There's a growing body of science that says injecting substances underground can cause earthquakes. Here in North Texas, we've had plenty associated with the injection of slippery frack water deep into earth. Motionless faults get lubricated into sudden shifting and a country not known for seismic activity suddenly gets active.
Turns out, carbon dioxide does the same thing. That's a problem, given its growing use in the revitalization of oil fields once thought to be played out. And it presents a conundrum for carbon-capture proponents who believe injecting the greenhouse gas underground could offer a way to reduce climate-altering emissions.
A paper published Monday in the Proceedings of the National Academy of Sciences by University of Texas researcher Cliff Froehlich is the first of its kind to draw a link between carbon dioxide injection and earthquakes.
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In the Codgell field near Snyder, west of Abilene, temblors of magnitude 4 and below shook the area from 2006 to 2011. The only comparable stretch of seismic activity took place decades before, when large amounts of water were injected into wells to enhance oil production, the study says. "Water injection cannot explain the 2006-2011 earthquakes. However, since 2004 significant volumes of gas including CO2 have been injected into Cogdell wells."
The gas displaces the oil within, stimulating old wells whose production has tailed off. Froehlich believes it may be stimulating localized faulting too. Now, he says, further research needs to establish the mechanism that triggers the earthquake. Not every gas injection field causes seismic activity.
The practice of carbon dioxide-aided oil recovery isn't going away. In an interview with Platts, U.S. Energy Secretary Ernest Moniz talked about expanding the technique to recover some 3 million barrels of oil per day.
Send your story tips to the author, Brantley Hargrove.