The jury is still out on this one, but when Oklahoma gets more than 100 earthquakes in less than three months, attention naturally turns to fracking, the natural gas and oil drilling method that involves pumping a vast amounts of chemical brine underground, with the resulting wastewater often disposed by injecting that underground, too.
It all makes for a messy, water-intensive operation, but a Bush/Cheney-era exemption from the Clean Water Act has enabled the fracking industry to largely evade the grasp of federal regulators. That leaves states like Oklahoma struggling to deploy scant oversight resources in the middle of a drilling boom.
Oklahoma Earthquake Investigators “Swamped”
The Oklahoma earthquake numbers are impressive. According to a report yesterday in Bloomberg, as the first week of April came to a close the state experienced had already experienced 109 earthquakes at or above magnitude 3.0, with more to follow.
That’s more 3.0-and-greater earthquakes than in all of last year, overwhelming the capacity of the Oklahoma Geological Survey to investigate the causes. Bloomberg’s Jim Efstathiou, Jr., cites OGS seismologist Austin Holland:
We certainly likely have cases of earthquakes being caused by different oil and gas activity. Evaluating those carefully can take significant amounts of time, especially when we’re swamped.
That’s the problem in a nutshell: lack of oversight capacity, leading to a significant knowledge gap. Without establishing a clear connection to fracking and/or fracking wastewater disposal, state officials cannot justify shutting down drilling or disposal operations.
In Oklahoma, the problem is compounded by weak data reporting regulations. Currently, injection well operators (injection wells are for fracking wastewater disposal) are required to report well pressure monthly. Regulators have proposed a daily reporting requirement but the supporting legislation has yet to be approved.
Earthquakes And Fracking: What We Know
On November 6, 2011 near the city of Prague, Oklahoma was hit by a 5.7 earthquake, the biggest ever recorded in the state.
A state investigation proved inconclusive, but seismologists from Columbia University and the US Geological Survey later released a report providing conclusive evidence linking injection wells to the earthquake.
Aside from providing the missing link, the Prague earthquake study revealed an area of concern regarding the long term use of injection wells, which are typically existing, abandoned or played-out wells.
The injection wells linked to the Prague quake had been in use for 17 years without incident, but apparently a relatively small amount of wastewater was the straw that broke the camel’s back. Wellhead records confirmed that as the wells filled over the years, the operator kept applying more pressure to add more fluid.
According to Columbia researchers, the link between wastewater injection and earthquakes is not a new thing. In the 1960’s, a 4.8 quake near Denver was attributed to wastewater injection. More recently, in 2010 a University of Memphis seismologist documented the link to increased seismic activity in central Arkansas.
The pace has been picking up since then. In 2012 a University of Texas study confirmed a connection between increased seismic activity and a group of injection wells in Texas.
Also in 2012, a preliminary Ohio Department of Natural Resources report on the Youngstown earthquake documented a link to an injection well.
A major USGS report on earthquakes and fracking released in 2012 reached no conclusion regarding the connection between earthquakes and fracking itself, but here’s some snippets from a summary of preliminary findings, in which USGS did have this to say about fracking wastewater disposal:
USGS’s scientists have found, however, that at some locations the increase in seismicity coincides with the injection of wastewater in deep disposal wells…
The fact that the disposal (injection) of wastewater produced while extracting resources has the potential to cause earthquakes has long been known…
We also have previously reported that the production of oil and gas (extraction) can potentially cause earthquakes when changes in the underground stresses created by the removal of large volumes of oil, gas or water are large enough.
…The injected wastewater in deep wells can counteract the frictional forces on faults, causing an earthquake.
With earthquake evidence piling up and little action by state regulators, scores of local governments have more justification at hand to ban fracking and wastewater disposal operations within their borders, one notable example being Los Angeles.
In the 2012 report, USGS was careful to note that only a small faction of the 150,000 Class II injection wells in the US (there are probably more now btw) induced large earthquakes.
But, take that last snippet about fault stress and go back to the Prague earthquake. It was particularly concerning to researchers because it was so unpredictable, following a long period of uneventful operation.
Here’s what USGS has to say about that (break added):
Currently, there are no methods available to anticipate whether a planned wastewater disposal activity will trigger earthquakes that are large enough to be of concern. Evidence from some case histories suggests that the magnitude of the largest earthquake tends to increase as the total volume of injected wastewater increases.
Injection pressure and rate of injection may also be factors. More research is needed to determine answers to these important questions.
Ticking time bomb, much?
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