A new study on the relationship between earthquakes and hydraulic fracturing in Alberta has both good and bad news for the tight oil industry. First, the good: the study, conducted by researchers at the University of Calgary, acknowledges that earthquakes associated with shale drilling in the U.S., especially in the state of Oklahoma, are not the direct result of fracking, but rather due to the practice of storing wastewater underground. But that finding came paired with a scarier discovery—namely the delineation of a direct link between an increase in seismic activity and the actual fracturing of rock by injecting a slurry underground at high pressure. The New York Times reports:
In the Fox Creek area in Alberta, where oil and gas companies have been drilling in recent years into a formation called the Duvernay shale, earlier research had seen links between the earthquakes — all of which were minor and caused little damage — and fracking, rather than wastewater injection.
In their work, Dr. Eaton and Xuewei Bao, a postdoctoral researcher, looked into the links in more detail, analyzing seismic data from a series of quakes at Fox Creek in late 2014 and early 2015, and records from wells where fracking was occurring at the time. They found two patterns to the seismicity. To the east in the fault zone, most of the earthquakes occurred during the fracking process itself, which lasted up to a month. To the west, there were few immediate quakes; they occurred intermittently over several months after the fracking ended. […]
“The key message is that the primary cause of injection-induced seismicity in Western Canada is different from the central United States,” said David W. Eaton, a professor of geophysics at the University of Calgary and co-author of a paper in the journal Science describing the research. The findings could help regulators take steps to avoid such induced earthquakes, he said.
Whatever the link between shale drilling and earthquakes, it’s important enough to address, both at an industry and a regulatory level. That said, it’s also important to note the specifics of the problem, namely that the magnitudes of the earthquakes that have been shown to correlate with shale drilling are small—most being too gentle to be perceived without the aid of a seismograph.
And, if we’re looking ahead to solutions, it’s crucial to understand that the problem isn’t as simple a causal relationship between fracking shale rock and causing earthquakes.In some regions, in certain rock formations, hydraulic fracturing can lead to increased seismicity, as these Canadian scientists have just shown. But in others, especially in the central United States, the relationship between shale drilling and earthquakes centers around the manner in which wastewater is stored.
That is so well understood in Oklahoma now that the state has moved to stop companies from storing used frackwater in old unused wells to help mitigate the pressures that that water inevitably places on underground faults. In the wake of that decision, seismicity quickly dropped by 20 percent, suggesting that targeted regulations can help mitigate the serious underlying issue (no pun intended) while also keeping the industry—and the extraordinarily positive effects it’s having on America’s economy and energy security—afloat and alive.