A Look at the West Virginia University Assessment of Technically Recoverable Gas in the Utica Shale

July 22, 2015

NOTE: Images in this archived article have been removed.

Image Removed
Drilling rig image via shutterstock. Reproduced at Resilience.org with permission.

Last week, members of the media breathlessly reported—based on a new study published by West Virginia University (WVU) entitled A Geologic Play Book for Utica Shale Appalachian Basin Exploration—that the Utica Shale could hold more recoverable gas than the Marcellus, the largest shale gas play in the country. The “Play Book” provides an interesting roundup of geological data on the Utica and associated shale units. However the sensational claim that these units contain a mean resource of 782 tcf (trillion cubic feet) of “technically recoverable” gas, 1947% higher than the USGS estimate of 38.2 tcf made in 2012, has little credibility.

Of course, one can get any “technically recoverable” resource number one wants, depending on input assumptions. Critical assumptions for the gas estimate are:

  • Area assigned to sweet spots and non-sweet spots.
  • Drainage area of individual wells.
  • Estimated Ultimate Recovery (EUR) of wells.
  • Success ratio of wells.
Typically these are expressed as a range. In the case of the USGS assessment they are characterized as “minimum”, “mode”, “maximum” and “mean”, and in the WVU assessment variably, when they are stated, as “minimum, medium, maximum” and “minimum, mode, maximum”.
Given that “sweet spots” comprise 99% of WVU’s purported technically recoverable resources, only the sweet spot assumptions are reviewed below in a comparison between the USGS and WVU assessments.
Area assigned to sweet spots
Whereas the USGS assessment provides a quantitative estimate of prospective area, the WVU assessment provides only a map, with a much larger proportion of the total area assigned to “sweet spots” than the USGS.
(Units are Acres) Minimum Mode Maximum Mean
USGS Total Area 25,800,000 31,600,000 37,400,000 21,600,000
USGS Sweet Spot Proportion 0.09 0.21 0.50 0.27
USGS Sweet Spot Area 2,322,000 6,636,000 18,700,000 5,832,000
WVU Assessment Not stated (map only)
Drainage area of individual wells
The USGS assessment provides estimates of well drainage area which allows the calculation of the number of wells required (a mean of about 4.3 wells per square mile). The WVU assessment provides no information on its assumptions.
(Units are Acres) Minimum Mode Maximum Mean
USGS Drainage area per well 120 150 180 150
WVU Assessment Not stated
Estimated Ultimate Recovery (EUR) of wells
For the oil part of the WVU assessment, WVU at least provides some cumulative recovery curves to back up its oil EUR calculations. For the gas assessment the WVU assessment provides nothing more than a map of cumulative recovery of wells drilled to date, none of which have recovered more than 5 bcf (billion cubic feet) and most of which have recovered considerably less than 2 bcf. The WVU then assumes every successful well will have a “medium” expectation of recovering 7 bcf over the entire area it calls a “sweet spot”, and a “maximum” expectation of 30 bcf (25 times the USGS “maximum” estimate). Although there are certainly a few very good wells, this is wildly optimistic and unfounded based on production data to date. The comparison with the USGS is as follows:
(Units are billion cubic feet) Minimum Mode Maximum Mean
USGS assessment 0.2 0.6 1.1 0.619
WVU assessment 0.19 7.09 30.37
Success ratio of wells
Similarly the WVU assessment is optimistic on the success ratio of wells compared to the USGS:
(Units are percent successful) Minimum Mode Maximum Mean
USGS assessment 75 85 95 85
WVU assessment 90 95 99
The WVU assessment of technically recoverable resources in the Utica is incomplete as presented and wildly optimistic compared to the earlier USGS assessment and compared to likely well performance. Although the WVU report does provide a valuable roundup of pertinent geological data, its assessment of technically recoverable resources should not be viewed as credible.

David Hughes

David Hughes is an earth scientist who has studied the energy resources of Canada for four decades, including 32 years with the Geological Survey of Canada as a scientist and research manager. He developed the National Coal Inventory to determine the availability and environmental constraints associated with Canada’s coal resources. As Team Leader for Unconventional Gas on the Canadian Gas Potential Committee, he coordinated the publication of a comprehensive assessment of Canada’s unconventional natural gas potential.

Over the past decade, Hughes has researched, published and lectured widely on global energy and sustainability issues in North America and internationally. His work with Post Carbon Institute includes: a series of papers (2011) on the challenges of natural gas being a "bridge fuel" from coal to renewables; Drill, Baby, Drill (2013), which took a far-ranging look at the prospects for various unconventional fuels in the United States; Drilling California (2013), which critically examined the U.S. Energy Information Administration’s (EIA) estimates of technically recoverable tight oil in the Monterey Shale, which the EIA claimed constituted two-thirds of U.S. tight oil (the EIA subsequently wrote down its resource estimate for the Monterey by 96%); Drilling Deeper (2014), which challenged the U.S. Department of Energy’s expectation of long-term domestic oil and natural gas abundance with an in depth assessment of all drilling and production data from the major shale plays through mid-2014; and Shale Gas Reality Check (2015) and Tight Oil Reality Check (2015), updates to Drilling Deeper. Separately from Post Carbon, Hughes authored BC LNG: A Reality Check in 2014 and A Clear View of BC LNG in 2015, which examined the issues surrounding a proposed massive scale-up of shale gas production in British Columbia for LNG export.

Hughes is president of Global Sustainability Research, a consultancy dedicated to research on energy and sustainability issues. He is also a board member of Physicians, Scientists & Engineers for Healthy Energy (PSE\Healthy Energy) and is a Fellow of Post Carbon Institute. Hughes contributed to Carbon Shift, an anthology edited by Thomas Homer-Dixon on the twin issues of peak energy and climate change, and his work has been featured in Nature, Canadian Business, Bloomberg, USA Today, as well as other popular press, radio, and television.

Tags: Fracking, Shale gas, tight oil