There have been more earthquakes strong enough to be felt in Oklahoma this year than in all of 2013, overwhelming state officials who are trying to determine if the temblors are linked to oil and natural gas production.
The state on April 6 experienced its 109th earthquake of a magnitude 3 or higher, matching the total for all of 2013, according to Austin Holland, a research seismologist with the Oklahoma Geological Survey. More quakes followed, including a magnitude 4 near Langston about 40 miles (64 kilometers) north of Oklahoma City.
A surge in U.S. oil and gas production by fracturing, or fracking, in which drillers use a mix of water and chemicals to coax liquids from rock formations, has generated large volumes of wastewater. As fracking expanded to more fields, reports have become more frequent from Texas to Ohio of earthquakes linked to wells that drillers use to pump wastewater underground.
“We certainly likely have cases of earthquakes being caused by different oil and gas activity,” Holland said in an interview. “Evaluating those carefully can take significant amounts of time, especially when we’re swamped.”
Within the past year, earthquakes thought to be tied to wastewater disposal wells were recorded in Azle, Texas; Jones, Oklahoma; and northeastern Ohio, according to Art McGarr, a geophysicist with the U.S. Geological Survey in Menlo Park, California.
Pumping fracking wastewater underground has been linked to a sixfold jump in quakes in the central U.S. from 2000 to 2011, according to the science agency, part of the Interior Department.
State regulators last year curtailed operations at one Love County injection well and shut down a second after a series of earthquakes in the area, according to Matt Skinner, a spokesman with the Oklahoma Corporation Commission. State officials are analyzing a swarm of earthquakes in the past 10 days near Langston, he said.
“This is the area we’re most concerned about,” Skinner said in an interview “We do have injection wells in the area.”
The ability to inject drilling wastewater underground is critical to the state’s oil and gas producers, according to Chad Warmington, president of the Oklahoma Oil and Gas Association, an industry group previously known as the Mid-Continent Oil and Gas Association of Oklahoma.
So far the link between injection wells and earthquakes isn’t conclusive, Warmington said.
“We’re trying to make sure we understand what data the state needs in order to start making some determinations on cause and effect” he said in an interview. “We don’t want anybody to jump to conclusions.”
The number of injection wells with suspected connections to earthquakes is a small fraction of total wells, according to America’s Natural Gas Alliance, an industry group in Washington.
Oklahoma’s biggest recorded earthquake, a 5.7-magnitude temblor near Prague, Oklahoma, on Nov. 6, 2011, was linked to wastewater wells by researchers from the University of Oklahoma, Columbia University and the U.S. Geological Survey.
The state’s geological office said the connection was inconclusive. Prague is about 50 miles east of Oklahoma City and 65 miles southwest of Tulsa.
State regulators last month said well operators should have to record injection well pressure daily instead of monthly. The rule needs state legislature approval and the signature of Governor Mary Fallin.
Arkansas and Ohio have also addressed earthquakes thought to be caused by injection wells with new regulations. Regulators from Kansas, Texas, Oklahoma and Ohio met for the first time in April in Oklahoma City to exchange information on the man-made earthquakes and help states toughen their standards.
“If we shut down injection wells we’re shutting down oil and gas production in the state,” Holland said. “You certainly don’t want to go shut down a hundred disposal wells in an area and not have the evidence to back that up.”