Posts Tagged ‘water contamination’

Drinking water contamination caused by weak water wells and not by fracking

September 16, 2014

It is fashionable for environmentalists to blame fracking for all manner of evils as a matter of faith. They have proclaimed that fracking causes earthquakes, water table contamination, emission of dangerous gases, damage to house price levels and even damage to crops. Such claims are usually based on no evidence whatsoever but presented as gospel.

A new paper published in PNAS reports on real experimental measurements (not just a computer model) using noble gases to trace methane leakage into drinking water in 130 water wells in Pennsylvania and Texas. They find that drinking water contamination was caused by weak walls and well construction faults and not by fracking.

TH Darrah et al, Noble gases identify the mechanisms of fugitive gas contamination in drinking-water wells overlying the Marcellus and Barnett Shales, 

Significance

Hydrocarbon production from unconventional sources is growing rapidly, accompanied by concerns about drinking-water contamination and other environmental risks. Using noble gas and hydrocarbon tracers, we distinguish natural sources of methane from anthropogenic contamination and evaluate the mechanisms that cause elevated hydrocarbon concentrations in drinking water near natural-gas wells. We document fugitive gases in eight clusters of domestic water wells overlying the Marcellus and Barnett Shales, including declining water quality through time over the Barnett. Gas geochemistry data implicate leaks through annulus cement (four cases), production casings (three cases), and underground well failure (one case) rather than gas migration induced by hydraulic fracturing deep underground. Determining the mechanisms of contamination will improve the safety and economics of shale-gas extraction.

A key source of groundwater contamination (labeled 5, center right) caused by faulty well casings. Credit: Image courtesy of Thomas Darrah, The Ohio State University

Press Release:

….  neither horizontal drilling nor hydraulic fracturing of shale deposits seems to have caused any of the natural gas contamination.

“There is no question that in many instances elevated levels of natural gas are naturally occurring, but in a subset of cases, there is also clear evidence that there were human causes for the contamination,” said study leader Thomas Darrah, assistant professor of earth sciences at Ohio State. “However our data suggests that where contamination occurs, it was caused by poor casing and cementing in the wells,” Darrah said.

In hydraulic fracturing, water is pumped underground to break up shale at a depth far below the water table, he explained. The long vertical pipes that carry the resulting gas upward are encircled in cement to keep the natural gas from leaking out along the well. The study suggests that natural gas that has leaked into aquifers is the result of failures in the cement used in the well.


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