Dr John Cherry, a hydrogeologist with the Council of Canadian Academies (CCA), says fracking wells in Canada aren't built for the long haul; they tend to spring leaks.
"In my view, well integrity is likely the most important shale gas issue," said Dr Cherry in Toronto, Thursday, May 29. Dr Cherry chaired the CCA's expert panel on understanding the environmental impacts of shale gas extraction (fracking). This panel released its report in early May.
"Oil and gas wells can develop gas leaks along the casing years after production has ceased and the well has been plugged and abandoned," said Dr Cherry, quoting a paper by professor Bernard Goldstein, who also sat on the CCA panel. "Current standards for oil [and gas] well cementing are either not well founded or based on a flawed view. In North America there are tens of thousands of abandoned or active oil and gas wells that currently leak to the surface."
Dr Cherry said hydraulic fracturing (fracking) is the process of drilling a well 1-3 km deep to reach the shale bed, then horizontally into the shale another 1-3 km. The well is pumped with a mixture of water, sand and industrial chemicals at high pressure until the rock fractures, releasing the natural gas (methane) trapped within. This gas is then collected as it migrates up the well, which is encased with cement.
Dr Cherry said using cement to seal gas wells has been historically ineffective - a long standing and unresolved engineering problem. However, he said the oil and gas industry can seal their wells using alternative methods which are more effective, but also more expensive.
"Just about everything engineers build [which] are intended to keep hazardous materials out of the environment leak to some degree at some time," said Dr Cherry. "The issue isn't whether these wells leak. The issue is: does this leakage matter? If it does matter, when is it going to matter? Where is it going to matter?"
Dr Cherry said according to some models, imperfectly built or aging wells have the potential to leak methane gas into surrounding groundwater, causing contamination, or into the atmosphere, hastening the pace of climate change. He said some studies suggest households within a kilometre of fracking operations show evidence of methane contamination in tap water, but he distrusts these studies because they don't demonstrate the relationship between fracking and groundwater, only one of the potential outcomes.
Dr Cherry said the actual impacts of fracking on groundwater are still largely unknown because the appropriate research hasn't been done. He said this has lead to a knowledge gap in the scientific community, fostering a public debate he described as both "crazy" and "irresponsible." He said reliable and transparent research monitoring needs to be implemented immediately to settle the matter.
"I haven't seen the evidence that groundwater monitoring methods have been applied in a rigorous way anywhere on this continent," said Dr Cherry. "What does industry need? Science based, outcome driven regulations with rigorous inspection and penalties for noncompliance."
He cited a number of other reports assessing the risks of fracking elsewhere in the world, including countries like Germany, Australia, the United Kingdom and the United States. He said the well integrity issue has been raised in almost every report as a major concern, though few solutions have accompanied these warnings.