The oil and gas industry has a pernicious engineering problem: leaky wells. When industry cements or seals a wellbore, stray gas from shallow or intermediate zones can migrate along the casing to the surface or into aquifers. So too can brine and other hydrocarbons. And with the advent of hydraulic fracturing, the scale of this largely unacknowledged liability to groundwater and climate change is growing dramatically.
In fact, a new University of Waterloo study warns that the leaky wellbore crisis in both active and abandoned energy wells has already contributed “to the erosion of the social license that permits the functioning of the upstream hydrocarbon industry.” Maurice Dusseault, one of the nation’s top petroleum geologists, contributed to the big study.
The subterranean problem, which effectively dogs the oil patch from Texas to British Columbia, has been simmering for a long time. Each and every well drilled into the ground can potentially become a superhighway for methane and other gases such as radon, which might otherwise take millions of years to migrate to the surface.
Methane, a gas lighter than air, can also migrate as far as 14 kilometres from its source. It can travel along a wellbore and then connect to pre-existing faults or natural fractures and then pop up into basements or groundwater sources. It can even exit rural kitchen taps in a milky, flammable, bubbling brew.
The scale of the largely invisible problem remains unsettling. In Norway, 24 per cent of offshore wells leak, and in the Gulf of Mexico more than half of aging oil wells have sprung leaks. Ten per cent of all active and suspended gas wells in British Columbia spew methane. In addition, some hydraulically fractured shale gas wells in the province have become “super emitters” that spew as much as 3,000 cubic metres of methane a year.
About 20 per cent of Saskatchewan’s more than 87,000 wells leak. Alberta regulators report that some 27,000 out of about 315,000 wells are chronic seepers. But that’s a mammoth underestimate. Heavy oil fields in Lloydminster, for example, have reported leakage rates as high as 45 per cent.
Hydraulic fracturing has magnified the problem. Unlike conventional drilling, the brute force of the technology exerts high pressures on wellbores. Horizontal wells that are greater in length than depth also tend to leak more. During oil and gas booms the quality of cement jobs deteriorates as companies cut corners to drill more wells.
Abandoned wells present another conundrum. Alberta has abandoned 150,000 oil and gas wells, but neither government nor industry monitors these wellbores for cracked cement seals or methane leaks.
A 2014 PhD thesis tells the bad news story. For the first time ever, Mary Kang, a civil engineer grad student at Princeton, directly measured leaks at 19 abandoned wells in a northern area of Pennsylvania. (The state pioneered US oil production in the 1850s and has between 280,000 and 970,000 abandoned wells.) All 19 seeped like hell. Moreover, the best-plugged wells leaked as badly as the unplugged ones. The methane emissions ebbed and flowed with the weather and seasons too.
But the startling finding was this: three of the wells were methane super emitters. That meant leaky abandoned wellbores – infrastructure that is ignored in climate change assessments – accounted for anywhere between 4 and 7 per cent of the state’s total man-made methane pollution.
If that sort of uncomfortable math were done in Alberta, or Texas, then shale gas might be outlawed. Whenever methane leaks account for more than 3.2 per cent of industry production, natural gas has a bigger climate footprint than coal-fired electricity, according to collaborative research by US scientists.
Fixing a leaky wellbore is not easy or cheap. Costs can range from $150,000 to $600,000 per well. More importantly, repair jobs have a poor track record, characterized by what the Waterloo study called “persistent underreporting of negative results.” (Dig deeper into the study here.)
So, Houston, we have an ugly methane problem. Every oil and gas well drilled in the ground will leak and become a methane pathway for eternity. To date, neither industry nor government has a cleanup plan.
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