Wednesday, July 29, 2015

Frackonomics: Frackquakes in Pennsylvania's Butler County? Edition

A couple of months ago, the U.S. Geological Survey (USGS) caused a bit of a ruckus when it declared that seismic events in Oklahoma and throughout the Midwest were related to the kind of deep injection wells associated with hydraulic fracturing.
Then the noise was drowned out by an actual cataclysm, the magnitude (M) 7.9 earthquake in Nepal.
The USGS, hasn't let the issue slide, and this month has released a pile of scholarly papers on the topic. Not one of them answers the question posed to me by Joanne Quinn-Smith, whose Positively Pittsburgh Live Magazine wants to keep the good news going in Pittsburgh. "Good news" needs to include the lack of earthquakes in the region, I think.
Here's the question again:

"Are there man-made earthquakes in Butler County?"

You can find my previous efforts to answer this question here and here. The short answer is "No."

So you can stop reading here. Or you can find out what the USGS has to say by reading further.
Note upper right hand corner.
The red dot represents the Youngstown events 2011-2012
The underlying question Joanne really wants answered is: "Are my friends in Butler County nuts or high on something?" Well, for two years I was one of her Butler County friends, and if I'm an appropriate sample size, the answer is yes. I have been nuts or high on something for a number of years.
But not because I felt earthquakes, which I didn't. And not because fracking is causing earthquakes, which it isn't.
So let's look at some of the heavy hyperventilating that occurred over the induced earthquake phenomenon in Oklahoma:

1. Fracking is causing earthquakes!
Fracking doesn't cause earthquakes. It causes a lot of other things, but it doesn't cause earthquakes. Okay, I hear you muttering, "Hydraulic fracturing is an induced earthquake anyway, isn't it? Doesn't the technology force water and chemicals into rock precisely to break it up?" Yes, that's the whole idea behind fracking; but the fracking process doesn't last long enough or produce enough pressure to trigger the faults that cause felt earthquakes. Deep injection disposal of wastewater does.

Process water destined for injection
(Photo courtesy USGS)
2. But hey! All of that water going down deep injection wells is from fracking!
If you're talking about the seismic events in Youngstown, Ohio for about 18 months starting in 2011, you'd have an argument. The culprit there was a deep injection well used to dispose of wastewater from the Marcellus Shale fracking operations. Most of the damaging earthquakes, according to the USGS, occur near wells that are used to get rid of process water from oil and gas recovery operations. Most of these types of wells are in Oklahoma.

3. Then all injection wells are bad because they cause earthquakes!
Actually, only a few dozen wells have been singled out. According to the USGS, a number of factors collide to make an induced earthquake: There must be a fault nearby that is large enough to produce a felt earthquake. The fault will already be under stress, and there will be variations in fluid pressure large enough to cause slipping along the fault. As you may recall from previous posts, Oklahoma is riddled with these kind of deep sleeper faults. Western Pennsylvania isn't. Here's another important consideration: the Baaken Shale oil play in North Dakota (and other locations in Montana and eastern Utah) have not experienced the same level of shaking as Oklahoma, despite the historic boom in fracking.

There is no evidence of earthquakes caused by fracking in Butler County. Butler County, and Mercer County are awfully close to the Youngstown events, and my friends may have felt those. These events have subsided since the well operator changed the way it injected the fluids.

One more thing: The USGS has a very science-y and technical set of documents on its website, and all sorts of peer-reviewed journal articles which will help calm shaky feelings.