A Princeton University study has found that leaks from abandoned oil and gas wellbores pose not only a risk to groundwater, but represent a growing threat to the climate.
Between 200,000 and 970,000 abandoned wells in the state of Pennsylvania likely account for four to seven per cent of estimated man-made methane emissions in that jurisdiction, a source previously not accounted for, the study says.
Pennsylvania, much like Alberta in Canada, is the oldest oil and gas producer in the United States and the scene of intense environmental controversy due to the impact of hydraulic fracturing on its well-punctured landscape.
WHAT’S HAPPENING IN SASKATCHEWAN?
By 2012, Saskatchewan, Canada’s second-highest oil producer, had planted more than 87,000 oil and gas wells on the landscape. About 58,000 remain active, but 24,000 wells weren’t pumping hydrocarbons.
Of the 24,000 non-producing wells, 9,700 have been dead for five or more years.
According to a recent University of Waterloo study, about 20 per cent of the province’s oil and gas wells, active and abandoned, are leaking methane into soils, groundwater or the atmosphere. But no one knows in what amounts. The problem is particularly acute in the Lloydminster region.
The province’s auditor general reported in 2012 that “environmental cleanup costs of existing oil and gas wells and their associated facilities” total nearly $4 billion.
The auditor concluded that as of Sept. 30, 2012, “the Ministry of the Economy did not have effective processes to manage the financial and associated environmental risks related to the future cleanup of oil and gas wells and related facilities.”
The auditor also described the ministry as a conflicted body: “The Ministry’s efforts to develop the industry may override its efforts to protect the environment. The cleanup of wells and facilities may be an example of an imbalance. The Ministry’s royalty programs have contributed to the growth in the number of oil and gas wells and facilities. However, the Ministry is making slow progress cleaning up orphaned wells and facilities.” — Andrew Nikiforuk
For the study, the first of its kind, PhD student and civil engineer Mary Kang measured methane emissions from 19 abandoned wells in northern Pennsylvania.
Abandoned oil and gas wells can serve as pathways for methane, radon, brine and other hydrocarbons that can migrate into shallow groundwater aquifers, people’s homes or into the atmosphere.
Methane is a powerful greenhouse gas with a global warming potential that is 86 times greater than carbon dioxide over a 20-year time frame.
As a consequence, leaks from the shale gas and conventional gas infrastructure could make the industry dirtier than coal production.
Scientists in the field have consistently found that models used by the oil and gas industry and regulators significantly underestimate methane leaks from valves, pumps, pipelines, gas plants and producing wells. Abandoned wells have now been added to the list.
Cornell University ecologist and methane expert Robert Howarth said the new study is important because it illustrates that emissions from oil and gas activities are much higher than government and industry estimates.
The problem of leaking abandoned wells “has not been well studied in the past and is not at all considered by the U.S. Environmental Protection Agency in their greenhouse gas emission estimates, nor by other academic studies such as mine. It is yet one more example of how little we really know about methane emissions from the oil and gas industry, and yet one more reason to believe that the EPA has been severely underestimating the total emissions,” he said.
There is nothing terribly unique about Pennsylvania, added Howarth, “so I would expect this to be a problem affecting most if not all gas and oil fields.”
The problem of wellbore leakage, however, is widespread and global, and involves millions of oil and gas wells. Well failures in Norway’s offshore fields, for example, averaged 24 per cent in one analysis while well failures for newly-fractured shale wells in Pennsylvania average 6.4 per cent.
Saskatchewan shows failure rates as high as 20 per cent. Extensive leaks from heavy oil wells (up to 45 per cent) have resulted in documented groundwater contamination in the Lloydminster area on the border of Alberta and Saskatchewan.
Kang’s findings reinforce the findings of a University of Waterloo study that called the nation’s 500,000 leaky wellbores a threat to public safety and the environment due to “potential groundwater quality deterioration, contributions to greenhouse gas emissions, and explosion risks if methane gas accumulates in inadequately ventilated areas.”