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U.S. Department of Energy
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Overburden characterization and post-burn study at the Hanna, Wyoming underground coal gasification site: stratigraphy, depositional environments and mineralogy, Hanna Formation

Technical Report ·
OSTI ID:5386737

Several underground coal gasification (UCG) experiments have been conducted in the Hanna No. 1 coal seam. During the fall of 1980 the Laramie Energy Technology Center performed a post-burn field study of the Hanna II, Phases 2 and 3 experiment at the Hanna UCG site. The field work consisted of high resolution seismic, drilling, coring, and geophysical logging. The Department of Earth Resources, Colorado State University, contributed to the post-burn study by doing laboratory work on the cores and geophysical logs. The purpose of the laboratory work was to provide an estimate of the temperatures and chemical conditions reached during the conversion experiment by studying the mineralogical and textural characteristics of thermally altered and ulaltered overburden. In the vicinity of the burn cavity, overburden rocks have been subjected to high temperature pyrometamorphism during the Hanna II Phases 2 and 3 UCG experiments. Paralava rocks, buchites and paralava breccias containing glass and various high temperature minerals such as oligoclase, clinopyroxene, ferrocordierite, mullite, cristobalite, magnetite, and tridymite formed. Textures of some of these minerals suggest crystallization directly from a melt. Mineralogy and melting relations of the paralavas, ash fusion temperatures, and thermocouple measurements made during the experiment suggest that tempratures in excess of 1200/sup 0/C were attained. Rock color and the presence of reduced iron bearing minerals and blebs of native iron indicate that the experimental burn and the product gases in the area of paralava formation were reducing.

Research Organization:
Colorado State Univ., Fort Collins (USA); Department of Energy, Laramie, WY (USA). Laramie Energy Technology Center
DOE Contract Number:
AT20-80LC10496
OSTI ID:
5386737
Report Number(s):
DOE/LC/10496-T1; ON: DE82009053
Country of Publication:
United States
Language:
English