Published on November 21st, 2016 | by Tina Casey0
New Study Nails Elusive Link Between Fracking & Earthquakes
November 21st, 2016 by Tina Casey
The natural gas picture just got a little more complicated last week, when researchers at the University of Canada released a study linking clusters of earthquakes in western Canada to oil and gas fracking operations. The finding adds yet another layer of risk to a fuel that is being promoted as a “cleaner” alternative to coal.
Fracking And Earthquakes 101
For those of you new to the topic, fracking is short for hydrofracturing, a method for recovering oil and gas. It involves pumping a chemical brine into shale formations at high pressure.
In the US, for many years fracking was a limited practice compared to conventional oil and gas drilling. That changed when the Bush Administration loosened federal water safety regulations. Combined with the identification of new oil-rich shale formations, the result has been a significant upswing in drilling activity.
The rapid growth of the industry raised concerns over seismic hazards, but so far in the US the operation itself has been linked directly to earthquakes only in isolated instances.
What has been emerging, in some US states, is a strong connection between earthquakes and the practice of injecting wastewater from oil and gas operations underground.
The University of Calgary Fracking Study
The new University of Calgary study could motivate a closer look at the direct causation angle.
The study was published last week in the journal Science under the heading “Fault activation by hydraulic fracturing in western Canada.” The area of study is in Alberta, about 30 kilometers away from a town called Fox Creek.
In recent years researchers have established a correlation between oil and gas fracking and seismic activity in this area, but not a direct causal link.
The new study represents the first time that the actual mechanism of causality has been identified and described:
Indirect evidence has pointed to activation of pre-existing faults as the underlying physical mechanism, but precise delineation of these features has been elusive. Without this deeper understanding, formulation of strong mitigation and prevention strategies has been a challenge for regulators and operating companies alike.
The researchers correlated seismic data and fracking records during and after a 4.0 earthquake that occurred last year near Fox Creek, to create a database of 905 distinct seismic events.
They traced the temblors to a previously undetected fault system running parallel to two horizontally drilled wells in the area.
According to their analysis, two different strands of the fault demonstrate two distinct ways in which fracking can touch off earthquakes.
The first way is mechanical. In one strand of the fault, fracking created mechanical stress on the rocks underneath the injection zone. Once the fracking operation stopped, so did the temblors.
The other way involves the infiltration of fracking fluids into the fault. This yields an effect dramatically different from mechanical stress. In this other strand of the fault, a 3.9 quake occurred at a depth of about four kilometers fully two weeks after fracking halted.
As indicated by the diagram at the top of this article, numerous smaller episodes occurred for several months after that, in a pattern that traveled from the lower point up toward the injection zone (for a link to the full diagram and video, take a look at the University of Calgary’s article titled, “Study reveals how hydraulic fracturing induces tremors”).
Putting The Squeeze On Fracking
The University of Calgary, like a number of US research institutions, is not fundamentally interested in compiling evidence leading to a blanket ban on fracking. Risk mitigation is the name of the game. That’s while you’ll find oil and gas stakeholders like Chevron Canada Resources Ltd., and ConocoPhillips in the funding stream for the new study.
More likely, the new research will provide policymakers with a platform for supporting stronger regulations, including localized bans where warranted by geological conditions.
Direct earthquake risks aren’t the only future obstacle faced by the industry. Here in the US, New York and several other states have already banned fracking outright or imposed a moratorium on the practice due to public health concerns.
Another type of obstacle is at play in the US state of Oklahoma, where swarms of earthquakes have transformed parts of this formerly dormant region in to the world’s number one hotspot.
Researchers have traced much of the increased activity to oil and gas wastewater disposal in a formation called Arbuckle.
Beginning last year, state officials began asking — and then requiring — disposal well operators to curtail and, in some cases, halt operations.
Despite these measures, a major 5.0 quake rocked the Cushing area earlier this month.
In another recent development, residents of Pawnee County have filed a lawsuit against 27 disposal well operators, in relation to a damaging 5.8 earthquake that hit the town of Pawnee in September.
Disposal wells have provided the oil and gas industry with a relatively cheap way to dispose of waste from fracking and conventional drilling.
If Oklahoma and other states shut that option down, oil and gas costs will rise.
Meanwhile, wind and solar energy are ready to pounce on the opportunity to push fossil fuels out of the market. Costs for both of the renewables have been rocketing southward, and further declines are in sight.
Image (screenshot, cropped): via University of Calgary.
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