Study: Surge In Okla. Quakes Can Be Traced To Drilling Operations

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2014 has been a shaky year so far for Oklahomans. The state has had more earthquakes than California. A growing body of research points to oil and gas production as fueling the increase in seismic activity. A paper published today in the journal Science suggests a small number of wastewater wells used in drilling operations could be responsible for many of the small quakes. StateImpact's Joe Wertz reports.

JOE WERTZ: Public officials held a town hall north of Oklahoma City last week to answer questions about the quakes. About 700 people showed up. Residents shouted at authorities to ban wastewater wells used by the oil and gas industry - something that would effectively be a ban on Oklahoma's biggest industry.

ANGELA SPOTTS: I'll tell you what, when the earthquakes happen, a couple of them scared the crap out of me. The animals are scared. My husband and I - we feel assaulted.

WERTZ: Local resident Angela Spotts spoke to me after the meeting.

SPOTTS: I am bothered. I asked, why are we going to be so slow on the reaction? The industry has a big hold on this state.

WERTZ: The industry needs these disposable wells because the drilling process produces a lot of waste water. It's briny and laced with metals and chemicals. To keep it away from drinking water, energy companies inject it into deep disposal wells like this one in a field behind a drugstore in southeast Oklahoma City.

Three large green tanks sit on a patch of gravel enclosed by a metal fence. Signs warn that I'm under video surveillance. This disposal well is named Chambers. It's one of the highest volume disposal wells in the state, taking in water at a rate of one and a half million barrels a month on average. It's one of four wells that attracted the attention of Katie Keranen. She's a geophysics professor and research seismologist at Cornell University.

KATIE KERANEN: These extremely high rates can cause a very large area to be stimulated or perturbed in the subsurface.

WERTZ: Knowing what's going on underground is key to understanding how wastewater might trigger earthquakes. Keranen and her team built a three- dimensional model of the rock layers, faults and water formations underneath an area northeast of Oklahoma City that's become one of the most earthquake prone parts of the state. They wanted to find out how the wastewater flows underground.

KERANEN: The area that is perturbed away from these wells is very large. So it's tens of kilometers away from the wells. You actually see a pressure increase in the subsurface.

WERTZ: Keranen's research shows that wastewater can travel a lot farther away from a well than previously thought.

KERANEN: As you create this bigger pressurized area, you're more likely to find a bigger fault that's, you know, able to be pushed over.

WERTZ: And that could cause an earthquake.

BILL ELLSWORTH: It's very interesting work.

WERTZ: Bill Ellsworth is with the U.S. Geological Survey.

ELLSWORTH: We've known for years that earthquakes can be triggered remotely by the influence of increasing pore pressure at distances of up to six miles. But this has extended that distance considerably, according to their hypothesis.

WERTZ: While the new research suggests that high-volume disposable wells might be playing a big role in Oklahoma's surge of earthquakes, it doesn't blame any specific well for causing the quakes. Scientists say they will likely never have the data they need to prove that kind of cause and effect. The company that owns the wells highlighted in Keranen's study declined an interview request, but dismissed the findings in an email. Oklahoma regulators call the study significant. Spokesman Matt Skinner...

MATT SKINNER: This is a very important piece that needs to be carefully reviewed.

WERTZ: Skinner suggests that if Keranen's research is correct, the problem could actually be easier to manage. That's because while Oklahoma has thousands of these wastewater wells, regulators might only have to write rules for the small number of high-volume wells that may be causing the most shaking.

For NPR News, I'm Joe Wertz in Oklahoma City.

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