Dueling Studies Continue the Debate Over Fracking Earthquakes

Dueling Studies Continue the Debate Over Fracking Earthquakes
City of Irving

Southern Methodist University seismologists recently revealed human-induced earthquakes in North Texas are not only caused by oil and gas operations but also have been occurring since the 1920s across Texas. Oil and gas industry professionals were quick to denounce seismologists findings, and the Texas legislature was quick to take action by calling for its own study, to be conducted by a team of experts appointed by the governor. 

In their May 2016 report, titled "A Historical Review of Induced Earthquakes in Texas," the study's lead author Cliff Frohlich, an associate director at the Institute for Geophysics at the University of Texas at Austin, pointed out that while earthquakes are caused by oil and gas operations, the specific reasons for these quakes have differed over the decades.

“I think we were all looking for what I call the silver bullet, supposing we can find out what kinds of practices were causing the induced earthquakes, to advise companies and regulators,” Frohlich noted in the study. “But that silver bullet isn’t here.”

Still, Frohlich said the evidence presented in the study should finally silence the naysayers among state officials. But oil and gas industry officials and think tanks say they doubt the study's conclusions.

Kate Zaykowski, a public information officer for Texas Oil & Gas Association, indicated the Texas legislature has appropriated almost $4.5 million to form a Governor-appointed technical advisory committee to investigate “more thoroughly” the recent seismic activity affecting North Texas.

She also took a shot at the study. “In reference to the SMU study, legitimate questions have been raised about the methodology and assumptions made,” Zaykowski wrote in a July 29 email response to the Observer.

Shortly after the study's release in May, Steve Everley, a senior advisor for Energy In Depth, also took a shot at the study when he claimed SMU seismologists' test was based on a “subjective approach” and excluded subsurface pressures — “a glaring omission,” he wrote in a May 17 article. He questioned the study's authors use of a question-based system to review the historical data.

The questions include "timing," if the earthquake occurred during the commencement of nearby petroleum production or fluid injection operations; "spatial correlation," if the epicenters were spatially correlated with production or injection operations; "depth," if the focal depths of the earthquake occurred near production or injection depths; "faulting," if faults were mapped near the production or injection operations or if the linear groups of epicenters lie along the fault; and if there are credible published paper or papers linking the earthquake to production or injection operations. 

Everley claims that analyzing subsurface pressures was based on research from the Environmental Protection Agency, which established the importance of linking pressure and geological pathways to human-induced earthquakes. Everley also cites evidence presented by state regulatory agencies in a report called "Potential Injection-Induced Seismic Associated with Oil & Gas Development." He even quotes a portion of the study: "Understanding induced seismicity requires knowledge about the relationship between injection activities and the activation or reactivation of faults, including the effects of pore pressure increases from injection and the spatial and temporal relationships between injection and critically stressed faults." 

Frohlich said in his study that he removed the subsurface pressure considerations because "this information is available for few events and, when reported, often relies on somewhat arbitrary (and arguable) assumptions about subsurface structure and flow properties." Everley disagrees. 

Energy In Depth, however, did agree in another article titled "Underground Wastewater Disposal" that wastewater injection wells sometimes do cause earthquakes but pointed out that the U.S. Geological Survey claims, “Only a small fraction of these (40,000) disposal wells have induced earthquakes that are large enough to be of concern to the public.” But the federal agency also reported that approximately 7 million people currently live in areas prone to earthquakes, including Dallas. 

The oil and gas industry, though, isn't completely resistant to calls of protecting the environment from unneeded harm like human-induced earthquakes, and current advances in oilfield technology over the past decade has made old and new oil and gas extraction techniques more affordable to implement and less damaging to the environment.  

One way developed to cut costs and lessen environmental impact involves recycling wastewater. The oil and gas industry’s recycling process combines flowback water (water, clay, chemical additives, dissolved metal ions and total dissolved solids) or produced water (water, barium calcium, iron and magnesium, as well as methane, ethane, and radium isotopes) with brackish water, a resource found in aquifers and unfit for consumption or agriculture use.

Devon Energy, BHP Billiton and the Apache Corporation are currently using this process in West Texas, reducing their freshwater use, in some cases, by 20 percent of total water used, according to the Texas Oil & Gas Association. Companies like Apache and Pioneer Natural Resources are also implementing another fairly new process: buying treated wastewater from municipal wastewater plants.

Buying municipal wastewater is a fairly new use for treated water that usually either returned to the water cycle or was reused for other municipal purposes, as in the case of Wichita Falls when they use treated wastewater as drinking water during the last drought. Cities across North Texas have been known to sell their drinking water to oil and gas companies in the past.

But these water conservation efforts by the oil and gas industry don’t stop with recycling contaminated water or buying treated wastewater.

The Texas Oil & Gas Association points out that oil and gas companies like Anadarko Petroleum have invested millions of dollars in recent years in water management, conservation, recycling and water infrastructure projects. Concho Resources, Inc., has partnered with the Gulf Coast Waste Disposal Authority on a water reuse system in Odessa, a small city about four hours west of Dallas.

The upside to recycling contaminated water or using treated wastewater: oil and gas companies are flushing less contaminated water down an injection hole. The downside: They’re still flushing contaminated water down an injection hole, an action SMU seismologists warn could be causing earthquakes. In April 2015, they connected wastewater injection combined with saltwater extraction from natural gas wells as the probable cause to earthquakes occurring in late 2013 through spring 2014 near Azle, a suburb of west Fort Worth.

Despite oil and gas companies striving to control their water addiction by reusing dirty water, activists like "Texas" Sharon Wilson claim the oil and gas industry is simply about cutting corners to save money, not developing new technology to lessen the environmental impact of its activities.

Recycling wastewater, for example, creates a whole new level of impacts on the environment, Wilson says, because the water needs to be stored somewhere. Usually a big pit or tanks with vents. “Either way, it lets off gasses,” she says.  

“I’ve been to oil and gas patches in about 13 states,” Wilson says. “If there is such a thing as responsible drilling or fracking, I’ve yet to see it.”


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