3. New Approach to Geologic Assurance of Coal Resource Estimates

Coal-fired electrical power generation still accounts for about 50 percent of the electricity production in the U.S. With falling estimates of natural gas supplies and the volatility of natural gas prices, coal is likely to remain an important energy fuel source in the foreseeable future, especially if the next generation of clean coal technology is successful. It has been over 25 years since USGS Circular 891 was developed which standardized a classification for coal resource/reserve base/reserve categories on the basis of the geologic assurance of the existence of those categories, both quantity and quality, and economic feasibility of their recovery. Geologic assurance in Circular 891 is related to the distance from points where coal is measured or sampled. Circular 891 established one set of geologic assurance criteria for all coal beds nationwide. These criteria roughly paralleled the stages of coal industry project development at the time from widely spaced exploration drilling to closer spaced initial in-fill drilling to tightly spaced development drilling and coring. Since that time, significant changes in the coal industry have occurred.

Most notably, the focus of coal production has shifted from Eastern bituminous coals to Western and Gulf Coast subbituminous and lignite coals. Accompanying this production shift has been differences in the coal geology, quality, and mining technology. These fundamental differences have raised several questions. First, is there a better methodology for estimating assurance? Secondly, is there a need to define geologic assurance on a regional basis rather than a "one size fits all approach?" Other countries such as Canada have found it desirable to set different criteria of geologic assurance based on the degree of geologic complexity in the different coal provinces. Furthermore, since Circular 891 was published, new opportunities like coal bed methane and carbon sequestration have become potentially important issues. Geologic assurance concerns associated with these issues should also be considered as well.

Previous statistical approaches to geologic assurance have typically started with detailed drilling data sets from a single coal bed and randomly selected sub sets of the database at differently spaced data points. This approach simply provides simple statistical analyses of the confidence based solely on thickness variations. However, the real problem in estimating the confidence of the quantity and quality of coal resources/reserves at different drilling densities involves more factors than simple variations in thickness. Regional geologic complexity affecting factors such as coal bed structural projections for estimating subcrops, variations in weathering depths, topographic slope, glaciation, and geological modeling uncertainties should also be considered. In the case of evaluation the assurance of coal quality projections, the availability of sufficient data on an individual deposit basis has been a significant obstacle in defining the minimum amount data necessary for adequate quality characterization.

A postdoctoral geologist is sought to investigate the feasibility of developing an improved methodology for coal reliability estimates. A fundamental difference in the approach envisioned will be the comparison of estimated resource tons and quality, the primary purpose of Circular 891, rather than a simple statistical analysis of variations on coal thickness data points. To facilitate this pilot project, permission to use proprietary sets of detailed digital drilling and coring data from four lignite deposits with multiple coal beds in the Gulf Coast region has been secured (derivative maps and other products are publishable with the exception of exact locations). A very useful feature of these databases is the ability to repartition drilling information into the original exploration, in-fill, and development data sets (following the inferred, indicated, and measured data point distance categories of Circular 891).

Proposed Duty Station: Reston, VA

Areas of Ph.D.: Geology, organic petrology and geochemistry, sedimentology and stratigraphy, or related fields

Qualifications: Applicants must meet one of the following qualifications: Research Geologist

(This type of research is performed by those who have backgrounds for the occupations stated above. However, other titles may be applicable depending on the applicant's background, education, and research proposal. The final classification of the position will be made by the Personnel specialist.)

Research Advisor: James A. Luppens, (703) 648-6460, jluppens@usgs.gov

Personnel Office contact: Rosetta Alexander, (703) 648-7468, ralexand@usgs.gov

Summary of Opportunities