Canterbury debate: Professor David Smythe

Emeritus Professor of Geology, University of Glasgow, who has been researching fracking in the US and Europe for the past four years.

Edited transcript of his presentation

I believe that there is a high chance, because of the complex geology in Europe of contamination of ground resources [from fracking].

What has been going on in the US can’t be applied to the UK. I started looking at the US shale basins. We are looking at big stretches of territory. What I found was in summary was that nowhere in the US in areas that are being fracked are there any faults that extend from the frack layer right up to the surface and thereby could provide potential contamination pathways.

The American shale basins, by and large, are called foreland basins. They develop in front of a mountain chain that is building up and the sediment comes off the mountain chain and is deposited, like in the Denver Basin, east of the Rockies, in a large, very deep basin, and in a very simple manner in front of the mountain. There may be faulting down deep, where the shale layer may lie, but in practically no instance does the faulting get up to the surface.

I quantified this in relation to the British shale basins and in round terms, the faulting that we see in the Weald or in Lancashire or in the Midland Valley in Scotland is about a thousand times greater than we see in the North American shale basins. In North America it is not a problem, whereas here in Europe it is an important problem.

The reason it is different in the UK and most of Western Europe is that the basins are extensional. This means the crust has been pulled apart and the top of the crust subsides, is faulted at the margins and in the middle. The basins are often called troughs because they more or less have the shape of a bath tub, they are very deep and narrow, they are not like the American shales, which are thin and extend for hundreds of miles in all directions with no faults in view.

So the structure of the UK shale basins is very different and the lesson is that faults extend from the shales right up to the surface and can act as potential contamination pathways. This is something that the Royal Society report of mid 2012 just failed to address. The Royal Society, in conjunction with the Royal Academy of Engineering, was hell bent on discussing the problems of earthquake triggering. I do accept that the risk of triggering earthquakes from fracking is a sideshow. It is not that important. The real risk from fracking is long term contamination of groundwater aquifers near the surface or even possibly affecting surface water itself. And this is something that the Royal Society just didn’t take on board.

In conventional oil exploration, faults are considered as part of the geology and people look for fault traps, where a pocket of oil or gas is trapped underground and then you drill it and out comes the oil or gas. Faults are considered rather dodgy, rather risky, because at least part of the time they act as a pathway to the surface.

In fact modern methods of 3D seismic imaging can now in offshore areas, where there is good quality imaging available, they can now image the gas clouds coming up directly from conventional oil or gas accumulation. And they can come up fault zones and they might stop near the surface, or they might go right up to the surface or the gas might just come up as a cloud in chimneys or distributed more generally, up to the surface as a continuous cloud of potential contamination.

Civilised countries, including France, where I live, and Germany, either have a moratorium on fracking or a complete ban. What they decided was that the risks of contamination are just too awful to consider. They can be long term. A German computer modelling process talked about contamination coming up a model ideal fault zone, maybe taking 30 or 50 years to get to the surface. So it can be a slow process so it’s not going to happen immediately.

My conclusion is that the environmental risks of fracking in the complex geological basins in Europe and, in particular Britain, are too great to be worth the risk. And like France we should just have a complete ban on fracking, full stop.

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