Industry

Tremors predicted before Lancashire fracking began

190826 GeoSierra chart

Chart: GeoSierra

An expert in hydraulic fracturing warned Cuadrilla and UK regulators in the days before fracking began near Blackpool that the operation would probably cause earth tremors.

This morning, the OGA suspended fracking at the Preston New Road shale gas site, just 12 days after operations resumed.

The UK’s largest fracking induced earth tremor, measuring 2.9ML, was felt across Lancashire at 8.31am today.

It was the latest in more than 90 tremors induced by fracking at Preston New Road since 15 August 2019, including four that were felt.

The tremors were predicted earlier this month by Grant Hocking, the founder and president of the US energy and environmental company, GeoSierra, which has reviewed previous Cuadrilla fracks at Preston New Road and at Preese Hall.

He warned in emails to Cuadrilla, the Oil & Gas Authority (OGA), the British Geological Survey (BGS) and the Environment Agency (EA) that there were likely to be tremors when the second Preston New Road well was fracked this month.

This morning, people living as far from the site as Preston and Chorley said they felt the the 2.9ML tremor. Six other tremors, each measuring more than 0.5ML, have been recorded in the past five days.

Cuadrilla attributed tremors at Preston New Road during autumn 2018 to the activation of a fault intersected by hydraulic-induced vertical fractures, oriented in the direction of the maximum horizontal principal stress.

But a different cause has been suggested by Dr Hocking, who has written scientific papers and worked with Haliburton on hydraulic fracturing innovative field trials and co-owns related patents.

He said there was evidence that Cuadrilla’s hydraulic fracturing operations at Preston New Road had opened near-horizontal, highly sensitive, slicken-sided bedding planes. These are smooth, highly polished surfaces, often with parallel grooves. They form at fault planes when rocks on either side slide past each other.

Dr Hocking said:

“Rather than hydraulic fracture the shale formation, Cuadrilla have opened near horizontal bedding planes creating a heightened risk of induced seismicity, as the frack fluids have migrated about 750m updip on these hyper-stress sensitive slicken-sided bedding planes”.

He said the presence of these slicken-sided bedding planes would limit the vertical growth of hydraulic fractures, raising the bottom hole pressure and allowing frack fluids to migrate significant distances from the well.

“This heightened risk of induced seismicity can be avoided by placing limits on bottom hole pressures during injection”, he warned the regulators this month but none responded. He said:

“We were being proactive in warning Cuadrilla and the regulators of the induced seismicity risks associated with excessive bottom hole pressures and the consequences of opening the slicken-sided bedding planes.”

GeoSierra has made a short video about its hypothesis:

Dr Hocking had previously warned the BGS and OGA in August and October 2018 about slicken-sided bedding planes, which had also been encountered in the Preese Hall well, Dr Hocking said.

Fracking at Preese Hall in 2011 induced a 2.3ML tremor, which led to a moratorium on fracking. This was lifted in 2012 with the introduction of the traffic light system regulations. They require a pause in fracking for 18 hours if tremors during fracking reached 0.5ML.

Dr Hocking warned the organisations in August and October 2018, that if the slicken-sided bedding planes were present at Preston New Road:

“without bottom hole pressure and tiltmeter monitoring, there is a high probability of repeating what happened in 2011.”

The OGA “noted” his comments.

Dr Hocking said the use of tiltmeters would provide more information on what was happening below the surface.

A government document on fracking from 2013 said

“until the characteristics of fracking in a particular formation are well established …. tiltmeters and a permanent buried seismometer system will record the usual micro-seismic events (of magnitude much less than ML 0.5) that accompany all fracking activity.”

DrillOrDrop asked Cuadrilla whether it had used tiltmeters in the two wells at Preston New Road and how bottom hole pressure was monitored. A company spokesperson said:

“This isn’t something we’re able to facilitate at the moment”.

Cuadrilla’s technical director, Sau-Wai Wong suggested that GeoSierra had misinterpreted some of Cuadrilla’s data and the general fracking process. But Dr Hocking said:

“I consider it absolutely mandatory that the UK agencies act on what GeoSierra has been trying to get across to them, on the unnecessary hazards being imposed on the public and the environment, by ill-conceived and technically incompetent design of hydraulic fracturing operations at Preston New Road.

“Surely isn’t it about time the UK government put some scientific oversight into this operation?

“From the discussions I have had with Cuadrilla, it was apparent that the company does not have a plan on how to tackle the slicken-sided bedding planes.”

  • Dr Hocking has pioneered the hydraulic fracture stimulation of ductile formations for the installation of Permeable Reactive Barriers (PRBs) for groundwater remediation, and for the oil and gas recovery in ductile formations like silty sands and turbidites.

Updated 1 September 2019 to include video

20 replies »

    • Thanks again, Ruth. Clearly Cuadrilla have little idea what they are doing and are unwilling to learn from the experienced. As for the so-called regulators, what reputable organisation would ignore such advice and allow fracking to take place knowing the risks to the public? Were it not such a cliche, I might say this “beggars belief”, but clearly not in the Cameron/May/Johnson UK, where all that matters is the quick buck. Do we need to put up with this?

  1. I think house prices in these parts will be heading downwards faster than something moving downwards very fast indeed.

    • There have been a number of high profile “ anti frackers” suggesting house prices have already fallen.
      2.9 M is no good reason for prices to drop, but the fear mongering is strongly enhanced by this event. [edited by moderator] I trust the result of any scientific and expert driven results of the investigation now ongoing provides the right outcome. I trust the results are expert driven and that the wail of the people is ignored, experts are not given much quo’s these days, but we must resist people’s bigoted ideas driving this country backwards. Especially with the backdrop of Brexit. Very worrying times.

      • It isn’t scaremongering that drives down house prices it is having a polluting, heavy industrial development close to your home and especially when it causes earthquakes that make your home shake and windows rattle. Consider lenders and insurers, they will see this as a risk and risk affects yields. You write of expert driven results but funny how supporters of fracking are only too happy to ignore experts that don’t suit their views, such as the experts from Nottingham University and BGS when they stated there may only be a five year gas resource, likewise other experts have been similarly disregarded, such as Professor Styles, ReFINE and so on. People are entitled to be angry when their homes shake, people that had not been opposed to fracking before yesterday were incensed and are now demanding a ban. It won’t be scientists that determine any impact on house prices it will be the market and having fracking and quakes impacting your property will not make it appealing to buyers. That is obvious not scaremongering. .

  2. It will be interesting to see how much of the data will be made available and how much Cuadrilla will ask to be deleted .

    • Jono

      I guess there may be a difference between what is available to the public and what is available to the OGA et al for them to carry out their review.

  3. “He said the presence of these slicken-sided bedding planes would limit the vertical growth of hydraulic fractures, raising the bottom hole pressure and allowing frack fluids to migrate significant distances from the well.” Could this explain the re-injected fluid migration and frequent tremors in Surrey / Gatwick / Newdigate?

    • Wandering Dutchman

      Fracking and re injection are different operations. With re injection you hope that the water does not need much pressure to pop it into a place willing to receive it.

      But I expect the issue will get aired again very soon as the opportunity to call for a ban on weald oil because of issues fracking the bowland shale will be too hard to resist.

  4. Charlie Hobson. The problem is that the experts mostly have to make a living, support a family, & build a career so they are unlikely to contradict the industry, establishment, or herd view. Earthquakes in Newdigate have a clear correlation with published well site actions at Horsehill. If UKOG would publish full well site activities (as is required at fracking sites like PNR) we would undoubtedly see even closer correlations. As an example, after a quiet spell when HH was flowing the Portland, there were 9 tremors on the day production switched to the Kimmeridge. Yet another remarkable coincidence that the experts will dismiss. The sooner the Government and experts recognise that UK shale isn’t the Baaken the better. Uk shale is heavily faulted and the risks of earthquakes is high. The shale is shallow depth so the risk of damage to buildings from earthquakes >2.0 is high, especially in The Weald where many buildings sit on clay without substantial foundations.

    • PeterM – there is zero correlation between seismicity and operations at HH. Furthermore, there is no physical mechanism to related the seismicity to activities at HH – the volume and hence stress changes are far too small. If such small injection/production rates caused Earth tremors then one would be seeing even more effects in drinking water aquifers and we don’t. Experts are fully aware that the UK isn’t the Baaken although some parts of the offshore UK are potentially similar.

      • Judith Green, please state your evidence for your statement that there is zero correlation between seismicity and operations at HH

  5. PeterM – the fact that the seismicity started before the activity at HH seems pretty obvious. There’s nothing publicly available about the activities at HH but friends of mine who have had access to the data think it’s laughable that people are suggesting a correlation and they are amongst the best in the world on this subject

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