By: Isaac Orr
Major media outlets are blaming a recent magnitude 5.6 earthquake that struck near Pawnee, Oklahoma on the disposal of hydraulic fracturing wastewater, proving once again many news editors know very little about the science behind hydraulic fracturing and the available research showing the process is relatively safe.
As many news reports have indicated in recent days, Oklahoma has experienced an increase in earthquakes, and it’s likely due to the disposal of wastewater generated by oil and natural gas production into underground injection wells. What they fail to report, however, is the vast majority of this wastewater is produced by oil production in the Mississippian Lime formation, where fracking is not used.
The Mississippian Lime is an oil-producing limestone formation that could be characterized as a saltwater formation that sometimes produces oil. Energy producers drill into this formation, which brings to the surface large amounts of saltwater and oil. As much as 10 barrels of this salty wastewater are co-produced for every barrel of oil brought to the surface.
According to Mark Zoback, a Stanford University geophysicist who conducted an extensive study on the earthquakes in Oklahoma, the amount of wastewater generated from energy production in the Mississippian Lime formation dwarfs the amount of wastewater generated from the hydraulic fracturing process.
Fracking does generate wastewater—approximately 800,000 to one million gallons per well—but the U.S. Geologic Survey (USGS) reports hydraulic fracturing wastewater comprised less than 10 percent of the total wastewater injected into disposal wells from oil and natural gas production in the three areas of Oklahoma experiencing the most seismicity. This means headlines linking the earthquakes in Oklahoma to disposal of fracking fluids, rather than wastewater produced from conventional oil production in the Mississippian Lime, are incorrectly attributing the cause of the quakes to fracking.
This distinction might be of little consolation to people living in the parts Oklahoma that are experiencing significant seismic activity, but it is important policymakers and the public understand where the vast majority of wastewater is coming from so that good public policy decisions will be made now and in the future.
Anti-fracking groups have sought to use these earthquakes as a means to justify a ban on fracking, but such a ban would not solve the earthquake problem. Instead, policymakers should continue to develop a regulatory framework that is designed to allow for the extraction of natural resources while also eliminating earthquakes.
To their credit, Oklahoma regulators responded quickly to the recent earthquake; they ordered 37 disposal wells to be shut down within a 500 square-mile area after the magnitude 5.6 quake occurred. This was done in addition to the passage of restrictions that had already been enacted by the Oklahoma Corporation Commission (OCC). The OCC restrictions reduced the annual wastewater injection volume by 40 percent below 2014 volumes in 406 disposal wells in the state. The OCC regulations have been credited, at least in part, for the 22 percent decrease in the number of earthquakes in the area from this time in 2015 to today.
In a video explaining the connection between disposal wells and earthquakes, Zoback explains energy producers in the Mississippian Lime formation can also reduce the volumes of wastewater they inject into disposal wells, and thus reduce the potential for earthquakes, by reinjecting the naturally occurring wastewater back into the formation it came from—the Mississippian Lime—instead of injecting it into the Arbuckle formation, as it does now. This costly change will take time, but it will control the earthquakes, according to Zoback.
These policies, coupled with the reality low oil prices make production in the Mississippian Lime formation uneconomical to develop, will lead to fewer earthquakes in the future, but banning fracking will only drive out of business a number of companies that aren’t harming anyone.
Isaac Orr () is a research fellow for energy and environmental policy at The Heartland Institute. Follow him on Twitter @thefrackingguy.