Oklahoma is requiring energy companies to greatly reduce the amount of wastewater they inject below ground in an earthquake-prone part of the state to determine whether this step could reduce the number of quakes that have plagued the state in the past few years.
Under new rules announced the night of Aug. 3 by the Oklahoma Corporation Commission, 12 companies operating in a 40-mile tract northeast of Oklahoma City must reduce by 38 percent the amount of wastewater they inject into 23 disposal wells over the next 60 days.
The commission, whose Oil and Gas Conservation Division issued the regulations, said they will cut wastewater volume by about 2.4 million barrels below their level in 2012, when a sudden increase in earthquakes began in the area.
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In fact, there’s been a marked increase in the number of earthquakes in Oklahoma and several other central states since 2009. Various scientific studies say they are caused by a corresponding increase in the underground disposal of salty wastewater, a byproduct of the recent boom in oil and gas drilling in the region.
Producing oil and gas generates this wastewater whether it is extracted conventionally or by hydraulic fracturing, also called fracking. Scientists say this newly disposed wastewater finds its way into cracks in underground rock, loosening them until they slip under the pressure of weight of rocks above them. This slip causes the earth to shake, they say.
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In Oklahoma alone, the number of earthquakes has risen to the point where noticeable quakes with a magnitude greater than 3.0 on the widely used Richter scale are felt at least twice a day. Before 2009, such earthquakes were felt no more than twice a year.
The Oklahoma quakes are puzzling not only because they used to be rare in the state, but also because the disposal wells are so small. In 2014, for example, the wells’ operators injected only about 8.8 million barrels in the affected area, far below the 1.1 billion barrels disposed of the year before. Therefore the new regulations rely largely on chance.
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“The seismicity is off the charts, and we don’t have any high-volume wells there,” said Tim Baker, the director of the agency that imposed the disposal limit. “So we’ll go ahead and reduce the volume and see if that has any effect on seismicity.”
Michael Teague, the state’s secretary of energy and environment, said it may take between six months and a year to determine whether the new regulations help resolve Oklahoma’s earthquake problem, especially since previous efforts to reduce them have been fruitless. “We’ve come a long way, but we’re not there yet,” he said.
Gov. Mary Fallin, who attended the meeting where the new regulations were announced, said that until the problem is solved, Oklahomans worried about their homes’ safety should buy private earthquake insurance. This prompted reporters to ask if she believed her administration was doing enough to end the threat.
“We’re sure trying to,” the governor replied.
By Andy Tully Of Oilprice.com
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Andy Tully is a veteran news reporter who is now the news editor for Oilprice.com