Cuadrilla forced to stop fracking as quake breaches threshold

Shale gas firm halts work near Blackpool after 17th quake is first over 0.5 magnitude limit

Cuadrilla has been forced to stop fracking after its operations at a well near Blackpool triggered an earthquake that breached the official threshold.

The company said it had paused work for 18 hours after the tremor on Friday morning. It was the 17th quake in the area since fracking began 11 days ago, but the first to be powerful enough to pass a regulatory threshold that requires fracking to stop.

Fracking, or hydraulic fracturing, is a way of extracting natural gas from shale rock formations that are often deep underground. It involves pumping water, chemicals and usually sand underground at high pressure to fracture shale – hence the name – and release the gas trapped within to be collected back at the surface.

The technology has transformed the US energy landscape in the last decade, owing to the combination of high-volume fracking – 1.5m gallons of water per well, on average – and the relatively modern ability to drill horizontally into shale after a vertical well has been drilled.

In England, the government placed a moratorium on fracking in November 2019 after protestslegal challenges and planning rejections. A year earlier, the energy company Cuadrilla was forced to stop work at its Preston New Road site in Lancashire twice in four days due to minor earthquakes occurring while it was fracking. The tremors breached a seismic threshold imposed after fracking caused minor earthquakes at a nearby Cuadrilla site in 2011. In March 2019 the high court ruled that the government's fracking guidelines were unlawful because they had failed to sufficiently consider scientific evidence against fracking.

The 0.8-magnitude quake centred 2km (1.2 miles) underground was too small for anyone to notice on the surface, but is ranked as a red event on the government’s traffic-light scheme of fracking regulation.

A red event is anything above 0.5 magnitude and requires Cuadrilla to stop injecting water and monitor the well for further seismic activity.

Any delays will cost the company financially. It has admitted that delays due to a legal challenge earlier this month were costing it £94,000 a day as workers stood idle.

Cuadrilla said it was hydraulically fracturing shale rock adjacent to one of its horizontal wells when the tremor occurred. The integrity of the well was intact and regulators had been informed, it added.

The company intends to restart fracking on Saturday morning, though it only has permission to frack until 1pm on Saturdays.

In a statement, the firm said: “Micro-seismic events such as these result in tiny movements that are way below anything that would be felt at surface, much less cause any harm or damage.”

The company voluntarily stopped fracking on Monday afternoon after a 0.4-magnitude tremor, which was classed as an amber event, meaning the company must slow down its work but does not have to stop.

In total, there have been 17 tremors, two of which happened while fracking was under way and 15 of which happened afterwards and are known as “trailing” events.

Seismologists have been quick to note that all the tremors so far have been very small, with a 0.4-magnitude one on Monday akin to the vibrations from road traffic. Today’s 0.8-magnitude event was around 200 times smaller than a 2.3-magnitude one caused by fracking in 2011.

However experts have said the key thing is not whether people notice the quakes but whether they damage Cuadrilla’s well.

Stuart Haszeldine, professor of geology at the University of Edinburgh, said: “The practical significance is not whether these tremors are felt at the surface or not, but in the potential to damage the borehole, and the potential to create gas pathways from the shale towards larger faults, towards shallower aquifers, and to the surface.”

The Guardian revealed earlier this month that energy minister, Claire Perry, had proposed raising the regulatory threshold for tremors caused by fracking, as the industry begins to mature.

But the government has subsequently denied it has any plans to relax the rules. Lord Henley, a junior minister at the Department for Business, Energy and Industrial Strategy, said this week: “There are no plans to make changes to the traffic light system for monitoring induced seismicity.”


Adam Vaughan Environment correspondent

The GuardianTramp

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