The state agency in charge of determining the cause of Oklahoma's earthquake swarms announced today that it is "very likely" that the shaking has been caused by oil and gas activity.
The statement posted this morning resolves contradictory statements by scientists at the Oklahoma Geological Survey (OGS) (EnergyWire, April 20). It also comes as the survey, part of the University of Oklahoma, seeks to show that a leading donor did not sway its science (EnergyWire, April 15).
Oklahoma had 585 earthquakes of magnitude 3 or greater last year, and is on track to have more than 800 this year. Before 2009, it averaged one to three a year. OGS said the state is now averaging 2.5 such quakes each day.
"The OGS considers it very likely that the majority of recent earthquakes, particularly those in central and north-central Oklahoma are triggered by the injection of produced water in disposal wells," the agency's statement said.
In response, the Oklahoma Independent Petroleum Association (OIPA) conceded a "possible relationship" between earthquakes and the industry.
"We are confident that the cooperation between public and private entities will offer a rational and reasonable response to seismic activity concerns," said Kim Hatfield, chairman of the Regulatory Committee for OIPA, the state's main oil and gas trade group, in a statement.
The Oklahoma Corporation Commission, the agency in charge of regulating oil and gas in the state, said the facts in today's statement have already been incorporated into its decisionmaking on new disposal wells (EnergyWire, March 9).
"There will no doubt be more steps to take, and all options available to the Commission are on the table," said the statement from the three-member elected commission. "There is no issue that has a higher priority for this agency, and the continuing work and commitment of OGS is central to this effort."
Corporation Commission officials, though, have said some aspects of the situation are beyond their control and in the hands of the state Legislature. Legislators, though, have not acted. No legislation related to man-made earthquakes or disposal wells was introduced this year, though it has moved to protect industry from municipal ordinances.
The cause of the quakes has been a tricky subject for both scientists and politicians in Oklahoma, where petroleum production is woven into the social and economic fabric. The state Capitol grounds sport a working oil well, and state officials estimate 1 in 5 jobs is tied to the oil and gas business.
Earlier this year, Gov. Mary Fallin (R) said she believed most of the earthquakes are natural.
"We know a lot of it's just natural earthquakes that have occurred since the beginning of the earth," Fallin told the Tulsa World, "but there has been some question about disposal wells."
But in conjunction with today's announcement, the Fallin administration today rolled out a new "Earthquakes in Oklahoma" website that cites the new OGS position.
"Seismologists have documented the relationship between wastewater disposal and triggered seismic activity," the website states.
Today's statement from State Seismologist Austin Holland and interim OGS Director Richard Andrews was careful to stress that it is not attributing the surge in shaking to hydraulic fracturing, or "fracking."
"The primary suspected source of triggered seismicity is not from hydraulic fracturing, but from the injection, disposal of water associated with oil and gas production," the statement said. Fracking can be a source of wastewater, the statement said, but "this volume represents a small percentage of the total volume of wastewater injected in disposal wells in Oklahoma."
Seismologists have made a stronger connection to a practice called "de-watering," in which huge volumes of water are sucked from old oil fields. In the process, perfected by New Dominion LLC, the oil is separated out and the water gets injected back deep underground.
But fracking is a key part of production in the Mississippi Lime play, which straddles a section of the Oklahoma-Kansas border where earthquakes have become common. Production in the Mississippi Lime also produces much more waste fluid than conventional drilling.
OGS officials made no mention of the state's largest recorded earthquake, a magnitude-5.7 temblor in November 2011 near Prague, Okla., that injured two people and damaged hundreds of buildings. The U.S. Geological Survey and numerous academic seismologists have attributed it to injection wells, but OGS has rejected those findings.
The statement replaces a "Position Statement on Triggered or Induced Seismicity" from 2012 pointing toward natural causes as the reason for the surge in shaking.
"While we are studying the possibility that some of this activity could be related to oil and gas operations, it is unlikely that all of the earthquakes can be attributed to human activities," the statement says.
That statement had been cited at times by OIPA when questions were raised about disposal wells and earthquakes.
Shifts at agency
Today's statement was not entirely unexpected. In interviews and appearances, Holland has been pointing in recent weeks toward the position that the surge in quakes is linked to oil and gas activity.
"It appears quite likely most of the seismicity we're seeing in northern and north-central Oklahoma is most likely due to this wastewater disposal," Holland said at a televised forum on earthquakes in Oklahoma City last month. "It's hard to explain this as a natural variation."
He had also been a co-author on studies that linked quakes to oil and gas activity.
But when Holland and the survey endorsed a similar position in 2013, he was called into a "coffee" meeting with Continental Resources Inc. founder Harold Hamm, a major donor to the university that houses OGS. At the time, Continental had made it known to Holland that company executives did not like "induced seismicity" being discussed (EnergyWire, March 3).
The change in position comes amid other key shifts at OGS. Randy Keller, who served as director of the survey as the number of earthquakes surged, retired at the end of last year. Larry Grillot, dean of the OU college that houses OGS, will retire when the school year ends. Their successors have not been announced.