The head of the Oklahoma Geological Survey said recent earthquakes have helped scientists learn more about the state’s fault system.
Seismic activity is occurring in cluster along certain fault lines. OGS Director Jeremy Boak said when oil and gas activity increases — even miles away — so does seismic activity along those faults.
"We know that's where the earthquakes are going to happen. As long as we're convinced that injection is the cause, injection is going to be the solution," Boak said. "The question is, have we reduced it enough?"
In 2014, energy companies injected 1.4 billion barrels of waste water into the ground across Oklahoma. Most of it came from highly diluted plays where oil is about 1 percent of the fluid being extracted.
The average number of earthquakes a day in the state peaked several months after wastewater injection volumes did.
"We had very few earthquakes that could even possibly be attributed to injection before we got this very high level, so I think, ultimately, if you can bring that back down to the levels it was at, you're probably going to see the earthquakes die away," Boak said.
Despite a couple recent big ones, there’s been a drop in seismic activity in Oklahoma. Boak, however, doesn’t know if cutting back injection to 2009 levels is the answer, because part of the solution is knowing how much shaking bothers people.
"Because if we're having a small number of relatively small earthquakes, people are going to be less troubled about it than if we're having 900 a year," Boak said. "I'm just eager to see it keep going down, and if it starts to flatten out, we'll be talking about it and trying to figure out, 'OK. What's step next?'"
Boak gave an update on the geological survey's research during a lecture at the University of Tulsa on Wednesday.
