What is fracking?

Our main topic for this week is fracking. Now, this has been all over the news recently with some people up in arms about the fact that it's going to be rolled out across England. But how exactly does fracking work and what are the risks?

Ginny - We're joined tonight by a panel of experts including Dr. Geoffrey Parker, a Water Engineer from Cambridge University. So Geoff, what exactly is fracking?

Geoff - Right. So, what people are trying to do, they're trying to get to this shale rock which is essentially mud formed from salt and clay particles, and sometimes there's algae in there as well, which is this organic matter. As that mud is deposited and other layers of sediment are applied on top of it, it undergoes pressure and heat over time, and it becomes shale rock. And this shale rock can hold significant quantities of fossil fuels. So, this is the source for fossil fuels for conventional reservoirs. So, we think about classic drilling of oil and gas, and you drill a well vertically downwards until you reach a reservoir formation. So, there's a source rock and there's a reservoir rock. The reservoir rock, the characteristic of that is, it has high permeability. So, you then are talking about things like limestone or sandstone. Shale rock, because it had a very small particle, does not have this high permeability. So, it only really works this conventional extraction if you have this high permeability. So, the breakthrough now, the hydraulic fracturing is the idea that if you use, if you inject fluid of high pressure, you can create fractures in the shale formation itself and create basically a reservoir or a tapable source from the shale rock itself. You don't need a reservoir rock above it. So, that potentially vastly increases in number of geologic formations from which you can extract energy.