The State Government supports Western Australian’s (WA’s) growth and development by sustainably managing the amount and quality of water available, for present and future generations.
This information sheet provides information on water requirements for shale and tight gas developments, and how water use is regulated and managed.
Where does the water come from?
In WA, most of the water currently used for petroleum activities is taken from underground aquifers. A water bore is constructed to extract groundwater for use in the drilling and hydraulic fracturing of petroleum wells. Prior to constructing bores or taking any water proponents must apply to the Department of Water (DoW) for a licence under the Rights in Water and Irrigation Act 1914.
The quality of water for use in drilling and hydraulic fracturing does not need to be potable. Brackish or saline water can be used, as well as recycled water. It may need to be pre-treated depending on the constituents.
The gas (or oil) is extracted from a separate petroleum well (i.e. not the water bore). The construction and operation of petroleum wells (including the injection of water/fluids for hydraulic fracturing) is regulated by the Department of Mines, Industry Regulation and Safety (DMIRS).
How much water is needed?
While some water is required to drill an oil or gas well, the greatest amount of water is used during hydraulic fracture stimulation (or fraccing). The fluid used in the hydraulic fracture process is typically 90% water, 9.5% sand (or proppants) and 0.5% chemicals.
When the fracture fluid is injected into the well under pressure, anywhere from 10 to 40% of the fluid will be returned to the surface for shale gas and up to 80% for tight gas operations. This water can be reused in further drilling and hydraulic fracturing operations.
The volume of water it takes to hydraulically fracture a well varies from project to project. It depends on the size and length of the well, and the properties of the rocks that are to be fractured. Hydraulic fracture stimulations occur in stages and each stage requires a certain amount of water.
The publication by the United States Department of Energy, Modern Shale Development in the United States: A Primer (2009), states that a single stage fracture in the US requires approximately 2,000 kilolitres (1,000 litres = 1 kilolitre (kL)) of water.
Fracture stimulation in the Perth Basin may require three stages of hydraulic fracturing per vertical well (of up to 3 km deep). This equates to using around 7,000kL of water per vertical well: 1,000kL for drilling and 6,000kL for hydraulic fracturing. This is equivalent to 2.8 Olympic size swimming pools (a standard Olympic sized swimming pool contains 2,500kL of water).
For horizontal wells (with a horizontal reach of one kilometre) using 10 fracture stages, around 20,000kL would be required for hydraulic fracturing and 1,000 kL for drilling. This equates to about 8.4 Olympic size swimming pools. In the United States horizontal wells are typically drilled to lengths of around 1.5 km, and occasionally to lengths of around 3 km. No horizontal wells for hydraulic fracturing have yet been proposed in WA.
As a comparison, an 18 hole golf course requires somewhere between 360,000 and 550,000 kL of water per annum to maintain the greens and fairways.
Other comparisons requiring the same amount of water as a 10 stage horizontal fracture well (20,000 kL) include:
- 1,100 head of cattle or 11,000 head of sheep for one year.
- irrigating just under 1 hectare of lucerne, or a 1 hectare commercial sized market garden for one year.
- 8 Olympic sized swimming pools.
- the amount of water used by 45 domestic garden bores in the Perth metro area.
- maintaining Domain Stadium’s (home of the Fremantle Dockers and West Coast Eagles) oval turf during the summer months.
How is water use regulated?
DoW regulates the taking or abstraction of groundwater and of surface water, and the construction of bores/works to access the water resources under the Rights in Water and Irrigation (RiWI) Act 1914 within proclaimed groundwater areas and artesian aquifers.
A Licence to Take Water (section 5C, RiWI Act 1914) is required to take water from a watercourse, or wetland within a proclaimed surface water area or from a non-artesian underground source within a proclaimed groundwater area. Any water taken from artesian aquifers is licenced everywhere in the State.
A Licence to Construct or Alter a Well (section 26D, RiWI Act 1914) is required to:
- commence, construct, enlarge, deepen or alter any artesian bore; or
- commence, construct, enlarge, deepen or alter any non-artesian bore in a proclaimed groundwater area.
Water bore construction details need to be provided to DoW in accordance with licence conditions.
Applications for licences are assessed against a rigorous set of statutory criteria including:
- is it in the public interest?
- is it ecologically sustainable?
- is it environmentally acceptable?
- would it prejudice other current and future needs for the water?
- would it have a detrimental effect on another person?
- could the water be provided by another source?
Proponents are required to provide information to DoW in support of their application. Specific requirements are determined by DoW and may include a hydrogeological assessment and groundwater modelling in accordance with DoW’s Operational Policy 5.12 – Hydrogeological reporting associated with a groundwater well licence. Proposals that do not meet the criteria (i.e. are likely to have unacceptable impact on the environment, the water resources, or existing water users) are not supported.
New licences are only granted where water is available (i.e. the allocation limit has not been reached for that resource). In fully allocated areas, operators will need to consider obtaining water through alternative sources (e.g. by trading, using recycled and/or saline water, or bringing water in from other areas).
The right to access the shale and tight gas resources is obtained from DMP which requires operators to submit an Environment Plan for assessment under the Petroleum and Geothermal Energy Resources’ (Environment) Regulations 2012. The plan must describe the existing environment (including water resources) and how environmental risks and impacts will be reduced to as ‘low as reasonably practicable’. During the course of assessing proposals DMP liaises with other agencies as required.
For example, DMP refers projects to the Environmental Protection Authority (EPA) according to the DMP/EPA Memorandum of Understanding (MoU) for assessment under the Environmental Protection Act 1986. The MoU triggers immediate referral to the EPA if a well is within 500 m of an Environmentally Sensitive Area, or within 2 km of a declared occupied town site.
DoW, DMP and EPA work together to understand the possible impact on water quality from a petroleum activity and where there is significant risk, place specific conditions on an approval. DoW advises DMP on all proposals that are considered by DoW to have a risk to a source of public drinking water. DoW also selects to provide advice on proposals that it considers will impact on other sensitive water resources. In addition, DoW advises the Office of EPA on proposals assessed under Environmental Protection Act 1986 and the DMP/EPA MoU.
How is wastewater regulated and managed?
There are three main sources of wastewater produced during the process of drilling and fracturing a well to extract shale or tight gas:
- Drilling fluid: Used to cool and clean the drill bit, stabilise the well bore and carry out drill cuttings (small broken pieces of rock formed during drilling).
- Flow back water: Fracturing fluid that is returned to surface following its use during hydraulic fracture stimulation.
- Produced formation water: Naturally occurring water trapped in oil and gas reservoirs/formations that may be recovered during extraction of fraccing fluids and production of gas (or oil). The volume of produced formation water is likely to be insignificant due to the low permeability of these formations.
DMP requires petroleum operators to meter and report the volume of fluids injected and extracted from petroleum wells.
Petroleum operators use different methods to dispose of wastewater. They are required to undertake a risk assessment process for each activity. The risk assessment process requires identification of the likely impacts and the mitigation measures. To ensure risks are managed to ‘As Low as Reasonably Practicable’ (ALARP), DMP undertakes risk assessment of individual methods of wastewater disposal proposed by the operator.
Wastewater from drilling and hydraulic fracturing stimulation may be re-used or disposed of through:
- Recycling: The fluid that flows back to the surface may be reused in the drilling/hydraulic fracturing of another well (typically within four weeks).
- Evaporation ponds: Open ponds or pits constructed with clay are lined with a double layer of high density polyethylene plastic. When the water evaporates, drill cuttings and chemicals remain in the pond. At the end of drilling operations, the contents of the ponds are tested for contaminants. If any contamination is present, all contaminated material is excavated and taken to a licenced waste facility for disposal. The plastic liners are also removed and disposed of at a waste disposal facility and the pond is backfilled, re-contoured and rehabilitated.
- Enclosed tanks: Fracture fluid can also be stored in enclosed tanks to be disposed of or re-used as required. This may be preferable in environmentally sensitive areas, or where there is risk of exposure to animals.
- Injection/re-injection: Where suitable ‘injection zones’ are available the wastewater may be injected deep underground. Depending on the injection site, the water may need to be treated prior to injection. Reinjection of flow-back water into aquifers is not permitted.
Where can I find more information?
Read other Petroleum information sheets on related subjects such as hydraulic fracture stimulation and well integrity.
For more information on regulating water visit the Department of Water website.