Could Largest US Coal Reserves Be Overstated By 50%? New USGS Dataset Seems To Say So

[hatrack]

More information on the USGS study, including estimates by the US of the effect of changing economic conditions on coal availability in Gillette, can be found below the fold. The study itself is available through this weblink (Beware! 92 megabyte, 123 pages)

http://pubs.usgs.gov/of/2008/1202/pdf/ofr2008-1202.pdf

EDIT

The USGS study approach - Mining in the Gillette coal field has so far only taken place in two out of eleven coal beds identified in the Gillette coal field, namely Anderson and Canyon. These are the thickest and most contiguous beds with average thickness of 45 and 26 feet respectively. To assess the resources and reserves in all the coal beds, a dataset was made with old and new drill hole data totaling 10,210 data points. This is ten times as many data points as in the 2002 study.

"In addition, prior to this study the distance between data drill holes used in the correlation process was sometimes large, thus creating uncertainty in correctly correlating individual coal beds from one drill hole to the next. Previous reports relied on drill hole data that were up to ten or more miles apart. However, with the recent drilling and development of CBM in the PRB, data from over 10,000 new drill holes in the Gillette coalfield alone are now available. Utilizing the more closely spaced coalbed methane drill holes, it was possible to more confidently define coal bed correlations, determine split lines, and outline paleo-channels (USGS 2008, pp. 6-7)."

For each coal bed, a geological grid model was made including coal thickness, parting thickness, coal height (coal plus parting), and roof and floor structures, with the aid of PC/Cores, a multi-bed modeling program. By using these models it was found that in 6 out of 11 coal beds, mining could take place in the future thanks to suitable geological characteristics. The six coal beds are the Roland, Smith, Dietz and Anderson Rider coal beds as well as Anderson and Canyon beds where mining already takes place. This assessment was based on coal bed thickness and the stripping ratio. This latter factor shows the amount of waste rock to coal. A stripping ratio of 4:1 implies that four tons of rock have to be moved to get one ton of coal. The larger the stripping ratio, the greater the technical difficulties and cost will be to get the coal out of the ground. Specifically, the USGS used the following criteria:

The basic assumptions used to qualify coal beds for potential reserve evaluation were to include: (1) coal beds above the Anderson or Canyon 5 ft or greater with significant areal extent and (2) coal beds below the Anderson or Canyon 5 ft or greater with significant areal extent and an incremental stripping ratio of 4:1 or less. The minimum thickness of at least 5 ft and the maximum incremental stripping ratio of 4:1 criteria for beds below the Anderson or Canyon were selected on the basis of current mining practices at existing mines in the Gillette coalfield (USGS 2008, p.10).".... "This stripping ratio criterion eliminated all beds below the Canyon. Six beds with significant areal extent and exceeding 5 ft thick were evaluated for potential recovery and reserves. In addition to the Anderson and Canyon beds, the Roland, Smith, Anderson Rider, and Dietz coal beds were included in the mine models (USGS 2008, pp. 22-23)."

As a result of the new dataset, a considerable number of insights were gained on the detailed geology of the Gillette coal field. An example is the Anderson coal bed which was found to be less continuous and thick at the eastern margin of the north-south traverse. At this side also the Smith bed previously thought to be quite thick appears to be much thinner at 20 ft or less. Hence the stripping ratio there is much larger, and this creates an economic barrier to mining.



EDIT

http://www.theoildrum.com/node/5122#more

[OKIsItJustMe]

1. Excess_3 disagrees

http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=115&topic_id=187596&mesg_id=187596

[excess_3]

2. estimates depend on some assumed price

the higher the price,
the deeper you can dig,
the more coal you get

[NickB79]

3. That's what they said about oil last year

And look how well that worked out.

The problem with the logic of "the higher the price, the bigger the reserves" is that prices can't keep going up indefinitely without demand destruction setting in and economies entering recessions. There comes a point at which coal or oil will never be developed because the derived energy would be so expensive there would be no market for it.