Shale gas

Our role

The BGS is proud to launch its refreshed Science Strategy. 'Gateway to the Earth' focuses on solving problems around the three science challenges:

  • decarbonisation and resource management
  • environmental Change, adaptation and resilience
  • multihazards and resilience

View our Science Strategy: Gateway to the Earth 2019-2023

Our research

The British Geological Survey (BGS), working in association with partners such as the Oil & Gas Authority (OGA), has completed several shale resource research papers and estimates. For more information please view the links below:

Frequently asked questions – shale gas

What exactly is shale gas?

Shale gas is mostly methane. Methane is also known as 'natural gas' and is the gas used to generate electricity and for domestic heating and cooking. Shale gas is extracted using technologies developed since the 1980s that enable gas to be recovered from rocks (mostly shale) that were previously considered to be unsuitable for extracting gas.

How does it differ from conventional gas?

Conventional gas comes from a 'source' rock that was buried and heated at considerable depth (up to thousands of metres below the surface). Temperature increases with depth and hydrocarbons, such as oil and gas, are released from the source rocks at different rates depending on how fast the rocks are heated. These hydrocarbons migrate upwards and may find their way into a porous 'reservoir' rock. If this is overlain by an impermeable 'cap' (or 'seal') rock the hydrocarbons become trapped. The hydrocarbons are extracted by drilling through the cap rock into the reservoir. These hydrocarbons, which can be relatively easily recovered, are known as 'conventional hydrocarbons' and have been exploited for more than 100 years. North Sea gas is a conventional hydrocarbon.

With 'unconventional' hydrocarbons, and shale gas in particular, the rock that contains the hydrocarbons is virtually impermeable and so acts as the hydrocarbon source rock, reservoir and seal. The gas is both produced and trapped within the shale. It is only when the shale is drilled and artificially fractured that the gas is released from the rock and can be extracted.

How do we get the gas out of the shale?

Advances in technology, developed principally in the USA, have meant that gas can now be extracted from shale and other low permeability rocks. Transferring these technologies from the USA to the UK could give rise to shale gas production if gas occurs in the rocks in commercial quantities.

After initial exploration of the shale deposits, a borehole is drilled into the shale horizon at a carefully selected site. It may be drilled horizontally to increase the volume of rock that can be accessed by the borehole. A process called hydraulic fracturing ('fracking') is undertaken. This involves pumping water into isolated sections of the borehole at pressures high enough to fracture the surrounding rock. Sand in the water helps to ‘prop’ open the fractures, creating permeability in the rock and allowing the gas to flow into the borehole. Chemicals are also added to improve the efficiency of the fracking operation.

Can shale gas meet the UK’s energy needs?

Estimates of the amount of recoverable gas and the gas resources (gas that is in the rock) are variable. In 2013 the BGS was commissioned by the Oil and Gas Authority (OGA) to estimate the amount 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. A better understanding of the shale gas resource and the amount of gas that is potentially recoverable will come from further geological research, such as that carried out in a new study by the University of Nottingham and the BGS.

What did the 'Shale gas reserve evaluation by laboratory pyrolysis and gas holding capacity consistent with field data' study find?

The new study found that, after taking samples of the Bowland Shale Formation and analysing them using a new, innovative technique, the shale gas resource in the Bowland Shale Formation could be smaller than previously thought.

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 and geological limits.

What happens now?

The BGS will continue to study the different shale formations within the UK. We are carrying out an environmental baseline monitoring project and continue to monitor induced seismicity at active shale gas sites, such as those in Lancashire.

What role does the BGS play in shale gas research?

The BGS's main role is to evaluate the amount of shale gas present and how safe it is to extract. The BGS is taking a central role in shale gas research in the UK and also across Europe as follows:

  • undertaking a baseline groundwater survey of methane concentrations and other relevant chemical indicators in ground waters across Great Britain
  • evaluating the spatial relationship between different potential shale gas source rocks and the principal aquifers in England and Wales
  • researching induced seismicity related to fracking
  • 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

The BGS provides independent, expert and impartial geological advice to both industry and government.

BGS research fact file
  • 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 can be recovered from shale using hydraulic fracturing or 'fracking'.
  • The BGS will play its part in providing up-to-date and accurate information on resources and the environment to the public, industry and government.
Are there any risks associated with fracking?

Shale gas extraction and fracking has received a huge amount of media interest. Just like any other industrial process there will be associated risks. Some of those relevant to shale gas include ‘induced seismicity’, such as the low magnitude earthquakes experienced in Lancashire in 2011. There is also the potential for groundwater and surface water contamination (see below for more infomation on potential impacts to groundwater). This may arise from surface activities that 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 borehole, the so-called ‘flowback and produced waters’. Other potential pathways for contamination of groundwater include poor well-design and well construction, and the migration of contaminants along natural pathways into overlying aquifers. 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.

How dangerous are the induced earthquakes caused by fracking?

The two main induced earthquakes in Lancashire in 2011 were very small. To put them into context, they were less powerful than some of the earth tremors that have been associated with coal mining in the 1950s and 60s and that occur today.

What is the chance of these risks occurring?

There is a broad regulatory framework that already exists. The use of fracking, shale gas technologies and associated activities is covered within the existing regulatory frameworks.

What do you think the likely impact will be on groundwater?

There are two potential impacts on groundwater. The first is associated with the supply and consumption of water for fracking as groundwater may be considered as a source of this water. The second is contamination of groundwater. In both cases the regulations that apply to shale gas extraction will require a detailed risk assessment before any authorisation or permit is granted. Before granting a permit the relevant regulatory authority (e.g. the Environment Agency in England) will need to be satisfied that the activity will not cause pollution of groundwater or lead to unsustainable abstraction. Once approved, monitoring of the environment will be required as part of permit conditions to demonstrate that no impact is occurring. To provide an independent environmental baseline against which this compliance monitoring can be compared, the BGS is undertaking a baseline survey of methane concentrations in groundwater ahead of any shale gas development as there is currently no UK baseline. The baseline study is not only restricted to methane. A wider range of chemical indicator parameters are also being measured and the results will supplement the data already published by the BGS and used to set groundwater threshold values (standards) for the EU Water Framework Directive.

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.

GeoBlogy

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

Contact Enquiries for further information.