Hydraulic fracturing and shale gas
It goes by a number of names - 'hydraulic fracturing', 'shale gas extraction', 'hydrofracturing' or 'hydrofracking. Not to forget the name beloved of headline writers around the world - 'fracking'. But what exactly is fracking, and why has it become such an environmental hot potato? Is it helping to save the world, or condemning it to climate chaos - or is it just perhaps a scam, stoking up a fossil-fuel financial bubble?
Hydraulic fracturing is the name given to a way of squeezing gas and oil out of tight rock reservoirs, places where these hydrocarbons just won't flow out naturally. So far, most of the oil and natural gas man has extracted, comes out of the ground on its own accord - so called conventional plays.
It gets pooled in deeply-buried reservoirs - sponge-like rocks where it has been trapped, unable to move any further. Down there it is also under a lot pressure. Simply drill a well into these conventional reservoir rocks, and that pressure drives out the fossil fuels, into the well and so up to surface - such wells are understandably called 'gushers'.
But there are plenty of rocks that are hold onto their gas (and occasionally oil) in tiny fractures, rather than larger pores. These 'unconventional' reservoirs are usually mudstones, buried and compressed into a hard rock that geologists call shale. Drill a well into them, and nothing happens - the shale gas is locked up too tightly. ...
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