To the Editor:
Roger Matile’s recent column headlined “Reflections: There’s a whole lotta shakin’ going on…” endorses the myth that hydraulic fracturing is the cause for Oklahoma’s recent earthquakes.
Experts actually agree the likely cause of Oklahoma’s spike in earthquakes is wastewater disposal from day-to-day oil and gas production – not fracking, which is a separate well-completion process. In fact, Stanford geophysicist Mark Zoback has said, quite bluntly, of the spike in seismic activity in Oklahoma, "It is not caused by the hydraulic fracturing process at all…”
To understand Zoback’s assessment, it is important to understand the difference between fracking and wastewater disposal.
Fracking refers to a well stimulation/completion process that enhances the flow of oil or natural gas from a production well. It is typically conducted on just one occasion on a newly-drilled well before that well goes into production, and it usually lasts a just a few days.
Wastewater disposal, on the other hand, consists almost entirely of the injection of wastewater from day-to-day production into a designated disposal well over the lifespan of a production well.
Media reports often indicate that most, if not all, the wastewater being disposed of in Oklahoma injection wells is spent fracking fluid or “flowback” water. This is untrue. A vast majority of it is the brackish, salty wastewater also known as brine or “produced” water.
“Produced” water is generated from oil and natural gas wells regardless of whether hydraulic fracturing is used. This is because hydrocarbon-bearing formations typically contain plenty of water from ancient oceans that naturally coexists with oil and gas within the Earth. This water is pumped to the surface along with oil or natural gas. Even without the use of fracking, underground disposal of wastewater would be needed because of the large volumes of “produced” water generated from oil and gas production.
For instance, most of the wastewater – between 90 to 95 percent – that is disposed of in Oklahoma injection wells is “produced” water that comes up with oil and gas during day-to-day production over the lifetime of a well.
Notably, thousands of wastewater disposal wells have been operating in Illinois for 100 years without a single instance of induced seismicity. Still, Illinois’ active seismic history was carefully considered during the drafting of the Illinois Hydraulic Fracturing Regulatory Act. Section 1-96 requires the IDNR to adopt rules in conjunction with the Illinois Geological Survey to establish a protocol for controlling operational activity of injection wells in instances of induced seismicity. Essentially, if a significant level of seismicity is detected near an injection well, injection will be scaled back or shut down completely.
Understanding that wastewater injection is the likely cause of Oklahoma’s earthquakes is essential to understanding why there is an exceedingly low risk of the same thing happening here in Illinois, where injection wells have been extensively regulated and operating without induced seismicity for decades.
Illinois Petroleum Resources Board
St. Peter, Illinois