Calling it a “matter of public safety,” Gov. Sam Brownback has appointed a committee to study whether oil and gas activity is behind the recent spate of minor earthquakes in Kansas.
Expansion of the oil and gas recovery method known as “fracking” has coincided with a series of small quakes in areas that had long been seismically stable. Fracking doesn’t appear to cause the problem, but an increase in oil and gas production and disposal of waste fluids associated with fracking could be behind the recent temblors that have shaken south-central Kansas and northern Oklahoma, scientists said Monday.
“It’s not the fracking itself, it’s this re-injection of the fluids into formations that are considered safe to hold it,” said Don Blakeman, a geophysicist with the National Earthquake Information Center in Golden, Colo. “It’s waste disposal.”
Fracking uses high-pressure water and chemicals injected deep underground to break rock strata and open previously unrecoverable pockets of gas and oil.
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Along with the oil and gas, the process brings up a lot of saltwater, which is pumped back underground for disposal along with the used fracking fluids, said Rex Buchanan, interim director of the Kansas Geological Survey and an appointee to the governor’s panel.
It is not clear whether the re-injection is causing earthquakes, but if it is, the saltwater is probably more to blame than the fracking fluid, because there is so much more of it to get rid of, he said.
Blakeman said the injection of drilling waste has been going on for decades. Part of what scientists are studying now is why it seems to cause problems only some of the time.
Some of the chemicals in the fracking fluid are used to keep passages within broken rock open so the gas and oil can flow out, Blakeman said.
In some cases, re-injection “seems to change the pressure environment on subsurface faults,” causing them to slip, he said. “There’s a lot of complex physics going on down there.”
Exact statistics were not available Monday, but there isn’t much doubt that seismic activity is on the rise in the Kansas-Oklahoma oil patch.
Caldwell, near the Kansas-Oklahoma state line, has had three earthquakes in the past two months, ranging in magnitude from 3.3 to 3.9.
“By Kansas standards, that’s a good earthquake,” Buchanan said, although it likely would hardly be noticed in a more earthquake-prone area such as California.
Oklahoma, where oil and gas activity is more intense, has experienced quakes ranging up to a magnitude of 5.6, which is a pretty good shake even by California standards, he said.
In addition to Buchanan, Brownback appointed Kim Christiansen, executive director of the Kansas Corporation Commission, and Mike Tate, chief of the Bureau of Water at the Kansas Department of Health and Environment, to the committee to study the issue.
“Recent seismic activity in south-central Kansas has raised concerns that fluid injection might be related,” Brownback said in a statement. “I have asked the task force to study the issue and report back with a state action plan.”
Pinning earthquakes to a specific cause is difficult, said Blakeman, who works in the earthquake center’s locating unit, which spots the locations and measures the magnitudes of quakes.
“The earthquake comes across here and I locate it; like we had a number of Oklahoma quakes overnight,” he said Monday. “By looking at those earthquake records, we can’t tell anything about the cause.
“The waveforms and everything look like natural earthquakes,” he added.
To identify the cause, “it takes a lot more study, typically more instruments on the ground and collaboration with companies to know when they’re re-injecting fluids and so forth so you can tell the timeline,” he said.
That kind of study is part of what the governor’s committee will look at, said Buchanan.
Kansas is hampered in analyzing earthquakes because the US Geological Survey, which runs the earthquake center, has only two monitoring stations in the state, Buchanan said.
He said the Kansas Geological Survey has talked with the Legislature about expanding the monitoring system to get better data. In addition, he said, the state has asked the USGS whether it could provide additional monitors on a temporary basis.
The governor’s committee is scheduled to hold its first meeting on April 16 at Wichita State University’s Eugene M. Hughes Metropolitan Complex.
By then, Buchanan said, he hopes the committee will have a draft action plan for industry and other stakeholders to respond to.