Report: Seismicity Linked to Wastewater Injection, Not Hydraulic Fracturing
Today, a new report focusing on recent seismic activity in Oklahoma – an issue that has garnered increased media attention in recent weeks – was published by the American Association for the Advancement of Science. According to the report, “the recent surge in central Oklahoma seismicity is attributable to injection of wastewater at a small number of exceedingly high-rate wells.”
It’s certainly not news that wastewater injection has, at times, been linked to small seismic events – but there are a few important takeaways from this new report that are worth highlighting.
Seismicity related to waste water injection, not hydraulic fracturing.
As the report indicates – and as a wide array of other studies have highlighted in the past – hydraulic fracturing poses an exceedingly low risk for seismic activity. According to the National Research Council (a research arm of the National Academy of Science), “The process of hydraulic fracturing a well as presently implemented for shale gas recovery does not pose a high risk for inducing felt seismic events.” Mark Zoback of Stanford University has also compared the seismic footprint of hydraulic fracturing to “on average, about the same amount of energy as a gallon of milk falling off a kitchen counter.”
Overwhelming majority of disposal wells show no signs of contributing to seismicity.
“Although thousands of disposal wells may operate aseismically, four of the highest-rate wells likely induced 20% of 2008-2013 central US seismicity.”
This echoes numerous other reports finding that the risk for seismicity associated with injection wells is also very low. For instance, the National Research Council stated, “Injection for disposal of wastewater derived from energy technologies into the subsurface does pose some risk for induced seismicity, but very few events have been documented over the past several decades relative to the large number of disposal wells in operation.”
The U.S. Geological Survey (USGS) has also commented on the issue, and how to rectify some of these concerns. According to USGS’s Bill Ellsworth, “…in many of these cases, it’s been fixed by either shutting down the offending well or reducing the volume that’s being produced. So there are really straight-forward fixes to the problem when earthquakes begin to occur.”
Okla. has a long history of safe disposal well use in the state
As president of the Oklahoma Independent Petroleum Association (OIPA) Mike Terry highlighted in response to the study, the state of Oklahoma has a long history of both oil and gas development and waste water injection. From OIPA:
“Disposal wells have been used in Oklahoma for more than half a century and have met and even exceeded current disposal volumes during that time. Because crude oil and natural gas is produced in 70 of Oklahoma’s 77 counties, any seismic activity within the state is likely to occur near oil and natural gas activity. We have also seen increased seismic activity in North America, including Idaho, Virginia, Arizona and northern Mexico, where dewatering projects and unconventional oil and gas development are nonexistent.”
It’s also important to remember that injection wells would exist with or without shale development: many sectors, including chemicals, manufacturing, agriculture, plastics and steel also use the process and the U.S. Environmental Protection Agency has said that injection wells are a “safe and inexpensive” option for disposing of industrial waste.
While wastewater injection is not unique to oil and gas production, it is certainly appropriate to continue evaluating the issue and exploring ways to reduce any potential disruption to the environment or surrounding population. That’s why the oil and natural gas industry remains dedicated to working with state and federal regulators, independent experts and others to the continued safe development of America’s vast shale resources, ensuring the continued protection of the surrounding environment and population.