Over the past eight years, earthquake activity in Oklahoma has increase substantially. Before 2009, Oklahoma experienced one or two low magnitude earthquakes per year. However, after 2014, Oklahoma has been suffering from one to two low magnitude earthquakes per day. While many people believe the huge increase in earthquake activity in Oklahoma is due to oil and gas fracking….. it isn’t.
Before we get into the real reason, let’s check out the two charts below:
As we can see, Oklahoma earthquake activity in 2016 is much greater than it was in 2009. Not only are there a lot more earthquakes, there have been several greater than a 5.0 magnitude. Again, many people assume that this huge increase in earthquake activity is due to the fracking of oil and gas wells. While fracking causes a lot of other environmental and health issues, it isn’t the root cause of Oklahoma’s increased earthquake activity.
So, what is? The culprit is the massive DEEP WASTEWATER INJECTION of the by-product of shale oil and gas production. Fracking an oil or gas well produces a great deal of wastewater. This wastewater is full of toxins and chemicals that cannot be stored above-ground… because there is so much of it. To get rid of this wastewater, the oil and gas industry re-injects it deep into the ground… under pressure.
Here is a chart from the U.S. EIA – Energy Information Agency that shows the increase in Oklahoma earthquake activity:
As we can see, the majority of the increase in earthquake activity is taking place in Oklahoma. This is due to Oklahoma’s geology. According to a recent report by the EIA called, Earthquake Trends In Oklahoma & Other States Likely Related To Wastewater Injection:
In addition to the increased use of wastewater injection related to oil and natural gas production in the region, the geologic conditions in central Oklahoma are conducive to triggering seismic activity. The rock underlying the formations where disposal water is being injected in the region has existing faults that are susceptible to the changing stresses caused by fluid injection. Without these geologic conditions, induced seismicity would be much less common. For example, induced seismicity in the Bakken region of North Dakota and Montana is relatively rare.
The USGS report indicates that the recent decline may be related to decreased wastewater injection, because production in the region has decreased since the 2014 drop in oil prices. Actions by authorities in various states to regulate wastewater injection practices and restrict injection into the most sensitive areas may also be helping to reduce both the number and intensity of small earthquakes.
What the EIA is saying is that Oklahoma’s geology is conducive to increased seismic activity from deep wastewater injection compared to other regions in the United States. This graphic below explains how deep wastewater injection causes increased earthquake activity:
(illustration by Bryan Christie)
Basically, the water is acting like a fluid that is allowing the geology to slip… much like car tire hitting an oil slick on the surface of a road. While the EIA suggests that earthquake activity has declined in Oklahoma due to less drilling activity since the oil price fell since 2014, and manual reduction of deep wastewater injection to areas prone to higher magnitude earthquakes… some scientists believe the impacts could be felt for many years even if the injection stops.
I spoke to an oil geologist about this subject matter last year and he shared some interesting information. The oil industry used to inject wastewater in shallow wells because there wasn’t a lot of wastewater from conventional oil production. However, as shale oil and gas production came online over the past eight years, the amount of wastewater increased tremendously.
According to this LifeScience article on the amount of wastewater waste for each fracked well:
Fracking, or hydraulic fracturing, is a method of extracting oil and gas that requires between 3 million and 5 million gallons (11 million to 19 million liters) of water per “frack.” Afterward, the water is removed from the reservoir, but instead of treating the toxic wastewater, companies pump it back underground, into deep disposal wells.
Wastewater pumping continues at the wells, which inject more than 4 million barrels (477,000 cubic meters) of water into the ground every month.
“It’s pretty clear high-volume pumping is having an impact on the natural system,” said study co-author Geoff Abers, a geophysicist at Cornell University in New York. “Modern waste disposal wells can trigger earthquakes.”
Furthermore, many of the shallow wells that were being used to inject wastewater from conventional oil and gas wells were being filled and needed a new place to get rid of the wastewater. So, companies paid to get deep wastewater injection wells drilled so they could dump not only the shale oil and gas wastewater, but also that which came from older conventional oil and gas wells (some are the thousands of stripper wells producing 1-30 barrels per month).
Thus, the reason we didn’t have to deal with increased earthquake activity from conventional oil and gas production in the past, was due to the fact that most of it was injected in shallow wells….. far above the geological fault areas or zones.
While Oklahoma has not suffered from major earthquake damage, there has been a great deal of minor damage to homes, businesses and public buildings.
Again…. the full impact of deep wastewater injection may not be felt for many years. Even if the industry stops deep wastewater injection, the fluid is already down in the geology. Some geologists have stated that the worst may not be felt for many years… up until a decade.
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