Study finds “no significant correlation between dissolved methane concentrations in groundwater and proximity to nearby oil/gas wells.”
A new peer-reviewed study discredits findings of controversial research claiming that higher concentrations of dissolved methane in domestic water wells can be associated with proximity to nearby gas-producing wells in northeastern Pennsylvania – and it does so using a much larger sampling size and pre-drill baselines. The new paper, titled “Methane Concentrations in Water Wells Unrelated to Proximity to Existing Oil and Gas Wells in Northeastern Pennsylvania,” was published by Environmental Science and Technology (ES&T) on March 12, 2015. The research was conducted by Donald I. Siegel from Syracuse Univ., Nicholas A. Azzolina, Bert J. Smith, A. Elizabeth Perry, and Rikka L. Bothun.
Specifically, this new paper addresses assertions made in papers published by researchers from Duke University in 2010 and 2013. As EID noted each time, the studies contained a number of flaws (several conceded by the authors), including a lack of baseline data, the decision not to randomly sample wells, and the presence of high levels of methane in lots of water wells residing nowhere near natural gas wells. A series of peer-reviewed comments took issue with the Duke team’s conclusions, saying there was a “lack of data” to support their conclusions, and that the report “misrepresents potential risks” of shale development.
The methods used in the new peer-reviewed paper specifically address the limitations of the previous study. These include using a dataset hundreds of times larger and the use of all commercial hydrocarbon wells, not just unconventional wells. The study uses four statistical approaches, which come to the same conclusion: “there is no significant correlation between dissolved methane concentrations in groundwater and proximity to nearby oil/gas wells.”
As the study concludes:
“Our results show that even among baseline groundwater samples collected near existing gas wells, there is no evidence of systematic increased dissolved methane concentrations closer to oil/gas wells. Indeed, we did not even remove the few cases of known fugitive gas releases in our study to be conservative in our approach. If they are present, then they are rare enough to not affect our results. Combined, the results of all four statistical approaches yield a defensible, compelling argument that there is no significant correlation between dissolved methane concentrations in groundwater and proximity to nearby oil/gas wells.” (emphasis added)
The findings of the new study are all the more remarkable after re-examining the comments made by the Duke’s Rob Jackson, and critics of his study, when the original report was released, specifically on the sample size and baseline data:
- “[Duke’s Robert] Jackson concedes that the study does not have baseline data and said he expected the criticism.” (NY Times/E&E News, May 9, 2011)
- “[Professional hydrogeologist John] Conrad also criticized the study for not starting with ‘baseline tests for the wells they sampled’ … ‘While they point to higher methane concentrations, we don’t know what the original water quality was before drilling occurred,’ he said. ‘That’s a data gap that could be very significant for this study.’” (Philadelphia Inquirer, May 10, 2011)
- No random sampling; authors appear to have simply cherry-picked water wells previously known to have high concentrations of methane, although they never actually mention in the report which wells they sampled or where they’re located: “Jackson said the study was indeed not random, but that was because they needed homeowners permission to test their water.” (CNN, May 9, 2011).
- Outrageously small data set; authors tested 68 wells in a state where more than 20,000 new water wells are drilled every year: “I’m not sure you can take 68 wells over a very broad geographic area and make any statistical conclusion,’ [Conrad] said. ‘Methane types and methane concentrations can vary radically over very short distances.’” (Bloomberg News, May 9, 2011)
Also of note, this new peer-reviewed paper was published not long after another study found that methane is also an issue even where no natural gas development is occurring in northeastern Pennsylvania. That study was based on work by researchers Fred Baldassare from Echelon Applied Geochemistry Consulting, Mark McCaffrey of Weatherford Laboratories, and John Harper from the U.S. Geological Survey who conducted an analysis of groundwater in the same area. They looked at more than 2,300 samples from 234 natural gas wells during mud gas logging, and 67 private groundwater supplies prior to natural gas development occurring nearby in a five county area.
These recent studies certainly won’t generate the headlines the initial Duke study did, but residents in northeastern Pennsylvania now have additional scientific evidence to answer their questions about the role of oil and gas production plays in their area.