Ujęcie związków między wskazaniami metod neutron-gamma oraz gamma-gamma a procentową zawartością żelaza

Jacek Majorowicz

Abstrakt


FORMULATION OF THE RELATIONSHIP BETWEEN INDICES OF NEUTRON-GAMMA AND GAMMA-GAMMA METHODS AND THE PERCENTAGE OF IRON

Summary
In this article, the author presents the possibility of a complex utilization of radiometric logging methods, neutron-gamma profiling and gamma-gamma density logging for determining percentage of iron and establishing geophysical possibilities of identifying zones of economically profitable ores in borehole profiles. Figures 1-3 present the correlations between indices of neutron-gamma and gamma-gamma logging methods and the percentage of iron, as well as the correlation of neutron-gamma and gamma-gamma indices for zones minerallized with iron ores. The article presents the correlational analyses of the results: the correlational coefficients are given as well as total error in determining iron content on the basis of each of the methods described. Next, a multidimensional statistical analysis is carried out on the results obtained. On the basis of the two-dimensional correlational coefficients calculated and the average standard deviation, an equation of linear regression was formulated, simultaneously involving three parameters – the indices of neutron-gamma and gamma-gamma logging and the percentage of iron. The multiple correlation coefficient obtained markedly exceeds the two-dimensional correlation coefficient (r = 0.974 > rxz>ryz>rxy). The given method of utilizing multidimensional statistics in borehole geophysics for identifying iron ores is an efficient one. On the basis of several relationships among independent variables which are less obvious (smaller values of correlational coefficient), it is possible to obtain a single distinct relationship involving all variables simultaneously.

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