm naturally occurring in the subsoil.
The NSW Department of Primary Industries Office of Water found:
“Gas seeps have been observed in Queensland rivers and are known to occur naturally, where coal seams are shallow, even in the absence of CSG activities.”
Overseas, some of the most widely cited cases of methane contamination have been thoroughly investigated and found to not be caused by gas activities.
For example, Colorado rancher Mike Markham made a formal complaint to the Colorado Oil and Gas Conservation Commission (COGCC) regarding methane in his drinking water.
After a full investigation, the COGCC concluded:
“There are no indications of oil & gas related impacts to water”
“Dissolved methane in well water appears to be biogenic [naturally occurring] in origin.”
In another case, the Railroad Commission of Texas:
“determined that the evidence is insufficient to conclude that Barnet Shale production activities have caused or contributed to methane contamination in the aquifer beneath the neighborhood”
Water that is extracted alongside natural gas is referred to as produced water.
The amount of produced water varies from well to well.
The management of produced water is a critical issue for responsible developers and local communities.
The Commonwealth Standing Committee on Energy and Resources recommends:
“There are a range of options for the management or disposal of large volumes of produced water. Wherever possible, produced water should be recycled for beneficial use and avoid damaging environmental impacts. Beneficial uses include reinjection into the same or different aquifers, appropriate discharge to surface waters, or direct provision to other water users providing the water is of a suitable quality and complies with required standards.”