As misleading headlines claiming fracking is responsible for Oklahoma’s increased seismic activity continue to proliferate, perhaps the most succinct – and accurate – information on the issue was posted recently in the comments section of an obscure column from The Southern Illinoisan.
In the column, Southern Illinoisan sports editor and outdoors writer Les Winkeler linked fracking to Oklahoma’s spike in seismic activity:
“Prior to fracking becoming commonplace in Oklahoma, the state had few measurable earthquakes. …. Earthquakes have become so common in Oklahoma the state legislature has actually passed laws regulating injection wells. Waste water from fracking operations is injected into the ground because it is too toxic for surface disposal.”
The claims were so wildly inaccurate that Jeremy Boak, Oklahoma Geological Survey Director, felt compelled to use the comments section to correct the record:
“The author needs to learn a good deal more about earthquakes in Oklahoma before he holds forth on associated risks of hydraulic fracturing.
“Less than 5% of the water being disposed of in the earthquake prone part of Oklahoma is flowback water from hydraulic fracturing operations. Most of it is formation water like that produced during the life of the well from virtually all oil and gas operations, and there is no evidence that high water cut is characteristic of hydraulically fractured plays.”
“It was the sheer volume of such water being produced in two major oil and gas plays that resulted in injection of so much water, and caused the earthquakes. The very small number of earthquakes being driven by a very small number of actual fracturing operations are smaller in magnitude, and cause virtually no documented damage (unlike the earthquakes caused by deep injection of waste water, which have caused damage).”
Boak stressed that his comments were not necessarily the official positions of the Oklahoma Geological Survey or the University of Oklahoma, which houses the OGS.
It cannot be emphasized enough that the fracking process is not responsible for Oklahoma’s increased seismicity, despite what a seemingly endless stream of headlines have suggested. Moreover, the vast majority of wastewater being injected into disposal wells is not related to fracking, either.
A recent study by Stanford geophysicist Mark Zoback found that more than 95 percent of wastewater injected in disposal wells located in Oklahoma’s most seismically active areas is produced water, which is co-produced with oil and gas. As Dr. Zoback has explained:
“Basically, it is not hydraulic fracturing and it’s not hydraulic fracturing flowback water. It’s produced water.”
This produced water is also known as brine or formation water and is typically ancient ocean water. It is not used fracking fluid, sometimes called flowback.
Brine is co-produced during production from all oil and gas wells, both conventional and unconventional. It comes up with oil and gas during the entire life of a well, irrespective of whether fracking was performed on the well at all. As Oklahoma’s official earthquake information website explains, this co-produced water is then separated from marketable oil and gas and disposed of into disposal wells:
“At a facility on the surface, operators typically separate the water from the oil and gas so the latter two can be brought to market. The remaining water, however, has a very high salt content and may also be contaminated by heavy metals or the oil and gas itself after centuries or even millennia sitting in the rock formation. That water must then be disposed of.”
Because Oklahoma oil and gas wells typically have a high water-to-hydrocarbon ratio — as high as 10 to 15 barrels of wastewater for every barrel of oil produced, according to Boak — the state has long had higher produced water volumes than most oil and gas producing regions. And when oil prices spiked to more than $100 per barrel a few years ago, wells that produced a much higher ratio of brine than oil suddenly became economical, which led to an increase of produced water volumes.
The recent Stanford report elaborated further on this fact,
“Most of the oil wells in Oklahoma produce more water than oil. Because the produced water is too saline to be put to beneficial use, it is usually recycled back into the producing formation as part of water flooding operations. However, in the past few years, extremely large volumes of produced saltwater were injected into the highly permeable Arbuckle group. This formation is in hydraulic communication with faults in the crystalline basement, where natural geologic processes have accumulated stress on preexisting faults. The increase in pressure resulting from injection reduces the frictional resistance to sliding and can trigger the release of the accumulated stress in earthquakes…”
The important differences between flowback and produced water are certainly a bit confusing, especially for those unfamiliar with oil and gas development. However, as Boak points out in his comments, it is something the media should make every effort to understand before opining on the subject of induced seismicity:
“There are important issues to be addressed with respect to seismicity in Oklahoma,” Boak concludes, “but hydraulic fracturing is not the critical one. The writer may know sports, but he does not understand this issue.”