Water and Soil
Risk to water supplies and aquifers is negligible
It is a legal requirement in the UK to disclose components of fracturing fluid
Shale gas has lower water intensity usage compared with nuclear and coal power generation
How much water is used? A key difference between a well that requires hydraulic fracturing and one that does not is the amount of water required for the process.
A hydraulic fracture is likely to use between 10,000 and 30,000m3 of water per well, which is significantly more than a conventional well.
However, the amount of water needed to operate a hydraulically fractured (fracked) well for a decade is the same as the amount of water:
- a golf course uses in a month
- used to run a 1,000MW coal-fired power plant for 12 hours
The groundwater protection council for the US Department of Energy has compared energy water intensity, which compares the volume of water used for each unit of energy produced, and found that shale gas has a lower intensity compared with nuclear (medium) and coal (high).
Hydraulic fracturing is also not a continuous process. Water is only needed at certain times during drilling and at each fracturing stage. As a result, operators can talk to local water authorities to schedule operations to avoid any times when water supplies are more likely to be under stress.
What is in hydraulic fracturing fluid?
The UK industry under UKOOG guidelines has agreed to publish on our website all chemicals that are used in hydraulic fracturing by composition and concentration. In the UK, unlike the USA, it is a legal requirement to disclose fully the composition of fracturing fluid additives.
The fluids most commonly used for hydraulic fracturing are water-based and have sand added to keep fractures opening. There are also very small amounts of additives used, such as friction reducers. A typical hydraulic fracturing fluid is made up of 94.6% Water; 5.23% Sand and 0.17% additives.
Can hydraulic fracture fluids leak into the water supply?
Shale gas formations are typically found much deeper underground than conventional oil and gas sources. In the UK, hydrocarbon extraction will therefore be taking place at a depth a long way from groundwater so as to ensure that the possibility of any fractures extending into aquifers is negligible.
Hydraulic fracturing has been used in over two million wells worldwide since the 1940s and comprehensive studies have found no historical cases in which hydraulic fracturing fluid has contaminated drinking water, a fact underlined by the UK Energy and Climate Change Select Committee.
Can methane leak into the water supply?
Methane gas can occur naturally in groundwater in areas where there has been no oil and gas activity or other previous industrial activity.
In the UK, the British Geological Survey (BGS) has been undertaking a National Baseline Survey of Methane, covering all prospective areas for shale gas in England and Wales. This will enable environmental regulators to understand pre-existing background methane levels prior to assessing permit applications and to monitor levels should a permit be granted.
All UK operators are required to monitor for methane prior to drilling activity to establish a ‘baseline’ data set and will then continuously monitor thereafter for signs of any increase to the background level.
The most likely source of unintended, not naturally occurring methane contamination in water would be due to poor well integrity where methane has leaked from piping or cement as it passes through the aquifer. Regulations in the UK are extremely stringent with respect to well integrity and control to ensure that this does not occur.
Can oil and gas extraction cause naturally occurring radioactive material to leak?
No radioactive material is used in the extraction of shale gas, either in the chemicals used or in the fracturing process itself.
Water used in hydraulic fracturing typically comes back to the surface containing Naturally Occurring Radioactive Material known as NORM.
Naturally Occurring Radioactive Materials (NORM) are radioactive substances that exist in all natural forms: soils, rocks, water and in air, as well as being found in foods such as bananas and Brazil nuts. Shale rock is no different and contains NORM, similar to those found in other rock types.
Managing NORM levels is not unique to shale gas extraction. NORM is present in waste fluids from the conventional oil and gas industries, as well as mining industries such as coal and potash.