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Title: Remanent and rock magnetic properties at the Hanna, Wyoming underground coal gasification site: Hanna II phases 2 and 3 experiment

Technical Report ·
DOI:https://doi.org/10.2172/7182603· OSTI ID:7182603

Several underground coal gasification (UCG) experiments have been conducted in the Hanna No. 1 coal seam. During the fall, 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 Paleomagnetism Laboratory, Department of Geology, Colorado School of Mines, contributed to the post-burn study by doing remanent and rock magnetic measurement laboratory work on the core material. Funding was provided by the Laramie Energy Technology Center. The purpose of the study was to determine the nature of the remanent magnetism of the overburden Hanna Formation and changes in the remanence and magnetic mineralogy attending underground coal gasification experiments. With this information, further estimates of the thermal and chemical conditions reached during the conversion experiment could be made. The magnetization data, together with previous petrographic observations, suggest that magnetite is being formed in a reducing process at the expense of detrital ferromagnesian silicates and possible hematite and geothite in the overburden sediments. Thermal gradients immediately above the burn cavity are difficult to estimate; changes in magnetic properties of unaltered Hanna Formation overburden are activated at temperatures as low as 300/sup 0/C. The magnetic expression of the burn cavity should be able to be modelled as being due to a thin slab overlying the cavity. Pyrometamorphosed material that has collapsed into the cavity, should have any magnetization which is randomized due to collapse and therefore should be able to be incorporated into a magnetic anomaly model. 32 references, 27 figures.

Research Organization:
Colorado School of Mines, Golden (USA). Dept. of Geology
DOE Contract Number:
AS20-81LC10694
OSTI ID:
7182603
Report Number(s):
DOE/LC/10694-1519; ON: DE84003019
Resource Relation:
Other Information: Portions are illegible in microfiche products. Original copy available until stock is exhausted
Country of Publication:
United States
Language:
English