Unnatural increases in methane concentrations
Disclaimer: If you can light your tap water on fire and you happen to live in close proximity to a fracking site, do consider the dizzying array of variables that can factor into the flammability of your water, such as the region in which you live and its unique subsurface characteristics, different companies’ drilling and well construction practices, naturally occurring methane concentrations, etc. As this article seeks to expose, every new study released that confirms or rejects fracking’s connection to increased methane levels in drinking water must be reviewed in conjunction with every other report released over the past 5 years. A new report does not necessarily debunk an older one.
When a considerable volume of fluid is pumped under high pressure into a gas well (fracking), there is risk of gas discharge into shallow water aquifers, which could increase the level of methane in the nearby groundwater supply and beget the hazards depicted across various YouTube videos we’ve all seen: combustion. Flammable water. These methane levels can also occur naturally, independent of drilling and fracking, as the companion article describes. Let’s review the studies that have uncovered a definitive relationship between higher methane levels in drinking water and fracking.
To date, there is only one reliable peer-reviewed research article that has tested numerous wells in an effort to demystify the “water on fire” reports. Four professors in environmental chemistry and biology at Duke University measured methane levels across 68 wells, comparing the shallow groundwater quality between areas with fracking sites and areas with no fracking sites. These wells were located on the Catskill and Lockhaven formations atop the Marcellus Shale in Pennsylvania and also the Genesee Group overlying the Utica Shale in New York. On non-active sites, they did find methane concentrations that clearly resulted from mixed biogenic and thermogenic sources of methane. Thermogenic methane comes from the specific, deep shale gas deposits sought by drillers (see “What is natural gas?” post). However, groundwater near active drilling sites showed higher values of dissolved, thermogenic methane consistent with the gas geochemistry from the fracking wells. Simply put, they did find that the closer a water well was to a fracking site(s), higher levels of methane were present. But scientists can also tell where the methane comes from (natural or unnatural leaks) by looking at a sample of gas and determining the ratio of methane concentration to other gases that occur naturally from bacteria and decaying plant & animal matter.
Methane concentrations were detected generally in 51 of 60 drinking-water wells (85%) across the region, regardless of gas industry operations, but concentrations were substantially higher closer to natural-gas wells. Methane concentrations were 17-times higher on average (19.2 mg CH4 L−1) in shallow wells from active drilling and extraction areas than in wells from nonactive areas. (page 8173)
How does methane leak?
One of the authors of the study, Robert Jackson, suspects that the well casing (a steel and concrete barrier between well and water table) at these particular drill sites has been weakened, allowing for natural gas to seep through. Weakened well casing may have been caused by fracking operations, particularly the frack sand and high pressure involved, but it may just as likely have resulted from previous drilling activities, general corrosion over time, poor well design, or some combination of those causes. Even when investigators found no trace of fracking fluids in their samples, hydo-fracturing cannot be ruled out as a cause; after all, it is far easier for gas to leak through the well casing than fluid.
In a separate and murkier case, the EPA charged Range Resources with methane contamination found in drinking wells over the Barnett Shale in Texas in 2010. Similarly, the extent to which fracking caused the methane gas leaks was unclear, and scientists have proffered yet other causes, or possible “gas flow pathways”:
Fracking may create at least some cracks that extend upward in rock beyond the horizontal shale layer itself. If so, those cracks could link up with other preexisting fissures or openings, allowing gas to travel far upward. (Scientific American)
Also called “out of zone” fracking, or “fracking communication”: this is the unintentional consequence involving new wells that end up connecting with older or nearby wells. Unfortunately, we have yet to see any new, peer-reviewed studies that explore these other explanations or methane leak possibilities.
Contradictory reports on methane leaks
Other studies are scarce and tend to contradict each other.
- 2013: the EPA recently released the results of its 16-month-long “methane study”, also highly publicized as the “Franklin Forks findings”. In this report, the EPA claims that the increased methane concentrations in drinking water reported by the three Pennsylvanian families were actually concentrations of a similar isotopic make-up to a naturally occurring gas commonly found in the state park nearby. Neighboring natural gas fracking operations were originally implicated and some critics maintain that we cannot be certain of the cause until an independent review of the EPA’s research is conducted.
- October 2012: The USGS confirmed higher methane levels and synthetic fracking chemicals detected in the Pavilion Aquifer in Wyoming. After the EPA’s 2011 findings in the same area were widely criticized, it is telling that the USGS confirmed the EPA’s data from 2 test wells as well as a few pre-existing domestic wells. Encana, the gas company with fracking operations in the area, has been charged with faulty well construction and failing to extend production casing in many of their wells, according to a Congressional report on the matter.
More research required
Obviously, it’s really difficult to determine if fracking is the primary, leading cause of methane leaks in water. For instance, Pennsylvania enforced stricter standards for well construction, design, and the materials used in well casing in 2011 and no studies on methane leaks in the water supply have been conducted in that region since. On the other hand, in a separate report on the natural gas wells newly constructed and investigated in Quebec, 50% were found to have leaked methane. The 19 leaky wells were owned by 5 different companies and date back only to 2006, but the nature of these emissions has yet to be studied and made publicly clear. That said, a discussion about what causes “flammable water” or increased methane concentrations in water aquifers must necessarily be broadened to examine all unnatural causes – not simply fracking, but every stage of the drilling and well construction process.