Friday, October 17, 2014

A brief word on Earthquakes and fracking.

Since the Keranen et al. paper a few months ago, there has been much discussion on the relationship between earthquakes and wastewater disposal wells from unconventional hydrocarbon extraction (a.k.a. fracking).

Most of this discussion related to earthquake swarms on Oklahoma, where seismicity has dramatically increased in recent years.   However, it is worth pointing out that Oklahoma is by no means the biggest fracking state.  That is Texas, with almost ten times the oil production of Oklahoma.  The USGS produces earthquake maps of every state, ad Texas (and Oklahoma) can be seen here

What is immediately apparent is that despite the much larger size and production, Texas has slightly fewer quakes.  The next biggest fracking state, after Texas, is North Dakota, which has recently surpassed Alaska and California to be the USA’s second biggest oil producer (three times more than Oklahoma).  Its earthquake map looks like this:

Even the Keranen et al. paper stresses that many injection wells are aseismic, and that a mere four wells account for the majority of earthquakes. This sort of attention to detail is important to consider when evaluating this technology.  Understanding facts and details is the first step in uncovering processes which we can then use to improve our use and stewardship of natural resources.

And finally, just for comparison, here is the seismic map for Alaska, which I’m putting up here because of the beautiful Benioff zone which has nothing to do with petroleum at all.

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