Separating fracking from aquifers can eliminate water risk: study

London (Platts)--25Apr2012/533 am EDT/933 GMT

Stopping oil and gas companies from fracking shale rocks within 600 meters of aquifers could virtually eliminate any risk of drilling operations leading to contamination of drinking water, according to a new study led by scientists from the UK's Durham University.

The study, based on available data from thousands of fracking operations in the US and natural rock fractures in Europe and Africa, found that the probability of rogue fractures caused by fracking extending beyond 600 meters was "exceptionally low."

The chance of fractures extending for more than 350 meters was found to be around 1%, according to the study.

"Our research found contamination of aquifers from drilling is very, very unlikely," Professor Richard Davies of Durham University told Platts, adding that the argument that oil and gas fracking could lead to water contamination was "probably a bit of red herring."

Oil and gas fracking is only at a very early stage in Europe, and in some countries has faced considerable opposition over its potential environmental impact.

Fracking, or hydraulic fracturing, uses water and other chemicals to widen fractures in shale rock and recover trapped oil and gas. Opponents fear that this could lead to the hydrocarbons or the chemicals involved in fracking leaking into shallower drinking water aquifers.

Davies said regulators should consider imposing a minimum vertical distance below aquifers for fracking operations, and that this distance should probably be greater than 600 meters.

"600 meters is probably a starting point but in a new area you'd probably want to be a lot further away. As new rocks are explored ... we're going to have to be very cautious," he said.

The study, titled "Hydraulic fractures: How far can they go?", was conducted by scientists from Durham, Cardiff University in Wales and the University of Tromso in Norway.

As well as studying natural rock fractures offshore Norway, Mauritania and Namibia, the research drew on data from operations in the Eagle Ford, Woodford, Barnett, Marcellus and Niobrara shale areas in the US.

In almost all these cases the fracking was occurring at depths below ground of 1,000-4,000 meters, Davies said, with the exception of some drilling at Pavillion in Wyoming, which has become the subject of a controversial groundwater review by the US Environmental Protection Agency.

--Richard Swann, richard_swann@platts.com

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