A new study led by Arizona State University has proposed a new method to mitigate man-made earthquakes caused by excessive injection of wastewater deep underground as a byproduct of oil and gas extraction techniques, including hydraulic fracturing or fracking.
The study, published in the journal Science, suggests that the researchers could estimate how much pressure is increasing underground due wastewater injection. As the pressure reaches near critical level, the wastewater injection could immediately be stopped to prevent potential pressure buildup, which leads to man-made earthquakes.
For the study, the researchers analyzed our high-volume wells used for disposing wastewater near the epicenter for the Timpson, Texas earthquake. Using space-borne Interferometric Synthetic Aperture Radar (InSAR), the researchers were able to measure the surface uplift of the area near the wells.
"Monitoring surface deformation using these remote sensing techniques is a proactive approach to managing the hazards associated with fluid injection, and can help in earthquake forecasting," explained Manoochehr Shirzaei, a geophysicist and assistant professor at ASU's School of Earth and Space Exploration and lead author of the study, in a press release.
By calculating the strain and pore pressure underneath the wells that resulted in an uplift, the researchers discovered that the rates of earthquakes increased, even when water injections declined. The researchers explained that continued seismic activities in these areas were caused by the pore pressure continuing to diffuse throughout the area from earlier injections.
Furthermore, the researchers found that injecting wastewater into the wells at high pressure could uplift the ground near the shallower wells. Additionally, the study showed that the denser rocks experience less seismic activity because pore pressure was prevented from disseminating into basement rock. This explains why wastewater injections can, but not always, producing earthquakes.
Hydraulic fracturing or fracking has become one of the most controversial oil and gas extraction technique. During fracking, high pressure mix of water and chemicals, combined sand and gravels from the ground, produces lost of wastewater. In the United States, about two billion gallons of wastewater are produced and injected into about 180,000 disposal wells that are located mainly in Texas, California, Oklahoma and Kansas.