New Study Finds Fracking, Wastewater Injection Rarely Linked to Seismicity
A new peer-reviewed University of Alberta study asks whether increased oil and gas production — specifically the hydraulic fracturing that made it possible and wastewater injection that is part of the day-to-day production process — leads to widespread increased induced seismicity rates. Contrary to the anti-fracking movement’s alarmist narrative, the answer is a resounding “no.”
The report finds that the well-documented increase in Oklahoma seismic activity linked to oil and gas development is the textbook definition of an anomaly. As University of Alberta professor, geophysicist and lead researcher Mirko Van der Baan also notes in the study’s press release:
“It’s not as simple as saying ‘we do a hydraulic fracturing treatment, and therefore we are going to cause felt seismicity.’ It’s actually the opposite. Most of it is perfectly safe.”
The study examines occurrences of magnitude-3.0 and greater earthquakes between 1965 and 2014 in six states — North Dakota, Ohio, Pennsylvania, Texas, West Virginia and Oklahoma — and three Canadian provinces — Alberta, British Columbia and Saskatchewan — that have all seen dramatic increases in hydrocarbon production in recent years, mostly attributable to fracking. The study finds that from 2008 to 2014, when a considerable increase in oil and gas production was observed in each of these areas, Oklahoma was the only region of the nine studied that saw an increase of felt earthquakes shallow enough to be potentially linked to induced seismicity (15 km deep or less). From the study,
“Contrary to Oklahoma, analysis of oil and gas production versus seismicity rates in six other States in the USA and three provinces in Canada finds no State/Province-wide correlation between increased seismicity and hydrocarbon production…
“We find that increased seismicity in Oklahoma, likely due to salt-water disposal, has an 85% correlation with oil production. Yet, the other areas do not display State/Province-wide correlations between increased seismicity and production, despite 8-16 fold increases in production in some States. However in various cases seismicity has locally increased.”
In fact, the study finds that four states/provinces — Pennsylvania, North Dakota, West Virginia and Saskatchewan — saw no trend of increased seismicity whatsoever from 2008 to 2014, despite hydrocarbon production increasing dramatically in each area during that time.
The report notes that North Dakota saw an 8.7-fold increase in oil production and six-fold increase in natural gas from 2005 to 2013, a trend that is all-the-more notable considering the prevalence of wastewater disposal wells in the Bakken.
Though EID has stated it countless times, it bears repeating that the United States Geological Survey (USGS) states in the very first sentence of its list of myths and misconceptions regarding induced seismicity that “Fracking is NOT causing most of the induced earthquakes,” further clarifying that, “Wastewater disposal is the primary cause of the recent increase in earthquakes in the central United States.”
It also bears repeating that fracking is a separate process from wastewater disposal, and that a vast majority of water disposed of wastewater injection wells is co-produced brine from day-to-day conventional and unconventional wells rather than fracking “flowback water,” meaning that wastewater injection is not exclusive to wells that have been hydraulically fractured. And although scientists agree wastewater injection from day-to-day oil and gas production can under very specific circumstances cause induced seismicity, it is important to understand that the risk is still very low, which the North Dakota data from this report illustrates,
“Like Pennsylvania and West Virginia, North Dakota is a state with significantly increased oil and gas production but no noticeable change in seismicity. Contrary to Pennsylvania and West Virginia, numerous salt-water disposal wells exist in North Dakota within the Bakken production zone, yet few injection wells are thought to be associated with seismicity in North Dakota. North Dakota is thus an example of a state with substantially increased underground fluid injection, yet no concurrent change in regional seismicity rates.”
Similar to the Bakken in North Dakota, the development of the Marcellus Shale in Pennsylvania and West Virginia has led to a 16-fold increase in natural gas production, yet there has been no increase in seismic activity in the Marcellus during that time, according to the study,
“Contrary to Oklahoma, there is no evidence for increased regional seismicity rates between 2008 and 2014 within the Marcellus shale play, despite the 16-fold increase in gas production, largely attributed to substantial hydraulic fracturing with associated increases in underground fluid injection (Ellsworth, 2013; Lutz et al., 2013).”
The report acknowledges that although there has been documented instances of felt seismicity in Ohio, Texas, Alberta and British Columbia as oil and gas production has increased recently in those regions, this activity has been regionally clustered, a sharp contrast to the widespread activity observed in Oklahoma.
The report notes that Ohio has experienced a single cluster of seismicity in excess of M-3.0 (Youngstown area, January 2011 to February 2012) while experiencing a 6.2-fold increase in natural gas production and 2.9-fold increase in oil production from 2012 to 2014.
And though 95 of the 187 M-3.0 or higher earthquakes Texas has experienced from 1964 to 2014 occurred between 2010 and 2014, the report notes,
“The recent increase in seismicity correlates visually with increased oil production in onshore Texas. However, unlike Oklahoma (Figures 2 and 3), seismicity in on-shore Texas is spatially constrained to local areas (clusters), whereas increased production comes from large regions.”
“In other words, recent changes in seismicity only occur locally, despite substantial increases in large-scale underground fluid injection across the State of Texas due to hydraulic fracturing and salt-water disposal. This raises the question what differentiates these specific local areas?”
Van der Baan noted in an interview with the Edmonton Sun that the much-publicized cluster of seven earthquakes that occurred recently in the Fox Creek area of Alberta are not indicators of a widespread, systemic issue,
“It is pretty clear immediately that not every single hydraulic fracturing treatment is going to cause an earthquake which is potentially damaging. And so it’s important to understand why this very small percentage of treatment, whether it’s a salt water disposal or hydraulic fracturing treatment, is anomalous.”
What This Means In The Big Picture
Bottom line, this study confirms what has long been true despite all the scary headlines in recent years regarding induced seismicity: Despite what anti-fracking activists have claimed, it is rare and certainly not a widespread issue.
And fortunately, the single area where this study found a direct correlation between increased seismic activity and increased oil and gas production, mitigation measures appear to be yielding positive results.
After mandatory wastewater volume reductions were implemented in Oklahoma in early 2016, Oklahoma Geological Survey (OGS) and United States Geological Survey (USGS) data showed Oklahoma saw a 31 percent reduction of magnitude 3.0 or greater earthquakes from 2015 to 2016. Earthquake rates have continued to decline dramatically so far in 2017. The Oklahoman recently reported that Oklahoma experienced half as many M-3.0 or greater earthquakes this past April than it did in April 2016, and according to data from Tulsa World, Oklahoma is on pace to see a near 60 percent reduction in felt earthquakes this year from 2016 levels.
Induced seismicity remains a complicated issue that industry and regulators continue to take very seriously. But as this study shows, efforts by the media and activists to link earthquakes to fracking have been exaggerated.