Study: Brine in Marcellus Shale could migrate upward, so drilling fluids might, too

A new study has concluded that salty, mineral-rich fluids naturally found below Pennsylvania's natural-gas fields could be seeping upward into residents' drinking water. The findings suggest that drilling waste and chemicals used in hydraulic fracturing "could migrate in ways previously thought to be impossible," Abrahm Lustgarten of ProPublica reports. (Getty Images photo by Spencer Platt: Gas drilling in South Montrose, Pa.)

Duke University and California State Polytechnic University researchers tested drinking-water wells and aquifers in northeastern Pennsylvania and found that water had mixed with brine that closely matches brine found in the Marcellus Shale in some samples. No drilling chemicals were found in the samples, and there was no correlation between where the natural brine was found and where drilling occurs. But, Lustgarten notes, its presence and finding that it had moved over thousands of vertical feet "contradicts the oft-repeated notion that deeply buried rock layers will always seal in material injected underground through drilling, mining or underground disposal."

The same Duke researchers found last year that methane gas was more likely to leak into water supplies in places adjacent to drilling. This is the second recent study finding that geology surrounding the Marcellus Shale region could allow contaminants to migrate more than previously expected. The other study, published in Ground Water in April, used modeling to predict that contaminants could reach the surface within 100 years. (Read more)