Abandoning years of official skepticism, Oklahoma officials and Texas researchers Tuesday embraced a scientific consensus that earthquakes rocking the region are largely caused by the underground disposal of billions of barrels of wastewater from oil and gas wells.
Kansas has yet to join in the conclusion that blames the disposal process.
In Texas, wastewater injection wells, along with brine production related to oil and gas drilling, are the most likely cause of a rash of earthquakes in the Azle and Reno area northwest of Fort Worth a couple of years ago, according to a newly published scientific study.
An article published Tuesday in the science journal Nature Communications states that the 27 earthquakes in that region from November 2013 to January 2014 can be traced to oil-and-gas operations. The article was written by researchers from Southern Methodist University, the University of Texas at Austin and the U.S. Geological Survey.
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Oklahoma’s state energy and environment Cabinet introduced a website Tuesday detailing the evidence behind the conclusion that underground disposal of wastewater was to blame for earthquakes, including links to expert studies of Oklahoma’s quakes. The site includes an interactive map that plots not only earthquake locations but also the sites of more than 3,000 active wastewater-injection wells.
The website coincided with a statement by the Oklahoma Geological Survey that it “considers it very likely” that wastewater wells are causing the majority of the state’s earthquakes.
Together, those steps are a turnabout for a state government that has long played down the connection between earthquakes and an oil and gas industry that is Oklahoma’s economic linchpin.
As recently as last fall, Gov. Mary Fallin, a Republican, indicated that suggestions of a relationship between oil and gas activity and seismicity were speculation, and that more study was needed.
In a news release issued Tuesday, Fallin called the Geological Survey’s endorsement of that relationship significant and said the state was taking action to address the problem.
Oklahoma oil and gas regulators have taken steps to ensure that newly drilled disposal wells do not create seismic risks. But they have limited authority to address the existing wells that are behind the increase in temblors, and neither the governor nor the Legislature has pushed to increase their powers.
In past decades, Oklahomans experienced fewer than two earthquakes exceeding magnitude 3.0 in an average year. But since a boom in oil and gas exploration began in the mid-2000s, that number has mushroomed. The state recorded 585 quakes of 3.0 or greater last year, more than any state except Alaska, and is on course to register more than 900 such temblors this year.
Most of the quakes result in little more than cracked plaster and driveways, but residents in quake zones say the cumulative damage — to their property and to their nerves — is far greater.
In January, the Kansas House Energy and Environment Committee heard testimony from representatives of the Kansas Geological Survey, the Kansas Corporation Commission and the Kansas Department of Health and Environment.
The dramatic increase in both the number and magnitude of earthquakes in south-central Kansas correlates to increased oil production activity – but not directly to the controversial extraction process known as “fracking” – agency officials told the committee.
“I think (researchers) do see a correlation between the increased number and volume of disposal wells in south-central Kansas and seismic activity,” said Rex Buchanan, interim director of the Kansas Geological Survey. “But again, and I think it’s been said at least three times here, we don’t make any connection between that seismic activity and hydraulic fracturing.”
In an Associated Press story Tuesday, scientists and regulators have said the injection deep underground of a byproduct of oil and gas production is likely triggering the temblors along existing but previously unknown fault lines in the region. The Kansas Corporation Commission issued an order on March 20 that set a new maximum daily amount of waste saltwater injection amounts in Harper and Sumner counties. The order also further limited disposal levels in five specific areas of “seismic concern.”
Officials with the KCC say “it’s too early to reach any conclusions” about whether the restrictions are resulting in a reduction in quakes.
In 2009, SMU and University of Texas at Austin researchers began investigating small quakes at DFW Airport that occurred from October 2008 to May 2009. They published their study in March 2010. The quakes stopped after Chesapeake Energy in August 2009 shut down one of two injection wells it operated on DFW property.
UT Austin researchers reviewed seismic data collected in several locations in the Barnett Shale between November 2009 and September 2011. Cliff Frohlich, senior research scientist at UT’s Institute for Geophysics, released his study in August 2012. He concluded that “injection-triggered earthquakes are more common than is generally recognized.”
Both studies also said it was “plausible” that the injection wells triggered the quakes. Frohlich is one of the authors of the article in Nature Communications. Heather Deshon, an associate professor of geophysics at SMU and one of the authors of the paper, said in 2014 that they hoped that additional study would allow them to be more “precise.”
Contributing: New York Times, Fort Worth Star-Telegram, Wichita Eagle, Associated Press