Regulators, researchers release update on fracking-related quakes
Oklahoma regulators and researchers said Tuesday new protocols to manage and prevent earthquakes linked to hydraulic fracturing operations are showing positive results in the first six months.
The update from the Oklahoma Corporation Commission and the Oklahoma Geological Survey said regulators contacted oil and gas operators about 27 seismic events greater than magnitude-2.5 since the protocols were released in December.
Those hydraulic fracturing-related events happened broadly in the fast-growing SCOOP and STACK formations west and southwest of Oklahoma City. They were mostly in Canadian, Kingfisher, Grady, Blaine and McClain counties.
“The actions taken under the directive have been in response to events that have occurred away from the Arbuckle injection wells that have been linked to most of the earthquake activity in the state,” said Tim Baker, director of the Corporation Commission’s oil and gas division. “Researchers have linked some of this smaller and relatively rare activity outside the main earthquake area to well-completion operations, including hydraulic fracturing.”
In contrast to deeper earthquakes linked to disposal of wastewater from oil and gas
production, researchers said fracking-related quakes are shallower and don’t appear to reactivate basement faults.
“Based on the present data, wastewater disposal into the Arkbuckle Group, not hydraulic fracturing operations, poses the highest risk when it comes to induced earthquake activity,” said Jeremy Boak, director of the Oklahoma Geological Survey.
The 27 seismic events related to well-completion activities happened within 1.25 miles of a hydraulic fracturing operation. Some operators had already noted the seismicity on a tool called a seismic array and had begun mitigation actions by the time regulators notified them of the issue.
Boak said in the cases where companies took mitigation actions, the earthquake activity stopped quickly or tapered off.
However, Baker said not all companies have seismic arrays.
“Not all operators have these proprietary arrays, and any response by the OCC is and must be based on the proven expertise, monitoring and data provided by the Oklahoma Geological Survey,” Baker said. “This data is not only critical for the public today, but also as part of the overall research effort.”
Still work to do
State Seismologist Jacob Walter said the research and regulatory response to the rise of seismicity in Oklahoma remains a work in progress.
“When it comes to all forms of induced seismicity, we know far more now than we did only a few years ago, but there’s much work that remains,” Walter said.
The Corporation Commission has limited wastewater injection into the deep Arbuckle layer in a broad area of northern and northwestern Oklahoma. Those actions affect more than 650 disposal wells in the Arbuckle layer.
The state’s two largest energy groups, the Oklahoma Independent Petroleum Association and the Oklahoma Oil and Gas Association, said the new protocols for handling earthquakes linked to hydraulic fracturing and other completion activities were working well for operators.
“The OIPA has led cooperative efforts between Oklahoma oil and natural gas companies and the state’s researchers and regulators studying Oklahoma’s seismic activity,” said Kim Hatfield, chairman of OIPA’s regulatory subcommittee on seismicity. “We are confident that the cooperation between public and private entities has offered a rational and reasonable response to seismic activity concerns.”
Chad Warmington, president of the Oklahoma Oil and Gas Association, said the anomalous seismic events outside the Corporation Commission’s areas of interest were “small, rare and manageable.”
“OKOGA member companies are working to exceed the standards set by the state,” Warmington said. “These companies are using the latest technology and best available science, and they are also actively a part of the OKOGA operators’ committee where industry is regularly discussing best practices and reviewing the latest research on this issue.”
Until 2009, Oklahoma averaged about one earthquake higher than magnitude 3.0 per year. But that spiked to more than 900 in 2015 before falling to 623 last year. If the number of quakes in that category remains at the same rate as this year, Oklahoma could end the year with about 260 quakes higher than 3.0.
However, the state’s largest recorded earthquake, a 5.8-magnitude, struck near Pawnee in September. It was followed by a 5.3-magnitude that hit downtown Cushing in November.
Walter said the geological survey continues to monitor and track seismic activity. Researchers are also studying possible links between initial small-scale seismic activity and later, larger events. They are also looking at how the physical properties of the Arbuckle layer and basement rocks may play a role in seismicity.