LITHOLOGY DETERMINATION FROM THE CALCIUM AND MAGNESIUM ACTIVATION LINES

摘要

In the illustrative embodiments of the invention disclosed, the lithology of an earth formation traversed by a well bore is investigated by irradiating the formation with a neutron source and generating an energy spectrum of the activation gamma rays resulting therefrom. From the spectrum thus obtained, the levelsof the activation gamma radiation emitted by 27Mg and that emitted by 49Ca are determined. The two intensity measurements are then combined, e.g. by forming a cross-plot or ratio thereof, to provide an indication of the lithology of the earth formation and, in particular, of the extent of dolomitization of the formation.