Home » Oklahoma, Texas Suggest Frack-water Disposal Link to Earthquakes
Oklahoma and Texas, two oil and gas strongholds that historically applied a very light hand to government regulation, are taking the steps to address the seismic effects of wastewater disposal associated with hydro-fracking.
In late April, the Texas Railroad Commission said that it was assessing results from a recent Southern Methodist University study linking disposal well activity to several 2013 earthquakes along an ancient fault line near Azle, Texas. TRC also put Exxon Mobil on notice to show cause as to why certain of its wells in the area should not be shut down to avoid further “injection induced” seismicity.
Shale fluid extraction techniques suck oil and water out of rock formations and separate them. This process water is too salty and chemical-laden to be recycled. Instead, fracking operators inject it back into large pockets deep in the earth's crust.
In Oklahoma, the Secretary of Energy and Environment on April 23 launched a website that acknowledges, and plans to monitor, the link between injection of large volumes of fracking brine and increased seismic activity. The online posting came the same day as a position statement from the Oklahoma Geological Survey suggesting that many of the earthquakes in Central and North-Central Oklahoma are triggered by waste-water disposal wells. Gov. Mary Fallin (R) said several state agencies have already begun to implement new policies to address increases in seismicity.
TRC also recently adopted new rules that require permit applicants to provide historical earthquake data from the U.S. Geological Survey within 100 square miles of a newly proposed well, and more frequent disclosure of injected fluid pressures and volumes.
Exxon Mobil's XTO Energy affiliate referred all of ENR's questions to the Oklahoma Oil and Gas Association, which said in a statement that the studies offered “no new insight” in the science of injection induced earthquakes.
Independent Petroleuem Association of America spokeswoman Katie Brown said that seismicity was linked to .01 percent of wastewater injection wells. That's why there must be a site-by-site analysis of wells to determine any link to seismicity, she says. “Very few wells have been linked to seismicity.”
In a statement last week, Chad Warmington, president of Oklahoma Oil and Gas said a ban on disposal wells is not feasible. “Not only would that halt oil and natural gas production in Oklahoma, there is no scientific evidence that stopping wastewater injection would result in fewer earthquakes,” he said. “That is why we need a better understanding of what is causing our earthquakes.”
Scientists have been puzzled for some time over the build up of seismic activity in Oklahoma, because it was not near injection wells, much less oil wells, says USGS' Bill Ellsworth. “So a hypotheses was developed that injection can cause pressure rises over long distances.”
USGS released an additional report in April, saying it was the first comprehensive assessment of the hazard levels associated with induced earthquakes in fracking areas. The agency said the new report describes for the first time how injection-induced earthquakes can be incorporated into U.S. seismic hazard maps.
“We believe that injection induced earthquakes can be managed, but it involves the application of a developing science,” Ellsworth, who worked on both studies, says. “The danger is that his issue was not on the radar of regulators or operators. The laws that affect injection arise from drinking water protection, not from earthquake protection. ”
Injection can be stopped at certain wells, and operators can perform a “blow-back” to release pressure to lessen the risk of increased seismicity. “They can reduce the amount of wastewater and refrain from injecting formation water into basement rocks,” Ellsworth says of the layers of sediment formed eons ago.
The discovery that injection of fluid underground at high pressure was responsible for the triggering of earthquakes near Denver goes back to 1966, Ellsworth says.
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