The operator of a new drilling wastewater disposal well in southern Oklahoma has shut it down as state officials investigate whether it triggered a series of damaging earthquakes nearby.
Injection at the Love County Disposal Well began two weeks before the earthquakes started near Marietta, Okla.
"The number of earthquakes increased as injection peaked," Oklahoma Geological Survey seismologist Austin Holland wrote in a report. "However, we cannot rule out that this observation could be simply a coincidence."
Well operator Tom Dunlap did not cite the earthquakes in his message to state officials that he would be "shutting in" the well until further notice.
"Our business is uneconomic at this point," he wrote in an email. An attempt by EnergyWire to reach him by phone was unsuccessful.
Injection began Sept. 3 and the earthquakes started Sept. 17 in the area near the Texas border about 100 miles north of Dallas. The strongest was magnitude 3.4, and they have damaged chimneys, broken windows, and caused objects to fall in homes and businesses.
The Geological Survey has moved four seismic stations into the area to determine more precise locations for the quakes.
Before Dunlap voluntarily closed the well, the Oklahoma Corporation Commission (OCC) had sharply curtailed its operations. The agency limited the well to 1,000 barrels a day (42,000 gallons) at a maximum pressure of 375 pounds per square inch, OCC spokesman Matt Skinner said. The well was designed to take as much as 19,000 barrels per day (798,000 gallons) at a pressure of up to 2,200 psi.
Skinner said the OCC was employing a "red light, yellow light, green light" approach. The limits on injection were a yellow light. The National Academy of Sciences recommended such a traffic light protocol in a 2012 report.
The well had never accepted its full daily capacity of wastewater, though. State records show injections got up to 9,500 barrels Sept. 21 before declining.
The well was not hydraulically fractured. But Holland's report said it was treated with 10,000 gallons of hydrochloric acid.
The OCC, which regulates drilling and other industries, has also ordered that a digital pressure reader be put on the well that gives seismologists and oil and gas officials precise, up-to-the minute readings.
Local news reports have indicated that some residents are blaming the disposal well.
Geologists have known for decades that deep injection of industrial waste can lubricate faults and unleash earthquakes. Some earthquake researchers now say the nation's drilling boom, fueled by advances in high-volume hydraulic fracturing, could be spurring a rash of such man-made quakes.
Most seismologists agree that the specific process of hydraulic fracturing, or fracking, presents little or no risk of triggering earthquakes that damage property or injure people.
Instead they point to injection wells. Fracking and production of shale gas produce millions of gallons of wastewater. Some can be reused, but eventually, what comes to the surface must be disposed of. Usually, that's into injection wells.
Causing an earthquake is not illegal under the federal environmental laws that cover deep injection of oil and gas waste. But it could be illegal to allow injection to damage drinking water supplies (EnergyWire, June 18, 2012). And lawyers have sued injection well operators under general nuisance provisions after earthquakes.
Very few of the 40,000 brine disposal wells in the country have been linked to seismic ruptures. But in the shale drilling boom of the last few years, earthquakes have been linked to injection wells in Arkansas, Colorado, Ohio, West Virginia and Texas.
In 2012, U.S. Geological Survey scientists said they were observing a "remarkable increase" in earthquakes in the middle of the country likely tied to injection.
An increase in earthquakes in Oklahoma was central to that finding. Since then, seismologists have linked a more damaging 2011 quake outside Oklahoma City to nearby injection wells (EnergyWire, March 27).