Map showing 2009-2011 earthquakes located in this study (red circles), gas injection wells active since 2004 (yellow squares), and focal mechanisms for regional events (beach balls). A series of small quakes occurred in the same region in 1979 and 1980 (green circles) and may have been related to injection of water for enhanced oil recovery. Sources: EarthScope, Texas Railroad Commission, S.T. Harding, and St. Louis University. Illustration: Cliff Frohlich/University of Texas at Austin.
AUSTIN, Texas - A new study correlates a series of small earthquakes near Snyder, Texas between 2006 and 2011 with the underground injection of large volumes of gas, primarily carbon dioxide (CO2) - a finding that is relevant to the process of capturing and storing CO2 underground. Although the study suggests that underground injection of gas triggered the Snyder earthquakes, it also points out that similar rates of injections have not triggered comparable quakes in other fields, bolstering the idea that underground gas injection does not cause significant seismic events in many geologic settings. No injuries or severe damage were reported from the quakes identified in the study. The study represents the first time underground gas injection has been correlated with earthquakes greater than magnitude 3. The results, from Wei Gan and Cliff Frohlich at The University of Texas at Austin's Institute for Geophysics , appear this week in an online edition of the journal Proceedings of the National Academy of Sciences . The study focused on an area of northwest Texas with three large oil and gas fields - the Cogdell field, the Salt Creek field and the Scurry Area Canyon Reef Operators Committee unit (SACROC) - which have all produced petroleum since the 1950s. Operators began injecting CO2 in the SACROC field in 1971 to boost petroleum production, a process known as CO2 Enhanced Oil Recovery (CO2 EOR).
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