A new study confirms that hydraulic fracturing is the cause of small, slow earthquakes and shaking that were previously unexplained. This shaking is caused by the same process that can cause devastating earthquakes.
Hydraulic fracturing involves forcing fluids below the earth’s surface to recover oil or natural gas. Although typically carried out using wastewater, this particular study looked at the results when using liquid carbon dioxide. This method pushes carbon deep into the earth, preventing it from contributing to the warming of the atmosphere.
by someone Estimate, carbon dioxide hydraulic fracturing could save the same amount of carbon as 1 billion solar panels a year. Fracking with liquid CO2 is much more beneficial for the environment than fracking with wastewater, which does not remove carbon from the atmosphere.
“This study investigates the processes that sequester carbon underground, so it may have positive implications for sustainability and climate science,” said Dr. Kremlin, associate professor of geophysics at the University of California, Riverside, in the journal said Abhijit Ghosh, co-author of the published study. science.
But since carbon dioxide is a liquid, Ghosh said the study’s findings almost certainly apply to water-based hydraulic fracturing. Both can cause tremors.
On seismographs, normal earthquakes and tremors look different. Large earthquakes cause sharp shaking with high amplitude pulses. The shaking is more gentle, rising slowly with much smaller amplitude than the background noise, and then slowly decreasing.
“We are pleased to be able to use these tremors to track fluid movement due to hydraulic fracturing and monitor fault movement due to fluid injection,” Ghosh said.
Previously, seismologists had debated the cause of the shaking. Some papers argued that the shaking signal was due to a large earthquake thousands of miles away, while others suggested it could be noise generated by human activity, such as the movement of trains or industrial machinery. I thought it was sexual.
“Seismographs are not smart. If you drive a truck nearby or kick a truck with your foot, it will record the vibrations,” Ghosh said. “So for some time we weren’t sure whether the signal was related to liquid injection.”
To determine their origin, researchers used seismometers placed around a hydraulic fracturing site in Wellington, Kansas. Data covered the entire 6-month fracking injection period, as well as 1 month before and 1 month after injection.
After discarding the background noise, the research team showed that the remaining signal was generated underground and only appeared while the liquid injection was taking place. “No tremor was detected before or after the injection, which suggests that the tremor is related to the injection,” Ghosh said.
It has long been known that hydraulic fracturing can cause larger earthquakes. To prevent faults from sliding underground and causing earthquakes and shaking, one option is to stop hydraulic fracturing. Because that’s unlikely, Ghosh says it’s important to monitor these activities to understand how the rock is deforming and track the movement of the fluid after injection.
Modeling experiments can and have been conducted to help companies determine the liquid injection pressure that should be exceeded. Staying within these limits ensures that fluids do not migrate toward large faults underground and cause harmful seismic activity. However, not all faults are mapped.
“We can only model experiments of this kind if we know there are pre-existing faults. There may be flaws that we don’t know about, in which case it is difficult to predict what will happen. I can’t,” Ghosh said.
Reference: “Microtremor signals during fluid injection are generated by fault slip,” by Shankho Niyogi, Abhijit Ghosh, Abash Kumar, and Richard W. Hammack, August 3, 2023. science.
DOI: 10.1126/science.adh1331