Many shale plays flow vigorously for just a few weeks and then tail off dramatically.

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But it takes only five days to complete, and then the shale gas begins to flow and the trucks, portable offices and hoppers are taken to another site to start all over again.

ECONOMIST: Fracking

To do so, fracking actually cracks the rock to allow for the natural gas to flow from the shale into the well.

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Hydraulic fracturing pumps many thousands of gallons of mainly water and sand, with a few chemicals, at high pressure into tight gas-bearing shale deposits (hardened muds), creating cracks that allow gas to flow back up the well to the surface ( Shale Shock).

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In this process, after a well is drilled, pressurized water is injected into the well to fracture the shale and open fissures that enable natural gas to flow more freely out of the well.

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Rather, as a consequence of injecting water and sand into the shale formation to crack the rocks so gas and oil will flow, massive amounts of waste water comes back to the surface with significant amounts of contaminants as a result of leaching out salt, heavy metals and trace amounts of radioactive materials from the rock formation itself.

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However, the inherit low porosity of the shale also implies that once the initial gush dies down, the flow will become a trickle.

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Every well that gets drilled into shale formations or other tight reservoirs requires hydraulic fracturing before the oil and gas will flow.

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