People living near fracking operations in north-west England might need to get used to earthquakes, a conference heard yesterday.
Dr Rob Westaway, of Glasgow University, told Shale UK that faults in the region could be reactivated by fracking fluid leaking into them. Not much fluid was needed and reducing the volume would not prevent earthquakes.
“A small amount of fluid needs to leak into faults to induce earthquakes considered to be a nuisance”, he said. “Reducing the volume of fracking fluid will not guarantee you will not get induced seismicity”.
Dr Westaway said the first and third stages of fracking at Cuadrilla’s Preese Hall well in 2011 did not lead to seismic events but stages two and four did.
“It is reasonable to assume that the fracking stages that induced seismicity were the ones where fracks intercepted the fault, enabling fluid to leak into it.”
He suggested that about 100 cubic metres of fluid may have leaked into the fault to cause the earthquakes. “It was not all of it”, he said.
If faults are left alone they will be ok, he said. But if 20-30% of the fluid leaks into them they could slip.
Cuadrilla plans to use up to 750 cubic metres of fluid for each stage of hydraulic fracturing at its proposed well at Preston New Road in Lancashire.
Dr Westaway said fracking that used 750 cubic metres of fluid could be predicted, in the right circumstances, to induce seismic events that measured 2.7 on the Richter scale.
“If fracking is allowed with that volume you will have to predict earthquakes of that size”, he said. “People will have to tolerate the nuisance or you will need to fine some ways of preventing them.”
This could be high-resolution seismic surveys or real-time control systems, he said.
Traffic light system “nonsense”
Dr Westaway also criticised the traffic light system developed by the Department for Energy and Climate Change, which requires fracking to stop if there is seismic activity above 0.5 on the Richter scale.
“My personal view is that it is a complete nonsense. It misleads people into thinking there is some way to control this. I think it is very poor that the UK has rushed into adopting this limit.”
But he said it was unlikely that the limit would change in the near future.
The issue was “toxic politically”, he said. “Doing anything in advance of a general election is not going to happen soon”.