RADIO NZ: “The Green Party says international research which suggests large earthquakes can trigger swarms of tremors near fracking sites, strengthens its calls for a moratorium on the oil and gas drilling technique. An article published in Science magazine has found fracking, which involves forcing large quantities of toxic chemicals into rock, has been accompanied by an increase in quakes that are triggered by distant seismic events…”
That’s some very careful wording there—to say that “fracking … has been accompanied by an increase in quakes that are triggered by distant seismic events.”
The key word here is “accompanied,” as you’ll understand once you read the abstract of the Science magazine article the Greens refer to so breathlessly:
More than 100,000 wells [across the US] have been subjected to fracking in recent years, and the largest induced earthquake was magnitude 3.6, which is too small to pose a serious risk. Yet, wastewater disposal by injection into deep wells poses a higher risk, because this practice can induce larger earthquakes. For example, several of the largest earthquakes in the U.S. midcontinent in 2011 and 2012 may have been triggered by nearby disposal wells. The largest of these was a magnitude 5.6 event in central Oklahoma that destroyed 14 homes and injured two people. The mechanism responsible for inducing these events appears to be the well-understood process of weakening a preexisting fault by elevating the fluid pressure. However, only a small fraction of the more than 30,000 wastewater disposal wells appears to be problematic—typically those that dispose of very large volumes of water and/or communicate pressure perturbations directly into basement faults. [Emphasis mine.]
Did you spot the bait and switch? What the Greens very carefully fail to mention is that there are two kinds of wells whose seismic activity has been measured:
- The first is the actual fracking wells themselves, which the research quoted by the Greens shows produces, at worst, seismic activity “which is too small to pose a serious risk.” This is not the “swarms of tremors” mentioned by the Greens.
- The second kind of well often accompanies the actual fracking well. These are deep wells used to dispose of the 20% or so of wastewater that comes back up out of the fracking well. At present, the disposal method is by high-pressure injection into the wastewater well, and it is these wells, these disposal wells and not the fracking wells themselves, that are subject to “a higher risk. “
Well, the research referred to by the Greens says, “The largest of these was a magnitude 5.6 event in central Oklahoma that destroyed 14 homes and injured two people.”
Serious for those injured, but not the apocalypse promised by the Greens.
“There were, as of 2010, just over 150,000 ‘Class II’ injection wells throughout the United States,” notes the Marcellus Drilling News. “Class II wells are used to dispose of brine and fracking fluids (the two are different, but close enough for this discussion). In Ohio, there were 2,455 Class II injection wells that could theoretically accept fracking wastewater as of 2010. One of those wells was located near Youngstown and the Ohio EPA concluded in March 2012 that yes indeed, it had caused several earthquakes in the Youngstown area … That’s one well out of 2,455, or .04% (four-tenths of one percent) by our mathematical reckoning. Statistically speaking–zero.”
Conclusion: Not for the first time, the Greens have very carefully talked up a non-problem from new research that shows nothing new. “Drilling for natural gas (and oil) in shale is an industrial process and has risks. Earthquakes, for all intents and purposes, are not one of those risks. Not in any meaningful way.”