Squinting into a laptop perched on the back of his pickup, Austin Holland searches for a signal from a coffee-can-sized sensor buried under the grassy prairie.
Holland, Oklahoma’s seismology chief, is determined to find the cause of an unprecedented earthquake epidemic in the state. And he suspects pumping wastewater from oil and gas drilling back into the Earth has a lot to do with it.
“If my research takes me to the point where we determine the safest thing to do is to shut down injection -- and consequently production -- in large portions of the state, then that’s what we have to do,” Holland said. “That’s for the politicians and the regulators to work out.”
So far this year, Oklahoma has had more than twice the number of earthquakes as California, making it the most seismically active state in the continental U.S. As recently as 2003, Oklahoma was ranked 17th for earthquakes. That shift has given rise to concern among communities and environmentalists that injecting vast amounts of wastewater back into the ground is contributing to the rise in Oklahoma’s quakes. The state pumps about 350,000 barrels of oil a day, making it the fifth largest producer in the U.S.
The rise in earthquakes isn’t just happening in Oklahoma, challenging scientists and regulators across the country. The growth of seismic activity alongside oil production in fracking states from Colorado to Ohio has sparked a series of studies tying the temblors to drilling activity. Most seismologists around the country are convinced that wastewater injected back into the ground is jolting fault lines and triggering earthquakes. Between 2006 and 2012, the amount of wastewater disposed in Oklahoma wells jumped 24 percent, to more than 1 billion barrels annually, according to the Oklahoma Corporation Commission, which regulates the industry.
“There’s a couple of good examples where I think it’s pretty clear that if you turn off the well the earthquakes stop,” said Justin Rubinstein, deputy chief of the U.S. Geological Survey’s induced seismicity project “It’s a pretty strong correlation.”
Oil companies say the science isn’t far enough along and that correlation in activity does not amount to proof that their wastewater wells are causing the earthquakes.
“We’ve been doing injection in the state for a long time,” said Chad Warmington, president of the Mid-Continent Oil and Gas Association of Oklahoma. “It deserves a lot more investigation before making a determination.”
Waiting on Science
Duane Grubert, executive vice president of investor relations for SandRidge Energy Inc., based in Oklahoma City, said his company is “waiting on the science” to become more conclusive. More than a half a dozen other oil companies contacted for this story declined to comment.
Warmington said the industry is concerned that oil and gas laws may be hastily rewritten, requiring costly changes in the way companies handle the billions of gallons of waste fluids they inject underground each year.
“We don’t want anyone to rush to judgment based on faulty or inaccurate data and that’s all we’re asking for,” he said.
Some studies done so far suggest that wastewater wells may be the culprit in what scientists say is an otherwise unexplained and unprecedented surge in temblors. One study published July 3 in the journal Science used data to show that the sharp rise in earthquakes near Oklahoma City starting in 2009 was caused by high levels of wastewater injection at four disposal wells.
A statistical analysis by the U.S. Geological Survey showed that recent jumps in Oklahoma’s earthquake rate do not seem to be a result of natural seismic changes and that wastewater disposal has likely played a role in the increase. The survey warned that the rise in activity has significantly raised the chance of a damaging earthquake of magnitude 5.5 or greater in the state.
One mystery is why some wastewater disposal wells pose problems while others don’t, said Rubinstein, of the Geological Survey’s induced seismicity project. If researchers could untangle that riddle, “it seems probable that the industry would be able to avoid the problem,” he said.
While the debate continues in Oklahoma, other states are already moving forward. Arkansas has banned wastewater disposal in a 1,200-square-mile area after four wells there were blamed for causing a series of temblors. Ohio has prohibited waste-fluid injection into some underground rock layers and requires companies to monitor for earthquakes before and after drilling new disposal wells. Colorado regulators shut down a disposal well last month on suspicion that it had caused two earthquakes there.
More local governments may also institute bans following a New York court ruling, not related to earthquake fears, that allows cities and towns to block hydraulic fracturing if deemed adverse to communities.
Among the most alarming statistics in Oklahoma is the rise in stronger earthquakes. Between 1990 and 2008, there were never more than three quakes registering a magnitude 3.0 or greater in a single year, according to data from the Oklahoma Geological Survey. In 2013 there were 109, and through June of this year there were 238.
The largest earthquake tied to injection wells was a magnitude 5.7 temblor centered about 50 miles west of Oklahoma City in 2011 that destroyed 14 homes, injured two people and buckled pavement, according to research led by Katie Keranen, an assistant professor of geophysics at Cornell University.
“I think it’s pretty critical to assess the hazard,” Keranen said.
Holland’s work may provide the additional evidence the state needs to underpin new safety regulations. The focus of his latest investigation lies about five miles east of where Holland has buried his sensor: Injection Well No. 8520296, just across the Texas border due north from Fort Worth, Texas.
The well sits on a site that was rattled nine months ago by a series of earthquakes that knocked over TVs, tumbling chimneys from rooftops and shattering the nerves of local residents. The temblors began two weeks after the wastewater company, Love County Disposal, began pumping millions of gallons of oilfield fluids down the well. When the pumping stopped weeks later, the shaking stopped.
Plans to begin using the Love County disposal well again later this year have given Holland a rare chance to study the link between wastewater disposal and earthquakes in real time.
“We’ve temporarily shut down to coordinate with the regulators and the geological survey,” said Thomas Dunlap, an owner of Love County Disposal. “Now let’s get the emotion out of it and get to the science of it to tell us what’s going on.”