New Mexico Geological Society Annual Spring Meeting — Abstracts

Coal cores that have been stored for a period of some years probably undergo some amount of oxidation/dehydration. Oxidation even to a very slight extent, severely reduces the calorific value and petrochemical use of the coal. Petrographic studies of these effects have only recently been put into use. This oxidation presents itself in the form of microcracks and micropores. Decreases in the amount of microcracks and micropores towards the center of the drill core might be an indication of post-coring oxidation. An attempt was also made to establish a relationship between the cracks and pseudovitrinite because it was believed that one might contribute to the distribution of the other.

Extensive petrographic examination of the polished sections has revealed that there apparently is n6 progressive decrease in oxidation/ dehydration towards the center of the core. The extremely variable amounts of cracks and pseudovitrinite seen indicate that there apparently is no relationship between these two. Vitrinite reflectance measurements also did not indicate that the dehydration cracks had served as a pathway for oxidation. Analyses seeking a relationship between cleats and maceral content on one hand, and oxidation/dehydration on the other have so far proven to be futile. Repolishing of the samples at the end of the study eliminated most petrographic evidence of oxidation/ dehydration seen. Petrography therefore is a useful tool for the detection of oxidation/dehydration, but apparently is not a good method for quantifying these effects.