Call for 600m fracking limit

 

A A A

Controversial "fracking" for shale gas should only take place at
least 600 metres down from aquifers used for water supplies, scientists
said today.

A new study revealed the process, which uses high-pressure liquid pumped deep underground to split shale rock and release gas, caused fractures running upwards and downwards through the ground of up to 588 metres from their source.

The research, published in the journal Marine and Petroleum Geology, found the chance of a fracture extending more than 600 metres upwards was exceptionally low, and the probability of fractures of more than 350 metres was 1%.

Researchers said the study showed it was "incredibly unlikely" that fracking at depths of 2km to 3km below the surface would lead to the contamination of shallow aquifers which lie above the gas resources.

Shale gas extraction has been controversial in the US because of claims that cancer-causing compounds used in the process have polluted water supplies and that the flammable methane gas itself can pollute drinking water.

But Professor Richard Davies, of Durham University, said it was more likely any contamination came from drilling down through rock containing methane and where the cement or steel well casing may fail, rather than the separate fracking procedure carried out several kilometres down where shale gas forms.

Prof Davies said: "What everyone's interested in is how far can fractures go upwards from that depth - could they go far enough to intersect and contaminate aquifers with fracking fluids or create pathways for methane to contaminate aquifers.

"There's a lot of debate over contamination of water supplies and that could be the case if they are less than 600 metres above shale gas fracking."

But he said that if the process was taking place 1km to 2km below aquifers it was very unlikely to be the source of pollution.

In most cases fracking occurs around 2km to 3km below the surface, where geological conditions are right for shale gas to form, but in one case in Wyoming it took place at around 600 metres down and there was now evidence of chemicals in the water supply.

Prof Davies said there was "just reason to be cautious" and said regulators should set a distance limit, which should be well in excess of 600 metres when fracking in new areas where there was no existing data on possible fractures.

He said the UK's only shale gas exploration scheme near Blackpool, carrying out fracking 3km down, would not affect water supplies in the area, which are around 300 metres below the surface.

The scheme was halted last year after it caused two small earthquakes but could get the go-ahead to resume, while other areas are being considered for exploration.

The researchers from Durham University, Cardiff University and the University of Tromso, Norway, looked at thousands of natural and induced rock fractures in the US, Europe and Africa and found none of the artificially caused ones were more than 600 metres.

However, the largest measured fracture found naturally occurring in the world - created over millions of years - was 1.1km high, prompting the researchers to suggest the 600-metre limit should be an "absolute minimum guideline".

Prof Davies added: "Based on our observations, we believe that it may be prudent to adopt a minimum vertical separation distance for stimulated fracturing in shale reservoirs.

"Such a distance should be set by regulators; our study shows that for new exploration areas where there is no existing data, it should be significantly in excess of 0.6km."

PA

Latest stories from i100
Have you tried new the Independent Digital Edition apps?
iJobs Job Widget
iJobs General

Recruitment Genius: Bookkeeper / Office Co-ordinator

£9 per hour: Recruitment Genius: This role is based within a small family run ...

Recruitment Genius: Designer - Print & Digital

£28000 - £32000 per annum: Recruitment Genius: This Design and marketing agenc...

Recruitment Genius: Quantity Surveyor

£46000 per annum: Recruitment Genius: This property investment firm are lookin...

Recruitment Genius: Telesales / Telemarketing Executive - OTE £30k / £35k plus

£18000 - £35000 per annum: Recruitment Genius: This company specialises provid...

Day In a Page

War with Isis: Fears that the looming battle for Mosul will unleash 'a million refugees'

The battle for Mosul will unleash 'a million refugees'

Aid agencies prepare for vast exodus following planned Iraqi offensive against the Isis-held city, reports Patrick Cockburn
Yvette Cooper: We can't lose the election. There's too much on the line

Yvette Cooper: We can't lose the election. There's too much on the line

The shadow Home Secretary on fighting radical Islam, protecting children, and why anyone in Labour who's thinking beyond May must 'sort themselves out'
A bad week for the Greens: Leader Natalie Bennett's 'car crash' radio interview is followed by Brighton council's failure to set a budget due to infighting

It's not easy being Green

After a bad week in which its leader had a public meltdown and its only city council couldn't agree on a budget vote, what next for the alternative party? It's over to Caroline Lucas to find out
Gorillas nearly missed: BBC producers didn't want to broadcast Sir David Attenborough's famed Rwandan encounter

Gorillas nearly missed

BBC producers didn't want to broadcast Sir David Attenborough's famed Rwandan encounter
Downton Abbey effect sees impoverished Italian nobles inspired to open their doors to paying guests for up to €650 a night

The Downton Abbey effect

Impoverished Italian nobles are opening their doors to paying guests, inspired by the TV drama
China's wild panda numbers have increased by 17% since 2003, new census reveals

China's wild panda numbers on the up

New census reveals 17% since 2003
Barbara Woodward: Britain's first female ambassador to China intends to forge strong links with the growing economic superpower

Our woman in Beijing builds a new relationship

Britain's first female ambassador to China intends to forge strong links with growing economic power
Courage is rare. True humility is even rarer. But the only British soldier to be awarded the Victoria Cross in Afghanistan has both

Courage is rare. True humility is even rarer

Beware of imitations, but the words of the soldier awarded the Victoria Cross were the real thing, says DJ Taylor
Alexander McQueen: The catwalk was a stage for the designer's astonishing and troubling vision

Alexander McQueen's astonishing vision

Ahead of a major retrospective, Alexander Fury talks to the collaborators who helped create the late designer's notorious spectacle
New BBC series savours half a century of food in Britain, from Vesta curries to nouvelle cuisine

Dinner through the decades

A new BBC series challenged Brandon Robshaw and his family to eat their way from the 1950s to the 1990s
Philippa Perry interview: The psychotherapist on McDonald's, fancy specs and meeting Grayson Perry on an evening course

Philippa Perry interview

The psychotherapist on McDonald's, fancy specs and meeting Grayson Perry on an evening course
Bill Granger recipes: Our chef recreates the exoticism of the Indonesian stir-fry

Bill Granger's Indonesian stir-fry recipes

Our chef was inspired by the south-east Asian cuisine he encountered as a teenager
Chelsea vs Tottenham: Harry Kane was at Wembley to see Spurs beat the Blues and win the Capital One Cup - now he's their great hope

Harry Kane interview

The striker was at Wembley to see Spurs beat the Blues and win the Capital One Cup - now he's their great hope
The Last Word: For the good of the game: why on earth don’t we leave Fifa?

Michael Calvin's Last Word

For the good of the game: why on earth don’t we leave Fifa?
HIV pill: Scientists hail discovery of 'game-changer' that cuts the risk of infection among gay men by 86%

Scientists hail daily pill that protects against HIV infection

Breakthrough in battle against global scourge – but will the NHS pay for it?