Oklahoma regulators told energy companies to reduce underground wastewater disposal across an earthquake-prone stretch of the state, a move that ratchets up an unsuccessful effort to reduce quakes related to oil and gas production.
The wastewater ends up pumped out of the ground when drillers extract oil or gas and then put back underground in a disposal or injection well. The instruction seeks a 38 percent cut in the amount of this wastewater pumped underground by the operators of 23 injection wells, largely northeast of Oklahoma City.
The 40-mile stretch that includes the wells has experienced a drastic increase in earthquakes in the last two years.
Those 40 miles are one hot spot in a state that has seen an increase in earthquakes since 2010, triggered by a boom in energy production. Seismologists said the briny wastewater seeps into faults in rock far below the surface, effectively lubricating the cracks until the rocks slip, causing a tremor.
The epidemic of tremors in that stretch is especially puzzling, officials said, because the 23 wells are comparatively small. The wells injected about 8.8 million barrels of wastewater into the earth last year, a tiny fraction of the 1.1 billion barrels buried statewide in 2013, the last year for which data are available. About 3,200 disposal wells are active at any one time, officials said.
“The seismicity is off the charts, and we don’t have any high-volume wells there,” said Tim Baker, the director of the Oklahoma Corporation Commission Oil and Gas Conservation Division. “So we’ll go ahead and reduce the volume and see if that has any effect on seismicity.”
Regulators previously took action against some individual disposal wells and tightened requirements for new ones. But Monday’s action goes well beyond those efforts, requiring reductions in wastewater disposal for all wells in the earthquake zone, regardless of whether they linked to tremors.
One of the commission’s three elected officers, Dana Murphy, said the new plan was an indicator of more sweeping actions to come.
“There was a time when the scientific, legal, policy and other concerns related to this issue had to first be carefully researched and debated in order to provide a valid framework for such action. That time is over,” she said. “We must continue to take progressive steps, and do so as quickly as possible.”
The commission, which oversees oil and gas production, has borne virtually all of the political and legal responsibility for curbing the quakes in a state where energy companies wield enormous power. Gov. Mary Fallin has established an advisory panel to research the issue, but conceded only last spring that wastewater disposal wells were the likely cause of the tremors.
Oklahoma’s energy companies have played down and even denied a connection between wastewater and earthquakes. Privately, however, many have voluntarily complied with regulators’ recommendations to reduce the risk of quakes, both out of a sense of public responsibility and a growing concern about liability for quake damages.
This latest action could change that. Reducing wastewater disposal inevitably reduces oil and gas production — and profits. Whether the dozen operators of the 23 wells at issue will willingly go along remains up in the air.