Earthquakes threaten future of UK gas fracking

Nov 01, 2011 BBC News/ clickgreen.org.uk

Fig 1. Fracking for shale gas

A report submitted to the British Government is recommending a series of counter-measures be taken to prevent gas extraction fracking from causing localised earthquakes.

The Department of Energy and Climate Control has warned gas company Cuadrilla Resources to follow the report recommendations before drilling at two sites in Blackpool can restart. The report concluded it was highly probable that the hydraulic fracturing of Cuadrilla's Preese Hall-1 well triggered a number of seismic events including earthquakes measuring 2.3 on the Richter scale in April this year (2011), and one of 1.5 a month later.

Cuadrilla says it intends to seek a peer review of the report, but has committed to making that review public. Mark Miller, the company's Chief Executive, said: "Cuadrilla is working with the relevant local and national authorities to implement the report's recommendations so we may safely resume our operations."

Fracking involves drilling down and creating tiny explosions to shatter and crack hard shale rocks to release gas inside. Water, sand and chemicals are injected into the rock at high pressure, which allows the gas to flow out of the head of the well (Fig 1).

It is estimated that at the Blackpool site alone there could be 200 trillion ft3 of shale gas reserves, and exploration companies have claimed that there is a potential £70 billion worth of reserves in rocks deep under south Wales. In the USA large shale gas deposits have contributed to halving gas prices in the domestic market, and are said to offer gas security for the next century.

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