Earthquakes linked to saltwater disposal wells in the Arbuckle formation have been well-documented. Thanks to the work of the Oklahoma Corporation Commission, Oklahoma Geological Survey and the oil and natural gas industry effective actions have been taken to significantly reduce seismicity caused by injection wells.
(For more about saltwater disposal wells and earthquakes, click here.)
And until 2015, earthquakes hadn’t been linked to hydraulic fracturing operations which takes place during well completions. So-called “frac quakes” can happen if a well bore is too close to a fault. With enough pressure, the fault can slip, triggering an earthquake.
“[We] started looking at this problem from a scientific standpoint,” says Tim Baker, former director of oil and gas conservation for the Oklahoma Corporation Commission. “We took all the well completion activity in the state, compared that to all the earthquakes that were going on in the state, and we saw that 4 percent of the earthquakes in Oklahoma might be attributed to well completion activity.”
With new information came new industry protocols that require companies to take action when a 2.0 magnitude or greater earthquake occurs. The protocols are: reduce the fluids used during the hydraulic fracturing process, reduce the pressures in the wellbore and pause operations and allow the wellbore pressure to equalize. Also, all operators in the defined area will be required to have access to a seismic array that will give real-time seismicity readings.
“We’ve seen all protocols to be effective in mitigating the risk of an earthquake,” Baker says.
Many operators voluntarily use seismic arrays, or monitoring systems, that alert them to any seismic activity during their well completion activities. In fact, most companies take actions well before the 2.5 magnitude benchmark set by the OCC. These seismic arrays also contribute to geological information that state regulators use to monitor oil and natural gas operations.
“That data goes into a database, and we can see who the engineer is,” Baker says. “If there is a well nearby any earthquake, we literally call the engineer on location and tell him what we’re seeing.”
New research, technology and protocols have gone a long way in reducing the seismic activity in Oklahoma. But Baker says it all comes back to the industry’s willingness to come to the table and help find the source of the state’s seismic challenges.
“They don’t want to be the industry that is the problem. They want to be the industry that is the solution,” he says. “If we did not have the industry cooperating with us, trying to stay ahead of the game, so to speak, and start addressing these issues when they start to see them, it could be a lot more difficult for everyone.”
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