Could fracking contaminate groundwater?

11 September 2013

Interview with

Geoffrey Parker, University of Cambridge

Ginny - So Geoff, your research group have been looking at risk assessment surrounding this sort of thing.  What are the chances of fracking chemicals actually getting into the water supply?

Geoff -   All these things, I think echoed everyone else's opinion.  Everyone, so far has AN opinion, that is very locally dependent and geology is very complex.  So, things like the Marcellus Shale was a pre-existing water fracture is vertically not geologic formation previously.  So, there is some question about, how much of that is the well, which impossibly could be leaking, and how much of that is sort of the natural geologic formation from previous tectonic activity or from glacial activity historically.  The shallow aquifers that we use for groundwater, the drinking water, 30% of the water in the UK comes from, that is supposed to be hydraulically non-connected to these shale reservoirs.  So, the question is, how can they be connected?  If the groundwater is at, maybe a couple of 100 meters deep, so 200 or 300 meters deep and the shale is at 2 kilometres, 3 kilometres deep, how can there be connections and how that occurs?  There are a couple of sort of modes of failure that have been theorised.  The one is this pre-existing fractures.  Another is ground operations on the surface, if there's spillage.  I mean, you're handling methane, but you're also handling these other fluids that then spills then there's potential.  So, it's operation as well.  There's potential for there to be contamination of groundwater.  And finally, the big one is the well.  So, where we should focus on, our efforts to making sure the well is really correct and not allowing these leakage in between the vertical well and the aquifer.  The vertical well runs from its surface to the deep shale - 2 km, 3km deep and it runs through the groundwater layers and a bunch of other layers.  And there's the horizontal well which is a big new part of technology since about 2005.  It's really viable and that actually really has reduced number of wells, the number of vertical wells.  So, this potentially, if the horizontal drilling becomes more significant, and the number of vertical wells goes down then potentially, that could also lower the risk profile.

Ginny -   What exactly are these chemicals we've been talking about?  Are they something we should worry about?

Geoff -   Again, the UK is doing the right thing here.  The EA has rights to require everything that is injected to be disclosed.  So, there has been some historical situation in the US where that's not been the case.  So, that's a big difference.  The fracking fluid is 90% water more or less, so significant quantities of water needed, something like 4 to 12 Olympic-size swimming pools of water and that's injected into these wells and then flows back out, 25% - 75% that flows back over the short term, and over the long term, the rest of it sort of seeps out.  So, 90% of that fracking fluid is water, about 9% of it is then called proppant which is usually sand and what the proppant does is it wedges the fractures open, keeps the gas flowing basically.  And then there's some other small components, less than 1% and one of them is friction reducer which is again to try and get the proppant really wedged in correctly.  I mean, you can find some of these friction reducers and things in face cream.  So, there's nothing necessarily... in that list that's been disclosed to the EA so far.  There's nothing that really causes too many alarms.  But of course, there is potential if you lack of transparency, there is potential that other things are in there.  The other concern is this flow back water which once in the shale formation, it's exposed to the rock and it can pick up minerals and possibly mildly radioactive things as well.  So, that might also be a concern.  So, those are sort of the mechanisms.

Kate -   We've got an email in from Hetty Jacobs earlier in the week and she's in Australia and she said, they over there got numerous reports of polluted water and they're one of the driest continents on the planet.  If we need to dispose of these water and clean up, would some areas of the world be concerned about droughts?

Geoff -   Absolutely.  I mean, you have to make a trade-off here.  If you're going to use significant quantities of water for this, then like anything, you have to get that water from some place.  So, how do you look at managing that?  Well, you could take the water from a water utility or you could take the water an aquifer, or you could take the water from a river system or a lake, or you could use possibly saline water which is a brackish water or what is essentially waste water already to do that and that's something they're looking at doing now as well.  But absolutely, I mean, there's no doubt there's significant quantities of water that are needed and that water needs to be trucked in sometimes and trucked out, and treated and disposed of in a reasonable way.

Ginny -   So, what can we do to minimise the risk?

Geoff -   My view on this is, sort of agnostic.  I'm an engineer, so if we're going to talk about this stuff, let's talk, identify which risks are sort of real and significant locally and which ones are less real, and less significant locally.  Let's try and make sure that we place our effort and our legislation and our monitoring and transparency on, what are the risks are.  So, things like making sure the wells are correct, making sure you know a baseline of methane already in the ground, you have increased monitoring, you have proper regulation, you have carbon regulation, inspection.  Things along those lines are sort of, 'an ounce of prevention is better than a pound of cure' kind of thing.

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