High-volume wastewater disposal wells likely have contributed to the swarm of earthquakes in central Oklahoma over the past few years, according to an updated report from a team led by former OU researcher Katie Keranen.
Now a professor at Cornell University, Keranen’s latest research shows that wastewater disposal wells can cause quakes more than 18 miles away, far more than the previously understood range of about three miles. With that range and pressure, the disposal wells could be responsible for the earthquake swarm the state has experienced over the past three years, the report published Thursday in the journal Science stated.
“The disposed fluids are capable of contributing to the seismic activity,” Keranen said in an interview with The Oklahoman. “These wells are capable. That doesn’t exclude anything else from contributing, but we have no reason to think these are tectonic. They don’t match tectonic activity in other areas. It does seem these are just linked to wastewater. Our research focuses on wastewater and shows it is sufficient.”
Oil and natural gas industry leaders, however, expressed some skepticism.
“Dr. Keranen’s study is just one part of continuing research into the increase of seismic activity in Oklahoma,” Mike Terry, president of the Oklahoma Independent Petroleum Association, said in a statement. “Others have focused on the state’s ongoing drought and previous seismic activity in the 1950s similar to recent seismic trends. The OIPA and the oil and gas industry as a whole support the continued study of Oklahoma’s increased seismic activity, but a rush to judgment based on one researcher’s findings provides no clear understanding of the causes.”
Industry leaders also have pointed to their ongoing cooperation with researchers and regulators.
“As an industry, we’ve been saying we need more data and we need to work with regulators and others to help determine what is causing the significant increase in seismic activity,” said Chad Warmington, president of the Oklahoma Oil and Gas Association. “But to unequivocally link it to wastewater injections, I think there still needs to be more research. “
Some attendees at a town hall meeting in Edmond last week called for a moratorium on injection wells or all oil and natural gas activity. Keranen said such steps are unwarranted.
“The vast majority of wells in Oklahoma are operating benignly. There would be no basis for changing their operation,” she said. “The goal is to figure out if there is something we can identify to focus on monitoring, policy and best practices that will bring all the wells to safe operating practices. The ultimate goal is safety. We don’t need extreme action.”
The study focused on 89 disposal wells in central Oklahoma. The report stated that four high-volume wells could have contributed to up to 20 percent of the recent outbreak.
“They might consider drilling more wells with less pressure each,” Keranen said.
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Sometimes referred to as fossil water, wastewater is recovered from deep below the surface along with oil and natural gas. The average Oklahoma oil well produces 10 barrels of the highly salty water for every barrel of oil.
Keranen’s team previously said it found a link between water disposal wells and the magnitude 5.7 quake centered near Prague in 2011. The Oklahoma Geological Survey, however, has said the Prague quake likely had natural causes.
Oklahoma Geological Survey seismologist Austin Holland told The Oklahoman this week that his agency appreciates the research Keranen’s team has conducted.
“It complements our work that we are currently doing or that has been published in the past and will improve the scientific discussion and understanding of what’s occurring in Oklahoma,” he said.
Keranen’s report states that disposal well injections have jumped in recent years as drilling activity has picked up. Industry representatives, however, point out that the state is dotted with more than 10,000 injection wells and that injection levels peaked along with oil production in the 1920s, 1950s and 1980s.
One possible difference, however, is that modern drilling techniques recover oil and water at a much higher rate per well. Operators also are moving more water to disposal wells through pipelines and relying less on tanker trucks.
The research is hampered, however, because detailed disposal volume information dates back only to the mid-1990s, she said.
Measuring long-term trends also is difficult because the state had no seismic monitors until the 1960s. More than a dozen additional monitors have been installed over the past three years.
Still, comparisons can be made to other parts of the country, Keranen said.
“Oklahoma is one area where we have data back only a number of decades, but we also have the rest of the world where we’re recording earthquakes,” she said. “This process is something we haven’t seen in recorded history in Oklahoma. We’re shifting to becoming active. It is an unusual phenomenon that has not been recorded.”
About 45 percent of the country’s magnitude 3 or larger earthquakes throughout from 2008 and 2013 were in Oklahoma, the report stated.
No other state — including California — contributed more than 11 percent.
Keranen said her team has shared the data and results with the Oklahoma Geological Survey and the Oklahoma Corporation Commission. What to do next is up to regulators.
Commission spokesman Matt Skinner said the agency received a copy of the study last week.
“It has been assigned to key OCC staffers for review and analysis,” Skinner said. “That effort is currently underway.”
While additional seismic monitors and data have helped, Keranen said more research is still necessary.
“I would like to do further studies on other higher-volume wells, especially in the northern part of the state where we’re seeing another swarm,” she said.