By JR on Thursday, January 12, 2012
It is "extremely unlikely" that ground water supplies would be polluted by methane as a result of controversial "fracking" for shale gas, UK geologists have said.
And although the process, which uses high-pressure liquid pumped deep underground to fracture shale rock and release gas, caused two earthquakes in Lancashire last year, the quakes were too small to cause damage, they said.
Campaigners have called for a moratorium on fracking in the UK in the face of the earthquakes and amid fears it could lead to pollution of drinking water by methane gas or chemicals in the liquid used in the process.
Fracking has proved controversial in the US, where shale gas is already being exploited on a large scale and where footage has been captured of people able to set fire to the water coming out of their taps as a result of gas contamination.
But Professor Mike Stephenson, of the British Geological Survey, said most geologists thought it was a "pretty safe activity" and the risks associated with it were low.
He said the distance between groundwater supplies around 40-50 metres below the surface and the deep sources of gas in the shale a mile or two underground, made it unlikely methane would leak into water as a result of fracking.
There was no evidence in peer-reviewed literature of pollution of water by methane as a result of fracking, he said, adding that the presence of the gas in US water supplies was likely to be natural. But a survey was currently being conducted in the UK, to establish a baseline of any gas naturally found in groundwater before drilling took place.
"If you don't know what the baseline is, you don't know if people are running a tight ship. There's natural methane in groundwater and you have to distinguish between what's there already and what might have leaked in."
He said two cases of methane pollution of water in the US, neither of which were due to fracking for shale gas, were the result of mismanagement. The UK has one of the strictest regulatory regimes in the world, he added.
Fracking by energy company Cuadrilla was halted in the Blackpool area last year, after two small quakes in the area which the geologists are certain were caused by fracking. Although they were felt by around 50 people in the area, they were too small to cause any damage.