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Organic petrology and coalbed gas content, Wilcox Group (Paleocene-Eocene), northern Louisiana

International Journal of Coal Geology

By:
, , and
DOI: 10.1016/j.coal.2006.05.009

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Abstract

Wilcox Group (Paleocene-Eocene) coal and carbonaceous shale samples collected from four coalbed methane test wells in northern Louisiana were characterized through an integrated analytical program. Organic petrographic analyses, gas desorption and adsorption isotherm measurements, and proximate-ultimate analyses were conducted to provide insight into conditions of peat deposition and the relationships between coal composition, rank, and coalbed gas storage characteristics. The results of petrographic analyses indicate that woody precursor materials were more abundant in stratigraphically higher coal zones in one of the CBM wells, consistent with progradation of a deltaic depositional system (Holly Springs delta complex) into the Gulf of Mexico during the Paleocene-Eocene. Comparison of petrographic analyses with gas desorption measurements suggests that there is not a direct relationship between coal type (sensu maceral composition) and coalbed gas storage. Moisture, as a function of coal rank (lignite-subbituminous A), exhibits an inverse relationship with measured gas content. This result may be due to higher moisture content competing for adsorption space with coalbed gas in shallower, lower rank samples. Shallower (< 600??m) coal samples consistently are undersaturated with respect to CH4 adsorption isotherms; deeper (> 600??m) coal samples containing less moisture range from under- to oversaturated with respect to their CH4 adsorption capacity.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Organic petrology and coalbed gas content, Wilcox Group (Paleocene-Eocene), northern Louisiana
Series title:
International Journal of Coal Geology
DOI:
10.1016/j.coal.2006.05.009
Volume
71
Issue:
1 SPEC. ISS.
Year Published:
2007
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
International Journal of Coal Geology
First page:
54
Last page:
71