Long before the controversial practice of hydraulic fracking; carbon dioxide injections used in gas and oil wells may have triggered a strings of earthquakes.
The study was the first-of-its-kind to look at the link between gas injections and earthquakes of a magnitude higher than three, the Sydney Morning Herald reported.
Researchers analyzed 93 earthquakes that occurred over the years 2009 and 2010 and believe they were related to CO2 injections at the Cogdell oil field near Snyder, Texas, Reuters reported.
Previously, tremors that took place between 1975 and 1982 were found to be related to the practice of injecting water into wells; the researchers don't believe the same thing is happening here.
"The timing of gas injection suggests it may have contributed to triggering the recent seismic activity," the study said, Reuters reported. "If so, this represents an instance where gas injection has triggered earthquakes having magnitudes 3 and larger."
The study looked at data from six seismograph stations that were a part of the USArray program.
"We have evaluated data concerning injection and extraction of oil, water, and gas in the Cogdell field. Water injection cannot explain the 2006-2011 earthquakes, especially as net volumes (injection minus extraction) are significantly less than in the 1957-1982 period. However, since 2004 significant volumes of gases including supercritical CO2 have been injected into the Cogdell field. The timing of gas injection suggests it may have contributed to triggering the recent seismic activity." The study abstract stated.
University of Texas seismologist Cliff Frohlich, who led the research, warned further research would be needed in order to confirm the findings, the Herald reported.
The team believes activities at the Cogdell oilfield may have triggered up to 18 earthquakes, one of which hit a 4.4 on the magnitude scale. The large earthquake occurred when energy companies had increased their use of carbon dioxide in fuel extraction.
