Microresistivity and SP Methods to Predict Coal Morphology and Quality

Rene Rodriguez

Microresistivity and SP have been used in conjunction with seismic methods to map, from the surface, the geometry of coal seams in southeast Kentucky. Although the resolution of the electrical method is not as good as high-resolution seismic, the method proved to be a very useful tool to discriminate coal and shaly rock partings otherwise unidentified by the seismic method. Resistivity also provides additional information about the saturation conditions of the coal seams.

In-seam microresistivity and in-seam SP were combined to determine coal quality related to sulfur content. In conjunction with chemical analysis of samples taken from the seam at each of the measuring points, we were able to see the complicated picture of discontinuous areal and depth distribution of sulfur in the seam, which signature also is reflected in the electrical data. Low resistivity and high SP values are commonly associated with high concentrations of sulfur. High resistivity and low SP are associated are associated with typical electrical membrane effects in the seam, and high resistivity and high SP are associated with high ash concentrations of the seam. The combination of resistivity and SP measurements in-seam provides a very useful tool to predict the average coal qua ity of the seam and also the relative areal and depth concentration of sulfur and ash.

AAPG Search and Discovery Article #91041©1987 AAPG Eastern Section Meeting, Columbus, Ohio, October 7-10, 1987.