DECC has published an independent evaluation of the seismic risks from hydraulic fracturing for shale gas, which argues that it is safe as long as certain basic precautions are put in place.

The report, now out for comments from the general public, was commissioned following two earthquakes last year with magnitude 2.3 and 1.5 in the Blackpool area, which subsequent investigations linked to hydraulic fracture treatments in nearby underground layers of Bowland shale by Cuadrilla Resources Ltd. as part of their commercial project to extract natural gas from the shale.

Cuadrilla subsequently provided DECC with a technical report, which has now been analysed by independent experts in the fields of seismology, induced seismicity and hydraulic fracturing: Dr Brian Baptie, head of seismology at the British Geological Survey; Professor Peter Styles of Keele University, and Dr Christopher A. Green, GFRAC.

Speaking on BBC Radio 4, Dr. Baptie said that there is only a "very small" risk of damage from earthquakes caused by hydraulic fracturing (known as fracking), and the highest would be around magnitude three, which poses no greater danger than that from conventional coal mining.

He said that as long as the four main recommendations of the report were adhered to then there would be minimal risk, adding that there was "no evidence of structural damage from these kinds of earthquakes".

The report was welcomed by Mark Miller, chief executive of Cuadrilla. "We are pleased the experts have come to a clear conclusion that it is safe to allow us to resume," he said.

DECC’s chief scientific advisor David MacKay commented that “if shale gas is to be part of the UK’s energy mix we need to have a good understanding of its potential environmental impacts and what can be done to mitigate those impacts”.

He added that the report “suggests a set of robust measures to make sure future seismic risks are minimised - not just at this location but at any other potential sites across the UK”.

Recommendations

The recommendations are that:

  • the hydraulic fracturing procedure should include a smaller pre-injection and monitoring stage
  • an effective monitoring system to provide near real-time locations and magnitudes of any seismic events should be part of any operations
  • future fracking operations should be subject to a “traffic light” control regime, similar to that recommended by Cuadrilla’s consultants
  • unusual seismic activity, even at lower levels than the magnitude 1.7 proposed by Cuadrilla, should be carefully assessed before operations proceed.

For any future operations elsewhere in the UK the review recommends suitable actions to assess the seismic risk before any operations take place, including:

  • establishing the background seismicity in the area of interest
  • characterisation of any possible active faults in the region
  • modelling to assess the potential impact of any induced earthquakes.

The report was criticised by Tony Juniper, former director of Friends of the Earth and chairman of Action for Renewables (A4R), who cited reports from Deutsche Bank and others which showed that the environmental impact of fracking is "comparable to coal and possibly worse", partly due to so-called "fugitive emissions" of methane from drilling sites.

Government support for fracking would cast "grave doubt" over the government's legal obligation to reduce greenhouse gas emissions by 80% by 2050, he said, adding that money would be better put into financing and developing renewable sources of energy.

Furthermore, he said that shale gas would be much more expensive than conventional gas to extract because of the precautionary measures required, and asked who would pay for the damage should anything go wrong.

Joss Garman, Greenpeace’s senior energy campaigner, agreed that "there’s absolutely no indication that fracking for shale gas will reduce soaring household energy bills, while scientific studies suggest that this kind of gas could be as polluting as coal. This would also be a major blow for the British renewable energy industry, which would see investment hijacked by a new dash for gas."

Rhian Kelly, CBI Director for Business Environment policy, welcomed the report, arguing that “shale gas could unlock significant new infrastructure investments, help meet our carbon reduction goals and create many new jobs around the UK.”

But Garman worried that this could be at the expense of jobs in the renewables industry. "Our home-grown renewable energy companies could provide thousands of jobs and develop world-leading cutting-edge technologies,” he said.

Speaking for the industry, Richard Moorman, CEO of Canadian company Tamboran Resources which has permits to operate in Northern Ireland, said that fracking is "perfectly safe if properly regulated", and that in his experience of fracking in Arkansas, US, accidents occurred at a low rate of one in every thousand drilling operations.

He said that it is likely to be at least two years before any commercial shale gas is extracted in the UK.

Other reports are still to be received, including one on the danger of pollution of watercourses from the chemicals used in the hydraulic fracturing process, and, even if drilling goes ahead, it is unlikely to provide a source of gas cheaper than current prices.

The risks of hydraulic fracturing

There are two problems with flushing methane gas from shale, a rock with low permeability.

Firstly, flowing liquids don't easily penetrate and open cracks through which the gas can be extracted, therefore the fluid used has to contain a range of chemicals to dissolve the rocks and create cracks in order to increase the amount of rock in contact with the fluid, and it has to be introduced under high pressure; up to 1,000bar or 15,000psi.

Secondly, this process produces sludge which can clog the cracks, which requires the addition of further chemicals; however, many of the hundreds of chemicals that may be used for this purpose have the potential to leak into the surrounding environment and contaminate water courses.

Their impact depends upon the geology of the area, and each operation would require its own environmental investigation before being allowed to proceed.

If the casing of the well below the drilling platform isn't properly sealed, fluid can leak back up the well bore and reach strata nearer to the surface, which may be used to supply drinking water or feed natural springs.

Even at depth, the release of fracking fluids might still cause contamination over the longer term, should the chemicals be lighter than water and given the presence of geological faults through which they could rise.

Campaign group Free Range Network has produced a report on hydraulic fracturing and unconventional gas in the UK, which attempts an assessment of whether the available resources in the UK could make up for the loss of North Sea production in coming years.

It estimates that in order to achieve this “we'll need to find another three fields over the next two decades. Taking the statements from Cuadrilla Resources in the press, its eight fields would require up to 6,400 wells to be drilled – far in excess of the couple of hundred analysed by DECC in their strategic environmental appraisal of the 14th Licensing Round".

It, too, says the price wouldn't be cheap and it would not provide the bonanza some in the industry have been touting.

The engineers' response

The Institution for Gas Engineers & Managers (IGEM) hosted a conference on the subject at Durham University on 28 March, off the back of its report: Shale Gas – A UK Energy Miracle?

This recommends that fracking liquid storage tanks should be able to withstand a once-in-a-300-year weather event. It also recommends the need for one body to bring all the standards together.

At the meeting, Tony Grayling, head of climate change at the Environment Agency, told the audience the organisation had made visits to established test sites and the UK had to learn lessons from the poor management of environmental standards across in North America.

He told the conference that in the UK “there is no significant, extraordinary ground water risk. The water aquifier tables are several kilometres above” where Cuadrilla is planning to drill.

Like IGEM, he recommends that flowback water is stored in double-lined tanks.

"We need to take the risks seriously and the necessary powers, as we are conscious that public confidence is low,” he said.

Huw Clarke, the exploration geologist from Cuadrilla Resources, told the meeting that “our wells are some 7,000 ft away from the water table”.

He added that each well has seismic censors and investment in 3D seismic imaging will search for fault lines, reducing the impact of small shocks.

Story: David Thorpe, News Editor