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Professor Mair’s Verdict On Shale Gas Risks

June 23, 2014

By Paul Homewood 



Aerial view of Cuadrilla site



There was a lively discussion after my recent post, “Fracking in Lancashire”, so I thought it worthwhile offering a summary of the official scientific position on fracking in the UK.


Professor Robert Mair, Head of Civil and Environmental Engineering at Cambridge University, was appointed in 2012 to chair a joint committee, set up by the Royal Society and Royal Academy of Engineering, to analyse the environmental, health and safety risks associated with shale gas exploration in Britain.


Last year, he wrote this article for the Telegraph, to summarise his committee’s findings.


In recent weeks, the Sussex village of Balcombe has found itself at the centre of the argument around hydraulic fracturing, or “fracking”. This debate has become heavily polarised, and there has been much speculation around the environmental risks of shale-gas extraction, concerning water contamination and earth tremors.

There are many factors that policy-makers and local people must consider before deciding whether or not they are in favour of fracking – but I believe that the scientific and engineering evidence should play a key part in that decision. Everyone deserves to know the evidence, as it currently stands.

Over the past 30 years, more than 2,000 onshore wells have been drilled in Britain, approximately 200 of which have used techniques similar to fracking to enhance the recovery of oil or gas. Chief among these is Wytch Farm in Dorset – Europe’s largest onshore oil field, located in one of England’s most famous regions of outstanding natural beauty and special scientific interest, and therefore an area where the aesthetic and environmental impact of drilling are highly sensitive issues.

Last year, I chaired a joint committee set up by the Royal Society and Royal Academy of Engineering to analyse the environmental, health and safety risks associated with shale gas exploration in Britain. We came up with a set of recommendations for the Government to make it as safe as possible, if they decided to go ahead. The report concluded that these risks could be managed effectively as long as operational best practices were implemented, and enforced through regulation. The Government has accepted all the report’s recommendations.

Fracking in Britain would take place at depths of many hundreds of metres or several kilometres. So far the only shale gas fracking in this country has been at depths of 1.06 miles (1.7km) and 1.93 miles (3.1km), equivalent to the height of many London Shards placed on top of each other. It would be highly unlikely for water contamination to occur by means of fractures extending upwards from these deep shales and intercepting an aquifer, since the two are separated by a vast cover of rock. Even if it were possible, pressure conditions mean that the fracking water would not flow that far upwards.

If there is water contamination, it is much more likely to be due to poorly constructed and regulated wells. These are lined with a steel casing, which is sealed into the ground by cement: ensuring the well’s integrity is very important if the risk of contamination is to be kept to an absolute minimum. Here in Britain, we have a long history of world-class oil and gas industry regulation, plus a unique examination scheme to ensure that the design, construction and abandonment of wells is reviewed by independent, specialist experts.

The other main potential cause of environmental contamination is poor site construction at the surface. However, any risks can again be minimised by best practice and good regulation, which Britain has a good track record of upholding. For example, every company must disclose the contents of the fracturing fluid they use, which is not mandatory in America.

There has also been concern about fracking causing earth tremors – but the evidence indicates that this will not be a big issue in Britain. Coal operations have been causing barely noticeable levels of seismicity for many years, and we expect that those caused by fracking will be at an even lower level, no more severe at the surface than the passing of a truck.

Another allegation against fracking in America is that it can result in methane leakage. We must therefore start to monitor methane emissions and groundwater composition at potential sites now, before any fracking takes place (as well as during and after such operations). This baseline monitoring is vital, since methane can be present in groundwater naturally. Such data will be the only way of keeping close track of the environmental impacts of fracking in situ, and should be submitted to regulators to inform local planning processes and address wider concerns.

Shale gas companies must also play their part in building public confidence. It should be mandatory for operators to conduct Environmental Risk Assessments. Local communities should be involved and informed from the very start. People need have a say in the planning process and to feel their concerns are being addressed.

In our report, we did not assess the climate risks associated with shale gas exploration, although we recommended that the Government should do so. The chief scientific adviser to the Department for Energy and Climate Change is currently leading a study on the potential for methane and other greenhouse gas leakages during extraction. The results will help form a clearer idea of the overall carbon footprint associated with shale gas.

Difficult decisions lie ahead for the Government. Opinions on all sides of the debate must be heard and considered, and uncertainties explored. However, at the heart of any judgment should be evidence-based science and engineering, which will help to ensure that the best decisions are made, unswayed by preconceived notions of risk or benefit.






  1. June 23, 2014 6:48 pm

    Reblogged this on windfarmaction and commented:
    Informed information allows informed judgement

  2. June 23, 2014 8:05 pm

    I believe that baseline monitoring is widespread if not uniform in the States and I’d be interested to learn if before-and-after comparisons have anything to teach us.

    • March 30, 2015 11:37 pm

      Baseline monitoring is in place in fairly populated Pennsylvania. Not just air samples. Every water well within a half mile radius of a frack well is sampled prior to beginning drilling, and again afterwards. So far, there has been only one incident of an improperly completed upper double casing down the first 1000 feet. That well was plugged and abandoned, and the groundwater recovered in weeks. Groundwater wells are usually a couple hundred feet deep (my Wisconsin farm is at 60 and 120, two first aquifers, three wells) and seldom more than 700 feet (my sisters ‘new’ deep well for her largish northeastern Washington state cattle/horse ranch in the mountains outside Tonasket).
      The target source rock shale formations are several thousand feed down. Everywhere. The Marcellus in Pennsylvania, from 8000 to about 11000 deep depending on dip/strike. BIG difference between 200 feet and 10000. Round about two miles of solid rock. Something that Greens ignore.

  3. Joe Public permalink
    June 23, 2014 9:07 pm

    Local communities should be involved and informed from the very start. People need have a say in the planning process and to feel their concerns are being addressed.” [My bold]

    Not out-of-town Rent-a-Mobs.

  4. Brian H permalink
    November 27, 2014 9:43 am

    Oh, noes! Ban fracking! Ban trucks! We don’t want the shakes!

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