Water usage: High volumes of water — up to a million gallons — are required to fracture, and hold open, the shales. About a third of the 'waste' water, containing treatments, sands and other chemicals, is returned to the surface.
Re-fracturing might be expected to be repeated every 4–5 years in successful wells.
With current technology freshwater is used for fracturing. However, as technology advances, it might be possible to re-use produced water by a recycling process, or to reduce the potential environmental impact by changing the chemicals added.
Drinking water: Drilling companies case the vertical borehole in steel that is further protected by a layer of concrete in order to prevent contamination of drinking water supplies should the borehole pass through an aquifer.
Surface obstacles or planning restrictions: Drilling close to urban areas may also pose problems. Similar problems on a smaller scale in the UK were found and solved by BP at Gainsborough Oilfield in 1959, where the field underlies the nearby village.
Similar horizontal drilling techniques used by BP at Wytch Farm, Dorset, have safely extracted oil from the area, which is the largest onshore oil field in western Europe, since 1979. Most of the oil field is protected by conservation laws, including the Jurassic Coast World Heritage site, and a number of sites of special scientific interest, areas of outstanding natural beauty and nature reserves.
The main problem in the UK is that, in contrast to the US, there are fewer or no local people with any vested interest in the success of these projects
Visit the BGS website to learn more about shale gas
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