Are oil and gas operations harmful to human health?
Properly regulated oil and gas operations are safe and the Australian oil and gas industry has a strong compliance record. The people most exposed to oil and gas are workers in the industry, and an independent epidemiology program linked with Monash University clearly shows that petroleum industry employees have better health than the general Australian community and are less likely to die of the diseases commonly causing death – including cancer, heart and respiratory conditions. For more information, see this webpage.
Is hydraulic fracturing a new technology?
Hydraulic fracturing has been around for a long time, with the first use of hydraulic fracturing taking place in 1949. The process has been used safely in oil and gas for almost 70 years in more than 2 million wells around the world.
Why are chemicals used in fracking?
Fracking fluid is generally 90% water, 9.5% sand and 0.5% chemical additives. Most of the chemicals used in fracking are found in familiar household products and food additives. Commonly used substances include guar gum (a thickener found in food products), acetic acid (in vinegar), sodium chloride (salt), ethanol, sodium bicarbonate (baking soda) and sodium hypochlorite and hydrochloric acid (both used in swimming pools), cellulose (used to make paper), acetic acid (the active part of vinegar) and small amounts of disinfectants. These chemicals are all used in very low concentrations and in almost all cases they are biodegradable, meaning they break down.
Chemicals are used because the tiny cracks in the rock created by fracking will quickly close unless they are held open in some way. This is done by injecting a proppant made from sand into the cracks. But sand does not dissolve in water so a thickener (guar gum) is needed to carry the sand. Other chemicals help reduce friction, remove bacteria and prevent scale from building up in the well.
For a list of chemicals used in Australian CSG operations click here.
Are BTEX chemicals used in CSG fracking?
No. In Australia, BTEX (benzene, toluene, ethylbenzene and xylene) chemicals cannot be used in fracking fluids. BTEX chemicals may occur in natural water sources, so in some instances trace levels of these chemicals may be detected following hydraulic fracturing. They can also be detected in industrial and irrigation waters that farmers and pastoralists use all the time.
How can we be sure fracking fluids won’t contaminate the environment?
Following the completion of a fracking stage, between 20% and 70% of fraccing fluid is recovered and stored in lined pits or in steel tanks so that it can be reused in another fraccing stage or in another well.
When no longer needed, the fluids and residue are placed in lined evaporation ponds. The bulk of the material is sand that returns from the bore plus the remaining fluid with the additives. Most of the additives will break down fairly quickly under light and the sand will settle out with the remaining small amount of salt. Once these have dried out, the remaining residue is taken away to a licensed facility for disposal.
Do drilling and fracking cause gas to migrate into waterbores and aquifers?
Natural gas wells are constructed to ensure gas cannot migrate to neighbouring bores and aquifers. It is not in the gas companies’ interests to allow leakage of gas into aquifers. Such leaks would make it difficult to extract the gas and would reduce the amount of gas available for sale.
Water in coal seams typically lies 200 metres or more below the water table used for stock and domestic purposes. In most cases, hundreds of metres of barrier rock separates fracture zones from useable water aquifers.
The design of the well and the cementing and casing practices also protect the aquifers from water entering the bore hole or the gas from the hole entering the aquifer. The standards for gas wells are far higher than those applying to water bores.
Wells have multiple layers of steel casing and specially engineered concrete. These separate the contents of the well from water aquifers. Each segment of steel casing is cemented in place then pressure tested and scanned to ensure there are no cracks or leaks before the next layer of casing is inserted and cemented in place. The standards applying to oil and gas wells drilled through water aquifers are very high – much higher than those applying to water bores.
The use of multiple layers of protection around wells to ensure no connectivity with water aquifers has been used in gas production for many decades. Instances of well failure are very rare.
Could the fractures extend vertically into drinking water aquifers?
No. Each fracture stage is individually engineered and controlled to limit fractures to the oil and gas bearing rocks. Extensive research on hundreds of wells in the US has conclusively demonstrated that the fractures induced by the process are confined to the rocks close to the target zone.
How do operators ensure they are not depleting or contaminating ground water sources?
Companies use extensive monitoring to detect any possible changes in the environment that could be a result of operations. Before, during and after activities begin, monitoring is used to measure the potential impact on the environment. Before drilling a well, companies undertake extensive surveys to fully understand the environment.
All exploration and drilling activities are closely regulated by the government. Before obtaining approval to drill or frac, operators must develop environmental management plans that describe what the risks are and how they will be managed. Every step of the drilling and fraccing process must be reported to the regulator, which will closely monitored these operations.
Will sink holes be created as water and gas are drained from the coal seams?
No. This has not occurred in two decades of Queensland CSG production. Once the water and gas have been pumped out, the coal seam remains in place, so it is not possible for underground caverns to be created.
Does CSG production require thousands of wells to be drilled closely together and restrict other land uses?
Operators have a cost incentive to minimise the number of wells required. With horizontal drilling, multiple wells can be drilled from the same drilling pad, which minimises both costs and land disturbance. The location of wells and pipeline routes is agreed in consultation with landholders. These are often placed along fencelines to minimise inconvenience.
How can we be sure that wells will not deteriorate over time and cause environmental problems 50 or 100 years from now?
The risk of a well casing failure in Australia is low because the industry is committed to ensuring that wells are constructed and maintained to the highest standards using the latest available technology. Specially engineered steels and cement used in well casings are designed to withstand pressures far in excess of those found underground. In the absence of air and water, steel does not corrode and there well casings have been recovered after 40 years with very little deterioration. A 2011 study by the US Groundwater Protection Council showed that less than 0.1% wells drilled since the early 1980s had issues with well integrity (12 out of 34,000 wells in Ohio and 2 out of 187,000 wells in Texas). Most of these were drilled in the 1980s and 1990s before improved cement formulas and regulations were in place.