A study of drinking water in Appalachian Ohio found no evidence of natural gas contamination from recent oil and gas drilling.
Geologists with the University of Cincinnati examined drinking water in Carroll, Stark, and Harrison counties, a rural region in northeast Ohio where many residents rely on water from private underground wells.
The
time-series study was the first of its kind in Ohio to examine methane in groundwater in relation to natural gas drilling.
“Some people had elevated concentrations of methane in their groundwater, but the isotopic composition showed it wasn’t from natural gas,” said Amy Townsend-Small, associate professor of geology in UC’s McMicken College of Arts and Sciences.
“What we found is in most cases it was probably from underground coal in the area or biological methane produced in groundwater.”
UC researchers collected 180 groundwater samples in total at homes in the three counties. Some of the sites were sampled multiple times. Researchers looked for evidence of methane, the primary compound in natural gas. They also studied changes in the acidity or pH of the water, and changes to its conductivity.
They found no increase in methane concentration or composition in groundwater over the four years of the study, despite the presence of new shale gas wells drilled in the study area. Likewise, they did not find higher methane levels in closer approximation to shale drilling.
Researchers did find wide variability in methane concentrations in the drinking water, ranging from 0.2 micrograms per liter to 25.3 milligrams per liter, which is strong enough to catch fire in enclosed spaces. But researchers found no relationship between the methane observed in drinking water and the new gas wells.
The National Ground Water Association developed an information brief,
Water Wells in Proximity to Natural Gas or Oil Development.
NGWA’s flagship technical journal,
Groundwater®, also had a special section on subsurface methane and its migration in its March-April 2018 issue. Five papers and a guest editorial make up the section exploring various aspects of methane occurrence and migration in groundwater.
These include, among others, the effects of CO2 injection on methane migration, gas leakage from faulty petroleum wells, and methane migration in shallow aquifers in the Karoo basin in South Africa.
The research papers highlight both natural and anthropogenic sources of methane related to unconventional drilling, as well as the techniques to distinguish between these and to model the migration of methane.
Since 1963,
Groundwater has published a dynamic mix of papers on topics focused on groundwater such as flow and well hydraulics, hydrogeochemistry and contaminant hydrogeology, application of geophysics, management and policy, and the history of hydrology.
NGWA members can read the Groundwater papers on methane at Wiley Online Library.