In situ analysis of coal using a 252CF-Ge(Li) borehole sonde

Abstract

A borehole sonde using a 252 Cf neutron source and a Ge(Li) gamma-ray detector was field tested in a coal bed in Belmont County, Ohio, to ascertain whether such a device could be useful as a coal-exploration tool. In continuous motion, the sonde was used to accumulate successive spectra over short time intervals. The intensities of the capture gamma rays from hydrogen and of the decay gamma rays from aluminum were determined simultaneously in each spectrum. A log of the intensities versus depth shows the depth and thickness of the coal bed. With the sonde stationary at points above, in, and below the coal bed, capture gamma rays were measured to show the variation in concentration of certain elements. From the spectrum recorded in the bed, a complete ultimate analysis, the percent ash content, and the heat content were determined without recourse to an external standard. With the sonde stationary at points above, in, and below the coal bed, capture gamma rays were measured to show the variation in concentration of certain elements. From the spectrum recorded in the bed, a complete ultimate analysis, the percent ash content, and the heat content were determined without recourse to an external standard. These experiments show that it is feasible to use a 252 CfGe(Li) borehole sonde as an aid in coal exploration.