Oklahoma Earthquakes Continue To Haunt the Oil and Gas Industry

The fracking industry got another shot of bad news on March 4, when Oklahoma regulators leaked word that a clampdown on oil and gas wastewater disposal would begin soon.

The new actions are the latest attempt to quell a spate of earthquake activity in the state, which has been linked to the practice of injecting massive quantities of fracking wastewater deep underground, in addition to wastewater from conventional drilling sites.

Oklahoma earthquake response: Round one

The numbers that link oil and gas wastewater disposal rates to earthquakes in Oklahoma are fairly straightforward. Wastewater disposal volumes rose 81 percent over the past six years, while earthquakes increased from an average of twice yearly to the current rate of twice daily.

The problem consists of making a direct connection between specific disposal wells and earthquakes. However, the U.S. Geological Survey has collected enough data to assert confidently that there is "a strong connection in many locations between the deep injection of fluids and increased earthquake rates."

Apparently the pileup of evidence finally convinced the OCC (Oklahoma Corporation Commission) to act last spring and summer, when it began asking companies in some parts of the state to trim their wastewater injection rates and to shorten their disposal depths.

Most agreed, with the exception of Sandridge Energy.

Oklahoma earthquake response: Round two

With earthquake swarms still occurring at a record pace through last fall, the OCC took a series of actions culminating in January 2016, when Sandridge agreed to cut its disposal rate by 40 percent. That involved closing eight wells altogether and reducing operations at 36 others. The company also agreed to provide nine wells to researchers for study.

On Feb. 16, the OCC implemented a more ambitious, region-wide approach recommended by seismologists and to be conducted over the next two months. As a first step in the plan, the agency ordered a reduction in wastewater disposal for 245 additional wells in the Arbuckle formation, located in the south-central part of the state. The Arbuckle is the deepest geological formation in Oklahoma, and in a press release outlining the earthquake response plan, OCC noted:

"Researchers largely agree that wastewater injection into the Arbuckle formation poses the largest potential risk for earthquakes in Oklahoma."

That observation probably stems from a 2015 earthquake report from Stanford University:

"Stanford geophysicists have identified the triggering mechanism responsible for the recent spike of earthquakes in parts of Oklahoma – a crucial first step in eventually stopping them," wrote Ker Than for the Stanford Review.

"In a new study published in the June 19 issue of the journal Science Advances, Stanford Professor Mark Zoback and doctoral student Rall Walsh show that the state's rising number of earthquakes coincided with dramatic increases in the disposal of salty wastewater into the Arbuckle formation, a 7,000-foot-deep sedimentary formation under Oklahoma."

The researchers also noted that most of the wastewater now being disposed in the Arbuckle formation consists of wastewater re-injected from producing wells, not the fracking brine that is used to drill new wells. (Fracking is short for hydraulic fracturing, a drilling method that involves injecting chemical-laced brine into shale formations.)

Oklahoma earthquake response: Round three

In the latest action on March 5, Corey Jones of Oklahoma's Tulsa World paper reported that the OCC will extend its plans to take preemptive action in areas of the state where seismic activity has not yet accelerated.

The agency is not yet ready to publicize the next step, but the idea is to prevent earthquakes from "fanning out" into new areas, Jones reported.

Another report places the new area of earthquake response in central Oklahoma, encompassing 5,000 square miles. The area includes more than 400 injection wells, dotted around a number of cities including Edmond, Luther, Perry, Stillwater and Pawnee.

The Los Angeles Times followed up with an in-depth article on March 6 under the headline, "Oklahoma Takes Action On Fracking-Related Earthquakes — But It’s Too Late, Critics Say." LA Times reporter William Yardley anticipates that the state will continue to ramp up its earthquake response, particularly because the surge in seismic activity is intruding into new areas, where residents are wealthier, politically-connected or both.

New earthquake area on the map

It looks like regulators have some catching up to do. On March 3, John Green of the Hutchinson News, a Kansas newspaper, reported that a new swarm of seismic activity was recorded last week near the town of Waynoka, which previously had no record of quakes.

As described by Green, the Waynoka region is located north and west of an area that has seen seismic activity in recent months, and south of another active area.

Meanwhile, geologists are concerned that another fault under Edmond, about 100 miles south, could produce more damaging earthquakes. The potential for damage to Cushing, a key storage and transportation hub for the nation's oil and gas industry, is also concerning researchers and planners.

Fracking not off the hook

To be clear, Oklahoma's earthquake problem is linked to wastewater disposal from oil and gas production in general, not solely to fracking itself.

For impacts more specific to fracking, the picture looks increasingly gloomy. For example, one recent, limited study of 23 fracked wells in Ohio has apparently failed to turn up evidence that local water resources have been compromised. But the cumulative evidence from other studies indicates that fracking can pollute local wells and produce other impacts.

In the latest development on that score, in January a team of researchers from Harvard tracked a surge in methane emissions from the U.S. corresponding to the increase in fracking, suggesting a causal relationship between the two.

Image via USGS.