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UK panel on fracking gives cautious approval for continued operations

16 May 2012

Hydraulic fracturing, or fracking, should continue under strict conditions, a government-appointed panel of experts says. The gas extraction method triggered two earth tremors near Blackpool in 2011, and has proved controversial elsewhere in the world with accusations of groundwater pollution and seismic damage where operations have been carried out on a large scale.

Cuadrilla Resources says Bowland Shale deposits in Lancashire contain 200 trillion cubic feet of gas
Cuadrilla Resources says Bowland Shale deposits in Lancashire contain 200 trillion cubic feet of gas

The panel's report, published in mid-April, now goes out for a six-week consultation period, with the Department of Energy and Climate Change (DECC) issuing a firm set of regulations to govern the fracking process within the UK at some point after that.

Report author Professor Peter Styles said any earthquakes were "not likely to cause significant damage"
Such events might well be felt at the surface but are extremely unlikely to be significant, he added, and said seismic events were not likely to be severe than those associated with past coal mining operations in the country.

Fracking involves pumping water and chemicals into shale at high pressure to break apart the rock, with natural gas then captured as it escapes upwards through the cracks.  

Exploitation of shale gas in the USA and Canada has seen a large increase in gas production and a consequent fall in prices. It is being considered by a number of countries around the world as a way of ensuring relatively cheap energy supplies into the future.

Test fracking by the Staffordshire-based company Cuadrilla Resources near Blackpool was stopped in 2011 when two earthquakes were felt at the surface. The panel agrees with a Cuadrilla report from late last year that test fracks at the company's Preese Hall site did cause the two earthquakes, of magnitudes 2.3 and 1.5, in April and May, but that there was a very low probability of other earthquakes.

The government-appointed panel, comprising Styles, a Professor of Geophysics at Keele University, Brian Baptie, head of seismology at the British Geological Survey (BGS) and Dr Chris Green, an independent fracking expert based in Lancashire, said they believed there will probably be more quakes but that they will be too small to do structural damage above ground. It recommends more monitoring.

"We agree that [last year's] events are attributable to the existence of an adjacent geological fault that had not been identified., their report said.  "There might be other comparable faults, (and) we believe it's not possible to categorically reject the possibility of further quakes."

Shale gas is found in layers of relatively weak sedimentary rock, typically several kilometres underground. Coal mining has generated thousands of earthquakes down the years; and on the basis of all the data gathered from this, the panel says, fracking is unlikely to produce anything larger than a magnitude 3.

"There's no record of a quake at this size doing any structural damage," said Prof Styles. "But they would be strongly felt, and there is a possibility of superficial damage."

The panel recommends four precautions regarding Cuadrilla's Preese Hall operation and other projects in the Bowland Shale:

*all injections of fracking fluid must include a preliminary injection, followed by monitoring
the growth of fractures in the shale should be monitored
*operations should monitor seismic events in real time
*operators should observe a ‘traffic light’ regime, with quakes of magnitude 0.5 or above triggering a "red light" and an immediate halt, followed by remedial action.
*This is a considerably lower threshold than the 1.7 proposed by Cuadrilla's experts, though the panel emphasised that other countries such as Switzerland use the still higher threshold of 2.3.

"We've opted for a much lower, more conservative option," said Baptie. "Even with real-time monitoring, there will be a time lag between what we've put into the ground and what we get back out in the form of earthquakes."

Operators should also minimise quakes by allowing the fracking liquid to flow back up the well soon after injection, the panel says, rather than keeping the rock under prolonged pressure.

It also recommends that seismic hazards should be properly assessed before new exploration is permitted. This would involve seismic monitoring to establish what levels of activity are normal in that location, analysis of geological faults, and the use of computer models to assess the potential impact of any induced earthquakes.

Mark Miller, Cuadrilla's chief executive, welcomed the report.

"We are pleased that the experts have come to a clear conclusion that it is safe to allow us to resume hydraulic fracturing, following the procedures outlined in the review," he said.

Cuadrilla claims that the site it has explored in the Bowland Shale contains 200 trillion cubic feet of gas, more than the UK's known offshore reserve - though only a portion of this would be economically recoverable.

Other companies want to explore for shale gas in Fermanagh, the Vale of Glamorgan, Somerset, Kent and Sussex.

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