Water used in gas operations is generally obtained from the area of those operations and is typically brackish (i.e. not potable).
As part of the approvals process, a company must demonstrate that using local water will not have unacceptable impacts on aquifers.
Australia’s shale gas deposits are typically 2-4km below ground, while freshwater aquifers are usually about 300m below the surface.
Shale gas deposits are separated from the fresh water aquifers by extensive layers of impermeable geological formations. These layers form efficient natural barriers between fresh water and gas resources.
Shale gas wells have several layers of steel casing and cement that form a continuous protective barrier between the well and the rock. Millions of oil and gas wells have been drilled through aquifers without causing problems.
Regulators require monitoring and management conditions appropriate to each site during and after production. This includes monitoring the levels and quality of local groundwater.
Minimising water use
Water use for hydraulic fracturing can vary depending on the geology and the Australian Council of Learned Academies estimates that between 4 and 22 megalitres per well is required depending on the number of fractures.
Up to 80% of the fluid used in shale gas fraccing can be recovered. Most of this can be recycled and reused for additional hydraulic fracturing or other beneficial uses such as irrigation of nearby crops.
Water that cannot be recycled is placed in specially designed ponds for evaporation. The residue from this process is tested and, if required, removed to a licensed disposal facility. At no point does this water contact or contaminate groundwater sources.
Recent proposals for hydraulic fracturing have estimated a water requirement of 1.1 megalitre per fracture treatment, with between 5 and 13 fracture treatments required in total depending on the well location and geology.