A team of scientists have developed an approach to disposing of sewage that reduces the risk of an earthquake triggering.
Oil production generates large volumes of wastewater, which is often injected into the ground as a means of disposal to avoid polluting surface water. However, the injections have the potential to cause earthquakes.
A study documenting the method devised by a multidisciplinary team of scientists to prevent such earthquakes was published today in the journal Nature. Their method has been tested in the largest onshore oil field in Western Europe, the Val d’Agri field in southern Italy.
Hundreds of small earthquakes have been detected there after field operators injected sewage into an abandoned well in 2006.
“The earthquakes were detected within hours of the injection,” said James Dietrich, study co-author and emeritus professor emeritus of geophysics at UC Riverside. “The cause and effect relationship was clear.”
Wanting to know which injection levels are safe, operators in the field assembled a team from UCR, Harvard, the Massachusetts Institute of Technology and the University of Texas.
Dieterich took data collected from the field and created models that accurately reproduce the seismic events observed between 1993 and 2016. Based on studies conducted in Dieterich’s lab, his models help explain how a small change in the amount of stress on a fault can cause a large change in the speed of earthquakes.
The research team then used models to predict the effects of using three different water injection rates. They determined that a relatively low injection rate was sustainable and should not induce shaking.
Between January 2017 and June 2019, these projections were field tested and the seismic activity was in line with expected levels. The authors suggest that this approach can be used to manage earthquakes generated by other activities, such as carbon sequestration.
This strategy for reducing global warming involves capturing industrial carbon dioxide and releasing it to the ground rather than to the atmosphere.
“One of the main obstacles to this is that gigantic volumes of fluids injected into the ground are likely to trigger earthquakes,” Dieterich said. “How can this be managed? We’ve learned a bit here that can help with this, and related issues like hydraulic fracturing.”
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Material provided by University of California – Riverside. Original written by Jules Bernstein. Note: Content can be changed for style and length.