A primer: How fracking works
How unconventional natural gas is brought to the surface
A hydraulic fracturing setup. Here, in this 2012 file photo, a fracking operation near Bowden, a town in central Alberta.Jeff McIntosh/The Globe and Mail
Fracking uses water, sand and chemicals which are injected at high pressure into rock. The process forms tiny cracks which can release gas.
Workers assemble high-pressure pipe near Bowden.Jeff McIntosh/The Globe and Mail
Sand is pumped down a shaft.Jeff McIntosh/The Globe and Mail
Fracturing balls can also be pushed through the ground.Jeff McIntosh/The Globe and Mail
The major shale gas plays of North America. In red, shale gas basins. In orange, Devonian/Mississippian shale fairway.
The process has its critics. In August of 2012, Yoko Ono and her son, Sean Lennon, launch Artists Against Fracking – a coalition of artists, musicians and filmmakers against fracking in New York state.Brendan McDermid/Reuters