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.