The belief that drilling waste injection wells are responsible for a spate of Oklahoma earthquakes has gathered pace in recent months; however, injection well-induced seismicity likely dates back to the 1950s or earlier, according to U.S. Geological Survey (USGS) research.
"In Oklahoma, seismicity rates since 2009 far surpass previously observed rates at any time during the 20th century [see Shale Daily, Oct. 19]," said Susan Hough, USGS seismologist and lead author of a new study. "Several lines of evidence further suggest that most of the significant earthquakes in Oklahoma during the 20th century may also have been induced by oil production activities. Deep injection of waste water, now recognized to potentially induce earthquakes, in fact began in the state in the 1930s."
The USGS study used archival reports at the Library of Congress and drilling permit records showing the location of wells from the Oklahoma Corporation Commission to track how wastewater injection evolved over time, with an increase around 1950 due to a rise in secondary oil recovery in response to increasing depletion of fields.
"Waste water injection has a strong correlation to the increase in earthquakes," said Morgan Page, USGS seismologist and co-author of the study. "The results further demonstrate that, while the rates seen in recent years are unprecedented, induced earthquakes are likely nothing new in Oklahoma."
Oil production in Oklahoma has been going on for more than 100 years. Prior to the 2011 magnitude 5.7 Prague, OK, earthquake, the largest historical earthquake in the area was the 1952 magnitude 5.7 El Reno earthquake, which the study concluded was likely induced by activities related to oil production near Edmond, OK.
The research paper, "A Century of Induced Earthquakes in Oklahoma?" was released online in the journal Bulletin of the Seismological Society of America.