Gary S. Swindell                 Back to top page

Marcellus Shale EUR Study - complete paper in pdf format


The Marcellus Shale in Pennsylvania is a remarkable success story. From almost no production in 2008, more than 5,400 Marcellus wells were on line in June 2014 and more than 1,200 wells are being added each year. Monthly unconventional gas production in the state was more than 323 Bcf per month over the last six months ending in June 2014 and continues to increase.

This study used the public reported production data for Marcellus wells in the State to make estimates of ultimate recovery (EUR). Distributions of the EUR were developed for individual counties and regions. The primary objective of the study was the distribution of EUR. Where the data was available, some correlations were made to other parameters such as estimated horizontal length, initial flow rate and others. Characterizing the decline curves, either through normalization or averaging was not a central purpose but some results are presented. This February, 2016 revision to the study adds about 1,200 wells with first production dates in 2013.

For 3,846 horizontal wells with enough history to forecast a decline profile, the estimated ultimate recovery averages 4.7 billion cubic feet equivalent (Bcfe) per well with a median of 3.9 Bcfe. The results vary considerably by region - in six counties in the Northeast part of Pennsylvania, the average is 5.5 Bcfe per well and in Wyoming County the mean EUR is 8.8 Bcfe. In that Northeast region, there are a number of wells exceeding 15 Bcfe EUR. (Lease condensate was converted to an equivalent gas volume using a price ratio of 20 thousand cubic feet (Mcf) per barrel).

Initial or maximum production rate from the horizontal wells has increased from approximately 43,000 Mcf/month per well in 2008 to 173,000 Mcf per month for the wells completed in 2013. The average EUR more than doubled from the 2008 wells to 5.4 Bcfe per well in the 2013 wells as horizontal length doubled, fracturing technology advanced and drilling activity focused on the most productive regions in the Northeast and far Southwest part of Pennsylvania. Across the whole state, the wells in the study show an average initial decline of 47 percent with an average hyperbolic b-factor of 0.60.

Marcellus Shale EUR Study - complete paper in pdf format