0918 GMT July 17, 2018
In their paper published in Proceedings of the National Academy of Sciences, the group describes their study of the area and the degree of hazard the gas leak poses, according to phys.org.
Back in 1965 a team working for the Dutch Petroleum Company (NAM-a venture between Exxon and Shell) accidentally caused a natural gas explosion at a gas field in Sleen, East Drenthe (in a northeastern part of the Netherlands).
The blowout turned the sand in the area to quicksand, and a drilling rig sank and disappeared into the ground.
After a period of time, the area was converted into a park. But now, the area is back in the news, because the researchers with this new effort have discovered that the site is still leaking methane.
NAM has also been in the news of late due to recent evidence implicating the company as the cause of small earthquakes impacting Groningen, a province just north of the former gas field.
The researchers made the discovery while looking into the environmental impact of shale gas production, including its possible contamination of groundwater.
To learn more, they began testing well water in and around the park and the farmland that surrounds it.
They report finding abnormally high levels of methane in the water and that its isotopic composition (its chemical signature) was very similar to that of the gas reservoir, suggesting that methane is leaking from cracks made below the surface as part of natural gas drilling operations a half-century ago.
The methane gas emissions do not present a health hazard, the researchers note, because methane is regularly cleared from drinking water as part of normal processing.
But it could pose a problem if the gas accumulates in a building or structure — that could result in an explosion. But that, too, is unlikely, they further report, because the amount of gas being emitted drops quickly as distance from the site increases.