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Marcellus Shale Reserves “Only” 43 TCF …


On August 23, 2011, the United States Geologic Survey (USGS) submitted 84 trillion cubic feet (84 TCF) as their estimate for undiscovered, recoverable natural gas in the Marcellus Shale, located primarily in Pennsylvania, New York and West Virginia.  Additionally, they believe 3.4 billion barrels of natural gas liquids will accompany that 84 TCF. (for reference, the great East Texas Oilfield, discovered in 1930, and which helped the Allies win World War II, will produce about 5.2 billion barrels.)

USGS Marcellus Press Release

The USGS actually published a range of estimated recoveries, ranked by probability or confidence in a given estimate.  So, a 50 % confidence level, or N50, is similar to the mean value, or the likelyhood that half the estimates would produce more than that amount, and half less.  Such is the 84 TCF number which the USGS quoted in their first paragraph.  One opponent of natural gas was quick to focus only on the very highest probability, and lowest reserve number, that being 43 TCF. Another writer smugly commented, “There may not be as much natural gas in our future as some claim.”

Additionally, neither of the two articles linked above happened to mention the associated 1.6 billion to 3.4 billion barrels of natural gas liquids (N95 to N50)!  That’s enough liquid hydrocarbons to qualify the Marcellus as what’s known as a “giant” oilfield.  How could they leave that detail out if they were trying to be objective, whatsoever?  The answer must be that they were not making any attempt to be objective, but were trying manipulate public opinion.  One of the articles also forgot to mention that there was a N5, or 5 % probability of having 144 TCF and 6.2 billion barrels recoverable from the Marcellus. Clearly, these folks want to suggest to the casual observer that “there just isn’t very much gas there, after all.”  How much could only 43 of something be???

Well, let’s look at that.  Some of the folks writing the articles like to use the entire domestic natural gas consumption as the dividend, in doing their comparisons. And they fail to include that multi-billion barrel NGL production that comes along with the gas.  Is that a fair way to look at it?  After all, this Marcellus is a relatively new discovery (2004), and as such it is incremental or additive to the reserves prior to that point.  So, in looking at just 43 TCF another way, using 1 mcf = 1 mmbtu of heat energy (approximation for methane, the primary component of natural gas), 293 kwh/mcf, a combined-cycle gas turbine generation plant efficiency of 57 %, and 570 MW/coal power plant (594 coal plants in 2009, with 338,000 MW of total capacity), we find that 43 TCF could replace the average coal power plant for … 34,000 years.  Or, that 43 TCF could replace ALL 594 coal power plants for … 57 years.  Oh, and then you still have the 1.6 BILLION barrels of natural gas liquids (ethane, propane, butane, etc.) to heat homes, make plastic, even run in vehicles – essentially to use in every application in which natural gas could be used, plus a few more.  (Total production from Prudhoe Bay, on the North Slope in Alaska, has only been about 11 billion barrels to date, by comparison.)

So, even 43 TCF and 1.6 billion barrels of NGL is an awful lot of lower carbon, comparatively clean energy.  Further, those are the low estimates, not the mean, and the mean is about twice those amounts.  It makes one wonder,  “What is going on with all these anti-natural gas efforts?”.  We’ll attempt to take that up in a future article.

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3 Comments on "Marcellus Shale Reserves “Only” 43 TCF …"

  1. BillT on Thu, 22nd Sep 2011 4:09 am 

    What is there and what is actually exploited are two totally different things. I suspect that the drilling will stop long before there is anywhere near 45tcf recovered…for many reasons that have zero to do with demand or price. Pollution will shut it down, just like it will shut down any other oil sands or shale oil production in the years to come.

  2. KM on Thu, 22nd Sep 2011 11:02 am 

    The real question raised by the Marcellus Shale is how many other giant shale fields there are around the world in places that have not been as thoroughly explored as the US. It seems obvious to me that the dominant fossil fuel for the next century will be NG and most NG will be consumed close to production.

  3. nathan walters on Thu, 22nd Sep 2011 8:00 pm 

    Sorry to disagree with the facts quoted here, however the calculations are wrong. The total production of electricity from coal fired power plants in the USA is about 2100 TWH yearly. Total electricity production in the USA is about 4200 TWH. There is 293x10E9KWH/TCF x (43TCF) = 12599 x 10E9KWH or 12599 x 10E6 MWH = 12599 TWH total available energy from the marcellus. multiply that by .57 for efficiency and total possible production from a gas turbine is 7181.43 TWH. Remember that production and consumption of electricity are not the same. We overproduce to keep voltage ready to give energy at your wall socket all the time. Using the actual coal electricity generation figure we have between 3-4 years of electricity in the shale if it were to replace coal. We have between one and two years electricity if it were to replace all production sources. Sorry to disagree.

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