After Further Review, At Least 15 Years of Gas in the Marcellus Shale

After publishing the piece about Terry Engelder's update on the Marcellus reserve estimate, I made an inquiry to confirm my assumption about the new estimate of recoverable gas in the play. To clarify, Professor Engelder notes that the new analysis is derived from a convergence of the latest data provided by Chesapeake, Range and several other operators. He provided the following assumptions used in his analysis:

Total Acreage 31,000,000
# Sections (640 acre) = 48,437.5
GIP/Section = 75 bcf
Total Gas in Place = 3,632 tcf
Recovery Factor = 30%
Technically Recoverable Gas = 1,089 tcf

Professor Engelder cautioned that a practical assessment of the amount of gas which could be expected to be recovered would need to consider how much of the acreage is accessible. There are, of course properties that cannot be developed, existing storage fields, terrain challenged areas, etc., which must be discounted. In his present assumption, 33.33% of the total acreage in the play can be considered developable. This would leave the truly recoverable reserves at 363 tcf, a sevenfold increase of the prior 50 tcf estimate and much greater than the double I reported earlier.

Under these assumptions, the Marcellus could now provide all of the natural gas consumed in the US for 15 years.