> Marcellus Brine Migration Likely Natural, Not Man-Made
> July 9, 2012
> July 9, 2012
> Hydraulic fracturing likely didn't create fissures, but gas from leaking well casings could exploit them.
> A Duke University study of well water in northeastern Pennsylvania
> suggests that naturally occurring pathways could have allowed salts and
> gases from the Marcellus shale formation deep underground to migrate up
> into shallow drinking water aquifers.
> The study found elevated levels of salinity with similar geochemistry
> to deep Marcellus brine in drinking water samples from three groundwater aquifers, but no direct links between the salinity and shale gas
> exploration in the region.
> "This is a good news-bad news kind of finding," said Avner Vengosh,
> professor of geochemistry and water quality at Duke's Nicholas School of the Environment.
> The good news, he said, is that it's unlikely that hydraulic fracturing for shale gas has caused the elevated salinity. He said the locations
> of the samples containing brine donât correlate with the locations of
> shale-gas wells. The results from the new study also are consistent with water-quality tests conducted in the aquifers in the 1980s before rapid shale-gas development began.
> The bad news is that the geochemical fingerprint of the salinity
> detected in well water from the Lock Haven, Alluvium and Catskill
> aquifers suggests a network of natural pathways exists in some
> locations, especially in valleys. These pathways allowed gases and
> Marcellus brine to migrate up into shallow groundwater aquifers from
> deeper underground shale gas deposits.
> "This could mean that some drinking water supplies in northeastern
> Pennsylvania are at increased risk for contamination, particularly from
> fugitive gases that leak from shale gas well casings," Vengosh said.
> Last May, the Duke team published the first peer-reviewed paper that
> found elevated levels of methane contamination in drinking water wells
> located within a kilometer of hydraulic fracturing, or "fracking," shale gas wells, but found no evidence of contamination from fracturing
> fluids or brines.
> The new paper complements that study by showing "there are likely
> pathways through which methane and brine could flow," Vengosh said. The Duke team evaluated 426 samples from groundwater aquifers in six
> counties overlying the Marcellus shale formation in northeastern
> Pennsylvania.
> The study appears this week in the online early edition of the
> Proceedings of the National Academy of Sciences. It was funded by Duke's Nicholas School of the Environment.
> "The small group of homes whose water we sampled may be at higher risk
> of contamination due to underlying geology," said Nathaniel Warner, a
> PhD student at Duke who was lead author on the study. "By identifying
> the geochemical fingerprint of Marcellus brine, we can now more easily
> identify where these locations are and who these homeowners might be."
> Robert B. Jackson, Nicholas Professor of Global Environmental Change
> and director of Duke's Center on Global Change, co-authored the paper
> with Warner and Vengosh. He said, "These results reinforce our earlier
> work showing no evidence of brine contamination from shale gas
> exploration. They do, however, highlight locations and homeowners more
> is vulnerable to contamination, something we'll need to follow up."
> The new findings also should help address concerns about barium contamination in local drinking water, Warner said.
> "Especially in valleys in the region, elevated salinity is associated
> with barium contamination in the water," Warner said. "Our study's
> findings suggest that homeowners living in these areas are at higher
> risk of contamination from metals such as barium and strontium."
> The Marcellus shale formation is located about a mile underground and
> contains highly saline water that is naturally enriched with salts,
> metals and radioactive elements.
> Hydraulic fracturing, also called hydrofracking or fracking, involves
> pumping water, sand and chemicals deep underground into horizontal gas
> wells at high pressure to crack open hydrocarbon-rich shale and extract
> natural gas. Accelerated shale gas drilling and hydrofracking in the
> northeastern Pennsylvania region in recent years has fueled concerns
> about water contamination by methane, fracking fluids and wastewater
> from the operations.
> "As shale gas exploration is becoming global -- including in Poland,
> China, Australia and New Zealand -- the take-home message of this study
> is that pre-drilling water quality monitoring is important for
> evaluating water-quality baselines that can be used to detect future
> changes in water quality, and for evaluating possible hydraulic 'short
> cuts' and pathways between fluids and gases in deep shale gas formations and shallow aquifers," said Vengosh. "Such geochemical reconnaissance
> would provide a better risk assessment for water contamination in newly
> developed shale gas exploration areas."
> Other members of the Duke team were Ph.D. student Adrian Down;
> postdoctoral researcher Kaiguang Zhao; research scientist Thomas H.
> Darrah; and recent bachelor's degree graduate Alissa White. Former Duke postdoctoral researcher Stephen G. Osborn, who is now an assistant
> professor of geology at California State Polytechnic University at
> Pomona, was also a co-author.
> SOURCE: Duke University Free Oil and Gas Online Newsletter
> suggests that naturally occurring pathways could have allowed salts and
> gases from the Marcellus shale formation deep underground to migrate up
> into shallow drinking water aquifers.
> The study found elevated levels of salinity with similar geochemistry
> to deep Marcellus brine in drinking water samples from three groundwater aquifers, but no direct links between the salinity and shale gas
> exploration in the region.
> "This is a good news-bad news kind of finding," said Avner Vengosh,
> professor of geochemistry and water quality at Duke's Nicholas School of the Environment.
> The good news, he said, is that it's unlikely that hydraulic fracturing for shale gas has caused the elevated salinity. He said the locations
> of the samples containing brine donât correlate with the locations of
> shale-gas wells. The results from the new study also are consistent with water-quality tests conducted in the aquifers in the 1980s before rapid shale-gas development began.
> The bad news is that the geochemical fingerprint of the salinity
> detected in well water from the Lock Haven, Alluvium and Catskill
> aquifers suggests a network of natural pathways exists in some
> locations, especially in valleys. These pathways allowed gases and
> Marcellus brine to migrate up into shallow groundwater aquifers from
> deeper underground shale gas deposits.
> "This could mean that some drinking water supplies in northeastern
> Pennsylvania are at increased risk for contamination, particularly from
> fugitive gases that leak from shale gas well casings," Vengosh said.
> Last May, the Duke team published the first peer-reviewed paper that
> found elevated levels of methane contamination in drinking water wells
> located within a kilometer of hydraulic fracturing, or "fracking," shale gas wells, but found no evidence of contamination from fracturing
> fluids or brines.
> The new paper complements that study by showing "there are likely
> pathways through which methane and brine could flow," Vengosh said. The Duke team evaluated 426 samples from groundwater aquifers in six
> counties overlying the Marcellus shale formation in northeastern
> Pennsylvania.
> The study appears this week in the online early edition of the
> Proceedings of the National Academy of Sciences. It was funded by Duke's Nicholas School of the Environment.
> "The small group of homes whose water we sampled may be at higher risk
> of contamination due to underlying geology," said Nathaniel Warner, a
> PhD student at Duke who was lead author on the study. "By identifying
> the geochemical fingerprint of Marcellus brine, we can now more easily
> identify where these locations are and who these homeowners might be."
> Robert B. Jackson, Nicholas Professor of Global Environmental Change
> and director of Duke's Center on Global Change, co-authored the paper
> with Warner and Vengosh. He said, "These results reinforce our earlier
> work showing no evidence of brine contamination from shale gas
> exploration. They do, however, highlight locations and homeowners more
> is vulnerable to contamination, something we'll need to follow up."
> The new findings also should help address concerns about barium contamination in local drinking water, Warner said.
> "Especially in valleys in the region, elevated salinity is associated
> with barium contamination in the water," Warner said. "Our study's
> findings suggest that homeowners living in these areas are at higher
> risk of contamination from metals such as barium and strontium."
> The Marcellus shale formation is located about a mile underground and
> contains highly saline water that is naturally enriched with salts,
> metals and radioactive elements.
> Hydraulic fracturing, also called hydrofracking or fracking, involves
> pumping water, sand and chemicals deep underground into horizontal gas
> wells at high pressure to crack open hydrocarbon-rich shale and extract
> natural gas. Accelerated shale gas drilling and hydrofracking in the
> northeastern Pennsylvania region in recent years has fueled concerns
> about water contamination by methane, fracking fluids and wastewater
> from the operations.
> "As shale gas exploration is becoming global -- including in Poland,
> China, Australia and New Zealand -- the take-home message of this study
> is that pre-drilling water quality monitoring is important for
> evaluating water-quality baselines that can be used to detect future
> changes in water quality, and for evaluating possible hydraulic 'short
> cuts' and pathways between fluids and gases in deep shale gas formations and shallow aquifers," said Vengosh. "Such geochemical reconnaissance
> would provide a better risk assessment for water contamination in newly
> developed shale gas exploration areas."
> Other members of the Duke team were Ph.D. student Adrian Down;
> postdoctoral researcher Kaiguang Zhao; research scientist Thomas H.
> Darrah; and recent bachelor's degree graduate Alissa White. Former Duke postdoctoral researcher Stephen G. Osborn, who is now an assistant
> professor of geology at California State Polytechnic University at
> Pomona, was also a co-author.
> SOURCE: Duke University Free Oil and Gas Online Newsletter
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