Shale gas explained

Shale gas is usually extracted using a technique called ‘hydraulic fracking’, or ‘fracking’, for short).


Drills bore down into the shale deposit (anything from 300 metres/
0.2 miles to 4.8km/3 miles beneath the surface), then (usually) horizontally into the shale deposit as far as they can. The horizontal bores are strengthened with concrete linings. Long metal cylinders (called ‘guns’) containing bullet-like explosive devices (called ‘shape charges’) are inserted into the (usually) horizontal bores. When everything is in place, the shape charges are triggered:

• perforating the guns’ walls and the concrete linings of the bore along the guns’ lengths
• sending jets of metal atoms through the newly-created perforations, fracturing and ‘melting’ the shale (such is the heat), and releasing the gas trapped in the shale

When the dust has settled, as it were, millions of gallons of water containing a large range of acids and (sometimes) toxic chemicals (for various reasons) are pumped down the vertical and horizontal bores and into the fractured shale beds at extremely high pressure (350-700 bars/atmospheres) to displace and bring to the surface 
the newly released gas.

Extracting shale gas is much more difficult and expensive than extracting gas from subterranean reservoirs (the conventional practice) and would not have been commercially viable (i.e. profitable) had not the world prices of oil risen so high. The high world prices for gas demonstrate either that:

• the people controlling gas prices have decided to maximise their profits, or
• world reserves of ‘reservoir’ gas are running out

Fracking is a dirty, polluting, resource-exhausting, health-threatening business. It pollutes the workplace and surrounding environment (particularly the sources of water) with toxic chemical and often radioactive waste (see ‘Radioactive pollution from fracking’ (Green Health Watch Magazine 45 page 19), and it consumes a huge amount of water (of major concern in these times of dwindling clean water sources).

(16425)  Nick Anderson. Green Health Watch Magazine 45:9 (6.8.2013)