Water use and management for hydraulic fracturing
The State Government supports Western Australia’s (WA) growth and development by sustainably managing the amount and quality of water available for present and future generations.
Where does the water come from?
Most of the water used for hydraulic fracturing comes from water wells that take water from underground aquifers. The water used in hydraulic fracturing does not need to be drinkable. Brackish or saline water can be used, as well as recycled water. It may need to be treated before it is used, depending on what is present in the water.
Alternative sources of water may also need to be considered, such as bringing water in from other areas. In particular locations, it is likely that there will be increased use of recycled and saline water, as has occurred in other jurisdictions.
Occasionally, groundwater may be discovered while drilling a well. These water discoveries will be reported to the Department of Water and Environmental Regulation (DWER) in accordance with the Administrative Agreement between DWER and the Department of Mines, Industry Regulation and Safety (DMIRS), as part of collaboration and data sharing concerning water resources.
How much water is required for hydraulic fracturing?
The amount of water used depends on several factors including the diameter and length of the well, the properties of the rocks, and how much hydraulic fracturing fluid can be re-used.
The fluid used in hydraulic fracturing is typically composed of 90 per cent water, 9.5 per cent proppants (solids that keep the fractures open – usually sand) and 0.5 per cent chemical additives.
The United States Department of Energy’s Modern Shale Development in the United States: A Primer (2009), states that a single-stage fracture in the US requires approximately 2,000 kilolitres (kL) of water.
Based on experience in the Perth Basin, up to three stages of hydraulic fracturing may be required per vertical well (typically 3km deep). This adds up to about 6,000kL for the hydraulic fracturing operation. For a horizontal well with a horizontal reach of 1km that may require up to 10 fracture stages, about 20,000kL may be required for hydraulic fracturing.
What protections are there for drinking water?
As announced on 27 November 2018 by the State Government, hydraulic fracturing is prohibited within 2,000m of gazetted Public Drinking Water Source Areas; and all onshore hydraulic fracturing proposals will be referred to the Environmental Protection Authority (EPA) for assessment under the Environmental Protection Act 1986.
Additionally, the Administrative Agreement between DWER and DMIRS supports the collaboration and coordination between the two departments when considering the potential impact on water resources by petroleum activities regulated under the Petroleum and Geothermal Energy Resources Act 1967.
How is water use regulated?
DWER regulates, on a case-by-case basis, the taking or extraction of groundwater and the construction of bores/works to access those water resources. These activities are licensed under the Rights in Water and Irrigation (RiWI) Act 1914 within proclaimed groundwater areas and artesian aquifers.
A Licence to Construct or Alter a Well (section 26D, RiWI Act 1914) is required to commence, construct, enlarge, deepen or alter any:
- artesian well; or
- non-artesian well in a proclaimed groundwater area.
Well construction details need to be provided to DWER in accordance with licence conditions.
A Licence to Take Water (section 5C, RiWI Act 1914) is required to take water from a watercourse, wetland or underground source in accordance with a set of terms and conditions.
DWER considers cumulative impact when allocating water and will not support proposals for water allocation that are likely to have unacceptable impacts upon the sustainability of water resources, the environment or existing water users.
In assessing an application for a licence to take water or construct a well, DWER considers a range of issues, including the following:
- Is it in the public interest?
- Is it ecologically sustainable?
- Is it environmentally acceptable?
- Would it compete with current and future needs for the water?
- Would it have a detrimental effect on another person?
- Could the water be provided by another source?
Allocation limits are set for most water resources to sustainably manage the resources and protect existing users and the water-dependent environment. Licences are granted by DWER, up to the allocation limit. In fully allocated areas, water may be obtained by trading.
Petroleum companies are required to provide information to DWER in support of their application. This may include a hydrogeological assessment and groundwater modelling in accordance with DWER’s Operational Policy 5.12 – Hydrogeological reporting associated with a groundwater well licence. Specific requirements are determined by DWER.
The Guideline for groundwater monitoring in the onshore petroleum industry (2016) recommends current best practice by operators to ensure that groundwater monitoring commences prior to on-ground disturbance activities, through the life of the activity and then beyond site decommissioning and rehabilitation.
Is there any wastewater?
There are two main sources of wastewater produced from hydraulic fracturing:
- Flow-back fluid: after hydraulic fracturing fluid has been injected into a rock formation under pressure, roughly 40 to 70 per cent of the fluid will flow back to the surface through the steel cased well. This ’flow-back’ typically occurs during well performance tests and over the production lifespan of the well. It is normal for some of this fluid to remain in the rock formation deep underground.
- Produced formation water (PFW): in most petroleum reservoirs there is some naturally occurring water. This water is recovered during the production stage and often mixes with flow-back fluid. The quality of this water is often poor, and saline to hypersaline. The amount of PFW recovered may increase as the petroleum resource is gradually depleted. The volume of PFW recovered is likely to be relatively low, partly due to the low permeability of the formations being targeted.
How is wastewater regulated?
The disposal of waste, including wastewater, must be detailed in regulatory approvals, such as the Environment Plan required by the Petroleum and Geothermal Energy (Environment) Regulations 2012. Wastewater must also be detailed within a field management plan and well management plan required by the Petroleum and Geothermal Energy Resources (Resource Management and Administration) Regulations 2015. DWER regulates the transportation of controlled waste on roads under the Environmental Protection (Controlled Waste) Regulations 2004.
Wastewater may be managed in several different ways, including the following:
- Recycling: drilling fluid may be reused on the next petroleum well. Flow-back fluid may be reused in the next stage of the hydraulic fracturing process.
- Injection/reinjection: PFW from producing petroleum fields may be disposed of by injecting it deep underground into depleted hydrocarbon rock formations using petroleum wells designed and approved for that purpose. In some cases reinjection of PFW into the hydrocarbon rock formation is allowed, because it can improve petroleum recovery. Disposal of flow-back water by injection is not permitted if it will degrade the quality of groundwater. Managed aquifer recharge to a suitable aquifer can provide an option for fit-for-purpose water supply in areas where water sources are limited. The water may be treated prior to injection, depending on the injection site, to ensure that water quality of aquifers is not degraded.
- Evaporation ponds: these are lined ponds or dams, usually with one or more layers of polyethylene plastic, used to hold the drilling fluids, flow-back fluids or PFW. When the water evaporates, the drill cuttings (solids) and chemicals remain in the pond. At the end of operations, the contents of the ponds and the soils beneath are tested for potential contaminants. If contaminants are present, the contaminated material and the plastic liner is excavated and taken to a licensed waste facility for disposal. Finally, the soil is tested once more to ensure no contaminated soil was missed, and after this the pond can be backfilled, re-contoured and the site rehabilitated.
- Enclosed tanks: these are generally metal tanks, and they allow fluid to be disposed of or reused as required. This may be preferable in environmentally sensitive areas or where there is risk of exposure to animals.
Petroleum companies use a variety of methods to manage their wastes, depending on the available technologies and particular circumstances and environmental sensitivities unique to their proposal. Where a proposal is assessed by the EPA, specific conditions may be applied that require wastes to be managed in a particular way. For facilities that are ‘prescribed premises’, DWER will determine the appropriateness of any given method, on a risk and case-by-case basis.