Five Things to Know about Induced Seismicity After Pawnee, Oklahoma Earthquake

This week’s coverage of the Pawnee, Okla., earthquake was the latest example of a troublesome trend: More often than not, the media continues to get it wrong when it comes to reporting on the issue of induced seismicity.

Whether this frustrating pattern is due to a deliberate mischaracterization of the facts — namely, using of the word “fracking” as a catchall, bogeyman term encompassing all things oil and gas related — or if an honest lack of understanding of the issue is to blame, the unfortunate byproduct in both instances is a misinformed public.

So in an attempt to counter to the countless misleading headlines and media accounts of this past Labor Day weekend’s earthquake in Oklahoma, here are five things everyone needs to know about induced seismicity that many media outlets have failed to convey.

Fact #1: Fracking is not the cause

Contrary to what you might have read in the local paper this week, the hydraulic fracturing process is not the cause of Oklahoma’s earthquakes, or induced seismicity in general. Expert after expert agree with this fact, including:

  • The United States Geological Survey: The 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.”
  • Stanford geophysicist Mark Zoback: explains in a recent YouTube video, quite bluntly, that Oklahoma’s induced seismicity “… is not caused by the hydraulic fracturing process at all.”
  • Former Interior Department Deputy Secretary David Hayes has said: “We also find that there is no evidence to suggest that hydraulic fracturing itself is the cause of the increased rate of earthquakes.”
  • University of Texas at Austin Geophysicist Cliff Frohlich has said: “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.”
  • A 2012 Inglewood, Calif., oilfield study concluded: “High-volume hydraulic fracturing…had no detectable effects on vibration, and did not induce seismicity (earthquakes).”
  • A Durham University study: found ““…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…”
  • The National Research Council – part of the prestigious National Academies —has similarly found: “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.”
  • And, as USGS noted in a separate report: “USGS’s studies suggest that the actual hydraulic fracturing process is only very rarely the direct cause of felt earthquakes. While hydraulic fracturing works by making thousands of extremely small ‘microearthquakes,’ they are, with just a few exceptions, too small to be felt; none have been large enough to cause structural damage.” (emphasis added)

Just as importantly, and contrary to what you might have read this week, fracking is a separate process from wastewater disposal — the latter which is believed to be the cause of induced seismicity.

Though EID has stated it countless times, the following bears repeating: Hydraulic fracturing (“fracking”) refers to a well stimulation process that enhances the flow of oil or natural gas from a production well. Wastewater disposal, on the other hand, refers to the injection of wastewater into a designated well, which is typically much deeper than the production well where “fracking” occurs.

It’s also essential to understand that wastewater is generated from oil and natural gas wells regardless of whether hydraulic fracturing is used. This is because hydrocarbon bearing formations typically contain plenty of water, which is called “produced water” as well as hydrocarbons. Produced water is naturally occurring water within the Earth that co-exists with oil and gas under the ground.  As oil and gas is extracted from the ground, the produced water is separated and often injected deep beneath the surface in wells designed to protect groundwater resources.

It is true that hydraulic fracturing treatments do produce wastewater, or “flowback” water, that must be disposed of. But the vast majority of wastewater disposal in Oklahoma is produced water from day-to-day production — not “flowback” water from the fracking process.

Several media accounts this week got this dead wrong, claiming ALL wastewater being injected in Oklahoma is fracking flowback water, and therefore, directly fracking related. A Forbes op-ed by James Conca was a prime example:

“Fracking takes a few hours to a few days, followed by a period where the fracking fluid is allowed to flow back to the surface where it is collected for disposal, treatment, or reuse. It is the disposal of this fluid by injection into deep wells that causes the earthquakes.”

Tim Baker, director of the Oklahoma Corporation Commission’s Oil and Gas Division, set the record straight this week during an earthquake forum at the University of Tulsa, clarifying that less than five percent of the wastewater in Oklahoma is from fracking operations. A recent Zoback-authored study on Oklahoma’s induced seismicity also found less than five percent of wastewater disposed of in Oklahoma’s most seismically active areas is fracking flowback water. The study’s press release states,

“We know that some of the produced water came from wells that were hydraulically fractured, but in the three areas of most seismicity, over 95 percent of the wastewater disposal is produced water, not hydraulic fracturing flowback water.”

The USGS induced seismicity fact sheet also concurs with the Zoback study and Baker’s comment, finding:

“In many locations, wastewater has little or nothing to do with hydraulic fracturing. In Oklahoma, less than 10 percent of the water injected into wastewater disposal wells is used hydraulic fracturing fluid. Most of the wastewater in Oklahoma is saltwater that comes up along with oil during the extraction process.”

As the Office of the Oklahoma Secretary of Energy notes, Oklahoma has historically had a high produced water-to-hydrocarbon ratio during its long history of oil and gas production,

“In Oklahoma, the oil and gas is being extracted from wells with a high water to hydrocarbon ratio. (Jeremy) Boak (Director of the Oklahoma Geological Survey) estimates that for every barrel of oil that can be produced, operators are left with 10 to 15 barrels of wastewater. That leaves a big disposal job that continues through the life of the well, long after drilling and hydraulic fracturing are complete.”

This is why the state has historically had a lot of produced water to dispose of in injection wells, which have been used extensively in Oklahoma since the 1930s. In fact, produced wastewater volumes in Oklahoma were actually about 30 percent higher in the 1980s — long before horizontal drilling and high volume hydraulic fracturing technology was developed.

So to sum up, wastewater disposal is a completely separate process from fracking, and a vast majority of the wastewater being disposed of is not from the fracking process at all. So bottom line, fracking is not the cause of induced seismicity, contrary to many media reports.

Fact #2: Even though wastewater injection is believed to be the cause, the risk is still extremely low

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.

An EID report released late last year found that only 0.15 percent of all Class II injection wells and 0.55 percent of all federally regulated disposal wells in the United States have been even tangentially associated or suspected to be linked with a seismic event of any size. While that data would no longer be up to date for Oklahoma, it remains current for the other states. In Texas, for instance, the top oil and gas producing state in the U.S., just 0.08 percent of injection wells and 0.34 percent of disposal wells have been potentially linked to induced seismicity.

It’s also worth noting that high production states such as California, Pennsylvania and North Dakota have had no instances of induced seismicity.

It is believed that Oklahoma’s unique geology have made the Sooner State uniquely susceptible to induced earthquakes. More specifically, Matt Skinner of the Oklahoma Corporation Commission has said seismologists are in broad agreement that injection of wastewater into the Arbuckle formation, specifically, is suspected to be the cause of earthquakes in Oklahoma.

The Arbuckle is a 7,000-foot deep, sedimentary formation which sits well below producing formations and is the farthest formation from groundwater, making it a seemingly ideal injection location in the past. But the Arbuckle is also very permeable and sits atop the crystalline basement. Therefore, experts believe it may be in hydraulic communication with the basement rock, where unknown faults are located, and have theorized wastewater injection may be reactivating these faults.

Fortunately, regulators and producers have already taken many steps to address the latter.

Fact #3: Producers are working with regulators to address this issue, as earthquakes have decreased

Oklahoma operators have taken the issue of induced seismicity very seriously.

Industry has been actively working with state regulators since 2014 to help mitigate and better understand the issue of seismicity in the state, with efforts including operators investing over $50 million to reduce earthquake risks from disposal wells since March 2015. A working group including operators, service companies, and the OGS and OCC was also formed in 2014 to meet regularly to share data, studies, developments and proposed actions related to Oklahoma’s earthquakes. Industry has also voluntarily contributed around $450 million in seismic data with regulators and researchers.

With regard to the injection into the Arbuckle formation specifically, the OCC last year implemented a new set of requirements in certain “Areas of Interest,” focusing on injections below the Arbuckle formation. The directive forced operators to prove that they were not injecting below that zone, or reduce disposal volumes by 50 percent. The state recently expanded that directive, and committed an additional $200,000 to help regulators respond to concerns about earthquakes. This yielded a shut in of 90 wastewater disposal wells and reduced disposal volumes on an additional 250 wells.

As a result, the Oklahoma Geological Survey (OGS) has reported about a million fewer barrels per day of wastewater is being injected into Arbuckle wells as of this past spring. And these efforts appear to be producing results.

A recent EID review of OGS data found earthquakes in Oklahoma were down 52 percent between January and April of this year, according to data from the Oklahoma Geological Survey. USA Today and The Oklahoman have also recently reported that Oklahoma is experiencing fewer earthquakes associated with injection wells, thanks to efforts from state officials and producers.

Recent executive powers granted to Oklahoma Gov. Mary Fallin also allowed the OCC to immediately take action after the Pawnee-area quake, indefinitely shutting down 37 disposal wells in a 500-square miles area of interest surrounding the epicenter over a 10-day period (wells within a five-mile radius in five days), continuing the proactive approach that has yielded declines in seismic activity so far this year. In addition, the EPA — which has jurisdiction in Osage County — is ordering 17 more injection wells be shut down.

Notably, injection wells in the impacted area had already seen a 40 percent reduction of their 2014 volumes, and as Oklahoma Oil and Gas Association president Chad Warner told the Tulsa World, the latter fact and the OCC’s quick response this past weekend should dispel the notion that the state isn’t moving in the right direction: “That (quick action) wouldn’t have been possible a year ago,” Warmington said.

Proactive measures are also underway. The Oklahoma Independent Petroleum Association is currently underwriting a project at a cost of $81,000 that involves dipping pressure monitors into inactive disposal wells to better understanding induced earthquakes. The six-month study is the first of its kind and just one of many examples of how industry, scientists and regulators are attempting to better understand the phenomenon.

Fact #4: Scientists are working to determine if injection was the cause of the Pawnee earthquake

Though OGS has concluded “that the majority of recent earthquakes in central and north-central Oklahoma are very likely triggered by the injection of produced water in disposal wells” Oklahoma does have a long history of seismicity that pre-dates wastewater injection, which is why officials aren’t jumping to any conclusions regarding determining the quake’s official cause.

Experts are still working to determine if there is a link between injection wells and the quake that happened over Labor Day weekend, as the USGS explained,

“Without studying the specifics of the wastewater injection and oil and gas production in this area, the USGS cannot currently conclude whether or not this particular earthquake was caused by industrial-related, human activities. However, we do know that many earthquakes in Oklahoma have been triggered by wastewater fluid injection.”

A USGS official has did reveal to Fox News in an email this week that the Pawnee-area quake occurred on a fault that experts hadn’t previously known about, roughly perpendicular to a larger known fault system. More details are expected to emerge in the coming weeks, so it is important to note that the state’s shutting down of injection wells was a precautionary matter and that the official cause of the quake will be determined by experts rather than the media.

Fact #5: A ban on injection wells would be devastating to the economy and could lead to more earthquakes

Environmental activists have argued a complete ban or moratorium on wastewater disposal in Oklahoma — as well as nationwide — would be the only solution.

But in fact, such an action may not only increase earthquake activity, it would prove devastating to the economy.

Even if state regulators were able to put a total end to all wastewater disposal operations today, the quakes might continue all the same, as OGS director Jeremy Boak has explained,

“If you shut it in completely, right away, you might get more earthquakes. Because then, you’ll get a negative pressure pulse moving out in these areas. Some of these earthquakes we’re now seeing are in areas where we’ve actually shut in injection. That might be one type of response.”

This is why state regulators did not require an immediate shutdown of injection wells near the Pawnee quake epicenter, explaining of the 10- and five-day timeframes, “The schedule is necessary because of warnings from seismologists that a large scale, sudden shutdown could cause an earthquake.”

Also, considering disposal of produced water from day-to-day production is an absolutely essential component of ALL oil and gas production, a ban on wastewater injection would basically be a ban on oil and gas production altogether.

EPA clearly states that wastewater injection is the safest method of dealing with produced water, and even the Environmental Defense Fund has observed:

“Permanent storage using underground injection wells remains by far the most common disposal method. At this point, it also appears to be the least risky, not to be confused with ‘unrisky’.” (emphasis added)

Kim Hatfield, chairman of the Oklahoma Independent Petroleum Association’s (OIPA) regulatory committee, recently noted that banning wastewater injection “would completely shut down oil and gas production” in Oklahoma.

Considering the oil and natural gas industry has accounted for nearly two-thirds of all jobs created in the state since 2010, according to an economist at Oklahoma City University, and the industry is also the “largest single source of tax revenue” in the state, according to a 2014 report prepared for the State Chamber of Oklahoma (over 20 percent of all state taxes come from the oil and natural gas industry), it is clear that a ban would create more problems than it would alleviate.

And considering induced seismicity is not a widespread issue affecting other oil and gas producing states in the U.S., a ban would prove to be even more ineffective, impractical and economically devastating — especially in states such as North Dakota, Pennsylvania and California that have seen no instances of induced seismicity.


The issue of induced seismicity is certainly a serious one that deserves the media attention that it has received. But all that attention considered, the media has the responsibility of reporting and clarifying the aforementioned facts regarding the issue. The facts— both here and countless other sources — are readily available. The grace period for ignorance has long passed, and click-bait-motivated excuses to get “fracking” in headlines is simply no longer acceptable.




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