The Tricky Art of Estimating Shale Gas Reserves


Photo credit: Marcellus Protest via Flickr/CC BY

Yesterday, I commented on the news that the US Geological Survey had drastically downscaled its estimates of how much recoverable natural gas was in the Marcellus Shale -- by a striking 80%. I received not one but two angry screeds from an employee of the natural gas industry on the topic, so I figured I'd follow up that report with this bit of analysis from the Washington Post, in which Brad Plumer essentially points out that the new number is hardly definitive ...... and that "there's a lot more work to be done in figuring out just how much gas is out there -- and how much can be drilled at a profit (the USGS focused on how much gas could technically be extracted, not how much gas could be profitably extracted, an important distinction)."

He notes that the 84 cubic trillion feet that the USGS says is recoverable is a mean number -- according to that report, it could be as little as 43 trillion to as much as 144 trillion square feet. Furthermore, the numbers are still estimates, and hardly the end-all. But there's still plenty of reason to believe that the previous projections from 2009 are still wishful thinking -- remember, they landed around 410 trillion cubic feet.

And yes, 84 trillion cubic feet is a crapload of gas any way you slice it -- and still more than studies had estimated were locked in the shale as recently as 2002. But that 2009 projection was the one that really sparked the latest nat gas gold rush, and was most responsible for attracting heaps of investment and newfangled interest in the industry (And it may yet turn out to be accurate, long shot though it is). As such, we need be wary of the headlong rush, led by profit-seeking corporations, to convince the public that shale gas is safe, plentiful, and responsibly obtained.

But we skeptics need to be honest in weighing the facts when we do.

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