Shale gas

Our role

The BGS has a role to evaluate the amount of shale gas present in the UK. Working in association with partners such as the Oil & Gas Authority (OGA), we have completed several shale resource research papers and estimates. For more information please view the links below:

Frequently asked questions — shale gas

What is shale gas?

Shale is a very fine-grained, sedimentary rock formed from clay, silt or mud and is one of the most abundant sedimentary rock types in the Earth's shallow crust. Shale gas is mostly composed of methane (CH4), otherwise known as natural gas, and is the same as the gas used to generate electricity and for domestic heating and cooking.

How do we get the gas out of the shale?

Shale gas is recovered from shale by drilling deep boreholes in to the shale and then carrying out an operation called hydraulic fracturing or 'fracking'. This releases the gas from the shale.

What is the difference between shale gas resource and shale gas reserve?

'Shale gas resource' is the amount of shale gas that is present within a rock formation. The 'shale gas reserve' is the amount of gas that can be recovered from a rock formation within regulatory, environmental, technical and economic limits. Further details on this can be found on the OGA website.

What role does the BGS play in shale gas research?

As the national geological survey, the BGS has an important, impartial role to play in helping us better understand the potential for shale gas as a new source of natural gas and the environmental risks and impacts that might arise from shale gas industry operations. Our work includes:

  • Undertaking long-term environmental monitoring (air, water, seismicity, ground motion and soil gas) in areas where shale gas exploration is taking place to establish an environmental baseline detect impacts from operations.
  • Evaluating the vertical separation between different potential shale gas source rocks and the principal aquifers in England and Wales to support risk assessment.
  • Researching and monitoring induced seismicity arising from hydraulic fracturing operations.
  • Developing integrated risk assessment methods that consider long-term cumulative impacts of shale gas development and other subsurface activities across a wider area.
  • Studying the organic content and the organic makeup of the shales to improve understanding of how much shale gas they might produce and how the gas is stored within the rocks.
  • Understanding the distribution and correlation of shale and how the shale layers behave in response to depositional and tectonic controls.
  • Issuing advice and guidance for the government in trying to understand the amount of gas that may be both in place and possibly recoverable within the shales in the UK, on effective environmental monitoring and risk assessment.

In doing so, the BGS provides independent, expert and impartial geological and environmental advice to industry, government and the public.

Can shale gas meet the UK's energy needs?

Estimates of shale gas resources (gas that is in the rock) and the amount of recoverable gas (reserve) are variable.

In 2013 the BGS was commissioned by the Oil and Gas Authority (OGA) to estimate the amount (resource) of shale gas in the Bowland Shale Formation. The outcome of this study was a range of estimates from 822 trillion cubic feet (tcf) to 2281 tcf, with a central estimate at 1329 tcf. However, despite the size of the resource, the proportion that can be recovered continues to be the critical factor, and is the focus of the exploratory drilling that is currently underway in parts of England.

Without the exploratory drilling and testing and further research on shale recovered from deep boreholes, there will remain uncertainty on the amount of gas that is present in the UK and that can be commercially extracted.

Are there any risks associated with fracking?

Shale gas extraction using 'fracking' is an industrial process and, like many any other industrial processes, there will be potential risks to health and the environment. Regulations are in place to require identification and management of risks. Until an operator can demonstrate to the regulators that the risks can be managed effectively, permits to operate will not be issued. Understanding the risks is a very important step in the design and approval process and very strict controls and regulations are in place to reduce the risks to an acceptable level.

Some of the specific risks relevant to shale gas include 'induced seismicity', such as the earthquakes experienced in Lancashire in 2011 and again in 2018 and 2019. There is also the potential for groundwater and surface water contamination and emissions to air (see below for more information).

For more information, please refer to the BGS briefing note on gas emissions.

Why is the BGS monitoring groundwater?

The BGS is monitoring groundwater (and other parts of the environment, including seismicity) to support risk assessment by characterising environmental conditions before industrial activity starts (a baseline) and then subsequently to detect any changes that might occur. Baseline data have been published, including a National Baseline Methane Survey of UK groundwaters and reports for monitoring in Lancashire and the Vale of Pickering. Monitoring in these areas is continuing and to date, no changes in groundwater conditions has been observed since drilling and hydraulic fracturing operations started.

Are there any risks to groundwater associated with fracking?

Just like many other industrial processes there will be risks to the environment, including groundwater. Surface activities may lead to spills associated with the storage and mixing chemicals at the drill/fracking site or the storage/management of fluids that return to the surface from the shake gas well (flowback and produced waters). Other potential causes of groundwater contamination can be as a result of poor well design and well construction. Understanding these risks and potential impacts is a very important step in the design and regulatory approval process, and very strict controls and regulations are in place to reduce and manage the risks.

Is there likely to be an impact on groundwater?

Effective risk assessment and management should mean that shale gas operations can be carried without impacting groundwater. When considering the risks, two potential impacts on groundwater are considered. The first is associated with overabstraction of groundwater to meet the requirements for drilling and fracking. The second is contamination of groundwater.

In both cases, the regulations that apply to shale gas extraction require a detailed risk assessment before any authorisation or permit is granted. Before granting a permit the relevant regulatory authority (for example, the Environment Agency in England) will need to be satisfied that the activity will not cause pollution of groundwater or lead to unsustainable abstraction. If approval is granted operations will only be allowed to take place within specific limits and monitoring of the environment will be required as part of permit conditions to demonstrate that no impact is occurring.

What percentage of the population use groundwater?

Groundwater supplies water to about 27 per cent of the population across the UK. This proportion varies widely depending on the underlying geology, with the highest proportion of drinking water being supplied by groundwater in the south-east of England (over 70 per cent). In this region, the Chalk aquifer is the principal source of groundwater. In the north and west, water supplies come predominantly from surface water but groundwater is still important as it is also used for private domestic supply.

Current estimated groundwater usage for public supply by region:

  • England: 35 per cent
  • Wales: 2 per cent
  • Scotland: 7 per cent
Which aquifers overlie the potential shale gas rocks?

The Aquifers and Shales webpages provide access to national-scale maps that show the extent of, and spatial relationships between, the principal aquifers of England and Wales and major shale and clay units. This is the product of the aquifers and shales project, which was undertaken by the BGS with the Environment Agency. We used the BGS bedrock fence diagram (UK3D) and aquifer designation data. The project examined the full extent of each rock type, identified where principal aquifers overlie shales and estimated the vertical separation between the different rock types forming the aquifers and those with potential for shale gas.

What is the vertical separation between aquifers and shale gas sources?

The aquifers and Shales webpages provide access to national scale maps which show the extent of, and spatial relationships between, the principal aquifers of England and Wales and major shale and clay units.

Where can I find further information on research on shale gas and groundwater in the UK and globally?

The BGS is currently carrying out the following projects in this area:

Where can I find out more on BGS research and information on shale gas?

The BGS, working in association with partners such as the OGA, has completed several shale resource research papers and estimates.

Research areas

Biological originsShale gas prospectivity

Shale gas prospectivity is controlled by the amount and type of organic matter held in the shale, thermal maturity, burial history, micro-porosity and fracture spacing and orientation.

Weighing a sampleSource rock quality and properties

BGS expertise in basin analysis and seismic processing, organic chemistry, palynology and palynofacies analysis, and mineralogy and petrology is available to assess source rock properties.

seismogramSeismic properties

Shale is extremely anisotropic, unlike sandstone and carbonates, which exhibit weak anisotropy.

Monitoring of methane in groundwaterShale gas environmental monitoring

As part of the enhanced research programme, groundwater, regional air quality, seismicity and ground movements will be independently monitored at two proposed hydraulic fracturing sites in Lancashire.


GeoBlogyDo Shale Resources Have Any Place in a Green Great Britain?... by Joe Emmings

Research focusing on understanding the fundamental mechanisms through which gas is generated and retained within deeply buried rocks in the UK and overseas.

More questions?

The BGS is also carrying out groundwater-related research. More about shale gas and groundwater.


Contact Enquiries for further information.