How is shale gas extracted?
Hydraulic fracturing
Shale gas or unconventional gas is extracted from the impermeable shale through a process called hydraulic fracturing (also known as hydrofracking or fracking). A crude form of this technique, involving nitroglycerine, was used for the first time around the 1860s to explore for oil and gas.
During hydraulic fracturing, a mixture of water, chemicals and sand is pumped down a borehole at high pressure. The water pressure opens up cracks in the rock and the sand grains lodge into the spaces to keep them open, allowing the released gas to flow out of the rocks and travel back up the borehole.
The hydraulic fracturing technique is not new; it has been used for over 50 years to improve recovery of conventional oil and gas.
How shale gas extraction works. BGS © UKRI.
The moratorium on hydraulic fracturing in the UK (2019)
Shale gas extraction is not presently allowed to proceed in the UK.
In November 2019, the UK Government announced a moratorium on hydraulic fracturing in shale in England. This decision was taken on the basis of a report by the Oil & Gas Authority.
In January 2015, the Scottish Government put a moratorium on unconventional oil and gas development in Scotland in place, following the publication of a report of an independent, expert, scientific panel.
Since 1 October 2018, licensing powers in Wales have been transferred to the Welsh Assembly Government, which has taken the decision not to support applications for hydraulic fracturing in Wales or fracking consents.
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Shale gas in the UK
The UK has a number of sites that have been explored for shale gas deposits.