Application of gamma-gamma spectrometric logging for lithological identification of coal seams and embedding rocks

The physical principles and the results of gamma-gamma spectrometric measurements performed in the models and in borehole conditions for evaluation of rock lithology are presented. Spectrometric measurements make possible to record S/H ratio in two energy windows i.e. (60/100)keV and (200/500)keV. The quotient S/H is a function of Pe (apparent photoelectric absorption cross section). Static measurements make possible to determine the influence of borehole diameter on the S/H value. The report illustrates how measurements of S/H and borehole diameter or natural gamma ray give means to identify rock lithology in field conditions. Original PELITO program for lithologic profile determination is given. 11 refs., 14 figs., 5 tabs. (author)