Poorly encased wells are to blame for water contamination in fracked wells, not the controversial drilling process, according to a new study. The BBC reports:
The researchers used noble gases to trace the path of methane as these inert chemicals are not affected by microbial activity or oxidation. […] By measuring the ratios of the noble materials to the methane they were able to accurately determine the distance to the likely source. […]
“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.”
This makes sense—fracking generally occurs thousands of feet underground, far, far below aquifers being tapped for drinking water. The water tables and the shale rock being hydraulically fractured are separated by impermeable layers of rock—that’s how these aquifers formed in the first place. It stands to reason, then, that contamination of drinking water would have to occur in the vertical parts of these wells that travel through these underground water reservoirs.
Water pollution is a serious issue, and one that certainly deserves ongoing scrutiny. But it seems as if the drinking water contamination issues that greens have pointed to as reasons to stop the shale boom have occurred due to well failures (often because of poorly poured cement casings), rather than due to fracking itself. That’s not to say that there isn’t room for improvement here, but it does suggest this is a manageable risk, rather than an indelible feature of the drilling process.