NSI Chairman’s Corner December 2019
It’s 4 am and I am thinking about….
Hydraulic fracturing and drinking water
The idea that hydraulic fracturing (I hate to use the made-up word “fracking”. Where is the “k” in fracture?) causes natural gas and frac fluid chemicals to permeate upward to drinking water has been debunked, but it still hangs around as “fact” in conversation outside of the industry. So, if you are in a group where someone hits you about the dangers of hydraulic fracturing, and their proof is the movie Gasland or some other bit of hyperbole, here is a bit of math to help your conversation, and a relevant memory from my youth.
I make the joke that I grew up in the heart of the oil patch….western Michigan. This was a great place to grow up. At the time, most of the land was owned by family dairy farms that had their cows pasture during the day and milked in the barn at night. Winters were long and the pastures were covered in snow, which meant a lot of hay had to be baled and stacked in the barns to feed the cows through the winter. Not the huge round bales that are common today. These were hand tossed onto a flatbed and hand stacked in the barn loft. Most everyone got to participate with baling and storing hay. My first experience behind the wheel was driving the hay truck in creeper gear through the hay field while the older kids tossed on bales. I was 10. It was Awesome!
Growing up in this area, which to my knowledge has never had a well frac’ed, we kids told one another the story of the farmer who blew up the bathroom lighting a cigarette while on the toilet. Methane from tap water is a really common thing in farm country because the water wells are usually shallow, rainwater recharged, and the surface is rife with soluble organics (e.g. cow poop). Add bacteria. Get methane.
When I first read about methane in farm tap water being a sign of hydraulic fracturing contamination, my “BS Meter” went to 100.
Another story……(Bear with me. We will get to do some math shortly. I know you can’t wait!) I bought a Tesla Roadster 10 years ago when they were still a novelty. My joke at the time was that it was my coal-powered vehicle, because most of the electrons in my area were generated from a coal-fired power plant. Happily, a lot of the coal has been displaced by natural gas generating plants, which are much cleaner and more efficient. So, now the roadster is my mostly-natural-gas-powered-vehicle, the conversion to electrons being just a bit of energy logistics.
Sometime after buying the roadster, Tesla held an owners’ driving school on a frozen lake near Dillon, Colorado. I went. It was a blast! At the end we had lunch, and as we introduced one another, a guy at my table, who was a pollster for the Democratic Party, upon hearing I was in the oil and gas industry, verbally jumped on me about the “evils of hydraulic fracturing.”
Well, not being shy about arguing something in my wheelhouse, I responded by doing the following math (sorry it took so long to get to this point. I know you have been itching to do some high school geometry! Also, I tend to do stuff in metric and then switch to English units because, well, I’m lazy.)
Here’s the example: A typical water well is less than 100 meters deep. Assume the horizontal gas well is 3,000 meters below that. Also, assume there are 60 fracs generated in this one well (we are way above that number today, but around 2011 it was a reasonable high-end number).
Hydraulic fractures are thin, planar features. Call the frac width ½ a centimeter (0.2”). Also, assume there are no geologic barriers causing the frac to preferentially grow outward not upward. In addition, there is a perfect barrier below the well, resulting in a fracture geometry that is ½ of a disk radiating upward from the horizontal well.
The volume of a disk is Pi times the radius squared times the thickness of the disk. Our half-disk example is then ½
For a horizontal well with fractures of this geometry, the volume of water required to reach the drinking water aquifer 3,000 meters away (assuming zero leak-off, water lost to the rock the frac penetrates) is:
=~70,000 cubic meters.
A cubic meter of water is about 260 gallons.
Which get us to needing over 18 million gallons of water injected per frac to generate a simple half-disk, assuming zero leak-off, that might impact a water well!
For a 60-frac horizontal well, that’s about 1 billion gallons of water required to grow the fracs from one well up to the drinking water aquifer. This is orders of magnitude greater than the maximum volume pumped in reality (less than 10 million gallons this example well). So, this isn’t going to happen.
While math is hard for some people, I assumed for our pollster, a professional data guy, it would be the easiest way to convince him that the popular press commentary about hydraulic fractures growing into and contaminating drinking water was pretty much nonsense. To the contrary. All I did was cause him to stew and leave the table as quickly as he could finish his lunch. Which was fine with the rest of us at the table, who were more than happy to chat about cars and laugh about our very amateurish attempts to drive fast on ice!
The moral of the story is that the math and physics are on our side, and we should not be shy about explaining the implausibility of the scenario where fracs grow into drinking water aquifers. As long as we all follow best practices for zonal isolation, hydraulic fractures are not going to penetrate drinking water aquifers. History is also on our side. It is disappointing to me that my childhood experience around farms with methane in the tap water, which is certainly a minority but also not a unique experience, was not part of the background research of the reporters who created the anti-fracturing story. My memory is from a time before rural areas had news articles digitized, thus none of the humorous stories of farmers with exploding toilets were found with a simple google search. I suppose it is asking too much to expect reporters from major newspapers to do more than a simple Google search for their research.
Today, the Google result is mixed when you search something like “methane in tap water.” Depending on what you want to believe, you can find headlines that will support your opinion. As an example, Penn State has an article with the sub-title “Methane gas can occur in water wells from natural processes or from nearby drilling activity.” However, there is no data in this article about actual measurement of gas well drilling-induced methane in drinking water, as one would think from the subtitle. To the contrary, there are two studies referenced that showed: a) 24% of water wells in Pennsylvania measured tested positive for methane prior to commencement of nearby drilling, and b) a USGS test of 239 water wells throughout the state of New York showed methane “in 53% of the water wells prior to any drilling of unconventional gas wells.”
And yet, 5 years ago New York instituted a total ban on hydraulic fracturing. Whatever.
Be safe. Be well. Do good.
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Very informative blog.