Hydraulic fracturing, more commonly known as fracking or fraccing, is a technique used to stimulate and accelerate the flow of gas to a well or bore. The process involves high-pressure injection of sand, water and chemicals into the gas-bearing rock. The injection causes fractures in the rock allowing the gas to flow to the surface of the well.
The coal seam gas industry provides this list of chemicals it says are used in coal seam gas fracking operations in Australia. The National Toxics Network has raised various concerns about the environmental and health risks associated with the chemicals associated with hydraulic fracturing and has said that these chemicals are not adequately assessed or monitored.
BTEX (an acronym that stands for benzene, toluene, ethylbenzene, and xylene) is one group of chemicals associated with hydraulic fracturing. BTEX can be naturally occurring and benzene is a known carcinogen (cancer causing).The National Toxics Network says that the fracking process itself can release BTEX from the natural-gas reservoirs, which may allow them to disperse into the groundwater aquifers or to volatilise into air. Doctors for the Environment point out that a range of other hazardous chemicals are reported to be used in Australian fracking operations including 2-butoxyethanol and ethylene glycol.
Research compiled by Doctors for the Environment found that 2-butoxyethanol is easily absorbed and rapidly distributed in the human body and is particularly toxic to red blood cells, carrying the risk of haemolysis, and damage to spleen, liver and bone marrow. Ethylene glycol is used to make anti-freeze and when ethylene glycol breaks down in the body it can affect kidney function as well as the nervous system, lungs and heart.
A report by the Committee for Economic Development of Australia said: In addition to concerns over contamination of aquifers from the chemicals added to fracking fluid, issues have also been raised about contamination of water supplies from fugitive gas after fracking, and seismic activity and tremors associated with the drilling and fracking process.
A process known as ‘flowback’ is used to recover fracking fluids previously pumped underground. The National Toxics Network says that “as well as the original fluid used for fracturing, flowback may also contain other fluids, chemicals and minerals that were present in the fractured formation such as heavy metals and hydrocarbons”. Flowback does not recover all of the fracking fluid. A report prepared in 2010 for the coal seam gas industry said “It is conservatively assumed that 40% of the hydraulic fracturing fluid volume would remain in the formation and this would correspond to 7400kg of chemicals per injection well…”
Other significant concerns associated with hydraulic fracturing including the potential to contaminate water sources and cause earthquakes. A study conducted in the United States in 2011 documented “systematic evidence for methane contamination of drinking water associated with shale-gas extraction”. In the United Kingdom in 2011 the British Geological Survey confirmed seismic events were a direct result of drilling and fracking activities by Cuadrilla Resources.
Fracking has been used during coal seam gas operations in both Queensland and NSW and there remain widespread calls for a moratorium or ban on its use. A moratorium on the use of hydraulic fracturing in NSW was recently lifted by the state government.