USGS Science⌕ Search

Geology topics

James A. Luppens

Publications and source records attributed to James A. Luppens.

17 recordsLinked to original sources
USGS2021

Probabilistic methodology for the assessment of original and recoverable coal resources, illustrated with an application to a coal bed in the Fort Union Formation, Wyoming

Executive Summary The U.S. Geological Survey (USGS) has been using its Circular 891 for evaluating uncertainty in coal resource assessments for more than 35 years. Calculated cell tonnages are assigned to four qualitative reliability classes depending exclusively on distance to the nearest drill hole. The main appeal of this methodology, simplicity, is also its main drawback. Reliability may depend so marginally on distance to the nearest drill hole that, over time, it has become evident that Circular 891 is inadequate for modeling reliability and is limited by other shortcomings. The present publication describes the use of geostatistics as an approach allowing a more satisfactory performance than that which is achieved following Circular 891. Geostatistics takes advantage of partly random and partly organized fluctuations in attributes such as coal thickness, coal density, and elevation of the top of a coal bed, borrowing concepts and tools that have been standard features in statistics and risk analysis for decades. Considering that readers interested in this study may not have the background to go directly into the details of the methodology, we start by explaining geostatistical concepts and modeling techniques. The remainder of the publication is devoted to formulating the assessment methodology, applying it to data from the Fillmore Ranch coal bed in the Fort Union Formation in Wyoming, and explaining the computer software applied for performing calculations and displays. The assessment methodology has been designed to report three different forms of resources: coal in place, coal mineable by surface mining methods, and coal mineable by underground mining methods. These three types of resources are reported graphically by displaying both the magnitude and the reliability of total coal resources and resources at the cell scale. In the case of the Fillmore Ranch coal bed example, there is a 90-percent probability that the resources in place are 9.687 ± 0.383 billion short tons (bst), while the coal available for underground mining is 2.279 ± 0.160 bst, and that available for surface mining is only 0.240 ± 0.025 bst because of the steep dip to the west away from the outcrop. These magnitudes are derived from numerical probability distributions not following any specific form.

Wyoming↗
USGS2019

Assessment of coal resources and reserves in the Little Snake River coal field and Red Desert assessment area, Greater Green River Basin, Wyoming

The assessment of the Little Snake River coal field and Red Desert area covers approximately 2,300 square miles in the eastern portion of the Greater Green River Basin in south-central Wyoming. Coal-bearing formations are present throughout the Eocene, Paleocene, and Cretaceous strata in the assessment area. Paleogene-age coal beds are present in the Eocene Wasatch Formation and Paleocene Fort Union Formation. Cretaceous-age coal beds are present in the Lance, Almond, and Allen Ridge Formations. Utilizing over 4,000 data points, 55 individual coal beds were identified in the assessment area. Coal resources were calculated using geologic models generated from these data points, using criteria for minimum thickness and areal extent. The geologic modeling criteria indicated that 33 of the 55 individual coal beds had sufficient thickness and areal extent to be economically significant. Calculated original coal resources within the assessment area were approximately 73.2 billion short tons (BST). After excluding coal resources lost due to land use and technical restrictions, recoverable coal resources were approximately 19.37 BST, including 2.14 BST of coal resources that could be extracted using surface mining methods and 17.23 BST of coal resources that could be extracted using underground mining methods. Due to mining costs and projected low potential sales value of the coal resources, only approximately 167 million short tons (MST) can be classified as reserves, which is less than 1 percent of the recoverable coal resources

Wyoming↗
USGS2015

The U.S. Geological Survey coal quality (COALQUAL) database version 3.0

Since the mid-1970s, the U.S. Geological Survey (USGS) has maintained a coal quality database of national scope named USCHEM, which currently contains data for over 13,000 samples. A subset of the USCHEM database called COALQUAL Version 1.3 was initially published in 1994 and was followed by Version 2.0 in 1997. Version 3.0 of the COALQUAL database represents a major editing effort to resolve some of the DOS software limitations used by earlier versions of the database. Because of database size limits during the development of COALQUAL Version 1.3, many analyses of individual bench samples were merged into whole coal bed averages. The methodology for making these composite intervals was not consistent. Size limits also restricted the amount of georeferencing information and forced removal of qualifier notations such as "less than detection limit" (<) information, which can cause problems when using the data. A review of the original data sheets revealed that COALQUAL Version 2.0 was missing information that was needed for a complete understanding of a coal section. Another important database issue to resolve was the USGS "remnant moisture" problem. Prior to 1998, tests for remnant moisture (as-determined moisture in the sample at the time of analysis) were not performed on any USGS major, minor, or trace element coal analyses. Without the remnant moisture, it is impossible to convert the analyses to a usable basis (as-received, dry, etc.). Based on remnant moisture analyses of hundreds of samples of different ranks (and known residual moisture) reported after 1998, it was possible to develop a method to provide reasonable estimates of remnant moisture for older data to make it more useful in COALQUAL Version 3.0. In addition, COALQUAL Version 3.0 is improved by (1) adding qualifiers, including statistical programming to deal with the qualifiers; (2) clarifying the sample compositing problems; and (3) adding associated samples. Version 3.0 of COALQUAL also represents the first attempt to incorporate data verification by mathematically crosschecking certain analytical parameters. Finally, a new database system was designed and implemented to replace the outdated DOS program used in earlier versions of the database.

Data Series↗
USGS2015

Mapping of coal quality using stochastic simulation and isometric logratio transformation with an application to a Texas lignite

Coal is a chemically complex commodity that often contains most of the natural elements in the periodic table. Coal constituents are conventionally grouped into four components (proximate analysis): fixed carbon, ash, inherent moisture, and volatile matter. These four parts, customarily measured as weight losses and expressed as percentages, share all properties and statistical challenges of compositional data. Consequently, adequate modeling should be done in terms of a logratio transformation, a requirement that is commonly overlooked by modelers. The transformation of choice is the isometric logratio transformation because of its geometrical and statistical advantages. The modeling is done through a series of realizations prepared by applying sequential simulation for the purpose of displaying the parts in maps incorporating uncertainty. The approach makes realistic assumptions and the results honor the data and basic considerations, such as percentages between 0 and 100, all four parts adding to 100% at any location in the study area, and a style of spatial fluctuation in the realizations equal to that of the data. The realizations are used to prepare different results, including probability distributions across a deposit, E-type maps displaying average properties, and probability maps summarizing joint fluctuations of several parts. Application of these maps to a lignite bed clearly delineates the deposit boundary, reveals a channel cutting across, and shows that the most favorable coal quality is to the north and deteriorates toward the southeast.

International Journal of Coal Geology↗
USGS2015

Geospatial data for coal beds in the Powder River Basin, Wyoming and Montana

The purpose of this report is to provide geospatial data for various layers and themes in a Geographic Information System (GIS) format for the Powder River Basin, Wyoming and Montana. In 2015, as part of the U.S. Coal Resources and Reserves Assessment Project, the U.S. Geological Survey (USGS) completed an assessment of coal resources and reserves within the Powder River Basin, Wyoming and Montana. This report is supplemental to USGS Professional Paper 1809 and contains GIS data that can be used to view digital layers or themes, including the Tertiary limit of the Powder River Basin boundary, locations of drill holes, clinker, mined coal, land use and technical restrictions, geology, mineral estate ownership, coal thickness, depth to the top of the coal bed (overburden), and coal reliability categories. Larger scale maps may be viewed using the GIS data provided in this report supplemental to the page-size maps provided in USGS Professional Paper 1809. Additionally, these GIS data can be exported to other digital applications as needed by the user. The database used for this report contains a total of 29,928 drill holes, of which 21,393 are in the public domain. The public domain database is linked to the geodatabase in this report so that the user can access the drill-hole data through GIS applications. Results of this report are available at the USGS Energy Resources Program Web site, http://energy.usgs.gov/RegionalStudies/PowderRiverBasin.aspx .

Montana, Wyoming↗
USGS2015

Coal geology and assessment of coal resources and reserves in the Powder River Basin, Wyoming and Montana

This report presents the final results of the first assessment of both coal resources and reserves for all significant coal beds in the entire Powder River Basin, northeastern Wyoming and southeastern Montana. The basin covers about 19,500 square miles, exclusive of the part of the basin within the Crow and Northern Cheyenne Indian Reservations in Montana. The Powder River Basin, which contains the largest resources of low-sulfur, low-ash, subbituminous coal in the United States, is the single most important coal basin in the United States. The U.S. Geological Survey used a geology-based assessment methodology to estimate an original coal resource of about 1.16 trillion short tons for 47 coal beds in the Powder River Basin; in-place (remaining) resources are about 1.15 trillion short tons. This is the first time that all beds were mapped individually over the entire basin. A total of 162 billion short tons of recoverable coal resources (coal reserve base) are estimated at a 10:1 stripping ratio or less. An estimated 25 billion short tons of that coal reserve base met the definition of reserves, which are resources that can be economically produced at or below the current sales price at the time of the evaluation. The total underground coal resource in coal beds 10&ndash;20 feet thick is estimated at 304 billion short tons.

Montana, Wyoming↗
USGS2014

Modeling uncertainty in coal resource assessments, with an application to a central area of the Gillette coal field, Wyoming

Standards for the public disclosure of mineral resources and reserves do not require the use of any specific methodology when it comes to estimating the reliability of the resources. Unbeknownst to most intended recipients of resource appraisals, such freedom commonly results in subjective opinions or estimations based on suboptimal approaches, such as use of distance methods. This report presents the results of a study of the third of three coal deposits in which drilling density has been increased one order of magnitude in three stages. Applying geostatistical simulation, the densest dataset was used to check the results obtained by modeling the sparser drillings. We have come up with two summary displays of results based on the same simulations, which individually and combined provide a better assessment of uncertainty than traditional qualitative resource classifications: (a) a display of cell 90 percent confidence interval versus cumulative cell tonnage, and (b) a histogram of total resources. The first graph allows classification of data into any number of bins with dividers to be decided by the assessor on the basis of a discriminating variable that is statistically accepted as a measure of uncertainty, thereby improving the quality and flexibility of the modeling. The second display expands the scope of the modeling by providing a quantitative measure of uncertainty for total tonnage, which is a fundamental concern for stockholders, geologists, and decision makers. Our approach allows us to correctly model uncertainty issues not possible to predict with distance methods, such as (a) different levels of uncertainty for individual beds with the same pattern and density of drill holes, (b) different local degrees of reduction of uncertainty with drilling densification reflecting fluctuation in the complexity of the geology, (c) average reduction in uncertainty at a disproportionately lesser rate than the reduction in area per drill hole, (d) the proportional effect of higher uncertainty in areas of higher tonnages, despite a regular drilling pattern, (e) the possibility of a local increase in uncertainty despite drilling densification to reflect a more complex geology as the deposit is known in more detail, and (f) for exactly the same drilling pattern, tonnage per individual beds with different uncertainty than the aggregated tonnage. These results should be considered realistic improvements over distance methods used for quantitative classification of uncertainty in coal resource, such as U.S. Geological Survey Circular 891. 1 The approach should be a welcome addition to the toolkit of Competent Persons preparing public disclosures according to international mineral codes such as those promoted by the Combined Reserves International Reporting Standards Committee 2 and the Joint Ore Reserve Committee. 3 1 Wood, G.H., Jr., Kehn, T.M., Carter, M.D., and Culbertson, W.C., 1983, Coal resources classification system of the U.S. Geological Survey: U.S. Geological Survey Circular 891, 65 p. 2 CRIRSCO (Combined Reserves International Reporting Standards Committee), 2013, International reporting template for the public reporting of exploration results, mineral resources and mineral reserves: Accessed February 2014 at http://www.crirsco.com/crirsco_template_may2013.pdf. 3 JORC (Joint Ore Reserves Committee), 2012, Australasian code for reporting of exploration results, mineral resources and ore reserves: Accessed September 2014 at http://www.jorc.org/docs/jorc_code2012.pdf.

Wyoming↗
USGS2013

Assessment of coal geology, resources, and reserves in the Montana Powder River Basin

The purpose of this report is to summarize geology, coal resources, and coal reserves in the Montana Powder River Basin assessment area in southeastern Montana. This report represents the fourth assessment area within the Powder River Basin to be evaluated in the continuing U.S. Geological Survey regional coal assessment program. There are four active coal mines in the Montana Powder River Basin assessment area: the Spring Creek and Decker Mines, both near Decker; the Rosebud Mine, near Colstrip; and the Absaloka Mine, west of Colstrip. During 2011, coal production from these four mines totaled approximately 36 million short tons. A fifth mine, the Big Sky, had significant production from 1969-2003; however, it is no longer in production and has since been reclaimed. Total coal production from all five mines in the Montana Powder River Basin assessment area from 1968 to 2011 was approximately 1.4 billion short tons. The Rosebud/Knobloch coal bed near Colstrip and the Anderson, Dietz 2, and Dietz 3 coal beds near Decker contain the largest deposits of surface minable, low-sulfur, subbituminous coal currently being mined in the assessment area. A total of 26 coal beds were identified during this assessment, 18 of which were modeled and evaluated to determine in-place coal resources. The total original coal resource in the Montana Powder River Basin assessment area for the 18 coal beds assessed was calculated to be 215 billion short tons. Available coal resources, which are part of the original coal resource remaining after subtracting restrictions and areas of burned coal, are about 162 billion short tons. Restrictions included railroads, Federal interstate highways, urban areas, alluvial valley floors, state parks, national forests, and mined-out areas. It was determined that 10 of the 18 coal beds had sufficient areal extent and thickness to be evaluated for recoverable surface resources ([Roland (Baker), Smith, Anderson, Dietz 2, Dietz 3, Canyon, Werner/Cook, Pawnee, Rosebud/Knobloch, and Flowers-Goodale]). These 10 coal beds total about 151 billion short tons of the 162 billion short tons of available resource; however, after applying a strip ratio of 10:1 or less, only 39 billion short tons remains of the 151 billion short tons. After mining and processing losses are subtracted from the 39 billion short tons, 35 billion short tons of coal were considered as a recoverable resource. Coal reserves (economically recoverable coal) are the portion of the recoverable coal resource that can be mined, processed, and marketed at a profit at the time of the economic evaluation. The surface coal reserve estimate for the 10 coal beds evaluated for the Montana Powder River assessment area is 13 billion short tons. It was also determined that about 42 billion short tons of underground coal resource exists in the Montana Powder River Basin assessment area; about 34 billion short tons (80 percent) are within 500-1,000 feet of the land surface and another 8 billion short tons are 1,000-2,000 feet beneath the land surface.

Montana;Wyoming↗
USGS2011

Methodology for quantifying uncertainty in coal assessments with an application to a Texas lignite deposit

A common practice for characterizing uncertainty in coal resource assessments has been the itemization of tonnage at the mining unit level and the classification of such units according to distance to drilling holes. Distance criteria, such as those used in U.S. Geological Survey Circular 891, are still widely used for public disclosure. A major deficiency of distance methods is that they do not provide a quantitative measure of uncertainty. Additionally, relying on distance between data points alone does not take into consideration other factors known to have an influence on uncertainty, such as spatial correlation, type of probability distribution followed by the data, geological discontinuities, and boundary of the deposit. Several geostatistical methods have been combined to formulate a quantitative characterization for appraising uncertainty. Drill hole datasets ranging from widespread exploration drilling to detailed development drilling from a lignite deposit in Texas were used to illustrate the modeling. The results show that distance to the nearest drill hole is almost completely unrelated to uncertainty, which confirms the inadequacy of characterizing uncertainty based solely on a simple classification of resources by distance classes. The more complex statistical methods used in this study quantify uncertainty and show good agreement between confidence intervals in the uncertainty predictions and data from additional drilling.

International Journal of Coal Geology↗
USGS2011

Assessment of coal geology, resources, and reserves in the Southwestern Powder River Basin, Wyoming

The availability of abundant new borehole data from recent coal bed natural gas development was utilized by the U.S. Geological Survey for a comprehensive evaluation of coal resources and reserves in the southwestern part of the Powder River Basin in Wyoming. This report on the Southwestern Powder River Basin assessment area represents the third area within the basin to be assessed, the first being for coal resources and reserves in the Gillette coal field in 2008, and the second for coal resources and reserves in the northern Wyoming area of the basin in 2010. There are no active coal mines in the Southwestern Powder River Basin assessment area. The only significant production is attributed to the Dave Johnston Mine, in the extreme southern part of the area, which accounted for some 104 million short tons of coal from 1959 to 2000. Several small mines were developed in the 1950s near the Lake DeSmet area in the northwestern part of the area; however, less than 25,000 short tons of coal were produced. Eight coal beds are present at depths between 1,000 and 2,000 ft in the Southwestern Powder River Basin assessment area. Portions of these coal beds might be recovered by underground mining methods in the future; however, the lack of sufficient drill data precluded an economic study to assess the potential of surface mineable coal resources. Consequently, none of the coal resources in the Southwestern Powder River Basin assessment area were designated as reserves or recoverable coal. A total of 37 coal beds were identified during this assessment, 23 of which were modeled and evaluated to determine in-place coal resources. The total original coal resource in the Southwestern Powder River Basin assessment area for these 23 coal beds, with no restrictions applied was calculated to be 369 billion short tons. Available coal resources, which are part of the original resource that is accessible for potential mine development after subtracting all restrictions, are about 341 billion short tons (92.4 percent of the total original resource). Approximately 61 percent are at depths between 1,000 and 2,000 ft, with a modeled price of about $30 per short ton. Therefore, the majority of coal resources in the South-western Powder River Basin assessment area are considered sub-economic.

Open-File Report↗
USGS2011

A critical review of published coal quality data from the southwestern part of the Powder River Basin, Wyoming

A review of publicly available coal quality data during the coal resource assessment of the southwestern part of the Powder River Basin, Wyoming (SWPRB), revealed significant problems and limitations with those data. Subsequent citations of data from original sources often omitted important information, such as moisture integrity and information needed to evaluate the issue of representativeness. Occasionally, only selected data were quoted, and some data were misquoted. Therefore, it was important to try to resolve issues concerning both the accuracy and representativeness of each available dataset. The review processes demonstrated why it is always preferable to research and evaluate the circumstances regarding the sampling and analytical methodology from the original data sources when evaluating coal quality information, particularly if only limited data are available. Use of the available published data at face value would have significantly overestimated the coal quality for all the coal fields from both the Fort Union and Wasatch Formations in the SWPRB assessment area. However, by using the sampling and analytical information from the original reports, it was possible to make reasonable adjustments to reported data to derive more realistic estimates of coal quality.

Wyoming↗
USGS2010

Assessment of coal geology, resources, and reserves in the northern Wyoming Powder River Basin

The abundance of new borehole data from recent coal bed natural gas development in the Powder River Basin was utilized by the U.S. Geological Survey for the most comprehensive evaluation to date of coal resources and reserves in the Northern Wyoming Powder River Basin assessment area. It is the second area within the Powder River Basin to be assessed as part of a regional coal assessment program; the first was an evaluation of coal resources and reserves in the Gillette coal field, adjacent to and south of the Northern Wyoming Powder River Basin assessment area. There are no active coal mines in the Northern Wyoming Powder River Basin assessment area at present. However, more than 100 million short tons of coal were produced from the Sheridan coal field between the years 1887 and 2000, which represents most of the coal production within the northwestern part of the Northern Wyoming Powder River Basin assessment area. A total of 33 coal beds were identified during the present study, 24 of which were modeled and evaluated to determine in-place coal resources. Given current technology, economic factors, and restrictions to mining, seven of the beds were evaluated for potential reserves. The restrictions included railroads, a Federal interstate highway, urban areas, and alluvial valley floors. Other restrictions, such as depth, thickness of coal beds, mined-out areas, and areas of burned coal, were also considered. The total original coal resource in the Northern Wyoming Powder River Basin assessment area for all 24 coal beds assessed, with no restrictions applied, was calculated to be 285 billion short tons. Available coal resources, which are part of the original coal resource that is accessible for potential mine development after subtracting all restrictions, are about 263 billion short tons (92.3 percent of the original coal resource). Recoverable coal, which is that portion of available coal remaining after subtracting mining and processing losses, was determined for seven coal beds with a stripping ratio of 10:1 or less. After mining and processing losses were subtracted, a total of 50 billion short tons of recoverable coal was calculated. Coal reserves are the portion of the recoverable coal that can be mined, processed, and marketed at a profit at the time of the economic evaluation. With a discounted cash flow at 8 percent rate of return, the coal reserves estimate for the Northern Wyoming Powder River Basin assessment area is 1.5 billion short tons of coal (1 percent of the original resource total) for the seven coal beds evaluated.

Open-File Report↗
USGS2008

Assessment of Coal Geology, Resources, and Reserves in the Gillette Coalfield, Powder River Basin, Wyoming

The Gillette coalfield, within the Powder River Basin in east-central Wyoming, is the most prolific coalfield in the United States. In 2006, production from the coalfield totaled over 431 million short tons of coal, which represented over 37 percent of the Nation's total yearly production. The Anderson and Canyon coal beds in the Gillette coalfield contain some of the largest deposits of low-sulfur subbituminous coal in the world. By utilizing the abundance of new data from recent coalbed methane development in the Powder River Basin, this study represents the most comprehensive evaluation of coal resources and reserves in the Gillette coalfield to date. Eleven coal beds were evaluated to determine the in-place coal resources. Six of the eleven coal beds were evaluated for reserve potential given current technology, economic factors, and restrictions to mining. These restrictions included the presence of railroads, a Federal interstate highway, cities, a gas plant, and alluvial valley floors. Other restrictions, such as thickness of overburden, thickness of coal beds, and areas of burned coal were also considered. The total original coal resource in the Gillette coalfield for all eleven coal beds assessed, and no restrictions applied, was calculated to be 201 billion short tons. Available coal resources, which are part of the original coal resource that is accessible for potential mine development after subtracting all restrictions, are about 164 billion short tons (81 percent of the original coal resource). Recoverable coal, which is the portion of available coal remaining after subtracting mining and processing losses, was determined for a stripping ratio of 10:1 or less. After mining and processing losses were subtracted, a total of 77 billion short tons of coal were calculated (48 percent of the original coal resource). Coal reserves are the portion of the recoverable coal that can be mined, processed, and marketed at a profit at the time of the economic evaluation. With a discounted cash flow at 8 percent rate of return, the coal reserves estimate for the Gillette coalfield is10.1 billion short tons of coal (6 percent of the original resource total) for the 6 coal beds evaluated.

Open-File Report↗
USGS2007

Performance audit of the U.S. Geological Survey, energy resource program inorganic geochemistry laboratory

A performance audit of the U.S. Geological Survey (USGS), Energy Resource Program (ERP) Inorganic Geochemistry Laboratory (IGL) was conducted between August, 2003 and October, 2005. The goals were to ensure that a high level of analytical performance was maintained and identify any areas that could be enhanced. The audit was subdivided into three phases. Phase 1 was a preliminary assessment of current performance based on recent performance on CANSPEX samples. IGL performance was also compared to laboratories world-wide with similar scope. Phase 2 consisted of the implementation of the recommended changes made in Phase 1. Phase 3 of the audit consisted of a reassessment effort to evaluate the effectiveness of the recommendations made in the Phase 1 and an on-site audit of the laboratory facilities. Phases 1 and 3 required summary reports that are included in Appendices A and B of this report. The audit found that the IGL was one of the top two laboratories compared for trace element analyses. Several recommendations to enhance performance on major and minor elemental parameters were made and implemented. Demonstrated performance improvements as a result of the recommended changes were documented. Several initiatives to sustain the performance improvements gained from the audit have been implemented.

Open-File Report↗
USGS2006

Preliminary estimate of coal resources in the Gillette coalfield affected by the location of the Burlington Northern/Union Pacific joint mainline railroad

This publication, primarily in graphic form, presents a preliminary resource assessment related to a major, near-term restriction to mining in that portion of the Gillette coalfield, Wyoming, that is traversed by the Burlington Northern/Union Pacific joint mainline railroad. This assessment is part of a current Powder River Basin regional coal assessment, including both resources and reserves, being conducted by the U.S. Geological Survey. The slides were used to illustrate a presentation of study results at a meeting of the Bureau of Land Management's Regional Coal Team in Casper, Wyoming on April 19, 2006 by the senior author.

Open-File Report↗