Appalachian Basin

Key Takeaways from a New Report on Seismicity and Fracking

This week, a report led by Paul A. Friberg of Instrumental Software Technologies, Inc. (ISTI) concluded that a number of positive magnitude seismic events in Ohio, which were not big enough to be felt, may have been caused by hydraulic fracturing.  Of course, news outlets produced the usual alarming headlines such as: “Study links hundreds of Ohio quakes to fracking,” but in reality, the study’s conclusions were actually something that we’ve known for years: seismic activity related to fracturing activities is “rare and uncommon,” according to the report itself.

As always, it’s important to view these types of small seismic events in the proper context.  Here are a few key facts to know about this new report:

Fact #1: Seismic events were not large enough to be felt

The largest earthquake detected was magnitude 2.2. In that range, the U.S. Geological Survey states that it could possibly be felt by “few persons at rest” if they are on the top floors of buildings.  However, the report is clear that “there were no felt reports for any of these earthquakes.” (p. 1)

As lead researcher Paul Friberg explained to Energy Wire,

“Earthquakes caused directly by fracking are mostly inconsequential magnitudes. Very few are even felt.”

Friberg also told Live Science:

“Fracking earthquakes pose no real hazard, because they are so small in the majority of cases.”

Fact #2: Researchers found no seismic activity in other wells

While the “Ryser wells operations” showed some seismic activity, the researchers looked at a number of wells, and many showed no seismic activity.  From the report:

“On the other hand, hydraulic operations occurred directly beneath the TA O53A station in May 2013 along Boyscout 4, 5, and 6 wells. There was no clear observable earthquake signal at the station during these operations. This implies that microseismicity produced during such operations did not reach positive magnitudes and consequently stayed below the detection threshold of a TA station.” (p. 11; emphasis added)

That leads us to our next point – why was the seismic activity located in one specific area of Harrison County?

Fact #3: Wells with seismic activity were located on a fault

The report finds that that the Ryser wells were “on a previously unmapped fault in Harrison County, Ohio.” (p. 1)

This particular fault apparently extended to the basement rock, and when that happens, there is a greater risk of seismic activity.  As the report puts it:

“The portable network data with double-difference location of earthquakes clearly show a vertical east–west-trending fault directly beneath the Ryser-2, Ryser-3, and Ryser-4 horizontal wells. The fault is located in the Precambrian crystalline basement formation and not in the Paleozoic formations in which the wells were located. Further, the highest concentration of cross-correlation detections along the well bores aligns with the portable earthquake locations, indicating that a possible hydraulic pathway to the basement fault exists through the Paleozoic formations.” (p. 12; emphasis added)

That’s precisely why the Ohio Department of Natural Resources has put in place new, stronger permit conditions, which place restrictions on developing shale resources near known fault areas or areas with past seismic activity.  Those new rules were implemented under an abundance of caution, as these events are exceedingly rare.

It’s also important to keep in mind that out of the 275,000 total wells and the 836 Utica and Marcellus Shale wells already developed in the state of Ohio, and out of the millions of wells that have been drilled across the United States, this report, according to the authors, shows “the first evidence of positive magnitude earthquakes” that “can be related to a hydraulic fracture operation.”

In other words, the rarity of these events is stressed by this new report, which leads to our next point.

Fact #4: Seismicity from hydraulic fracturing is “still rare and uncommon”

The researchers are very clear that, despite their findings on the Ryser wells, “positive magnitude earthquakes triggered during such operations are still rare and uncommon.”  (p. 11)

This is one of the most important points of the report, and something that numerous other studies have concluded as well.  According to a report from Durham University:

Hydraulic fracturing of sedimentary rocks, for recovery of gas from shale, usually generates very small magnitude earthquakes only […] It should be noted, however, that after hundreds of thousands of fracturing operations, only three examples of felt seismicity have been documented. The likelihood of inducing felt seismicity by hydraulic fracturing is thus extremely small but cannot be ruled out.” (p.18, emphasis added)

The National Research Council has also looked into this issue and come to a similar conclusion:

“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.”

Cliff Frohlich, Associate Director of the Institute for Geophysics at the University of Texas at Austin, studied seismicity in the Eagle Ford Shale and found:

“Although there is a considerable amount of hydraulic fracturing activity in the Eagle Ford, we don’t see a strong signal associated with that and earthquakes.”

Stanford geophysicist Mark Zoback has also explained the small effect these events have:

“These microseismic events [from hydraulically fracturing a well] affect a very small volume of rock and release, on average, about the same amount of energy as a gallon of milk falling off a kitchen counter.”

No doubt anti-fracking activists will try to use this latest report to rally their troops in an effort to ban fracking.   But in reality, the report is just further evidence that seismic activity from hydraulic fracturing is exceedingly rare. Moreover, it’s even clearer now that there are straightforward ways to reduce this extremely small risk in Ohio, which state regulators have already begun to address through new rules.

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