Seismic shift: Oklahoma’s earthquakes triggered by wastewater disposal wells

Michael Walsh
Drilling rigs dot the landscape in northern Oklahoma on Nov.17, 2013. (Les Stone/Corbis)

The onslaught of seismic activity in Oklahoma in recent years has captured the attention of the nation.

State scientists say they have uncovered the root cause of the majority of the state’s earthquakes: the oil and gas industry’s disposal of billions of barrels of water underground.

Now, as the public absorbs this information, Oklahoma’s regulatory bodies are keeping a watchful eye on these disposal wells and planning their next moves.

Link between earthquakes and industry

On Tuesday, the Oklahoma Geological Survey (OGS) issued its most strongly worded statement yet linking the oil and gas industry to the state’s earthquakes.

State geologist Richard D. Andrews and state seismologist Austin Holland say the spike in earthquakes — particularly in central and north-central areas of the state — is “very unlikely to represent a naturally occurring process.”

“The primary suspected source of triggered seismicity is not from hydraulic fracturing but from the injection/disposal of water associated with oil and gas production,” the report from the Oklahoma Geological Survey (OGS) reads.

The seismicity rate in Oklahoma is about 600 times greater than it was before 2008, around the time dewatering started in the state.

Oklahoma Geological Survey seismologist, Austin Holland, installs a seismometer in southwest Oklahoma City, Okla., on January 26, 2015. (Linda Davidson/The Washington Post/Getty Images)

Just last year, 585 magnitude 3+ earthquakes hit Oklahoma — compared with 109 in 2013.

“The rates have increased phenomenally since just a few years ago,” Andrews said in an interview with Yahoo News. “We feel we had to make a statement.”

For the dewatering process, extremely salty water, which coexists with oil and gas below the Earth’s surface, is separated from those substances after extraction. Then barrels of wastewater are deposited into wells far deeper than their point of origin.

Some of this wastewater is a byproduct of hydraulic fracturing, or fracking: a process in which high-pressure liquids are blasted beneath the ground to fracture rock, releasing natural gas. But fracking only accounts for a small percentage of the water deposited in these wells.

How this happens

The majority of the state’s wastewater is deposited in the Arbuckle formations, which are underground reservoirs of dolomite, limestone and other rocks.

Parts of the Arbuckle are highly fractured with expansive systems of cavities and caverns that the energy sector found perfect for dumping wastewater.

“It is known to have bulk porosity, voids in the rocks that can hold fluids,” Andrews said. “They don’t need to inject the water under any other pressure. They just funnel it in. It will take as much water as you can put into it.”

Much of the wastewater, with much higher salinity levels than ocean water, travels many miles away from its injection site and seeps into the underlying crystalline basement; such permeability makes it difficult to link a specific well with seismic activity.

It can take anywhere from weeks to more than a year of this water pouring in before it triggers naturally occurring stresses in the Earth — causing earthquakes.

“There are faults pretty much all across the country. It doesn’t take much change to the system to cause those faults to slip. Those wells are providing the little bits of change needed,” Briana Mordick, a staff scientist for the Natural Resources Defense Council, told Yahoo News.

Most of the earthquakes have occurred within the crystalline basement, on faults within Oklahoma’s tectonic stress regime, according to the OGS.

“Water and fault zones are a formula for seismicity,” Andrews said. “We do have the science to back it up.”

Maintenance workers inspect the damage to one of the spires on Benedictine Hall at St. Gregory's University in Shawnee, Okla. on , Nov. 6, 2011. Two earthquakes in the area in less than 24 hours caused one of the towers to topple, and damaged the remaining three. A team of scientists have determined that a 5.6 magnitude quake in Oklahoma in 2011 was caused when oil drilling waste was injected deep underground. (Sue Ogrocki/AP Photo)

Restrictions on oil and gas companies

The Oil and Gas Conservation Division of the Oklahoma Corporation Commission (OCC) is the governing body that regulates the state’s oil and gas companies.

Matt Skinner, a spokesman for the division, says the group’s number one mandate is water protection and that given the current state of affairs its top concern is seismicity.

“The thing we face as an agency under Oklahoma law is that we have to be able to show that what we’re doing in not arbitrary or capricious and is not considered a taking of private property,” Skinner told Yahoo News.

Private property laws are exceptionally strong in the state; natural gas and oil are often privately owned.

In response to OGS’s findings, the commission has already started requiring seismicity reviews for all proposed disposal wells and limiting how many wells can get permits for a particular area.

They also started to run a “traffic light” system: A “red light” indicates that well operators cannot reingest wastewater because it would go directly into a fault, whereas a “yellow light” indicates that there are enough concerns with the location that the well operator must agree to particularly strict terms that are subject to change.

The OCC started working on seismicity in 2010 as more of an “academic interest” and eventually teamed up with the OGS after learning about its ongoing research; urgency rose concurrently with earthquakes.

“Oklahoma has had seismic events. It’s a seismically active state, but nothing like we are seeing now,” Skinner said.

Due to the aforementioned property laws, the OCC had been dealing with culpable parties with a well-by-well approach — tracking pollution back to its source and holding the operator accountable. With the seismic upswing, this approach became untenable.

On April 18, the commission issued new directives for 347 of the roughly 900 Arbuckle disposal wells in Oklahoma. Each operator was required to show that it did not go too deep.

In response, roughly 25 disposal wells have ceased operations — at least temporarily.

“We quite frankly thought we would have a court challenge to that directive,” Skinner said. “Anyone who is ignoring a division directive does so at their peril. They would have their day in court, but if they lose, the penalty may even be higher.”

Oklahoma Geological Survey seismologist Amberlee Darold wires a solar power panel to a seismograph in southwest Oklahoma City, Okla., on January 26, 2015. (Linda Davidson/The Washington Post/Getty Images)

Industry response

The Oklahoma Oil and Gas Association issued a statement saying additional research is needed to determine how the wells can be operated without causing more earthquakes.

“There may be a link between earthquakes and disposal wells, but we — industry, regulators, researchers, lawmakers or state residents — still don’t know enough about how wastewater injection impacts Oklahoma’s underground faults,” Chad Warmington, the trade association’s president, said in the statement.

Warmington argued that a moratorium on disposal wells is not feasible.

The Oklahoma Independent Petroleum Association shared a statement regarding the OGS findings when contacted by Yahoo News for comment.

Kim Hatfield, chairman of the association’s regulatory committee, said the board will continue to work with the Governor’s Coordinating Council on Seismic Activity, the OCC and the OGS to understand the “possible relationship” between the oil and natural gas industry and earthquakes.

“The OIPA has led cooperative efforts between Oklahoma oil and natural gas companies and the state’s researchers and regulators studying Oklahoma’s increased seismic activity, and we are confident that the cooperation between public and private entities will offer a rational and reasonable response to seismic activity concerns,” he said in the statement.

Hatfield, who is also president of Crawley Petroleum, went on to say that the state’s oil and natural gas producers have a proven history of developing the state’s resources “in a safe and effective manner.”

In this Friday, July 20, 2012 photo, pipe for a pipeline is readied for installation near a drilling rig, near Calumet, Okla. (Sue Ogrocki/AP Photo)

The two big oil and gas trade groups — to their credit — have told their members to cooperate with the directives, according to Skinner.

Trade associations by definition advocate on behalf of their industries’ interests, so these sorts of responses are to be expected.

But for many critics, they only exacerbate the problem and widen the knowledge gap between the scientific community and the general public à la climate change or evolutionary biology.

“Putting it all together in one place draws a line in the sand,” Skinner said of the OGS statement. “A lot of the debate that still lingers is over with.”

Environmentalist response

Briana Mordick said the scientific community has known for decades that injecting or moving fluids underground can trigger earthquakes.

The geologist still wants regulators to place more restrictions on the gas and oil industry, but she was glad to see OGS use such strong language.

“After sort of dragging their feet for quite some time, they took a good and important step forward, showing there is a clear link between these injection wells and the earthquakes. So I’d say it’s a welcome development,” she said to Yahoo News.

Oklahoma earthquake map. (USGS)

Mordick used to work in the oil and gas industry as a petroleum geologist but left to focus on mitigating its environmental impact.

She criticized the trade groups’ responses to the OGS findings, that experts “still don’t know enough,” as a misleading justification for inaction.

“There’s certainly more science to do and information to gather, but there’s enough right now that we can act,” she said. “The science is clear enough right now that there is a clear reason to act right now. Sure, there’s definitely going to be more to learn, but we don’t need to wait.”

Jesse Coleman, a researcher at Green Peace, agrees that the appeal for more research before decisive action has run its course.

“I don’t know how many more studies would be enough to convince the oil and gas industry that their practices are dangerous,” he said to Yahoo News. “Nobody really knows what to do with the now-contaminated water.”

Throughout the country, he said, the industry has tried to dump the wastewater in rivers or spread it on roads, causing serious contamination issues.

Coleman said that burying the water is clearly not a sustainable solution.

“If an industry cannot be responsible for cleaning up the pollution it creates, it shouldn’t be allowed to use public resources as their dumping ground,” he said.

In this Friday, July 20, 2012 photo, Workers are pictured on a drilling rig near Calumet, Okla., on July 20, 2012. (Sue Ogrocki/AP Photo)

Broader implications

Disposal wells are potentially a problem wherever they are located, but different states need to allocate their resources to address their unique circumstances and concerns.

Differences in geology and the prevalence of certain practices dictate where state environmentalists and regulators focus their energies. For instance, Ohio has closed down multiple disposal wells, but the state’s primary concern is fracking.

The Interstate Oil and Gas Compact Commission, an organization of state regulatory bodies, is dedicated to maximizing oil and natural gas resources while protecting the health of the nation and the environment.

Gerry Baker, associate executive director of the commission, said its 30 members states, which represent 99 percent of the nation’s oil and gas production, have teamed up with the Groundwater Protection Council to form the States First Coalition.

Together, they want to give states the tools to develop regulations that deal with issues — such as wastewater disposal wells — as they see fit.

“There is very different geology across the country, and there are all kinds of factors in play,” Baker said to Yahoo News. “We don’t pretend to believe that there is a one-size-fits-all approach.”

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