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Tuesday, September 16, 2014

Study finds faulty wells - not fracking - pollutes drinking water

A new study has found - not surprisingly, in my view - that contamination of drinking water by fugitive methane is due to faulty wells and not hydraulic fracturing.

That's what the data has suggested all along, but the issue has become muddied because of imprecise use of terms like "fracking" to - in some quarters - embrace the total unconventional natural gas development process. That imprecision too often masks urgent problems - and self-evident solutions.

According to this report by BBC News: 
The scientists analysed content from 113 wells in the Marcellus shale in Pennsylvania and 20 in the Barnett shale in Texas. They found eight clusters of wells with problems. 
"The mechanism of contamination looks to be well integrity," said one of the authors, Prof Robert Jackson from Stanford University.
"In about half the cases we believe the contamination came from poor cementing and in the other half it came from well casings that leaked."
Cement is used in the oil and gas extraction industry to fill the spaces between the well casing and the sides of the well.
In one case the methane was linked to the failure of an underground well. In none of the investigated wells was there a direct link to fracking.
"These results appear to rule out the possibility that methane has migrated up into drinking water aquifers because of horizontal drilling or hydraulic fracturing, as some people feared," said Prof Avner Vengosh, from Duke University.
The solution is self-evident:  
The scientists believe that most of the problems they have identified can be resolved with better enforcement of existing regulations.
"You need strong rules and regulations on well integrity," said Prof Jackson.
"You need generous setbacks that protect homes and schools and water sources from drilling, sometimes farther than the drillers would want. You need enough inspectors on the ground to keep people honest and you need separation between the industry and the inspectors and you don't always have that in the US." 
Words for shale gas-producing states to live by.

The Guardian, in its report on the study, notes:
The finding was in line with a number of earlier studies on leaks in the cement casing of natural gas wells.
In Pennsylvania, state inspectors found about 9% of steel and cement casings on wells drilled since the start of the natural gas boom were compromised. There was an even higher risk on newer wells drilled since 2009, especially in the north-western part of the state, the inspectors found.
These high well-failure rates are totally unacceptable. They demand swift, strong regulatory action - including a rewrite of our bloodied, flawed Act 13.

The paper concludes on an important cautionary note - that the fracking process may affect the integrity of gas wells, and needs further study: 
Future work should evaluate whether the large volumes of water and high pressures required for horizontal drilling and hydraulic fracturing influence well integrity. 
And that evaluation should cover not only the first time a well is fracked, but also when it’s refracked - perhaps multiple times – a point I raised here

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